Rw. Gould et Ra. Arnone, ESTIMATING THE BEAM ATTENUATION COEFFICIENT IN COASTAL WATERS FROM AVHRR IMAGERY, Continental shelf research, 17(11), 1997, pp. 1375-1387
This paper presents an algorithm to estimate particle beam attenuation
at 660 nm (c(p)660) in coastal areas using the red and near-infrared
channels of the NOAA AVHRR satellite sensor. In situ reflectance spect
ra and c(p)660 measurements were collected at 23 stations in Case I an
d II waters during an April 1993 cruise in the northern Gulf of Mexico
. The reflectance spectra were weighted by the spectral response of th
e AVHRR sensor and integrated over the channel 1 waveband to estimate
the atmospherically corrected signal recorded by the satellite. An emp
irical relationship between integrated reflectance and c(p)660 values
was derived with a linear correlation coefficient of 0.88. Because the
AVHRR sensor requires a strong channel 1 signal, the algorithm is app
licable in highly turbid areas (c(p)660 > 1.5 m(-1)) where scattering
from suspended sediment strongly controls the shape and magnitude of t
he red (550-650 nm) reflectance spectrum. The algorithm was tested on
a data set collected 2 years later in different coastal waters in the
northern Gulf of Mexico and satellite estimates of c(p)660 averaged wi
thin 37% of measured values. Application of the algorithm provides dai
ly images of nearshore regions at I km resolution for evaluating proce
sses affecting ocean color distribution patterns (tides, winds, curren
ts, river discharge). Further validation and refinement of the algorit
hm are in progress to permit quantitative application in other coastal
areas. Published by Elsevier Science Ltd.