Re: how to use the ncl program of Lancos filter

Hello,

There are two possible issues here. First, make sure that your data
array has the FillValue attribute assigned to it. If it doesn't, and
there isn't a missing_value attribute either, then do this:

(I am referring to the data array that you will be passing into
wgt_runave, below I named it finarr)

finarr@_FillValue = 1.e+20

If finarr already has a missing_value attribute assigned to it, you can
simply do this:
finarr@_FillValue = finarr_at_missing_value

Second, you will get missing values at the beginning and end of the
output of wgt_runave. The number will be equal to whatever you set nwt
to in filwgts_lancos -1. For instance, if you set nwt to 501, after
weighting your output timeseries will have the first 250 timesteps
missing, and the last 250 timesteps missing.

You generally want to set nwt to as large a value as possible, as the
larger the number of weights the more accurate the filter. The downside
of this is that the larger nwt is, the more timesteps will be missing at
the beginning/end of your timeseries after weighting...

Good luck,
Adam

temeching gladice joelle wrote:
> Hi Everyone
>
>
> Please, i want to use NCL program of lancos filter to filter OLR data
> I use the publication of Adrian J. Matthews: Intraseasonal variability
> over Tropical Africa during Northern Summer; J. Climate; vol 17 pp 2427-2440
> I am trying to filter out the band-pass-frequency signal and
> using "wgt_runave" to compute this with lancos weights
> But the output file contains many missing value denoted by nan
>
>
> if anyone can tell me how to filter out it in using NCL
> build-in function or has any other method for the band-pass filter
> Thanks
>
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-- 
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Adam Phillips			             asphilli_at_ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000	  http://www.cgd.ucar.edu/cas/asphilli
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