MYD17A3HGF v061

MODIS/Aqua Net Primary Production Gap-Filled Yearly L4 Global 500 m SIN Grid


PI: Steve Running

Description

The MYD17A3HGF Version 6.1 product provides information about annual Net Primary Production (NPP) at 500 meter (m) pixel resolution. Annual Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) NPP is derived from the sum of all 8-day Net Photosynthesis (PSN) products (MYD17A2H) from the given year. The PSN value is the difference of the Gross Primary Productivity (GPP) and the Maintenance Respiration (MR).

The MYD17A3HGF will be generated at the end of each year when the entire yearly 8-day MYD15A2H is available. Hence, the gap-filled MYD17A3HGF is the improved MYD17, which has cleaned the poor-quality inputs from 8-day Leaf Area Index and Fraction of Photosynthetically Active Radiation (FPAR/LAI) 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 MYD17A3HGF 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 Version 6.1 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: changes to the response-versus-scan angle (RVS) approach that affects reflectance bands for Aqua and Terra MODIS, corrections to adjust for the optical crosstalk in Terra MODIS infrared (IR) bands, and corrections to the Terra MODIS forward look-up table (LUT) update for the period 2012 - 2017.
  • A polarization correction has been applied to the L1B Reflective Solar Bands (RSB).
  • The product uses Climatology LAI/FPAR as back up to the operational LAI/FPAR.

Product Maturity

Validation at stage 3 has been achieved for the MODIS Gross and Net Primary Productivity data products. Further details regarding MODIS land product validation for the MYD17 data products are available from the MODIS Land Team Validation site.

Collection and Granule

Collection

Characteristic Description
CollectionAqua MODIS
DOI10.5067/MODIS/MYD17A3HGF.061
File Size~0.8 MB
Temporal ResolutionYearly
Temporal Extent2002-12-27 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) Layers2
Columns/Rows2400 x 2400
Pixel Size500 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Npp_500m Net Primary Productivity kgC/m²/year 16-bit signed integer 32761 to 32767 N/A -30000 to 32700 0.0001
Npp_QC_500m Quality Control Percent 8-bit unsigned integer 249 to 255 N/A 0 to 100 N/A

Npp_500m Fill Value Classes

Value Classes
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

Npp_QC_500m Fill Value Classes

Value Description
249 Land cover assigned as "unclassified" or not able to determine
250 Land cover assigned as urban/built-up
251 Land cover assigned as "permanent" wetlands / inundated marshland
252 Land cover assigned as perennial snow, ice
253 Land cover assigned as barren, sparse vegetation (rock, tundra, desert)
254 Land cover assigned as perennial salt or water bodies
255 Fill

Product Quality

Quality for MYD17A3HGF is expressed as a percentage in the Npp_QC_500m science dataset layer. More information on how this value is derived can be found in Section 4.2 of the User Guide.

Known Issues

Operational and uncertainty issues are provided under Section 2 in the User Guide.

For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

Documentation

Using the Data

Access Data

Citation

DOI: 10.5067/MODIS/MYD17A3HGF.061

About the Image

Aqua MODIS net primary productivity (NPP) data from the MYD17A3HGF product over Venezuela, 2020.

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