, , (1)
Or, solving for the surface wind divergence we find that wind divergence depends on the second spatial derivatives of SST,
(2)
In this equation we allow the friction coefficients in the zonal and meridional directions, and , to take on differing values of 10-5 1/s and 2*10-5 1/s, respectively, based on the analysis of Chiang and Zebiak [2000]. The coefficient of proportionality between surface air pressure variations and SST, , is assumed constant and estimated from data in
, 
, 
(1)
(2)
and 
, to take on differing values of 10-5 1/s and 2*10-5 1/s, respectively, 
, is assumed constant and estimated from data in