Become “spectrally aware” ! ARM SGP site is dominated by two land cover types “grass vegetation” and “bare soil”. U. of Wisconsin measured the IR emissivity at high spectral resolution. Grass Vegetation Bare Soil 12  m9  m 4  m Emissivity Wavenumber (cm -1 ) UW AERIbago

Best fit to T skin when spectral variance in emissivity is minimum. T skin = K Validation Case Study: Southern Great Plains Site S-HIS Observation

Aircraft validation measurements are consistent with a linear combination of vegetation and bare soil. Aircraft S-HIS LSE Wavenumber (cm -1 ) Bare Soil Pure Vegetation S-HIS OBS 12  m 9  m

Infrared Radiative Transfer Equation (lambertian surface) Surface Emission Surface Reflection Skin Temperature & Surface Emissivity N dn (60deg)

Emissivity Survey ARM SGP site is dominated by two land cover types “pasture” and “wheat”. Notice that the measured wheat field emissivity can be approximated by a linear combination of pure scene types; bare soil and grass.

QUARTZ Reflectivity (JPL Spectral Library from Lab Tests). IR Land Surface Signatures: QUARTZ R R Solid Coarse Fine > 75  m > 2  m & < 75  m

QUARTZ Emissivity (JPL Spectral Library from Lab Tests). 1-R Solid Coarse Fine > 75  m > 2  m & < 75  m IR Land Surface Signatures: QUARTZ

QUARTZ Emissivity (JPL Spectral Library from Lab Tests). R R IR Land Surface Signatures: JPL Library Granite Sandy Loam Quartz (coarse grain)

QUARTZ Emissivity (JPL Spectral Library from Lab Tests). 1-R IR Land Surface Signatures: JPL Library Granite Sandy Loam Quartz (coarse grain)