Domain anomalies series

[Hyacinth Cyprain Nnamchi]

Dear Grads users,
I have two datasets for which i want get the areal anomaly time series (anom = x-mean)for two domains:
a) lon=0,lon=360; lat=60S,lat=45S
b) lon=15W,15E;lat=2N,lat=10N
For each domain i want to have a single time series for t=1,t=last.My problem is how to apply the appropriate weighting functions.

Can anyone help with a Fortran subroutine? Is there any GrADS function that can do this?

Thanks in advance.
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Hyacinth C. Nnamchi
TWAS-CAS Fellow
State Key Laboratory of Numerical Modeling for
Atmospheric Sciences and Geophysical Fluid Dynamics (LASG)
Institute of Atmospheric Physics (IAP)
Chinese Academy of Sciences (CAS)
P.O.Box 9804, Beijing 100029, China
Tel: +86-13488719702
Fax: +86-10-82995172
E-mail:hc.nnamchi at lasg.iap.ac.cn