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Aqua Product Descriptions: MYD21

Last update: May 9 2017

Data Set Short Name:
MYD21

Data Set Long Name:
MODIS/Aqua Land Surface Temperature/3-Band Emissivity 5-Min L2 1km

Platform:
Aqua

Instrument:
MODIS

Product Description:
The new MODIS/Aqua Land Surface Temperature/3-Band Emissivity 5-Min L2 1km product (MOD21), available in Collection 6, uses a physics-based algorithm to dynamically retrieve both the LST and Emissivity simultaneously for the three MODIS thermal infrared bands (29, 31 and 32) at a spatial resolution of 1 km at nadir. The MOD21 product addresses the documented cold bias of 3-5 K in the MOD11 heritage split-window products over arid and semi-arid regions.
The MYD21 algorithm is based on the ASTER Temperature Emissivity Separation (TES) algorithm, which uses full radiative transfer simulations for the atmospheric correction, and an emissivity model based on the variability in the surface radiance data to dynamically retrieve both LST and spectral emissivity. The TES algorithm is combined with an improved Water Vapor Scaling (WVS) atmospheric correction scheme to stabilize the retrieval during very warm and humid conditions. Simulations and validation results available in the ATBD have shown consistent accuracies at the 1 K level over all land surface types including vegetation, water, and deserts.
The operational science quality MYD21 product from MDOAPS always lags by a month because of the delay in the availability of the MERRA2 ancillary input. So, for near real time uses requiring the data with 1-2 days of latency, the same product is being generated on the NRT system using the NCEP Global Forecast System 3 Hour Forecast File as ancillary input instead of the 6-Hourly, Instantaneous, Pressure-Level, Analysis, Analyzed Meteorological Fields, MERRA2 ancillary input data. However, the NRT MOD21 product generated using NCEP ancillary input would have larger error margin and more data gaps.

For more information download product's Users’ Guide

And, the Algorithm Theoretical Basis Document (ATBD)

Production Frequency:
288 file per day

Spatial Coverage:
Global

Spatial Resolution:
1 km

File Size (MB):
~5

Citation:

Dataset Originator/Creator:
MODIS Land Science Team/ MODIS Adaptive Processing System (MODAPS)

Data Authors:
Dr. Glynn Hulley

Dataset DOI:
http://dx.doi.org/10.5067/MODIS/MYD21.NRT.006