Development of a Global Infrared Land Surface Emissivity Database for Application to Clear Sky Sounding Retrievals from Multispectral Satellite Radiance Measurements

Abstract

A global database of infrared (IR) land surface emissivity is introduced to support more accurate retrievals of atmospheric properties such as temperature and moisture profiles from multispectral satellite radiance measurements. Emissivity is derived using input from the Moderate Resolution Imaging Spectroradiometer (MODIS) operational land surface emissivity product (MOD11). The baseline fit method, 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 m), while the retrievals of atmospheric temperature and moisture from satellite IR sounder radiances require surface emissivity at higher spectral resolution. Emissivity in the database presented here is available globally at 10 wavelengths (3.6, 4.3, 5.0, 5.8, 7.6, 8.3, 9.3, 10.8, 12.1, and 14.3 m) with 0.05°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 m. The surface emissivity from this database is applied to the IR regression retrieval of atmospheric moisture profiles using radiances from MODIS, and improvement is shown over retrievals made with the typical assumption of constant emissivity.

A 6-year global cloud climatology from the Atmospheric InfraRed Sounder AIRS and a statistical analysis in synergy with CALIPSO and CloudSat

“…These are provided for the latitude band 30 • N-30 • S as climatological monthly averages from three years of AIRS data (Péquignot et al, 2008), at a spatial resolution of 1 • latitude×1 • longitude. For the rest of the globe we use climatological monthly averages from six years of MODIS data (Seemann et al, 2008), at a spatial resolution of 0.5 • latitude×0.5 • longitude, which have then been spectrally interpolated to the AIRS channels.…”

“…depth as low as 0.1, day and night (e.g. Wylie et al, 1994;Ackerman et al, 1995;Smith et al, 1998;Stubenrauch et al, 1999bStubenrauch et al, , 2006Wylie and Menzel, 1999;Chung et al, 2000;Kahn et al, 2007).…”

Methane profiles from GOSAT thermal infrared spectra

“…Here, the surface reflection of down-welling atmospheric radiation is governed by the emissivity, following Kirchhoff's law. We determine the initial surface emissivity over land with the High Spectral Resolution Algorithm developed by Borbas (Borbas et al, 2007;Borbas and Ruston, 2010) using the University of Wisconsin Baseline Fit (UW-BF) Emissivity Database (Seemann et al, 2008) as input. For water surfaces, we use the IRSSE model by van Delst and Wu (2000) to calculate the surface emissivity 10 in RemoTeC.…”

Synergy of stereo cloud top height and ORAC optimal estimation cloud retrieval: evaluation and application to AATSR

“…The surface temperature is a retrieved parameter, with the emissivity at each thermal channel determined using the University of WisconsinMadison Baseline Fit Emissivity Database (Seemann et al, 2008). …”