MODIS/Terra+Aqua BRDF/Albedo QA SnowStatus Daily L3 Global 30ArcSec CMG V006

The MCD43D40 Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the [MCD43D40 Version 6.1](https://doi.org/10.5067/MODIS/MCD43D40.061) data product. The MCD43D40 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) QA Snow Status dataset is produced daily using 16 days of Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data at 30 arc second (1,000 meter (m)) resolution. Data are temporally weighted to the ninth day which is reflected in the Julian date in the file name. This Climate Modeling Grid (CMG) product covers the entire globe for use in climate simulation models. Due to the large file size, each MCD43D project contains just one data layer. MCD43D40 provides snow cover information for the MCD43D products. MCD43D40 contains the snow status quality layer which identifies each pixel as either "Snow-free Albedo Retrieved" or "Snow Albedo Retrieved" for the acquisition period. Users are urged to use the band specific quality flags to isolate the highest quality full inversion results for their own science applications as described in the [User Guide](https://www.umb.edu/spectralmass/modis-user-guide-v006-and-v0061/mcd43d-cmg-30-arc-second-products/). Known Issues * The incorrect representation of the aerosol quantities (low average high) [in the C6 MYD09 and MOD09 surface reflectance products](https://landweb.modaps.eosdis.nasa.gov/displayissue?id=86) may have impacted downstream products particularly over arid bright surfaces. This (and a few other issues) have been corrected for C6.1. Therefore users should avoid substantive use of the C6 MCD43 products and wait for the C6.1 products. In any event, users are always strongly encouraged to download and use the extensive QA data provided in MCD43A2, in addition to the briefer mandatory QAs provided as part of the MCD43A1, 3, and 4 products. * [Corrections](https://landweb.modaps.eosdis.nasa.gov/data/userguide/LSRHighAerosolFlagFinal.pdf) were implemented in Collection 6.1 reprocessing. * For complete information about MCD43D40 known issues refer to the [MODIS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=MODIS&as=6). Improvements/Changes from Previous Version * Observations are weighted to estimate the BRDF/Albedo on the ninth day of the 16-day period. * MCD43 products use the snow status weighted to the ninth day instead of the majority snow/no-snow observations from the 16-day period. * Better quality at high latitudes from use of all available observations for the acquisition period. Collection 5 used only four observations per day. * The MCD43 products use L2G-lite surface reflectance as input. * When there are insufficient high quality reflectances, a database with archetypal BRDF parameters is used to supplement the observational data and perform a lower quality magnitude inversion. This database is continually updated with the latest full inversion retrieval for each pixel. * CMG Albedo is estimated using all the clear-sky observations within the 1,000 m grid for MCD43D as opposed to aggregating from the 500 m albedo.

Tags: earth-science-surface-radiative-properties-land-surface-albedo, earth-science-surface-radiative-properties-land-surface-anisotropy, earth-science-surface-radiative-properties-land-surface-reflectance
Organization: National Aeronautics and Space Administration