The MODIS/Aqua Collection 41 (C41) products use a modified Collection-4 (C4) LST algorithm and Collection-5 (C5) data inputs. The C41 products primarily address underestimation problems in the C5 Climate Modeling Grid (CMG) products. Recent validation activities reveal that the C5 CMG products underestimate LSTs up to 6K especially in desert and semi-arid regions. The production date for this collection starts with MODIS/Aqua data acquisition from 2007-001. This beginning date is driven by the availability of the MODIS C5 data inputs (level-1B radiance data, geolocation data, cloud mask, atmospheric profiles, and land and snow cover data).
The MODIS/Aqua C41 and C5 level-2 LST/E data (Short name: MYD11_L2) incorporate 1 km pixels, which are produced daily at 5-minute increments using the generalized split-window LST algorithm. This algorithm is optimally used to separate ranges of atmospheric column water vapor and lower boundary air surface temperatures into tractable sub-ranges. The surface emissivities in bands 31 and 32 are estimated from land cover types. The data inputs include the MODIS L1B calibrated and geolocated radiances, geolocation, cloud mask, atmospheric profiles, land and snow cover.
The C41 MYD11_L2 data set comprises swath data obtained in 5-minute sensor collection periods, and includes the following Science Data Set (SDS) layers: LST, quality assurance control assessment, error estimates, bands 31 and 32 emissivities, zenith angle of the pixel view, observation time, and the geographic coordinates for every five scan lines and samples. Produced daily, MYD11_L2 is an unprojected level-2 data set, which provides the input for the level-3 products.
The C41 and C5 MODIS/Aqua LST/E products, including the MYD11_L2, are validated to Stage-2 with well-defined uncertainties over a range of representative conditions. Further details regarding MODIS land product validation for the LST/E products are available from the MODIS land team validation site referenced under the 'Links' section.
The C41 MYD11_L2 product acquisitions started on January 1, 2007 (2007-001) and will continue until the C6 reprocessing completes.
The C5 MYD11_L2 product acquisition range started March 5, 2000 (2000-065) and will continue until some time after the C6 reprocessing is complete.
The C41 LST products from 2007-001 will remain consistent with similar products from C4, and hence are amenable to combine in a time-series analysis. Users should exercise caution, and not mix the C4.x (i.e., C4 and C41) and C5 LST products in their analyses.