The "fstguess.dat" file lists parameters for generating typical seasonal variations in
ozone profile. The latitude-dependent climatology of monthly averages of ozone profiles
was compiled by NASA/Goddard (McPeters and Labow, 2003). The cosine fit to the
climatology is as following:
AP(i)=COEF1(i) +COEF2(i)*COS((JULDAY-COEF3(i))*2*p/365),
where AP(i) is a priori ozone amount in DU in layer i, COEF1 (i), COEF2 (i), COEF3 (i)
are coefficients of the fit for layer i tabulated in the file "fstguess.dat", and JULDAY is a
Julian day of the year. The file is organized in 14 blocks of three coefficients, where each
block represents the fit for a climatology averaged over 10-degree latitude band. The first
block has data for 60-degrees Northern latitude and above, and the last block has data for
60-degrees Southern latitude and above. Each block is organized as following:
COEF1(i=1,13)
COEF3(i=1,13)
COEF3(i=1,13),
where i=1 is the bottom layer, i=13 is the top layer. The layering system is given in
pressure-level coordinates, where the bottom layer is confined between 1 and 0.5 atm, the
top pressure level of the layer is half of the pressure at the bottom level.