Bendix, J., <b>Determination of fog horizontal visibility by means of NOAA-AVHRR</b>(Proc. of IGARSS'95, 1995), pp. 1847-1849.
Resource Description
Title:
Determination of fog horizontal visibility by means of NOAA-AVHRR
FOR816dw ID:
207
Publication Date:
1995-01-01
License and Usage Rights:
PAK 823-825 data user agreement. (www.lcrs.de/dataagreementp3.do)
Resource Owner(s):
Individual:
Jörg Bendix
Contact:
email:
bendix <at> staff.uni-marburg.de
Deutschhausstraße 12
Room No. 02 A 48
35032 Marburg
Faculty of Geography
Germany
Abstract:
Two schemes for the determination of fog horizontal<br/>
visibility using AVHRR data both, day and night, are<br/>
presented. Ground truth has been performed by the<br/>
comparison of calculated visibilities and simultaneous<br/>
transmissometer measurements. The daytime approach is<br/>
based on the calculation of fog albedo from AVHRR #1 and<br/>
the relation of fog optical depth and geometrical thickness to<br/>
spectral extinction and horizontal visibility. The mean<br/>
deviation between observed and calculated visibilities is<br/>
about 56 m. The nighttime approach uses the relation<br/>
between fog and air temperature derived from AVHRR # 4<br/>
and 5 and a simple model for the approximation of the fog<br/>
droplet distribution. The resulting fog extinction is directly<br/>
related to horizontal visibility. Because fog optical depth is<br/>
not available at night, the calculation of horizontal visibility<br/>
using the nighttime approach is only valid if fog extinction is<br/>
nearly homogeneous over the whole fog layer. Mean<br/>
deviations between observed and calculated visibilities<br/>
therefore slightly increase to about 61 m.
