DANDONNEAU: MONITORING SEA SURFACE CHLOROPHYLL CONCENTRATION 



20*N 



M'S 



20*N 



20*S . 



20*N 



M'S 



20* N 



20*S 



UO'E 



100" W 



20* N 



20*S 



100'W 



Figure 1. -Quarterly charts of SSCC (sea surface chlorophyll concentrations) in the tropical Pacific from January 1, 1982 to December 

 31, 1983. Areas where SSCC is >0.10 mg nT 3 are shaded with large dots. Smaller dots represent the data points. 



1=1 1=1 



where i 3 is the SSCC estimate at longitude Xj and 

 latitude y^, and p tj is the weight given to observa- 

 tion t { for the estimation tj. p^ is given by 



Vij = [R 2 + (Xi - xf + a 2 (y t - t//]" 1 



where a accounts for anisotropy of the SSCC varia- 

 tions in space. We used a = 2, so that observations 



at a distance Ay in latitude are given the same 

 weight as observations at a distance kx = 2hy in 

 longitude, p^ was set to zero when (x t - Xjf + a 2 

 (Vi ~ Vj) 2 was >160, so that the observations were 

 considered as "non useful" when outside an ellipse 

 centered at (Xj, y^) with a principal axis equal to 

 about 25° longitude, and a small axis equal to about 

 13° latitude. In order to avoid hazardous estimates 

 at the margin of the contoured area, tj has not been 

 estimated when rij (the number of useful observa- 

 tions) was <12. 



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