Cloud area determination from AVIRIS data using water vapor channels near 1. mu. m

Journal Article · Wed Feb 20 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JD02394· OSTI ID:5560813

Gao, B C; Goetz, A F.H. ^[1]

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1. Univ. of Colorado, Boulder (USA)

Fractional cloud area is derived from spectral images collected by the airborne visible-infrared imaging spectrometer (AVIRIS). AVIRIS covers the spectral region from 0.4 to 2.5 {mu}m with 224 channels and has a ground instantaneous field of view of 20 {times} 20 m from an altitude of 20 km. The derivation is made by ratioing radiances near the 0.94- and the 1.14-{mu}m water vapor band centers against those in the intermediate atmospheric window regions. The derivation makes use of the facts that (1) the reflectances of most ground targets vary approximately linearly with wavelength in the 0.94- and the 1.14-{mu}m water vapor band absorption regions, and (2) the peak absorptions of the water vapor band over cloudy areas are smaller than those over nearby clear surface areas because of the rapidly decreasing atmospheric water vapor concentration with height. The band ratioing technique effectively discriminates among clouds and surface areas having similar reflectance values. Such discrimination is not possible using standard radiance thresholding techniques. It is expected that the use of water vapor channels in the near-infrared region in future satellites will improve the ability to determine cloud cover over the land.

• OSTI ID: 5560813
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:D2; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ABSORPTION
AIRCRAFT
CLOUD COVER
DETECTION
DIMENSIONS
ELECTROMAGNETIC RADIATION
FLUIDS
GASES
INFRARED RADIATION
MEASURING METHODS
MULTISPECTRAL PHOTOGRAPHY
OPTICAL PROPERTIES
PERFORMANCE
PHOTOGRAPHY
PHYSICAL PROPERTIES
RADIATIONS
REFLECTIVITY
SIZE
SURFACE PROPERTIES
SURFACES
VAPORS
VISIBLE RADIATION
WATER VAPOR
WAVELENGTHS