Re: how to calculate seasonal means

Vishali,

I'm also not certain what you have in mind, but I'm guessing it's something
like CDO's seasmean
operator<https://code.zmaw.de/embedded/cdo/current/cdo.html#x1-3650002.8.22>,
which computes a timeseries of three-month seasonal means (DJF,MAM,JJA,SON)
from a timeseries (which could be 3-hourly, daily, monthly, whatever). For
example, if you have a 10-year record of daily winds, the operator would
reduce it to a record of 40 timesteps, each of which contains a three month
mean. (BTW, I would call what Dennis is describing the "annual cycle of
daily winds" but this may just be a function of the local dialect among the
folks I work with.)

I'm not aware that NCL has a comparable operator, but
month_to_seasonN()<http://www.ncl.ucar.edu/Document/Functions/Contributed/month_to_seasonN.shtml>should
work if you're starting with monthly data. For daily or
higher-time-resolution data, you'll probably need to iterate through your
timeseries, computing each three-month mean separately. How you do this is
going to depend on the particular structure of of your data, the time
format, etc.

~Rob

-- 
Robert Nicholas
Department of Atmospheric Sciences
University of Washington, Box 351640
Seattle, WA 98195-1640
rnicholas@atmos.washington.edu
tel 206-438-3509, fax 206-543-0308

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Received on Thu Aug 12 10:51:44 2010