Sentinel-5 precursor/TROPOMI Level 2 Product User Manual NPP Cloud · 2018. 7. 9. · S5P L2 PUM...

Sentinel-5 precursor/TROPOMILevel 2 Product User Manual NPPCloud

document number : S5P-RAL-L2-PUM-001authors : Richard Siddans, Andy SmithCI identification : CI-7570-PUMissue : 1.0.1date : 2018-06-08status : released

S5P L2 PUM NPP Cloudissue 1.0.1, 2018-06-08 – released

S5P-RAL-L2-PUM-001Page 2 of 74

Document approval record

digital signature

Prepared:

Checked:

Approved PM:

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Document change record

issue date item comments0.1.0 2014-05-12 All Initial version

0.2.0 2015-09-18 All Document ported to LATEXUpdated for limited release to S5p Validation Team

1.0.0 2018-04-03 All Consolidated version for release at end of commissioning phase

1.0.1 2018-04-03 Sec. 7 Included standard instrument description



Contents

Document approval record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Document change record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.1 Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.2 Purpose and objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3 Document overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2 Applicable and reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.1 Applicable documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2 Standard documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.3 Reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.4 Electronic references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Terms, definitions and abbreviated terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.1 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.2 Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4 Overview of the Sentinel 5 precursor/TROPOMI Level 2 Products . . . . . . . . . . . . . . . . . . . . . . . . 104.1 File name convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5 Data Distribution and Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.1 Information to supply with a support request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6 General Reader and Visualisation Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

7 Instrument description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8 S5p/TROPOMI L2 NPP Cloud Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148.1 Data Product Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158.2 Product Geophysical Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178.3 History of product changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178.4 Using the S5p/TROPOMI L2 NPP Cloud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

9 General structure of S5P/TROPOMI Level 2 files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179.1 Dimensions and dimension ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199.2 Time information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199.3 Geolocation, pixel corners and angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

10 Description of the S5P NPP cloud product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2110.1 Group “BAND7_NPPC” in “NP_BDx” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2210.1.1 Group “STANDARD_MODE” in “BAND7_NPPC” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2210.2 Group “METADATA” in “NP_BDx” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2910.2.1 Group “QA_STATISTICS” in “METADATA” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2910.2.2 Group “ALGORITHM_SETTINGS” in “METADATA” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

11 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

12 Quality Assurance parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

13 Generic metadata and attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7013.1 The Climate and Forecast conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7013.2 NetCDF User Guide Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7113.3 Global attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7113.4 ESA earth observation header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7113.5 Inspire directive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7213.6 ISO and OGC standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7213.7 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72



List of Tables

1 Standard S5P L2 products with name, identifier and responsible institutes . . . . . . . . . . . . . . . . . . . 102 Components of an S5P file name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Reference times available in a S5P L2 file. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Abbreviations used in metadata descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705 Metadata in the fixed header required by the ESA earth observation file format standard . . . 716 Fields in the Validity_Period group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717 Fields in the source group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 netCDF-4 type definitions and fill values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 739 Attributes for variables used in S5p netCDF-4 files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

List of Figures

1 Panoply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 TROPOMI measurement principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Example of viirs_delta_time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Example of viirs_viewing_zenith_angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Example of vcm_confidently_clear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Example of band07_fov_mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Example of band07_fov_stdev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Example of band07_fov_nvalid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Graphical description of the structure of a Level 2 NPP cloud file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1810 Pixel corner coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20



1 Introduction

1.1 Identification

This document, identified as S5P-RAL-L2-PUM-001, describes the technical characteristics of the S5p/TROPOMILevel 2 products that are needed for efficient and correct use of the data contained. This product user manualis specific for NPP Cloud.

1.2 Purpose and objective

The Sentinel-5 Precursor (S5p) mission is a low Earth orbit polar satellite system to provide information andservices on air quality, climate and the ozone layer. The S5p mission is part of the Global Monitoring of theEnvironment and Security (GMES/COPERNICUS) space component programme. The S5p mission consistsof a satellite bus, the payload consisting of the TROPOspheric Monitoring Instrument (TROPOMI), and aground system. A journal paper describing the mission and its objectives can be found in [RD1], while acomprehensive description of the mission can be found in [RD2]. Furthermore, various websites are maintainedwith S5p/TROPOMI information, e.g. [ER1, ER2].

From the data collected by the TROPOMI instrument, a number of geophysical (L2) products are derived.The algorithms for the raw data treatment (L0 – L1b) and the actual L2 data processing are each described inan algorithm theoretical basis document (ATBD). This Product User Manual (PUM) describes the technicalcharacteristics of the S5p/TROPOMI Level 2 geophysical data products that are needed for efficient and correctuse of the data contained.

In the PUM, the common structure of the datafiles and metadata used in all the delivered L2 products aswell as a specific section related to the NPP Cloud product are described.

1.3 Document overview

We start with a summary of the S5p L2 products and information needed to obtain and inspect data, as well ashow to obtain product support. The NPP Cloud data product is described next, with examples, and informationabout the use of the data. Format, L2 structure and metadata are addressed in the next chapter, followedby the detailed description of the NPP Cloud data. We then continue with a discussion of units and qualityassurance parameters. The final chapter contains information about generic metadata and the Appendix listsmeasurement flags, processing quality flags, and surface classifications.



2 Applicable and reference documents

2.1 Applicable documents

[AD1] Tailoring of the Earth Observation File Format Standard for the Sentinel 5 precursor Ground Segment.source: ESA/ESTEC; ref: S5P-TN-ESA-GS-106; issue: 2.2; date: 2015-02-20.

2.2 Standard documents

There are no standard documents

2.3 Reference documents

[RD1] J. P. Veefkind, I. Aben, K. McMullan et al.; TROPOMI on the ESA Sentinel-5 Precursor: A GMESmission for global observations of the atmospheric composition for climate, air quality and ozone layerapplications. Remote Sens. Environ.; 120 (2012), 70; 10.1016/j.rse.2011.09.027.

[RD2] Input/output data specification for the TROPOMI L01b data processor.source: KNMI; ref: S5P-KNMI-L01B-0012-SD; issue: 5.0.0; date: 2015-09-22.

[RD3] S5P/TROPOMI ATBD Cloud Products.source: DLR; ref: S5P-DLR-L2-ATBD-400I; issue: 1.1.0; date: 2016-06-30.

[RD4] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Cloud.source: DLR; ref: S5P-L2-DLR-PUM-400I; issue: 1.0.0; date: 2018-04-30.

[RD5] S5P-NPP Cloud Processor ATBD.source: RAL Space; ref: S5P-NPPC-RAL-ATBD-0001; issue: 0.11.0; date: 2014-05-15.

[RD6] S5P/TROPOMI HCHO ATBD.source: BIRA; ref: S5P-BIRA-L2-400F-ATBD; issue: 1.0.0; date: 2016-02-05.

[RD7] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual HCHO.source: DLR; ref: S5P-L2-DLR-PUM-400F; issue: 1.0.0; date: 2018-04-30.

[RD8] S5P/TROPOMI SO2 ATBD.source: BIRA; ref: S5P-BIRA-L2-400E-ATBD; issue: 1.0.0; date: 2016-02-05.

[RD9] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual SO2.source: DLR; ref: S5P-L2-DLR-PUM-400E; issue: 1.0.0; date: 2018-04-30.

[RD10] S5P/TROPOMI Total ozone ATBD.source: DLR/BIRA; ref: S5P-L2-DLR-ATBD-400A; issue: 1.0.0; date: 2016-02-01.

[RD11] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Total Ozone Column.source: DLR; ref: S5P-L2-DLR-PUM-400A; issue: 1.0.0; date: 2018-04-30.

[RD12] TROPOMI ATBD of tropospheric ozone data products.source: DLR/IUP; ref: S5P-DLR-IUP-L2-400C; issue: 1.0.0; date: 2016-02-05.

[RD13] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Ozone Tropospheric Column.source: DLR; ref: S5P-L2-DLR-PUM-400C; issue: 1.0.0; date: 2018-04-30.

[RD14] TROPOMI ATBD of the aerosol layer height product.source: KNMI; ref: S5P-KNMI-L2-0006-RP; issue: 1.0.0; date: 2016-01-29.

[RD15] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Aerosol Layer Height.source: KNMI; ref: S5P-KNMI-L2-0022-MA; issue: 0.11.6; date: 2017-06-24.

[RD16] TROPOMI ATBD of the aerosol index.source: KNMI; ref: S5P-KNMI-L2-0008-RP; issue: 1.0.0; date: 2016-02-03.

http://dx.doi.org/10.1016/j.rse.2011.09.027



[RD17] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Aerosol Index.source: KNMI; ref: S5P-KNMI-L2-0026-MA; issue: 0.11.6; date: 2017-06-24.

[RD18] TROPOMI ATBD Ozone profile and tropospheric profile.source: KNMI; ref: S5P-KNMI-L2-0004-RP; issue: 0.13.0; date: 2015-09-15.

[RD19] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Ozone Profile and Tropospheric OzoneProfile.source: KNMI; ref: S5P-KNMI-L2-0020-MA; issue: 0.11.6; date: 2017-06-24.

[RD20] TROPOMI ATBD of the total and tropospheric NO2 data products.source: KNMI; ref: S5P-KNMI-L2-0005-RP; issue: 1.2.0; date: 2018-06-08.

[RD21] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Nitrogen Dioxide.source: KNMI; ref: S5P-KNMI-L2-0021-MA; issue: 0.11.6; date: 2017-06-24.

[RD22] Algorithm Theoretical Baseline Document for Sentinel-5 Precursor: Carbon Monoxide Total ColumnRetrieval.source: SRON; ref: SRON-S5P-LEV2-RP-002; issue: 1.10; date: 2018-05-10.

[RD23] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Carbon Monoxide Column.source: SRON/KNMI; ref: SRON-S5P-LEV2-MA-002; issue: 0.11.6; date: 2017-06-24.

[RD24] Algorithm Theoretical Baseline Document for Sentinel-5 Precursor methane retrieval.source: SRON; ref: SRON-S5P-LEV2-RP-001; issue: 1.0.0; date: 2016-02-05.

[RD25] Sentinel-5 precursor/TROPOMI Level 2 Product User Manual Methane.source: SRON/KNMI; ref: SRON-S5P-LEV2-MA-001; issue: 0.11.6; date: 2017-06-24.

[RD26] Tailoring of the Earth Observation File Format Standard for the Sentinel 5 precursor Ground Segment.source: ESA/ESTEC; ref: S5P-TN-ESA-GS-106; issue: 2.2; date: 2015-02-20.

[RD27] Algorithm theoretical basis document for the TROPOMI L01b data processor.source: KNMI; ref: S5P-KNMI-L01B-0009-SD; issue: 6.0.0; date: 2015-09-22.

[RD28] S5P-NPP Cloud processor ATBD.source: RAL; ref: S5P-NPPC-RAL-ATBD-001; issue: 1.0.0; date: 2016-02-12.

[RD29] Earth Observation – Ground segment file format standard.source: ESA/ESTEC; ref: PE-TN-ESA-GS-0001; issue: 2.0; date: 2012-05-03.

[RD30] Geographic information – Metadata.source: ISO; ref: ISO 19115:2003(E); issue: 1; date: 2003-05-01.

[RD31] Geographic information – Metadata – Part 2: Extensions for imagery and gridded data.source: ISO; ref: ISO 19115-2:2009(E); issue: 1; date: 2009-02-12.

[RD32] Geographic information – Data quality.source: ISO; ref: ISO 19157; issue: 1; date: 2013-10-10.

[RD33] Earth Observation Metadata profile of Observations & Measurements.source: Open Geospatial Consortium; ref: OGC 10-157r3; issue: 1.0; date: 2012-06-12.

[RD34] Metadata specification for the TROPOMI L1b products.source: KNMI; ref: S5P-KNMI-L01B-0014-SD; issue: 2.0.0; date: 2014-12-09.

[RD35] Data elements and interchange formats – Information interchange – Representation of dates andtimes.source: ISO; ref: ISO 8601:2004(E); issue: 3; date: 2004-12-01.

[RD36] Geographic information – Metadata – XML schema implementation.source: ISO; ref: ISO 19139:2007(E); issue: 1; date: 2010-12-13.

[RD37] Observations and Measurements – XML Implementation..source: Open Geospatial Consortium; ref: OGC 10-025r1; issue: 2.0; date: 2011-03-22.



[RD38] Sentinel 5 precursor/TROPOMI KNMI and SRON level 2 Input Output Data Definition.source: KNMI; ref: S5P-KNMI-L2-0009-SD; issue: 5.0.0; date: 2016-04-19.

[RD39] Sentinel-5 Precursor Level 2 UPAS Processor Input/Output Definition Document.source: DLR-IMF; ref: S5P-L2-DLR-IODD-3002; issue: 3.0.0; date: 2015-03-09.

[RD40] S5P-NPP Cloud Processor IODD.source: RAL; ref: S5P-NPPC-RAL-IODD-0001; issue: 0.10.0; date: 2014-05-28.

[RD41] John Caron; Annotated Schema for NcML (2011). URL http://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/AnnotatedSchema4.html.

[RD42] INSPIRE Metadata Regulation, Commission Regulation (EC), No1205/2008.source: EC; ref: Commission Regulation (EC) No 1205/2008; date: 2008-12-03.

[RD43] INSPIRE Metadata Implementing Rules: Technical Guidelines based on EN ISO 19115 and EN ISO19119.source: EC JRC; ref: MD_IR_and_ISO_v1_2_20100616; issue: 1.2; date: 2010-06-16.

[RD44] Geographic Information – Observations and Measurements.source: ISO; ref: ISO 19156:2011(E); date: 2011-12-20.

[RD45] Observations and Measurements - XML Implementation.source: OGC; ref: OGC 10-025r1; issue: 2.0; date: 2011-03-22.

2.4 Electronic references

[ER1] Tropomi official website. URL http://www.tropomi.eu.

[ER2] S5P official website. URL https://sentinel.esa.int/web/sentinel/missions/sentinel-5p.

[ER3] Robert B. Schmunk; Panoply netCDF, HDF and GRIB Data Viewer. URL http://www.giss.nasa.gov/tools/panoply/.

[ER4] Infrastructure for Spatial Information in the European Community (INSPIRE) Directive 2007/2/EC. URLhttp://inspire.jrc.ec.europa.eu/.

[ER5] Brian Eaton, Jonathan Gregory, Bob Drach et al.; NetCDF Climate and Forecast (CF) Metadata Conven-tions. Lawrence Livermore National Laboratory (2014). Version 1.7 draft; URL http://cfconventions.org.

[ER6] ESIP; Attribute Conventions for Dataset Discovery (ACDD). 1st edition (2013). URL http://wiki.esipfed.org/index.php/Attribute_Convention_for_Data_Discovery_(ACDD).

[ER7] NetCDF Users Guide (2011). URL http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html.

[ER8] UDUNITS 2 Manual (2011). URL http://www.unidata.ucar.edu/software/udunits/.

[ER9] Cooperative Ocean/Atmosphere Research Data Service; Conventions for the standardization of NetCDFfiles (1995). URL http://ferret.wrc.noaa.gov/noaa_coop/coop_cdf_pro�le.html.

http://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/AnnotatedSchema4.htmlhttp://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/AnnotatedSchema4.htmlhttp://www.tropomi.euhttps://sentinel.esa.int/web/sentinel/missions/sentinel-5phttp://www.giss.nasa.gov/tools/panoply/http://www.giss.nasa.gov/tools/panoply/http://inspire.jrc.ec.europa.eu/http://cfconventions.orghttp://wiki.esipfed.org/index.php/Attribute_Convention_for_Data_Discovery_(ACDD)http://wiki.esipfed.org/index.php/Attribute_Convention_for_Data_Discovery_(ACDD)http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.htmlhttp://www.unidata.ucar.edu/software/udunits/http://ferret.wrc.noaa.gov/noaa_coop/coop_cdf_profile.html



3 Terms, definitions and abbreviated terms

Terms, definitions, and abbreviated terms that are specific for this document can be found below.

3.1 Terms and definitions

TBA To be AddedTBC To be ConfirmedTBD To be Defined

3.2 Acronyms and Abbreviations

ATBD Algorithm Theoretical Basis DocumentDLR Deutsches Zentrum für Luft- und RaumfahrtESA European Space AgencyKNMI Koninklijk Nederlands Meteorologisch InstituutIODD Input Output Data DefinitionOCRA Optical Cloud Recognition AlgorithmPUM Product User ManualROCINN Retrieval of Cloud Information using Neural NetworksQA Quality AssuranceUPAS Universal Processor for UV/VIS Atmospheric Spectrometers

4 Overview of the Sentinel 5 precursor/TROPOMI Level 2 Products

The Sentinel 5 Precursor mission aims at providing information and services on air quality and climate in thetimeframe 2017–2023. The S5p mission is part of the Global Monitoring of the European Programme forthe establishment of a European capacity for Earth Observation (COPERNICUS). TROPOMI will make dailyglobal observations of key atmospheric constituents, including ozone, nitrogen dioxide, sulfur dioxide, carbonmonoxide, methane, formaldehyde as well as cloud and aerosol properties. The list of standard S5p/TROPOMIL2 products is given in table 1. Other products, such as UV index, are under development and will madeavailable at a later date.

Table 1: Standard S5P L2 products with name, identifier, and responsible institutes.

Product ATBD PUM Identifier InstitutionCloud [RD3] [RD4] L2__CLOUD_ DLRNPP-VIIRS Clouds [RD5] This document L2__NP_BDx RALHCHO [RD6] [RD7] L2__HCHO__ BIRA/DLRSO2 [RD8] [RD9] L2__SO2___ BIRA/DLRO3 Total Column [RD10] [RD11] L2__O3____ BIRA/DLRO3 Tropospheric Column [RD12] [RD13] L2__O3_TCL IUP/DLRAerosol layer height [RD14] [RD15] L2__AER_LH KNMIUltra violet aerosol index [RD16] [RD17] L2__AER_AI KNMIO3 Full Profile [RD18] [RD19] L2__O3__PR KNMIO3 Troposheric Profile [RD18] [RD19] L2__O3_TPR KNMITropospheric NO2 [RD20] [RD21] L2__NO2___ KNMICO [RD22] [RD23] L2__CO____ SRON/KNMICH4 [RD24] [RD25] L2__CH4___ SRON/KNMI



4.1 File name convention

The table specifies an identifier that is a substring of real name. The complete filename conventions for all theS5p products can be found in [RD26, chapter 4]. Note that intermediate L2 products beside those listed intable 1 may exist within the PDGS framework. For each of the products listed in the table, a PUM is available.Note that product documentation, e.g. ATBDs and PUMs, will be updated with new releases of processors.User documentation is distributed through the tropomi website [ER1]. Information about S5p mission can befound at the official ESA website for the Sentinel 5 precursor mission [ER2].

In the current PUM the NPP Cloud product is described and an example of the full real name is as following:S5P_OFFL_L2__NP_BDx_20140101T000000_20140102T000000_00099_01_000200_20141010T173511.nc

The components of this file name are given in table 2

Table 2: Components of an S5P product file name. Components are separated by underscores, except for thefile extension at the end, which is separated by a period. Character indices start counting at 0, the end-index isa Python style index, it lists the first character not in the block.

Start End Length Meaning0 3 3 Mission name, always “S5P”4 8 4 Processing stream, one of “NRTI” (near real-time), “OFFL” (offline) or “RPRO”

(reprocessing)9 19 10 Product identifier, as listed in table 120 35 15 Start of granule in UTC as “YYYYMMDDTHHMMSS”. The “T” is a fixed char-

acter.36 51 15 End of the granulein UTC as “YYYYMMDDTHHMMSS”. The “T” is a fixed

character.52 57 5 Orbit number58 60 2 Collection number61 67 6 Processor version number as “MMmmpp”, with “MM” the major version number,

“mm” the minor version number, and “pp” the patch level.68 83 15 The time of processing for this granule in UTC as “YYYYMMDDTHHMMSS”.

The “T” is a fixed character.84 86 2 The file name extension. All Sentinel 5 precursor files are netCDF-4 files and use

the extension “nc”

5 Data Distribution and Product Support

5.1 Information to supply with a support request

We have been very careful in the preparation of the processors, the processing system, the data distributionsystem and all other components that generate the level 2 products for the Sentinel 5 precursor mission. Youmay encounter problems when reading the level 2 files despite our care, or you may not understand what wehave written in the product user manual or the ATBD. You can contact us through the earth observation helpdesk operated by ESA at [email protected]. Please clearly indicate that you are requestingsupport for Sentinel 5 precursor (S5p) / TROPOMI mission.

If you are requesting technical support it is helpful to provide us with details of the file you are trying toread. The easiest way to do this is to provide a “dump” of the header of the file. This can be generatedusing the “ncdump” tool provided with the netCDF-4 library. Only the header is required, so “ncdump -h FILE.nc > FILE.cdl” will provide us with all metadata in the file and help us pinpoint how the file wasproduced. Here you replace FILE.nc with the actual file name on the command line.

If generating the header fails, please provide us with the exact original file name of the granule you aretrying to read, the exact error message you get and the exact version of the software you are using, includingthe versions of netCDF-4 and HDF-5. Providing us with a checksum to verify file integrity can also speed upour response.

mailto:[email protected]



Figure 1: Panoply

6 General Reader and Visualisation Tools

For reading and visualising you may find Panoply [ER3] a useful tool. Panoply is a cross-platform applicationthat plots geo-gridded and other arrays from netCDF, HDF, GRIB, and other datasets, including the Sentinel 5precursor Level 2 datafiles. With Panoply 4 you can:

• Slice and plot geo-gridded latitude-longitude, latitude-vertical, longitude-vertical, or time-latitude arraysfrom larger multidimensional variables.

• Slice and plot "generic" 2D arrays from larger multidimensional variables.• Slice 1D arrays from larger multidimensional variables and create line plots.• Combine two geo-gridded arrays in one plot by differencing, summing or averaging.• Plot lon-lat data on a global or regional map using any of over 100 map projections or make a zonal

average line plot.• Overlay continent outlines or masks on lon-lat map plots.• Use any of numerous color tables for the scale colorbar, or apply your own custom ACT, CPT, or RGB

color table.• Save plots to disk GIF, JPEG, PNG or TIFF bitmap images or as PDF or PostScript graphics files.• Export lon-lat map plots in KMZ format.• Export animations as AVI or MOV video or as a collection of invididual frame images.

7 Instrument description

On 13 October 2017 the Copernicus Sentinel 5 Precursor (S5P), the first of the European Sentinel satellitesdedicated to monitoring of atmospheric composition, was launched. The mission objectives of S5P are toglobally monitor air quality, climate and the ozone layer in the time period between 2017 and 2023. The



first 6 months of the mission were used for special observations to commission the satellite and the groundprocessing systems; the operational phase started in April of 2018.

The single payload of the S5P mission is TROPOspheric Monitoring Instrument (TROPOMI), which hasbeen developed by The Netherlands in cooperation with the European Space Agency (ESA). TROPOMI is anadir viewing shortwave spectrometer that measures in the UV-visible wavelength range (270 – 500 nm), thenear infrared (710 – 770 nm) and the shortwave infrared (2314 – 2382 nm).

The instrument uses passive remote sensing techniques to attain its objective by measuring at the topof the atmosphere the solar radiation reflected by and radiated from the Earth. The instrument operates ina push-broom configuration with a wide swath. Light from the entire swath is recorded simultaneously anddispersed onto two-dimensional imaging detectors: the position along the swath is projected onto one directionof the detectors, and the spectral information for each position is projected on the other direction.

The instrument images a strip of the Earth on a two dimensional detector for a period of approximately 1second during which the satellite moves by about 7 km. This strip has dimensions of approximately 2600 kmin the direction across the track of the satellite and 7 km in the along-track direction. After the 1 secondmeasurement a new measurement is started thus the instrument scans the Earth as the satellite moves. Thetwo dimensions of the detector are used to detect the different ground pixels in the across track direction andfor the different wavelengths. The measurement principle of TROPOMI is shown in figure 2.

~7 km(1 s flight)

~2600 km

wave

length

s

across track (swath)

Flight direction

Figure 2: TROPOMI measurement principle.

TROPOMI has a spatial resolution of 7×3.5km2 at nadir for bands 2 – 6 (UVN), 7×7km2 at nadir forbands 7 and 8 (SWIR), and 21×28km2 at nadir for band 1 (deep UV). For the UVN spectrometers about 20million spectra are observed per day. With that resolution TROPOMI is a major step forward compared to itspredecessors OMI (Ozone Monitoring Instrument), SCIAMACHY (Scanning Imaging Absorption Spectrometerfor Atmospheric Chartography) and GOME-2 (Global Ozone Monitoring Experiment-2). The spatial resolutionis combined with a wide swath to allow for daily global coverage. The TROPOMI/S5P geophysical (Level 2)operational data products are listed in section 4.

The S5P will fly in a so-called loose formation with the U.S. Suomi NPP (National Polar-orbiting Partnership)satellite. The primary objective for this formation flying is to use the high spatial resolution cloud observationcapabilities of the VIIRS instrument (Visible Infrared Imager Radiometer Suite). The temporal separationbetween TROPOMI and VIIRS is less than 5 minutes, both having an equator crossing time near 13:30 localsolar time. This formation enables synergistic data products and scientific research potentials.

The spectral range is split over 4 different detectors. By design these detectors do not observe on thesame geographic grid. Combining products that were derived from different detectors will require some carefulre-mapping to take care of this spatial mismatch.

More details on the TROPOMI instrument and the operational concepts can be found in the Level 0 to 1BATBD [RD27, parts I – III].



8 S5p/TROPOMI L2 NPP Cloud Product Description

The S5P-NPPC product contains summarised information from the VIIRS imager which flies in formation withS5P on the NPP platfom. VIIRS information relating to cloud is summarised for for each S5P across-trackobservation, in a given band.

The spatial response function (SRF) associated with each S5P TROPOMI ground pixel depends on theinstantaneous spatial response function, the extent of along-track motion during the integration, and the extentto which individual observations are co-added (averaged) across-track. We associate with each scene anominal field-of-view (FOV), the quadrilateral area on the ground which corresponds to the half-maxima pointsof the SRF (considering along- and across-track dimensions independently). It should be noted that this area isdifferent from the corners defined at L1B, which refer to boundaries mid-way between the ground-pixel centres.The nominal FOV is larger than this, particularly in the along-track direction and especially at the edges of theswath.

For some applications it is necessary to be aware of the presence of cloud over a more extended area thanjust the nominal FOV, so a number of scaled FOV are defined relative to the nominal FOV, and VIIRS statisticsreported for each of these. Currently S5P-NPPC products are generated for scaled FOV which are 1, 1.1, 1.5and 2x the extent of the nominal FOV (scaling both in the along and across-track dimensions). For each ofthese FOV, the following VIIRS statistics are computed (the corresponding variable name in the file is indicatedin bold font):

• The number of VIIRS pixels classified (by the VIIRS cloud mask) as

– confidently cloudy (vcm_confidently_clear)

– probably cloudy (vcm_probably_cloudy)

– probably clear (vcm_probably_clear)

– confidently clear (vcm_confidently_clear).

The fraction of valid VIIRS observations in each class can be trivially computed by dividing the number ina given class by the total over all four classes (all valid VIIRS observations will be classified into one ofthe four classes).

• The mean sun-normalised radiance in a number of VIIRS moderate resolution bands, currently M7 (0.865microns), M9 (1.378 microns), M11 (2.25 microns) (e.g. band07_fov_mean). Band M9 is of particularinterest as the spectral coverage coincides with a strong water vapour absorption band. Except wherethere is significant scattering by cloud or aerosol at elevated altitude, sunlight in this spectral range willbe almost completely absorbed by the atmosphere. The band is therefore expected to be useful forflagging thin cirrus which may not be revealed by the standard VIIRS cloud flag but still potentially affectthe S5P methane retrieval. Bands M7 and M11 provide observations which are directly comparableto S5P measurements in the NIR and SWIR bands, and are expected to be useful for monitoring therelative geolocation and radiometric calibration of S5P compared to VIIRS.

• The standard-deviation in the mean of the sun-normalised radiance in each VIIRS band (e.g. band07_-fov_stdev).

• The number of valid VIIRS radiances contributing to the mean/standard deviation in each band (e.g.band07_fov_nvalid).

• In addition, for each VIIRS band, an estimate of the mean VIIRS radiance, weighted by the S5P SRF iscomputed (e.g. band07_srf_mean). This is complemented by a measure of the coverage of the S5PSRF by valid VIIRS observations (band07_srf_coverage). Under most circumstances this measure ofcoverage should be 1.

• The product also provides two basic measures of the difference between the VIIRS observing conditionsand those of S5P:

– viirs_delta_time, which gives the time difference between the VIIRS observation and that of S5P.

– viirs_viewing_zenith angle the view zenith angle of VIIRS.

These are both provided for the VIIRS pixel which is closest in space to the centre of the S5P field-of-view(FOV), the position of which is reported in the S5P L1B file.



Figure 3: Example scene showing values of viirs_delta_time.

Figure 4: Example scene showing values of viirs_viewing_zenith_angle.

Figure 5: Example scene showing values of vcm_confidently_clear.

A single S5P-NPPC product is generated for each S5P band for which the product is required, currentlybands 3 (VIS), 6 (NIR) and 7 (SWIR).

See ATBD [RD28] for more details.

8.1 Data Product Examples

In this chapter, examples of S5P-NPPC products are given.



Figure 6: Example scene showing values of band07_fov_mean.

Figure 7: Example scene showing values of band07_fov_stdev.

Figure 8: Example scene showing values of band07_fov_nvalid.



8.2 Product Geophysical Validation

In this chapter, main results from L2 geophysical validation will be presented when it becomes available. To beupdated with changes to the ATBD and implementation.

8.3 History of product changes

This manual describes the current version of the L2 NPP Cloud product. A brief description of data productchanges will be given here. To date there have been no changes to the released product.

8.4 Using the S5p/TROPOMI L2 NPP Cloud

The following limitations should be noted when using the S5p/NPP cloud product:

• Results are provided for a single nominal FOV/SRF per band. In practice the FOV/SRF has spectralvariations within a band.

• The geolocation of VIIRS and S5P are assumed to be correct (at least mutually consistent). Co-location has been verified by some limited tests in the commissioning phase, confirming that the relativegeolocation is certainly accurate to better than the spatial sampling interval of S5P.

• The S5P processor relies on the delivery of VIIRS L1 and cloud mask files to the PDGS. Each VIIRSproduct contains data spanning approximately 2400km along track. Gaps in the coverage of validinformation in the S5P-NPP product will arise if there are missing VIIRS products at PDGS at the time theprocessor is run (this is generally several days after the S5P measurement time). Since cloud mask andradiances are containined in different VIIRS files, such gaps will not necessarily occur in all S5P-NPPfields.

9 General structure of S5P/TROPOMI Level 2 files

This section gives an overview of the basic structure of a the Sentinel 5 precursor NPP Level 2 file. Thestructure is similar to that of all other L2 files, though it more closely follows the L1B organisation. Figure 9gives a graphical representation of the structure of the file. The outermost layer is the file itself. Within thefile there are two groups: “BANDx_NPPC” and “METADATA”. Both of these groups contain sub-groups. Thepurpose of each group will be discussed below.

BANDx_NPPC/STANDARD_MODE Reflecting the L1B structure, data is stored within top level group ‘BANDx_-NPPC’, where ‘x’ indicates the S5P band number. Note each L1B files contains data from only oneband and this is also true of the L2 NPP cloud file. Below this all observations are stored in sub-group‘STANDARD_MODE’. This group is further divided into two sub-groups:

VIIRSDATA Contains the derived parameters from VIIRS for each S5P pixel.

GEODATA Contains a sub-set of elements from the corresponding L1B group, specifically the latitudeand longitudes of the pixel centres and boundaries (as identified at L1B), together with the viewingzenith angle.

METADATA This is a group to collect metadata items, such as the items that appear in the header file [RD29,section 7] and items required by INSPIRE [ER4], ISO 19115 [RD30], ISO 19115-2 [RD31], ISO 19157 [RD32]and OGC 10-157r3 [RD33]. These metadata standards are all meant to facilitate dataset discovery.

The metadata will be stored as attributes, while grouping attributes that belong to a specific standardwill be done by using sub-groups in the Metadata group. Some attributes are required to be attached tothe global level by convention, such as the CF metadata conventions [ER5], the Attribute Conventionfor Dataset Discovery [ER6] and the NetCDF-4 user guide [ER7]. For interoperability reasons theconventions are followed, and the specified global attributes are added to the output files.

ALGORITHM_SETTINGS An attribute is added to this group for each key in the configuration file. Theexact contents differ for each processor.



Figure 9: Graphical description of the structure of a Level 2 file NPP cloud file. The elements labelled as adimension are coordinate variables. See section 9 for a full description.



GRANULE_DESCRIPTION Parameters describing the granule, such as an outline of the geolocationscovered in the granule, the time coverage, the downlink station and processing facility and alternaterepresentations of the reference time.

QA_STATISTICS Quality assurance statistics. This group contains two types of data:1. The total number of pixel matching a certain criterium: number of input pixels, number of pixels

successfully processed and the number of pixels that failed for specific reasons.2. A histogram of the main parameter in the file. Histograms are additive and allow for easy

monitoring of changes over time. This can be a valuable addition for quality monitoring of thescience data.

ESA_METADATA The metadata items that are required in the ESA header.ISO_METADATA The ISO metadata items, organised in subgroups.EOP_METADATA The EOP metadata items, organized in subgroups.

The work of Level 1B on metadata as described in the metadata specification for TROPOMI L01bdata processor [RD34] is used as the basis for the Level 2 metadata, in particular for the items in the‘ISO_METADATA’ subgroup. The listed metadata standards give a data model and an implementationguideline for producing an XML file with the metadata – as a side-file to the data-file itself. The Level 1BIODS [RD2] describes a method to store the metadata in the NetCDF-4 file, and produce XML side-filesas needed. A detailed discussion on metadata as it applies to Level 2 can be found in section 13.

9.1 Dimensions and dimension ordering

All variables in a NetCDF-4 file use named and shared dimensions. This explicitly connects variables todimensions, and to each other. A few of the dimension names were already shown in figure 9. The NPP cloudproduct uses the following dimensions:

time A time dimension. The length of this dimension is 1, at least for S5P. The reason this dimension is usedare compatibility with Level 1B, and forward compatibility with Sentinel 4 and Level 3 output. Details areprovided in sections 9.2.

scanline The dimension that indicates the flight direction.

ground_pixel The dimension perpendicular to the flight direction.

scaled_field_of_view The dimension corresponding to the number of scaled fields-of-view over which VIIRSdata is summarised.

Other dimensions are used for the histogram axes used in the QA_METADATA.

9.2 Time information

Time information is stored in two steps. We have the time dimension, which indicates the reference time.This reference time is defined to be UTC midnight before the start of the orbit, which itself is defined byspacecraft midnight. The time variable contains the reference time in seconds since 2010-01-01, UTC midnight.Alternative representations of the reference time are listed in table 3. The offset of individual measurementswithin the granule is given in milliseconds with respect to this reference time in the variable delta_time.

The reason for this double reference is to more closely follow the CF conventions. Because the flightdirection relates the latitude and the time within the orbit, we have Y and T dimensions that are closely related.By separating these into a time dimension of length 1 and a scanline dimension, we obtain independent Y andT dimensions. The actual observation time of an individual observation must be reconstructed from an offsetand a time-delta.

As a service to the users, the time is also stored in the ‘time_utc’ variable. This variable is a string array,with each observation time stored as an ISO date string [RD35].

Table 3: Reference times available in a S5P L2 file. Types: (A) global attribute, (D) dimensional variable, (V)variable. All reference times ignore leap seconds.

Name Type Descriptiontime_reference (A) ISO date/time string [RD35]



Reference times available in a S5P L2 file (continued).Name Type Descriptiontime_reference_days_since_1950 (A) The number of days since January first, 1950, UTC mid-

night, as used in several weather and climate models(ECMWF, TM5).

time_reference_julian_day (A) The Julian date of the reference time as used in astronomy.This is the reference time system as used in IDL.

time_reference_seconds_since_1970 (A) The number of seconds since January first, 1970, UTCmidnight. This is also known as the unix epoch. Timefunctions on many systems will accept this number.

time (D) This variable contains the number of seconds since 2010-01-01, UTC midnight.

time_utc (V) Array of ISO date/time strings [RD35], one for each obser-vation, i.e. one for each element in the scanline dimension

9.3 Geolocation, pixel corners and angles

The latitude, longitude, pixel corner coordinates and related angles and satellite position in the level 2 files arecopied from the level 1B input data [RD27, chapters 26 and 27]. Details about the definitions can be foundthere. Note that the latitude and longitude have not been corrected for the local surface altitude, but are insteadgiven at the intersection of the line of sight with the WGS84 ellipsoid.

The geo-coordinates of the pixel corners are shown in Figure 10. Note that this choice follows the CFmetadata standard [ER5, section 7.1].

0 = (j-1, i-1

)1 = (j

-1, i+1)

2 = (j+1, i+

1)

3 = (j+1, i-1

)

(j, i)

Flight direction

Figure 10: Pixel corner coordinates. The sequence {0,1,2,3} refers to the elements in the corner dimension.

The azimuth angles, i.e. the solar azimuth angle ϕ0 and the viewing azimuth angle ϕ give the angle ofthe sun and the instrument respectively at the intersection of the line of sight with the WGS84 ellipsoid. Bothangles are given as degrees east relative to the local north. This definition is identical to the definition ofthe azimuth angles in both the OMI and GOME-2 instruments, but requires some care when comparing to aradiative transfer model. A radiative transfer model will typically use ϕ−ϕ0 which differs by 180◦ as it followsthe path of the light.



10 Description of the S5P NPP cloud product

Description of the output file for the S5P NPP cloud product from the TROPOMI instrument on the Sentinel5-precursor mission.

Note that various quantities are given for specific VIIRS bands. Here we explicity describe the parametersfor VIIRS band 7 only, however actual files contain similar entries for other VIIRS bands. The band in questionin explitly defined in each relevant variable name e.g. band07_srf_mean.

Global attributes in NP_BDx

Group attributes attached to NP_BDx

Name Value Type

Conventions ‘CF-1.7’ (static) NC_STRINGName of the conventions followed by the dataset. Note that while we try to follow the climate and forecastmetadata conventions, there are some features – notably the use of groups to hierarchicaly organize thedata – that are not part of version 1.6 of the CF metadata conventions. In those cases we try to follow thespirit of the conventions. This attribute originates from the NUG standard.

institution ‘RAL’ (dynamic) NC_STRINGThe institute where the original data was produced. The actual processing center is given in the Process-ingCenter attribute. This attribute originates from the NUG standard.

source ‘Sentinel 5 precursor, TROPOMI, space-borne remotesensing, L2’ (dynamic)

NC_STRING

Method of production of the original data. Value includes instrument, generic description of retrieval, productlevel, and adds a short product name and processor version. This attribute originates from the CF standard.

history NC_STRINGProvides an audit trail for modifications to the original data. Well-behaved generic netCDF filters willautomatically append their name and the parameters with which they were invoked to the global historyattribute of an input netCDF file. Each line shall begin with a timestamp indicating the date and time of daythat the program was executed. This attribute originates from the NUG, CF standards.

comment NC_STRINGMiscellaneous information about the data or methods used to produce it. This attribute originates from theCF standard.

tracking_id NC_STRINGThis unique tracking ID is proposed by the Climate Change Initiative – European Space Agency project.This ID is a UUID and allows files to be referenced, and linked up to processing description, input data,documentation, etc. This attribute originates from the CCI standard.

time_reference ‘YYYY-MM-DDT00:00:00Z’ (dynamic) NC_STRINGUTC time reference as an ISO 8601 [RD35] string. This corresponds to the UTC value in the timedimensional variable. By definition it indicates UTC midnight before the start of the granule.

time_coverage_start ‘YYYY-MM-DDTHH:MM:SS.mmmmmmZ’ (dynamic) NC_STRINGStart of the data granule in UTC as an ISO 8601 [RD35] string. See the discussion of the time_deltavariable on page 24 for details.

time_coverage_end ‘YYYY-MM-DDTHH:MM:SS.mmmmmmZ’ (dynamic) NC_STRINGEnd of the data granule in UTC as an ISO 8601 [RD35] string. See the discussion of the time_deltavariable on page 24 for details.

orbit 0 (dynamic) NC_INTThe absolute orbit number, starting at 1 – first ascending node crossing after spacecraft separation. Forpre-launch testing this value should be set to “−1”.product_version NC_STRINGIncluded for compatibility with the CCI project, where this item is defined as “the product version of this datafile.” We will use the file format version for this attribute following several CCI sub-projects. This attributeoriginates from the CCI standard.



processor_version ‘%(version)s’ (dynamic) NC_STRINGThe version of the data processor, as string of the form “major.minor.patch”.

summary ‘Information related to cloud derived for eachTROPOMI/S5P field-of-view from VIIRS/NPP data’ (dy-namic)

NC_STRING

processing_status ‘Nominal’ (dynamic) NC_STRINGtitle ‘TROPOMI/S5P VIIRS/NPP Cloud product’ (dynamic) NC_STRINGreferences ‘Sentinel-5 Precursor NPP-Cloud Processor ATBD;

Source: RAL; ref: S5P-NPPC-RAL-ATBD-0001’ (dy-namic)

NC_STRING

10.1 Group “BAND7_NPPC” in “NP_BDx”

10.1.1 Group “STANDARD_MODE” in “BAND7_NPPC”

Dimensions in NP_BDx/BAND7_NPPC/STANDARD_MODE

time The time dimension.

size 1 (dynamic)source Processor.

scanline The number of measurements along the swath, in the flight-direction.


ground_pixel The number of ground pixels across track. This depends on the product and will follow thedimension found in the main input Level 1B product.


ncorner The number of corners for a pixel.


scaled_field_of_view The number of scaled fields of view for which VIIRS statistics are reported.


10.1.1.1 Group “GEODATA” in “STANDARD_MODE”

Variables in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATA

latitude in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.



Attributes: Name Value Type_FillValue 9.96921e+36f (dynamic) NC_FLOATThe latitude of the pixel centers of the ground pixels in the data. Latitude, longitudecoordinates for the ground pixel center and the ground pixel corners are calculated at theWGS84 ellipsoid.long_name ‘pixel center latitude’ (dynamic) NC_STRINGmax_val 90.f (dynamic) NC_FLOATmin_val -90.f (dynamic) NC_FLOATstandard_name ‘latitude’ (dynamic) NC_STRINGbounds ‘latitude_bounds’ (dynamic) NC_STRINGunits ‘degrees north’ (dynamic) NC_STRING

longitude in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADescription: The longitude of the pixel centers of the ground pixels in the data. Latitude, longitude

coordinates for the ground pixel center and the ground pixel corners are calculated at theWGS84 ellipsoid.

Dimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Type_FillValue 9.96921e+36f (dynamic) NC_FLOATlong_name ‘pixel center longitude’ (dynamic) NC_STRINGmax_val 180.f (dynamic) NC_FLOATmin_val -180.f (dynamic) NC_FLOATstandard_name ‘longitude’ (dynamic) NC_STRINGbounds ‘longitude_bounds’ (dynamic) NC_STRINGunits ‘degrees east’ (dynamic) NC_STRING

latitude_bounds in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADescription: The latitude of the pixels corners as defined at L1B, based on tracing the mid-points of

the pixel centres. NB This is not correspond to the nominal field of view, which takes intoaccount the effect of the instantaneous field of view.

Dimensions: time, scanline, ground_pixel, ncorner.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Type_FillValue 9.96921e+36f (dynamic) NC_FLOATunits ‘degrees north’ (dynamic) NC_STRING

longitude_bounds in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADescription: The longitude of the pixels corners as defined at L1B, based on tracing the mid-points of

the pixel centres. NB This is not correspond to the nominal field of view, which takes intoaccount the effect of the instantaneous field of view.

Dimensions: time, scanline, ground_pixel, ncorner.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Type_FillValue 9.96921e+36f (dynamic) NC_FLOATunits ‘degrees east’ (dynamic) NC_STRING

solar_zenith_angle in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADescription: Solar zenith angle at the ground pixel location on the reference ellipsoid. Angle is measured

away from the vertical. ESA definition of day side: SZA less the 92 degrees



Dimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typecoordinates ‘longitude latitude’ (dynamic) NC_STRING_FillValue 9.96921e+36f (dynamic) NC_FLOATlong_name ‘solar zenith angle’ (dynamic) NC_STRINGmax_val 180.f (dynamic) NC_FLOATmin_val 0.f (dynamic) NC_FLOATstandard_name ‘solar_zenith_angle’ (dynamic) NC_STRINGunits ‘degree’ (dynamic) NC_STRING

viewing_zenith_angle in NP_BDx/BAND7_NPPC/STANDARD_MODE/GEODATADescription: Zenith angle of the satellite ϑ at the ground pixel location on the reference ellipsoid. Angle

is measured away from the vertical.Dimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typecoordinates ‘longitude latitude’ (dynamic) NC_STRING_FillValue 9.96921e+36f (dynamic) NC_FLOATlong_name ‘viewing zenith angle’ (dynamic) NC_STRINGmax_val 180.f (dynamic) NC_FLOATmin_val 0.f (dynamic) NC_FLOATstandard_name ‘platform_zenith_angle’ (dynamic) NC_STRINGunits ‘degree’ (dynamic) NC_STRING

10.1.1.2 Group “VIIRSDATA” in “STANDARD_MODE”

Variables in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATA

time in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Reference time for delta_time variable.Dimensions: time (coordinate variable).Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘reference start time of measurement’ (dynamic) NC_STRINGstandard_name ‘time’ (dynamic) NC_STRINGunits ‘seconds since 2010-01-01 00:00:00’ (dynamic) NC_STRING

delta_time in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATA



Description: The delta_time(scanline) variable indicates the time difference with the reference timetime(time) (see page 24). Thus combining the information of time(time) and delta_-time(scanline) yields the start of the measurement time for each scanline as TAI2010 time.Combining the information in the global attribute time_reference with delta_time(scanline)yields the start of the measurement time in UTC time. The UTC time derived for the firstscanline corresponds to the global attribute time_coverage_start. However, the UTC timederived for the last scanline does not correspond to global attribute time_coverage_end.One scanline measurement is the result of adding independent measurements during onecoaddition period. The scanline measurement is given the measurement time of the firstsample in this co-addition. It is the measurement time of the last sample in the coadditionperiod of the last scanline that corresponds to time_coverage_end.This variable gives the time offset in ms accuracy.

Dimensions: time, scanline.Type: NC_INT.Source: Processor.

Attributes: Name Value Type_FillValue -2147483647 (dynamic) NC_INTlong_name ‘offset from the reference start time of measure-

ment’ (dynamic)NC_STRING

units ‘milliseconds since 2014-08-29T23:59:59Z’ (dy-namic)

NC_STRING

ground_pixel in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: The coordinate variable ground_pixel refers to the across-track dimension of the measure-

ment. The ground_pixel ordering is from west to east, i.e. a higher index corresponds to ahigher longitude during the ascending part of the orbit. This variable merely contains anindex to ensure that when indicating a pixel in a file the same index is used. This avoids theoff-by-one confusion that frequently occurred in OMI discussions.

Dimensions: ground_pixel (coordinate variable).Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘across track dimension index’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

scanline in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: The coordinate variable scanline refers to the along-track dimension of the measurement.

The scanlines are time-ordered, meaning that “earlier” measurements have a lower indexthan “later” measurements. This variable merely contains an index to ensure that whenindicating a pixel in a file the same index is used. This avoids the off-by-one confusion thatfrequently occurred in OMI discussions.

Dimensions: scanline (coordinate variable).Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘along track dimension index’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

scaled_field_of_view in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Index referring to the scaled field-of-view for which VIIRS statistics are reported.Dimensions: scaled_field_of_view (coordinate variable).Type: NC_INT.Source: Processor.



Attributes: Name Value Typelong_name ‘dimension index corresponding to each defined ge-

ometric scaling of the S5P nominal field of view forwhich VIIRS statistics are summarised’ (dynamic)

NC_STRING

units ‘1’ (dynamic) NC_STRINGscaled_field_of_view_ymin in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Value of the scaled field-of-view corresponding to the minimum across-track coordinate.Dimensions: scaled_field_of_view.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘S5P scaled field-of-view normalised coordinate:

Minimum across-track’ (dynamic)NC_STRING

scaled_field_of_view_ymax in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Value of the scaled field-of-view corresponding to the maximum across-track coordinate.Dimensions: scaled_field_of_view.Type: NC_FLOAT.Source: Processor.


Maximum across-track’ (dynamic)NC_STRING

scaled_field_of_view_zmin in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Value of the scaled field-of-view corresponding to the minimum along-track coordinate.Dimensions: scaled_field_of_view.Type: NC_FLOAT.Source: Processor.


Minimum along-track’ (dynamic)NC_STRING

scaled_field_of_view_zmax in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Value of the scaled field-of-view corresponding to the maximum along-track coordinate.Dimensions: scaled_field_of_view.Type: NC_FLOAT.Source: Processor.


Maximum along-track’ (dynamic)NC_STRING

viirs_delta_time in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Time difference from S5P observation’ (dynamic) NC_STRINGDifference in time between the NPP and S5P observation.standard_name ‘time’ (dynamic) NC_STRINGunits ‘s’ (dynamic) NC_STRING_FillValue -999.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRING



viirs_viewing_zenith_angle in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Mean viewing zenith angle of VIIRS over the S5P nominal field-of-view.Dimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘VIIRS viewing zenith angle’ (dynamic) NC_STRINGstandard_name ‘platform_zenith_angle’ (dynamic) NC_STRINGunits ‘degree’ (dynamic) NC_STRINGvalid_min 0.f (dynamic) NC_FLOATvalid_max 180.f (dynamic) NC_FLOAT_FillValue -999.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRING

vcm_confidently_cloudy in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Number of VIIRS pixels classified as CONFIDENTLY CLOUDYDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_SHORT.Source: Processor.

Attributes: Name Value Typelong_name ‘Number of VIIRS pixels classified as CONFI-

DENTLY_CLOUDY’ (dynamic)NC_STRING

valid_min 0 (dynamic) NC_SHORTvalid_max 99 (dynamic) NC_SHORT_FillValue -999 (dynamic) NC_SHORTcoordinates ‘longitude latitude’ (dynamic) NC_STRING

vcm_probably_cloudy in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Number of VIIRS pixels classified as PROBABLY CLOUDYDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_SHORT.Source: Processor.

Attributes: Name Value Typelong_name ‘Number of VIIRS pixels classified as PROBABLY_-

CLOUDY’ (dynamic)NC_STRING


vcm_probably_clear in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Number of VIIRS pixels classified as PROBABLY CLEARDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_SHORT.Source: Processor.

Attributes: Name Value Typelong_name ‘Number of VIIRS pixels classified as PROBABLY_-

CLEAR’ (dynamic)NC_STRING

valid_min 0 (dynamic) NC_SHORTvalid_max 99 (dynamic) NC_SHORT_FillValue -999 (dynamic) NC_SHORT



coordinates ‘longitude latitude’ (dynamic) NC_STRINGvcm_confidently_clear in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Number of VIIRS pixels classified as CONFIDENTLY CLEARDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_SHORT.Source: Processor.

Attributes: Name Value Typelong_name ‘Number of VIIRS pixels classified as CONFI-

DENTLY_CLEAR’ (dynamic)NC_STRING


band07_srf_mean in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Mean of valid VIIRS band M07 sun-normalised radiances weighted by the S5P spatial

response functionDimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Mean of valid VIIRS band M07 sun-normalised

radiances weighted by the S5P spatial responsefunction’ (dynamic)

NC_STRING

valid_min -100.f (dynamic) NC_FLOATvalid_max 999.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING_FillValue -999.f (dynamic) NC_FLOAT

band07_srf_coverage in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Fractional energy of SRF covered by valid VIIRS band M07 radiancesDimensions: time, scanline, ground_pixel.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Fractional energy of SRF covered by valid VIIRS

band M07 radiances’ (dynamic)NC_STRING

valid_min 0.f (dynamic) NC_FLOATvalid_max 1.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING_FillValue -999.f (dynamic) NC_FLOAT

band07_fov_mean in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Mean of valid VIIRS band M07 sun-normalisd radiances in each S5P scaled field-of-viewDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Type



long_name ‘Mean of valid VIIRS band M07 sun-normalisd radi-ances in each S5P scaled field-of-view’ (dynamic)

NC_STRING

valid_min -100.f (dynamic) NC_FLOATvalid_max 999.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING_FillValue -999.f (dynamic) NC_FLOAT

band07_fov_stdev in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Standard deviation of valid VIIRS band M07 sun-normalised radiances in each S5P scaled

field-of-viewDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Standard deviation of valid VIIRS band M07 sun-

normalised radiances in each S5P scaled field-of-view’ (dynamic)

NC_STRING

valid_min 0.f (dynamic) NC_FLOATvalid_max 999.f (dynamic) NC_FLOATcoordinates ‘longitude latitude’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING_FillValue -999.f (dynamic) NC_FLOAT

band07_fov_nvalid in NP_BDx/BAND7_NPPC/STANDARD_MODE/VIIRSDATADescription: Number of valid VIIRS band M07 pixels in each S5P scaled field-of-viewDimensions: time, scanline, ground_pixel, scaled_field_of_view.Type: NC_SHORT.Source: Processor.

Attributes: Name Value Typelong_name ‘Number of valid VIIRS band M07 pixels in each

S5P scaled field-of-view’ (dynamic)NC_STRING


10.2 Group “METADATA” in “NP_BDx”

10.2.1 Group “QA_STATISTICS” in “METADATA”

Attributes in NP_BDx/METADATA/QA_STATISTICS

Group attributes attached to QA_STATISTICS

Name Value Type

number_of_S5P_groundpix-els

274688 (dynamic) NC_INT

Number of S5P ground pixels processed



number_of_S5P_groundpix-els_with_VIIRS_geolocation


Number of S5P ground pixels with matching VIIRS geolocation data

number_of_S5P_groundpix-els_with_VCM


Number of S5P ground pixels with matching VIIRS cloud mask data

number_of_S5P_groundpix-els_with_VIIRS_band07


Number of S5P ground pixels with matching VIIRS band M07 radiance data

Dimensions in NP_BDx/METADATA/QA_STATISTICS

vertices


VIIRS_delta_time_histogram_axis Dimension of the axis for the histogram of the given variable


VIIRS_view_zenith_histogram_axis Dimension of the axis for the histogram of the given variable


number_viirs_pixels_histogram_axis Dimension of the axis for the histogram of the given variable


sun_normalised_radiance_histogram_axis Dimension of the axis for the histogram of the given variable


SRF_coverage_histogram_axis Dimension of the axis for the histogram of the given variable


cloud_fraction_histogram_axis Dimension of the axis for the histogram of the given variable


scaled_field_of_view >The number of scaled fields of view for which VIIRS statistics are reported


Variables in NP_BDx/METADATA/QA_STATISTICS

VIIRS_delta_time_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: VIIRS_delta_time_histogram_axis (coordinate variable).Type: NC_FLOAT.Source: Processor.



Attributes: Name Value Typelong_name ‘Axis for the histogram of the Time difference from

S5P observation’ (dynamic)NC_STRING

units ‘s’ (dynamic) NC_STRINGVIIRS_view_zenith_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: VIIRS_view_zenith_histogram_axis (coordinate variable).Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Axis for the histogram of the VIIRS viewing zenith

angle’ (dynamic)NC_STRING

units ‘degrees’ (dynamic) NC_STRINGnumber_viirs_pixels_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: number_viirs_pixels_histogram_axis (coordinate variable).Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Axis for histograms of the number of VIIRS pixels’

(dynamic)NC_STRING

units ‘1’ (dynamic) NC_STRINGsun_normalised_radiance_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: sun_normalised_radiance_histogram_axis (coordinate variable).Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Axis for histograms of sun-normalised radiance’

(dynamic)NC_STRING

units ‘1’ (dynamic) NC_STRINGSRF_coverage_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: SRF_coverage_histogram_axis (coordinate variable).Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Axis for histograms of SRF coverage’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

cloud_fraction_histogram_axis in NP_BDx/METADATA/QA_STATISTICSDescription: Axis for the histogram of the given variableDimensions: cloud_fraction_histogram_axis (coordinate variable).Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Axis for histograms of cloud fraction’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

scaled_field_of_view in NP_BDx/METADATA/QA_STATISTICS



Description: Index referring to the scaled field-of-view for which VIIRS statistics are reported.Dimensions: scaled_field_of_view (coordinate variable).Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘dimension index corresponding to each defined ge-

ometric scaling of the S5P nominal field of view forwhich VIIRS statistics are summarised’ (dynamic)

NC_STRING

units ‘1’ (dynamic) NC_STRINGVIIRS_delta_time_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: VIIRS_delta_time_histogram_axis, vertices.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for the histogram of the Time difference

from S5P observation’ (dynamic)NC_STRING

units ‘s’ (dynamic) NC_STRINGVIIRS_view_zenith_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: VIIRS_view_zenith_histogram_axis, vertices.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for the histogram of the VIIRS viewing

zenith angle’ (dynamic)NC_STRING

units ‘degrees’ (dynamic) NC_STRINGnumber_viirs_pixels_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: number_viirs_pixels_histogram_axis, vertices.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for histograms of the number of VIIRS

pixels’ (dynamic)NC_STRING

units ‘1’ (dynamic) NC_STRINGsun_normalised_radiance_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: sun_normalised_radiance_histogram_axis, vertices.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for histograms of sun-normalised radiance’

(dynamic)NC_STRING

units ‘1’ (dynamic) NC_STRINGSRF_coverage_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: SRF_coverage_histogram_axis, vertices.



Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for histograms of SRF coverage’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

cloud_fraction_histogram_axis_bounds in NP_BDx/METADATA/QA_STATISTICSDescription: Bounds of the histogram for the given variableDimensions: cloud_fraction_histogram_axis, vertices.Type: NC_FLOAT.Source: Processor.

Attributes: Name Value Typelong_name ‘Bounds for histograms of cloud fraction’ (dynamic) NC_STRINGunits ‘1’ (dynamic) NC_STRING

viirs_delta_time_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: VIIRS_delta_time_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Time difference from S5P obser-

vation’ (dynamic)NC_STRING

number_of_un-derflow_values


number_of_over-flow_values

0 (dynamic) NC_INT

viirs_viewing_zenith_angle_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: VIIRS_view_zenith_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the VIIRS viewing zenith angle’ (dy-

namic)NC_STRING


0 (dynamic) NC_INT


2 (dynamic) NC_INT

vcm_confidently_cloudy_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: scaled_field_of_view, cloud_fraction_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Number of VIIRS pixels classified

as CONFIDENTLY_CLOUDY’ (dynamic)NC_STRING


0, 0, 0, 0 (dynamic) NC_INT





vcm_probably_cloudy_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: scaled_field_of_view, cloud_fraction_histogram_axis.Type: NC_INT.Source: Processor.


as PROBABLY_CLOUDY’ (dynamic)NC_STRING





vcm_probably_clear_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: scaled_field_of_view, cloud_fraction_histogram_axis.Type: NC_INT.Source: Processor.


as PROBABLY_CLEAR’ (dynamic)NC_STRING





vcm_confidently_clear_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: scaled_field_of_view, cloud_fraction_histogram_axis.Type: NC_INT.Source: Processor.


as CONFIDENTLY_CLEAR’ (dynamic)NC_STRING





band07_srf_mean_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: sun_normalised_radiance_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Mean of valid VIIRS band M07

sun-normalised radiances weighted by the S5Pspatial response function’ (dynamic)

NC_STRING


0 (dynamic) NC_INT




0 (dynamic) NC_INT

band07_srf_coverage_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: Histogram for the given variableDimensions: SRF_coverage_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Fractional energy of SRF covered

by valid VIIRS band M07 radiances’ (dynamic)NC_STRING


0 (dynamic) NC_INT


0 (dynamic) NC_INT

band07_fov_mean_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: >Histogram for the given variableDimensions: scaled_field_of_view, sun_normalised_radiance_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Mean of valid VIIRS band M07

sun-normalisd radiances in each S5P scaled field-of-view’ (dynamic)

NC_STRING





band07_fov_stdev_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: >Histogram for the given variableDimensions: scaled_field_of_view, sun_normalised_radiance_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Standard deviation of valid VIIRS

band M07 sun-normalised radiances in each S5Pscaled field-of-view’ (dynamic)

NC_STRING





band07_fov_nvalid_histogram in NP_BDx/METADATA/QA_STATISTICSDescription: >Histogram for the given variableDimensions: scaled_field_of_view, number_viirs_pixels_histogram_axis.Type: NC_INT.Source: Processor.

Attributes: Name Value Typelong_name ‘Histogram of the Number of valid VIIRS band M07

pixels in each S5P scaled field-of-view’ (dynamic)NC_STRING







10.2.2 Group “ALGORITHM_SETTINGS” in “METADATA”

Attributes in NP_BDx/METADATA/ALGORITHM_SETTINGS

Group attributes attached to ALGORITHM_SETTINGS

Name Value Type

ProcessorName ‘S5P_NPPC’ (dynamic) NC_STRINGName of the processor

ProcessorVersion ‘00.90’ (dynamic) NC_STRINGVersion of the processor

Number_of_scaled_FOV ‘4’ (dynamic) NC_STRINGThe number of scaled fields of view for which VIIRS statistics are required to be reported

Scaled_FOV ‘Fov 1: ymin = -1, ymax = 1, zmin = -1, zmax = ’(dynamic)

NC_STRING

Definition of the scaled fields of view.

Number_of_VIIRS_Bands ‘3’ (dynamic) NC_STRINGNumber of VIIRS bands to be analysed

VIIRS_Bands ‘7; 9; 11; ’ (dynamic) NC_STRINGDefinition of the VIIRS bands to be analysed

S5P_L1B_file ‘S5P_TEST_L1B_RA_BD7_20140830T080409_-20140830T083916_53811_01_000800_-20150327T115159.nc’ (dynamic)

NC_STRING

The S5P L1B file to be processed

Number_of_VIIRS_L1B_RR_-files

‘75’ (dynamic) NC_STRING

Number of VIIRS L1B files to be processed

VIIRS_L1B_RR_files ‘SVM07_npp_d20140715_t0709288_e0715092_-b14058_c20140715131510546633_noaa_ops.h5;...’(dynamic)

NC_STRING

List of VIIRS L1B files to be processed

Number_of_VIIRS_L1B_-Geo_files


Number of VIIRS L1B geolocation files to be processed

VIIRS_L1B_Geo_files ‘GMODO_npp_d20140715_t0709288_e0715092_-b14058_c20140715131510548844_noaa_ops.h5;...’(dynamic)

NC_STRING

List of VIIRS L1B files to be processed

Number_of_VIIRS_Cloud-Mask_files


Number of VIIRS cloud mask files to be processed

VIIRS_CloudMask_files ‘IICMO_npp_d20140715_t0709288_e0715092_-b14058_c20140715131510535714_noaa_ops.h5;...’(dynamic)

NC_STRING

List of VIIRS cloud mask files to be processed



S5P_SRF_file ‘S5P_TEST_NSRF_BD7_YYYYMMDDThhmmss_-YYYYMMDDThhmmss_YYYYMMDDThhmmss.nc’(dynamic)

NC_STRING

Name of file defining the S5P spatial response function for this S5P band

Output_file ‘S5P_TEST_L2__NP_BD7_20140830T080409_-20140830T083916_53811_01_000800_-20150327T115159.nc’ (dynamic)

NC_STRING

Name of the output file to be generated

S5P_Band_Number ‘7’ (dynamic) NC_STRINGThe S5P band number to be analysed

10.2.2.1 Group “ISO_METADATA” in “iso_metadata”

Metadata that is structured following the ISO metadata standards [RD30, RD36], especially part 2. Themetadata in this group is structured using the methods from Level 1B, which is described in the Level 1Bmetadata specification [RD34].

All “objectType” attributes indicate the XML object when generating an ISO 19139 [RD36] compliant XMLmetadata file.

Note that this group is meant to be treated as a ‘black box’. The information is collected here so that it canbe extracted into XML side-files for ingestion into data search tools and metadata collections.

Attributes in NP_BDx/METADATA/ISO_METADATA

Group attributes attached to ISO_METADATA

Name Value Type

gmd:dateStamp ‘2015-08-24’ (static) NC_STRINGDate of creation of the metadata, as ISO 8601 [RD35] string specifying year, month and day.

gmd:fileIdentifier ‘urn:ogc:def:EOP:ESA:SENTINEL.S5P_TROP_-%(shortname)s’ (dynamic)

NC_STRING

Unique identifier for metadata file, see the Level 1B metadata specification [RD34, table 5] for a discussionof the value.Replace %(. . . )s with the “ProductShortName” value from the Level 2 “/METADATA/GRANULE_-DESCRIPTION” metadata group.

gmd:hierarchyLevelName ‘EO Product Collection’ (static) NC_STRINGName of the hierarchy levels for which the metadata is provided.

gmd:metadataStandardName ‘ISO 19115-2 Geographic Information - Metadata Part2 Extensions for imagery and gridded data’ (static)

NC

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