UW Baseline Fit Emissivity Database:
This global database of infrared land surface emissivity is derived using input from the Moderate Resolution Imaging Spectroradiometer (MODIS) operational land surface emissivity product (MOD11). The baseline fit method (Seemann et al., 2008), based on a conceptual model developed from laboratory measurements of surface emissivity, is applied to fill in the spectral gaps between the six emissivity wavelengths available in MOD11.
The six available MOD11 wavelengths span only three spectral regions (3.8-4, 8.6, and 11-12 microns), while the retrievals of atmospheric temperature and moisture from satellite IR sounder radiances require surface emissivity at higher spectral resolution. Emissivity in the baseline fit database presented here is available globally at ten wavelengths (3.6, 4.3, 5.0, 5.8, 7.6, 8.3, 9.3, 10.8, 12.1, and 14.3 microns) with 0.05 degree spatial resolution. The wavelengths in the database were chosen as hinge points to capture as much of the shape of the higher resolution emissivity spectra as possible between 3.6 and 14.3 microns.
UW High Spectral Resolution Emissivity Algorithm:
The algorithm - called UW HSR Emissivity Algorithm - to create a continuous spectral emissivity with high spectral resolution (HSR) from the UW BF Emissivity Database has been developed and is available by request sent to Eva E. Borbas.
At the UW-Madison, based on the UW HSR emissivity Algorithm, an infrared land surface emissivity module (called UWiremis module) has been also developed for RTTOV forward model users providing improved techniques for simulating infrared radiances over land. This work has been supported by an Associate Scientist Mission of the EUMETSAT NWP_SAF.
The Monthly Mean ASTER Global Emissivity Database Version4:
Using data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra spacecraft, NASA/JPL recently released the most detailed emissivity map of the Earth termed the ASTER Global Emissivity Database (ASTER GEDv3), available at https://lpdaac.usgs.gov/dataset_discovery/community/community_products_table. ASTER GEDv3 was created by processing millions of cloud free ASTER data from 2000-2008 and calculating an average emissivity of the surface at ~100 m spatial resolution at the five ASTER TIR wavelengths. Validation over a global set of sites showed a close match in spectral shape with lab measured spectra, and average band error of ~1%. Since the ASTER-GEDv3 emissivities are static (mean from 2000-2008), an emissivity adjustment was necessary to account for land surface changes over heterogeneous land cover types that are subject to annual and inter-annual variability; for example due to snow and ice melt, agricultural practices, and droughts. The emissivity over desert regions will remain invariant over time in the absence of soil moisture. To account for these changes, a monthly mean ASTER GEDv4 emissivity product at 0.05 degree resolution has been produced from 2000-2015 by using snow cover data from the standard monthly MODIS/Terra snow cover monthly global 0.05 deg product (MOD10CM), and vegetation information from the MODIS monthly gridded NDVI product (MOD13C2). The methodology for producing the monthly mean product is described here
Last updated: 2017-May-03