Part IStatus of BSRN: database and FTP file archive

April 27, 2005 CEOS/ WGCV/Land Product Validation Workshop

on Albedo Products, Vienna

Andreas Roeschreas Institute for Atmospheric and Climate Research, ETH Zurich

• Current status of the database

• Synop/ Radiosounding

• Albedo (reflected SW radiation)

• UV/AOD (Aerosol optical depth)

• FTP file archive

37 operational BSRN stations

Operational BSRN stations (North America)

Operational BSRN stations (Europe)

Status of BSRN database

NOAA

ARM

SURFRAD

Status of BSRN database

Status, ff.

13 BSRN stations with SYNOP measurements (logical record 1000, tables STA_SYNOPBAS_YEAR and STA_SYNOPEXT_YEAR)

Station State/ Country Acronym Period of record

Barrow Alaska BAR 1992-2003

Bermuda CO, USA BER 1992-2003

Boulder USA BOU 1992-2003

De Aar South Africa DAA 2000-2004

Georg v. Neumayer Antarctica GVN 1992-2002

Kwajalein Marshall Islands, USA KWA 1992-2003

Ny Alesund Spitsbergen, Norway NYA 1992-2002

Payerne Switzerland PAY 1992-2003

Sede Boqer Israel SBO 2003

South Pole Antarctica SPO 1992-2003

Syowa Antarctica SYO 1994-2001

Tamanrasset Algerie TAM 2000-2001

Tateno Japan TAT 1996-2004

18 BSRN stations with radiosonde measurements

1992-2002: BAR, BER, BOU, GVN, KWA, NYA, SPO

1994-2004: BIL

1995-2003: BON, BOS

1996-2003: PAY

1996-2004: TAT

1997-2004: E13, MAN

1998-2003: DRA

1998-2004: NAU

2000-2004: DAA

2003: SBO

BSRN stations reporting 10m-observation to BSRN (logical record 3010, table „STA_RMH1000_YEAR“)

Station State/ Country Acronym Organisation Period of record

Bondville IL, USA BON SURFRAD 1995-2003

Boulder CO, USA BOS SURFRAD 1995-2003

Desert Rock NV, USA DRA SURFRAD 1998-2003

E13 USA E13 ARM 1997-2004

Fort Peck MT, USA FPE SURFRAD 1995-2003

Goodwin Creek MS, USA GCR SURFRAD 1995-2003

Payerne Switzerland PAY Swiss meteo 1994-2003

Rock Springs PA, USA PSU SURFRAD 1998-2003

All these stations provide reflected SW radiation and thus surface albedo

BSRN stations reporting reflected SW radiation(at standard height)

Station State/ Country Acronym Organisation Period of record

Barrow Alaska, USA BAR NOAA/ CMDL 01/1992 - 11/1993

Ny Alesund Spitsbergen, Norway NYA AWI, Germany 08/1992 - 12/2003

South Pole Antarctica SPO NOAA/ CMDL 01/1992 - 12/2003Georg v. Neumayer Antarctica GVN AWI, Germany 04/1992 -12/2003

Syowa Antarctica SYO NIPR, Japan 04/1998 - 01/2002

Payerne Switzerland PAY Meteo Swiss 03/1992 - 04/2004

Toravere Estonia TOR Est. Met. Inst. 01/1999 - 03/2004

Tateno Japan TAT Jap. Met. Agency 02/1996 - 01/2004

BSRN stations reporting UV to BSRN (logical record 500, table „STA_RMUV_YEAR“)

Station State/ Country Acronym Organisation Period of record

Boulder CO, USA BOS SURFRAD 1995-2003Goodwin Creek MS, USA GCR SURFRAD 1995-2003

Fort Peck MT, USA FPE SURFRAD 1995-2003Bondville IL, USA BON SURFRAD 1995-2003Rock Springs PA, USA PSU SURFRAD 1998-2003Desert Rock NV, USA DRA SURFRAD 1998-2003Momote, Manus Is.

Papua New Guinea MAN ARM 1996-2004

Nauru IslandTropical Western Pacific

NAU ARM 1998-2004

Payerne Switzerland PAY Swiss meteo 1998-2003Toravere Estonia TOR EMHI 2000-2001

Payerne provides both direct and diffuse UV-a and UV-b, all others only provide total UV-b

BSRN stations measuring UV, not reporting to BSRN

Station State/ Country Acronym Organisation Period of record

Tateno Japan TAT From 1990

Syowa Antarctica SYO From 1991

Alice Springs Australia ASP BoM From 1993

Chesapeake Virginia, USA CHL NASA

Tamanrasset Algerie TAM From 1997

Georg von Neumayer Antarctica GVN From 1992

Lauder New Zealand LAU NIWA From 1991

From B. Forgan, based on information from station scientists (at the request of Ohmura/ Roesch)

BSRN stations planning to measure UV radiation

Station State/ Country Acronym Organisation

Camborne UK CAM MetOffice

Lervick UK LER MetOffice

From B. Forgan, based on information from station scientists

Aerosol optical depth (AOD) in BSRN

Current status: No station provides spectral shortwave radiation (record 200 or 400) Only GVN and NYA includes record 1300 (but provides missing values for spectral AODs)

Future plan:

Database: Insertion of computed AOD values (for 3 wavelengths) into record 1300 only after transmission data have passed several consistency checks.

-> No change in the database schema is required.-> Block 1300 is excluded from the instrument consistency checks.

File archive: All measured and calculated data (at all wavelengths) are included in the ftp file archive, including QC/ QA

FTP file archive (ftp://ezksun3.ethz.ch)

Motivation • Most scientists are more familiar with file archives than with databases • The web interface does not allow the retrieval of all data• Access and download via file archive is simple and fast• Can be easily modified (value-added data)

Current status The file archive is automatically updated (cron-job) every night -> The database and the file archive generally contain identical data.

Differences between the database and the file archive• Improved quality check flags (recommended by Ells Dutton and Chuck Long)• Global radiation „global1“ added (sum diffuse plus direct SW radiation)

Format Compressed ASCII-files (use „gunzip“ to uncompress data)

FTP file archive - some details to the format

Format is the same as described in the „Update of the Technical plan for data management (1998)“ but with the following extensions: • Logical record 100 line 1: X, I1, X, I1, X, I1, X, I1

Global radiation: Physically possible, extremely rareDirect radiation: Physically possible, extremely rare

line 2: X, I1, X, I1, X, I1, X, I1, X, I1, X, I1, X, I1, X, I1

Diffuse radiation: Physically possible, extremely rareLongwave downward rad. : Physically possible, extremely rareGlobal radiation: Comparison between „global 1“ and „global 2“Comparison between diffuse and direct radiationComparison of longwave downward and 2m- temperature

FTP file archive - some details to the format (ff)

• Logical record 300 Extension to each line: X, I1, X, I1, X, I1, X, I1, X, I1, X, I1, X, I1, X, I1

LW upward radiation: Physically possible, extremely rareReflected SW radiation : Physically possible, extremely rareGlobal radiation: Comparison between reflected SW and global radiationComparison of LW up to air temperatureLW up to LW down comparison

Meaning of the quality flags2 -> suspected to be erronous5 -> cannot be performed9 -> passed the procedure

Conclusions (Part I)• The BSRN database currently contains 37 operating stations with a total of

approximately 2950 monthly data files.

• Number of stations which report

SYNOP: 13

Radiosounding: 18

UV: 10

Albedo: 15

• More and more scientists prefer to download data from the FTP file archive.

• The FTP file archive is automatically updated from files that have been successfully inserted into the BSRN database.

• The FTP file archive includes the quality flags according to E. Dutton and C. Long as well as „global 1“ (computed from direct and diffuse measurements).

• Data in the FTP file archive can be easily modified/ extended.

Part II

Some applications of MODIS/ BRDF data

Validation of seasonal cycles of surface albedo in ECHAM4 and ECHAM5

Masks

Annual cycles of surface albedo

Sub-grid scale variability

and

how representative are point measurements?

Correlation of MODIS 0.05x0.05 surface albedo with PAY pixel (2000-2003)

PAYPAY

ZHBS

BON

MODIS versus ground truth from BSRNMODIS versus ground truth from BSRN

Surface albedo: MODIS vs. BSRN

Data from Greenland summit have been kindly provided by Sebastian Hoch, ETH Zurich

Zenith angle dependence of surface albedo

Black sky albedo, 6-21 March 2002, Resolution: 0.5o

Solar angle at local solar noon

MODIS white sky albedo minus black sky albedo

VIS: blue

NIR: red

Conclusions (Part II)• MODIS/ BRDF provides high-quality data for validation of GCMs and

improving their parameterizations

• MODIS (at 0.05 resolution) agrees well with ground truth from BSRN sites during snow-free periods. Under snow conditions, deviations are significant due to differing vegetation cover (-> snow masking of forest).

• MODIS Version 4 differs from Version 3 (in both the mean and the MODIS Version 4 differs from Version 3 (in both the mean and the variability)variability)

• MODIS Version 3 is too low over pure snow such as Greenland (Version 4 provides improved data).

• ECHAM4 surface albedo is too high over boreal forests and the Himalayas/ Tibetan Plateau.

• ECHAM5 is closer to the observations over the Himalayas than ECHAM4, but positive albedo biases over snow-covered boreal forests are even more pronounced in ECHAM5.

Conclusions (ff)• MODIS & BSRN clearly show that neglecting the zenith angle dependence

leads to significant errors in the net shortwave radiation. The approach of Briegleb et al. (1986) is suggested for land surface albedo models.

• Intracell variability of surface albedo is largest in snow-covered areas and deserts. Normalized intracell variances are largest in mountainous regions.

• Intracell variability in the VIS spectrum is much higher than in the NIR band over (partially) snow covered regions (difference snow - ,no snow is also higher in the VIS)

• Surface albedo at specific sites are generally representative for a limited Surface albedo at specific sites are generally representative for a limited area only.area only.

Correlation of MODIS surface albedo with 0N/65W pixel (rain forest)