Findout SD

[Paul Emck]

Hello,

has somebody an elegant solution (in Stergios' style) for calculating the
daily ltm SD from NCEP Reanalysis data?

That is from 1968 - 1996. The skript would access the daily mean variable
(e.g. air.19nn.nc) which in this case are 29 files.

I tried using the concatenating Grads command for all these files and then
used begin time, end time and increment but for some reasons, probably
size, this crashes Grads. In addition, this would not do the job very well
anyhow as a constant time increment (365 days) does not respect the leap
year (and the calculation of SD jan 1 would use Nov 2/1996 e.g.).

A solution that accesses the nc-files seperately and uses t=1 to t=365
would be fine (ignoring leap years), in my opinion.

Cheers,
Paul

I use
v1.8SL11 32-bit little-endian readline sdf/xdf netcdf lats printim


On Wed, 11 Feb 2009 16:06:14 +0100, Stergios Misios
<stergios.misios at ZMAW.DE> wrote:

>You can do it easily with the following segment,
>mean=ave(variable,t=start_time,t=end_time)
>std=sqrt(ave(pow(variable-mean,2)),t=start_time,t=last_time)*
(number_of_time_steps/(number_of_time_steps-1))
>
>Good luck,
>Stergios