# Re: Alternative for rmMonAnnCycTLL?

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,

> 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,
>
> 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
>>
>>
>
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*************************************
Soumik Basu
International Arctic Research Center