The MYD16A2 Version 6 Evapotranspiration/Latent Heat Flux product is an 8-day composite dataset produced at 500 meter (m) pixel resolution. The improved algorithm is based on the logic of the Penman-Monteith equation, which includes inputs of daily meteorological reanalysis data along with Moderate Resolution Imaging Spectroradiometer (MODIS) remotely sensed data products such as vegetation property dynamics, albedo, and land cover.
Provided in the MYD16A2 product are layers for composited Evapotranspiration (ET), Latent Heat Flux (LE), Potential ET (PET) and Potential LE (PLE) along with a quality control layer. Two low resolution browse images, ET and LE, are also available for each MYD16A2 granule.
The pixel values for the two Evapotranspiration layers (ET and PET) are the sum of all eight days within the composite period, and the pixel values for the two Latent Heat layers (LE and PLE) are the average of all eight days within the composite period. Note that the last acquisition period of each year is a 5 or 6-day composite period depending on the year.
Validation at stage 1 has been achieved for MODIS Evapotranspiration products.
|File Size||~5 MB|
|Temporal Extent||2002-07-04 to Present|
|Geographic Dimensions||1200 km x 1200 km|
|Number of Science Dataset (SDS) Layers||5|
|Columns/Rows||2400 x 2400|
|Pixel Size||500 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|ET_500m||Total Evapotranspiration||kg/m²/8day||16-bit signed integer||32761 to 32767||N/A||-32767 to 32700||0.1|
|LE_500m||Average Latent Heat Flux||J/m²/day||16-bit signed integer||32761 to 32767||N/A||-32767 to 32700||10000|
|PET_500m||Total Potential Evapotranspiration||kg/m²/8day||16-bit signed integer||32761 to 32767||N/A||-32767 to 32700||0.1|
|PLE_500m||Average Potential Latent Heat Flux||J/m²/day||16-bit signed integer||32761 to 32767||N/A||-32767 to 32700||10000|
|ET_QC_500m||Evapotranspiration Quality Control flags||Bit Field||8-bit unsigned integer||255||N/A||0 to 254||N/A|
Users are asked to disregard the class assignments for Fill Values 32761 through 32767 irrespective of the assigned quality for these pixels. Class assignments may be incorrect and users are advised to exercise caution while using the product in their application. See known issue PM_MOD16_18074 for further information.
The pixel level quality control layer (ET_QC_500m) is a copy of the quality control data layer of the corresponding input LAI/FPAR (MYD15A2H) granule of the same 8-day composite period and does not reflect the quality of the retrieved evapotranspiration. The current operational process does not generate pixel level science quality information. Users are advised to exercise caution while using the product in their application.
Additional information related to the cloud/aerosol screening and quality for input products are provided on page 16 in the User Guide. Mappings for the ET QC layer and an explanation on how to interpret this information are provided under Section 6.2.1 beginning on page 20 in the User Guide.