blems encountered and possikle solutions are presented here. 
2. Sea Truth 
Each vessel assigned to sea truth data collection was to make continuous 
surface measurements of chlorophyll, turbidity, salinity, and tempera- 
ture. Moreover, at approximately 20 equidistant pesitions along the track 
near-surface water samples were to be taken and to he analyzed later 
in a central laboratory. The results of the analysis wore to be used for 
calibration of the continuous measurements, and for determining other 
parameters such as yellow substances, inorganic suspended matter, etc. 
The ships were to take vertical sample profiles and Secchi disk depth at 
a position approximately in the middle of the track when they were an- 
nounced by radio that the Mystère was to fly over. 
Within the arca covered by the three usable fligk* *racks of June 27, three 
vessels, "Zander" on ship-track B, "Octans" on ship-track H, and 
"iJmond' on shij track Y, acquired sea truth deta (Fig. 3). Because of 
the state o! the filing of sea truth data in Juue 1978, only readings at the 
camping positions were available from the continuous sea truth measu- 
rements. It turned out that for the ship tracks of inierest here, no other 
sea truth data were available since the laboratory analysis of water sam- 
ples proved to be unreliable. In particular, the following data were avail- 
able: position and time of measurement, sounded depth, water tempera - 
ture, salinity and turbidity from all vessels; chlcz ophyll concentration 
for tracks B and H only. Salinity, turbidity aad chlorophyll content are 
relative values, given in instrument-defined units. 
On flight line 1, phenomena apparently linked to local water currents can 
be observed ou ihe OCS image. Since there are nu current data available 
for this area. cor”clation of the sea truth with the ccrnner data is diffi- 
cat. 
Current velocity might have been estimated using the accurate position 
data, had drift and veiocity of the vessel, relative to water, been mea- 
sured. 
3. Data Processing 
The analog output of the OCS is digitized into 10 bit words and written 
on four PCM tracks of an analog tape unit on board the aircraft), On 
one of these tracks also the roll of the aircraft is coded. The conver- 
sion to computer-compatible tapes, carried out by the Electronics Divi- 
sion of the JRC-Ispra, requires two steps: 
1. On a General Automation SPC 16 minicomputer the contents of each 
of the PCM tracks is copied onto a CCT; 
  
   
  
  
     
  
  
   
    
  
     
  
  
  
  
  
    
   
    
   
  
   
  
  
   
   
     
   
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