Valued-Added Albedo and Ecosystem Products Derived From MODIS Data.
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Valued-Added Albedo and Ecosystem Products Derived From MODIS Data. Eric G. Moody 1,2 , Michael D. King 1 , Steven Platnick 1,3 , Alan H. Strahler 4 , Crystal Schaaf 4 , Feng Gao 4 1 NASA Goddard Space Flight Center 2 L3 Communications EER 3 University of Maryland Baltimore County 4 Boston University Outline Motivation. Descriptions of Value-Added Products. Methodology for Generating Products. Conclusions.
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Valued-Added Albedo and Ecosystem Products Derived From MODIS Data. Eric G. Moody 1,2 , Michael D. King 1 , Steven Platnick 1,3 , Alan H. Strahler 4 , Crystal Schaaf 4 , Feng Gao 4 1 NASA Goddard Space Flight Center 2 L3 Communications EER 3 University of Maryland Baltimore County - PowerPoint PPT Presentation
Transcript of Valued-Added Albedo and Ecosystem Products Derived From MODIS Data.
Valued-Added Albedo and Ecosystem Products Derived
From MODIS Data.
Eric G. Moody1,2, Michael D. King1, Steven Platnick1,3, Alan H. Strahler4,
Crystal Schaaf4 , Feng Gao4
1NASA Goddard Space Flight Center2L3 Communications EER
3University of Maryland Baltimore County4Boston University
Outline Motivation. Descriptions of Value-Added Products. Methodology for Generating Products. Conclusions.
2 St. Michaels - March 18, 2003.
Albedo is ratio of upwelling to downwelling radiative flux at the surface.Albedo is ratio of upwelling to downwelling radiative flux at the surface.
White sky albedo (bihemispherical reflectance)White sky albedo (bihemispherical reflectance)
Absence of direct component when diffuse component is isotropic. Absence of direct component when diffuse component is isotropic.
Black sky albedo (directional hemispherical reflectance)Black sky albedo (directional hemispherical reflectance)
Absence of diffuse component and is a function of solar zenith angle. Absence of diffuse component and is a function of solar zenith angle.
Albedo is intrinsically related to ecosystem classification.Albedo is intrinsically related to ecosystem classification.
Albedo is dependent:Albedo is dependent:
SpatiallySpatially
TemporallyTemporally
SpectrallySpectrally
Albedo Characteristics
3 St. Michaels - March 18, 2003.
Value Added Products - Motivation. Production and research requirements:
– Complete global maps.– High spatial resolution.– Seasonal representation.– Specific wavelengths of interest.– Available in projections standard within community.
Issues with data sets prior to MODIS:– Broadband only.– Lower resolution.– Static maps.
MODIS Land data sets provide needed characteristics
4 St. Michaels - March 18, 2003.
Terra/Aqua MODIS Data Relevant global Land Level 3 products:
– MOD12Q1 - Ecosystem Classifications Product 1 km resolution, globally. Classification Schemes include:
– IGBP scheme– 14 class UMD scheme
– BGC Biome scheme
– LAI/fPAR Biome scheme Produced using supervised (non-production) approach.
– MOD43B3 - Albedo Product (White- and Black-Sky) 1 km resolution, 16-day global composites. 7 specific wavelength data sets:
– 0.47, 0.555, 0.659, 0.858, 1.24, 1.64, and 2.13 3 broadband data sets:
– 0.3-0.7, 0.3-5.0, 0.7-5.0
5 St. Michaels - March 18, 2003.
Terra/Aqua MODIS Data Stored in equal area Integerized
Sinusoidal Projection (ISIN). – Approximately 300 tiles contain some land.
(From the MODLAND website)
6 St. Michaels - March 18, 2003.
Terra/Aqua MODIS Data Data Volume:
– MOD12Q1 - Ecosystem Classification Product ~ 300 tiles per global map. 22 MB/tile, ~6.6 GB per map.
– MOD43B3 - Albedo Product (White- and Black-Sky) ~300 tiles per 16-day composite global map. ~6,900 tiles per year. 66MB/tile, ~20 GB per map. 23 maps per year, ~ 460 GB per year.
7 St. Michaels - March 18, 2003.
Important Caveats1. ISIN Projection.
2. Large Data Volume.
3. Large Number of Files.
4. Incomplete Maps.
8 St. Michaels - March 18, 2003.
Proposed Value-Added Products.1. Complete Albedo maps.
- Reformat, apply QA, and fill in missing data.
2. Albedo/Ecosystem statistics.- For each ecosystem class in NxM degree boxes.
3. Parameterization of complete Albedo maps.- Store temporal fit coefficients.
Pilot Study -- Y2001 and Y2002 data sets.
9 St. Michaels - March 18, 2003.
Value-Added Products - Methodology.
Series of steps to generate products:1. Mosaicing of ISIN tiles to equal angle map.
2. Application of Quality Assurance.
3. Generation of Albedo/Ecosystem statistics.
4. Filling in of missing points.
5. Parameterization of complete maps.
10 St. Michaels - March 18, 2003.
Mosaic ISIN Tile Data - Description. Two Step Process.
– “Pure” mosaicing of data onto grid.– Application of QA and exclusion of pixels.
Stored in equal angle grids.– 1 minute resolution (2km at equator, < 1km at poles).
Stored in HDF files:– Data arrays– Geolocation– QA -- original and processing.– Metadata -- original and processing.
Albedo and Ecosystem data are mosaiced.
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Mosaic IGBP Ecosystem Map. The product contains the following data sets:
– IGBP classification map.– Classification assessment. – Secondary ecosystem type and percentage.– QA -- original and processed.– Metadata -- original and processing.
Reduces number of files from ~300 to 1, per map. Data volume reduced to 600 MB from 6.6 GB
Codes modifiable for:– Other classification schemes. – Different resolution.
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Mosaic Albedo Data. Mosaiced data stored in 10 HDF files per 16-day period.
– One file per wavelength (7 specific wavelengths and 3 broadband)
Each file contains:– White- and black-sky albedo data.– QA -- original and processing.– Metadata -- original and processing.
Pixels excluded for:– Simulated seasonal polar darkness.– Seasonal snow/ice coverage.– General and band specific QA.
Reduces number of files per 16-day period from ~300 to 10. Reduces data volume to 390 GB/year from 460 GB.
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Mosaiced Albedo Map, July 2001, 0.659 m. Step 1 - “Pure” Mosaicing of MOD43B3 data.
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Mosaiced Albedo Map, July 2001, 0.659 m. Step 2 - Application of QA and Pixel Exclusion.
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Mosaiced Albedo Map, July 2001, 0.47-2.13 m. Step 2 - Application of QA and Pixel Exclusion.
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Mosaiced Albedo Map, Year 2001, 1.24 m. Step 2 - Application of QA and Pixel Exclusion.
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Missing data points. Remaining issue -- missing data points.
Fill methodologies:1. Spatial Fit.
2. Spectral Fit.
3. Temporal Fit.
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Temporal data. Three scenarios:
1. Nearly complete temporal curve.
2. One or more missing seasons.
3. Very few temporal points.
QuickTime™ and aVideo decompressorare needed to see this picture.QuickTime™ and aVideo decompressorare needed to see this picture.QuickTime™ and aVideo decompressorare needed to see this picture.
20 St. Michaels - March 18, 2003.
Fitting Temporal data. Goal: Fill in with geophysically meaningful data.
How to fit the three scenarios?
1. Nearly complete temporal curve.
2. One or more seasons missing.
3. Very few temporal points.
21 St. Michaels - March 18, 2003.
Temporal Fitting Using Regional Information.
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0 50 100 150 200 250 300 350 400
Julian day
Vegetation index
Senescence onset
Dormancy onset
Duration of growth
Duration of maturity
Maximum VI
Greenup onset
Maturity onset
• Ecosystem class behaves according to phenological events.
Image provided by Xiaoyang Zhang, Boston University.
• Region’s ecosystem class has unique temporal behavioral curve.
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Temporal Fitting of Eco Class Mean Albedo. Impose Regional Temporal Behavior curve.
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Fill Methodology.
1. Compute Albedo/Ecosystem statistics.
2. Describe behavioral curve of statistics.
3. Apply metrics to determine “best” behavioral curve.
4. Impose shape of behavioral curve to pixel data.
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Albedo/Ecosystem Statistics - Description Generate albedo statistics for each ecosystem class:
– 0.5 x 0.5 degree box
– For each specific or broad albedo wavelength
– Water albedo set to 5%.
Combine boxes for larger boxes and belts.– Squares of up to 10x10 degree.
– Latitude belts of 10 x Lon degree.
– Subcontinent belts of 60 x Lon degree.
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Mosaiced Albedo Map with Excluded Pixels. July 2001, 0.858 .
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Regenerated Albedo Map From Alb/Eco Statistics.
July 2001, 0.858 .
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Box/Belts of Alb/Eco Statistics. July 2001, 0.858 .
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Albedo/Ecosystem Statistics - Product Statistics stored in 15 HDF files per 16-day period.
– One file per box size.
Each file contains:– White- and black-sky albedo/ecosystem statistical data.– Metadata.
Reduces data volume to 25 GB/year from 460 GB.
Regenerate albedo maps:– Lat/lon and ecosystem classification.
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Parameterization of Albedo Maps. Albedo maps have large data volume. Reduce data volume through parameterization.
Data set consists of fit coefficients stored in HDF file. Reduced data volume ~10-20 GB/year (from 450 GB).
Regenerate maps by inputting lat/lon and julian day.
31 St. Michaels - March 18, 2003.
Take Home Message Three proposed value-added products.
1. Year of complete albedo maps.
2. Albedo/Ecosystem statistics.
3. Parameterized complete albedo maps.
Products provide: – Complete global maps.
– High spatial resolution.
– Seasonal representation.
– Specific wavelengths of interest.
– Available in projections standard within community.
– Reduced data volume and number of files.
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Future Directions. Complete analysis and development of filling in maps.
Provide Data Sets and FORTRAN Utilities for working with the Data Sets.
MODIS Land team is using this project as pilot for an official product.
Visits and talks with user communities to publicize product. Several papers in the works.
![Relating MODIS-derived surface albedo to soils and rock ...dust.ess.uci.edu/ppr/ppr_TSG02.pdf · rockor surfacesediment(e.g.,volcanics, intrusives,eolian,fluvial). [8] The three data](https://static.fdocuments.in/doc/165x107/5f5806c42645ce0c3c0180b8/relating-modis-derived-surface-albedo-to-soils-and-rock-dustessuciedupprpprtsg02pdf.jpg)
