A METHOD FOR THE RETRIEVAL OF PHYTOPLANKTON AND SEDIMENT 
CONTENTS FROM REMOTE MEASUREMENTS OF SEA COLOUR IN THE COASTAL ZONE 
RESULTS OF VALIDATION TESTS 
by 
S. TASSAN 
Commission of the European Communitiés 
Joint Research Centre, Ispra Establishment 
21020 ISPRA (Va) 
ITALV 
A method for the retrieval of phytoplankton and inongante 
sediment contents in coastal waters, including a procedure for the determtna- 
tion of the atmospheric correction, has been elaborated through a theoretical 
simulation pattern and tested by sensitivity analysis techniques (TASSAN, 1981). 
This paper presents some results of a series ob validation tests 
focused on the problem of sediment retrieval, which were performed using 
experimental data collected in a zone of the Adriatic Sea where high quantities 
o( inorganic sediment (uncorrelated to phytoplankton) are discharged by the 
Po river. The data considered (Coastal Zone Colour Scanner images and sea 
truth values) were provided by the Joint Research Centre of the European 
Community, 4n collaboration with the Istituto per Lo Studio delle Grandi 
Masse of the Italian National Research Council. 
The experimental tests were integrated with predictions supplied 
by theoretical simulations, yielding results applying also outside the 
considered water compositions range (chlorophyll-a : 1 - 5 mg/m3, sediment : 
5 - 30 g/m3). 
The sediment retrieval algorithm tested was the Logarithmic 
expression 
logS = A + B log [R(}) — RN) (1) 
with X;7 550 nm, N — 670 nm (i.c. channels 3 and 4 of 
CZCS). 
A best fit to a comprehensive set of data yielded 
log S = 4.250 4 2.365log[R(550) — R(670)] (2) 
which applies to the range 
5 <S(g/m*)<30, 1 X chl (mg/m?) € 1 
An operational variable with Lower sensitivity to the chlorophylt 
content was found to be 
y * [R(550) - R(670)] 
{1 +B[R(520)/R(550)] } (3) 
with A - 8, y” -3. 
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