Re: Alternative for rmMonAnnCycTLL?

From: <sbasu_at_nyahnyahspammersnyahnyah>
Date: Thu Feb 03 2011 - 17:34:44 MST

Hi,

I got the mean and I am trying to add a 10 year filter before doing the
mean calculation. I am using the function "filwgts_lanczos" and here is
that portion of my script.

;************************************************
; Filtering
;************************************************

            dt = 1 ; 1 month per time step
            t1 = 12 ; 1yrs or 12 months (low frequency cutoff,
expressed in time domain)
            t2 = 120 ; 10 yrs or 120 months (high frequency
cutoff, expressed in time domain)

            fca = dt/t1 ; (low frequency cutoff)
            fcb = dt/t2 ; (high frequency cutoff)
    nwt = 3
    ihp = 0
    nsigma = 1.
    wgt = filwgts_lanczos (nwt, ihp, fca, fcb, nsigma)
    opt =0
    sst = wgt_runave_n (sst, wgt, opt,0)
   printVarSummary(sst)

For doing 10yr filter is this a correct function to use? My dataset is
monthly sst from NOAA Reconstructed. Have I defined t1 and t2 values
properly in order to get 10yr filter?

Thanks,

Adam Phillips wrote:
> Hi Soumik,
> There are various other functions that do the same thing. Take a look at
> this list:
> http://www.ncl.ucar.edu/Document/Functions/climo.shtml
>
> There are various forms of rmMonAnnCycTLL (ex. rmAnnCyc1e1D), along with
> functions that calculate the climatology (ex. clmMonLLT), and other
> functions that take the climatology and remove it from an array (ex.
> calcMonAnomLLT).
>
> Now, of course, you could remove the annual cycle manually with a do
> loop like this:
>
> ; arr is an array dimensioned time x lat x lon, starts in Jan,
> ; ends in Dec. (UNTESTED)
>
> do gg = 0,11
> arrT = arr(gg::12,:,:)
> mon_avg = dim_avg_n_Wrap(arrT,0)
> printVarSummary(mon_avg)
> mon_avg_c = conform(arrT,mon_avg,(/1,2/))
> printVarSummary(mon_avg_c)
> delete(mon_avg)
> arr(gg::12,:,:) = (/ arrT - mon_avg_c /)
> delete(mon_avg_c)
> delete(arrT)
> end do
>
> Good luck,
> Adam
>
> On 02/03/2011 03:12 PM, sbasu@iarc.uaf.edu wrote:
>> Hi,
>>
>> Is there any other way to calculate monthly anomalies from monthly SST
>> data other than using "rmMonAnnCycTLL" ?
>>
>> Thanks,
>> Soumik
>>
>>
>
> --
> __________________________________________________
> Adam Phillips
> asphilli@ucar.edu
> National Center for Atmospheric Research tel: (303) 497-1726
> Climate and Global Dynamics Division fax: (303) 497-1333
> P.O. Box 3000
> Boulder, CO 80307-3000 http://www.cgd.ucar.edu/cas/asphilli
> _______________________________________________
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>

-- 
*************************************
Soumik Basu
Graduate Student, Research Assistant
International Arctic Research Center
University of Alaska Fairbanks
Fairbanks,Alaska,USA
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Received on Thu Feb 3 17:35:04 2011

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