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 m

9 m

4 m0.75

1.0

Em

issi

vity

Wavenumber (cm-1)500 3000

UW AERIbago

NTB

NNNe

S

totatmobs

)(

/)(

• Best fit to Tskin when spectral variance in emissivity is minimum.

Tskin = 295.4 K

Validation Case Study: Southern Great Plains SiteS-HIS Observation

Aircraft validation measurements are consistent with a linear combination of vegetation and bare soil.

Aircraft S-HISLSE

Wavenumber (cm-1)

0.85

1.0

Bare Soil

Pure Vegetation

S-HIS OBS

12 m 9 m

Infrared Radiative Transfer Equation (lambertian surface) NeTBedPTBN tot

Stot )1()())((

atmNSurfaceEmission

SurfaceReflection

Skin Temperature & Surface Emissivity

Ndn (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

SolidCoarseFine

0.0

0.5

0.0

0.5

> 75 m> 2 m & < 75 m

• QUARTZ Emissivity (JPL Spectral Library from Lab Tests).

1-R

1-R SolidCoarseFine

1.0

0.5

0.5

1.0

> 75 m> 2 m & < 75 m

IR Land Surface Signatures: QUARTZ

• QUARTZ Emissivity (JPL Spectral Library from Lab Tests).

R

R

0.5

0.0

0.0

0.5

IR Land Surface Signatures: JPL Library

GraniteSandy LoamQuartz (coarse grain)

• QUARTZ Emissivity (JPL Spectral Library from Lab Tests).

1-R

1-R

1.0

0.5

0.5

1.0

IR Land Surface Signatures: JPL Library

GraniteSandy LoamQuartz (coarse grain)