An objective technique for Arctic cloud analysis using multispectral AVHRR satellite imagery
By: John P. Barron
Contributors: Naval Postgraduate School (U.S.)
Publisher: Naval Postgraduate School
Published: 1988
Place of publication: Monterey, California
Language: eng
Number of pages: 80
Subjects: Meteorology
Description: An established cloud analysis routine has been modified for use in the Arctic. The separation of clouds from the snow and sea ice backgrounds is accomplished through a multispectral technique which utilizes VHRR channel 2 (visible), channel 3 (near infrared) and channel 4 (infrared) data. The primary means of cloud identification is based on a derived channel 3 reflectance image. At this wavelength, a significant contrast exists between liquid clouds and the arctic backgrounds, unlike in the standard visible and infrared images. The channel 3 reflectance is obtained by first using the channel 4 emission temperature to estimate the thermal emission component of the total channel 3 radiance. This thermal emission component is subsequently removed from the total radiance, leaving only the solar reflectance component available for analysis. Since many ice clouds do not exhibit a substantially greater reflectance is channel 3, the routine exploits differences in transmissive characteristics between channels 3 and 4 for identification. The routine was applied to six case studies which had been analyzed by three independent experts to establish 'ground truth'. Verification of the cloud analysis results, through a comparison to the subjective analyses, yielded impressive statistics. A success rate of 77.9% was obtained with an arguably small data base of 131 undisputed scenes.
Notes: Thesis advisor(s): Durkee, Philip A. ; Wash, Carlyle H.

"March 1988."

Thesis (M.S. in Meteorology and Ocean.)--Naval Postgraduate School, March 1988.

Includes bibliographic references:  (p. 77-780).

Approved for public release, distribution unlimited.

US Navy (USN) author.