MYD17A2HGF v006

MODIS/Aqua Gross Primary Productivity Gap-Filled 8-Day L4 Global 500 m SIN Grid


PI: Steve Running

Description

The MYD17A2HGF Version 6 Gross Primary Productivity (GPP) Gap-Filled product is a cumulative 8-day composite of values with 500 meter (m) pixel size based on the radiation use efficiency concept that can be potentially used as inputs to data models to calculate terrestrial energy, carbon, water cycle processes, and biogeochemistry of vegetation. The data product includes information about GPP and Net Photosynthesis (PSN). The PSN band values are the GPP less the Maintenance Respiration (MR). The data product also contains a PSN Quality Control (QC) layer. The quality layer contains quality information for both the GPP and the PSN.

The MYD17A2HGF will be generated at the end of each year when the entire yearly 8-day MYD15A2H is available. Hence, the gap-filled MYD17A2HGF is the improved MYD17, which has cleaned the poor-quality inputs from 8-day Leaf Area Index and Fraction of Photosynthetically Active Radiation (LAI/FPAR) based on the Quality Control (QC) label for every pixel. If any LAI/FPAR pixel did not meet the quality screening criteria, its value is determined through linear interpolation. However, users cannot get MYD17A2HGF in near-real time because it will be generated only at the end of a given year.

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Characteristics

Improvements/Changes from Previous Versions

  • The product uses updated Biome Property Look-Up Tables (BPLUT) and an updated version of the daily Global Modeling and Assimilation Office (GMAO) meteorological data.
  • The products are now generated at the native resolution of 500 m using the Moderate Resolution Imaging Spectroradiometer (MODIS) Leaf Area Index (LAI)/Fraction of Photosynthetically Active Radiation (FPAR) (MYD15A2H) 8-day composite at 500 m resolution.

Product Maturity

Stage 3 validation has been achieved for MYD17 products.

Collection and Granule

Collection

Characteristic Description
CollectionAqua MODIS
DOI10.5067/MODIS/MYD17A2HGF.006
File Size4 MB
Temporal ResolutionMulti-Day
Temporal Extent2002-01-01 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
DatumN/A
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers3
Columns/Rows2400 x 2400
Pixel Size500 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Gpp_500m Gross Primary Productivity kgC/m²/8day 16-bit signed integer 32761 to 32767 N/A 0 to 30000 0.0001
PsnNet_500m Net Photosynthesis kgC/m²/8day 16-bit signed integer 32761 to 32767 N/A -30000 to 30000 0.0001
Psn_QC_500m Quality Control Indicators Bit Field 8-bit unsigned integer 255 N/A 0 to 254 N/A

Non-Terrestrial Fill Value Classes

Value Description
32761 Land cover assigned as "unclassified" or not able to determine
32762 Land cover assigned as urban/built-up
32763 Land cover assigned as "permanent" wetlands/inundated marshland
32764 Land cover assigned as perennial snow, ice
32765 Land cover assigned as barren, sparse veg (rock, tundra, desert)
32766 Land cover assigned as perennial salt or inland fresh water
32767 Fill Value

Product Quality

For the year-end gap-filled MYD17A2HGF, users may ignore the QC data layer because cloud-contaminated LAI/FPAR gaps have been temporally filled prior to calculation.

Mappings for the Psn_QC_500m layer and an explanation of how to interpret this information are provided under Section 4.1 in the User Guide.

The quality layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret this layer.

Known Issues

Operational and uncertainty issues are provided under Section 2 in the User Guide.
For complete information about the MYD17A2HGF known issues refer to the MODIS Land Quality Assessment website.

Documentation

Using the Data

Access Data

Citation

DOI: 10.5067/MODIS/MYD17A2HGF.006

About the Image

Aqua MODIS gross primary productivity (GPP) data from the MYD17A2HGF product over Central America from January 1 - 8, 2003.

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