From: Soumik Basu <sbasu_at_nyahnyahspammersnyahnyah>

Date: Fri Sep 06 2013 - 10:59:53 MDT

Date: Fri Sep 06 2013 - 10:59:53 MDT

Thanks for the reply.

If I put 751 weights I get this error

fatal:wgt_runave_n: The length of wgt must be less than or equal to the

dim-th dimension of x

fatal:["Execute.c":8128]:Execute: Error occurred at or near line 6664 in

file $NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl

fatal:["Execute.c":8128]:Execute: Error occurred at or near line 188 in

file eke_x8.ncl

So I guess as I have 360 time steps (Dec to Jan 6 hourly data) I have to

lesser no. of weights than 360.

I am wondering if it is possible that using wrong number of weights will

make the weighted running average to give out wrong results?

Thanks,

Soumik

-- "Numbing the pain for a while will make it worse when you finally feel it. ~J.K. Rowling" ***************************************** Soumik Basu Graduate Student, Research Assistant International Arctic Research Center University of Alaska Fairbanks Fairbanks,Alaska,USA ***************************************** On 2013-09-05 16:59, Dennis Shea wrote: > For 2 to 6 daya [ 1.0/(2*365) to 1.0/(6*365) cycles per year] > > You need a *lot* of weights: say 751 > > On 9/5/13 4:37 PM, Soumik Basu wrote: > Hi, > > I am trying to a band pass filter 0f 2-6 days. My data has 6 hourly > time > steps. My questions are: > > 1) For using 2-6 days band pass filter on transient eddy kinetic energy > how many weights should I use? I am using 101 weights. > > 2)How can negative values come when it does not have any negative > values > before doing the running average. > > Here is the printVarSummary before running average > > Variable: eke775 > Type: float > Total Size: 47185920 bytes > 11796480 values > Number of Dimensions: 3 > Dimensions and sizes: [time | 360] x [lat | 128] x [lon | 256] > Coordinates: > time: [30.5..120.25] > lat: [-88.92773535229591..88.92773535229591] > lon: [ 0..358.59375] > Number Of Attributes: 2 > lev_p : 775 > _FillValue : 9.96921e+36 > (0) > (0) min=6.84898e-06 max=2269.73 > > Here is the printVarSummary and min max after running average > > > Variable: eke_f > Type: float > Total Size: 47185920 bytes > 11796480 values > Number of Dimensions: 3 > Dimensions and sizes: [time | 360] x [lat | 128] x [lon | 256] > Coordinates: > time: [30.5..120.25] > lat: [-88.92773535229591..88.92773535229591] > lon: [ 0..358.59375] > Number Of Attributes: 3 > lev_p : 775 > _FillValue : 9.96921e+36 > wgt_runave_op_ncl : wgt_runave_n > (0) > (0) min=-689.534 max=1134.18 > > > This is the part of the script I am using for filtering and running > average: > > ;******************************************************* > ; Calculate band pass filter weights > ;******************************************************* > ;lanczos weights for 2-6 day bandpass using 6-hourly data > > > ;number of timesteps in low pass cutoff -- in this case 6 days (6*4 = > 24 > time steps) > > > low = 24 > > > ;number of timesteps in high pass cutoff -- in this case 2 days (8 time > steps) > > > high= 8. > > > nwt = 101 ;A scalar indicating the total number of weights > > ;(must be an odd number; nwt >= 3). > > ;The more weights, the better the filter, but there is a > > ;greater loss of data. > > fca = 1./low ;A scalar indicating the cut-off frequency of the ideal > > ;high or low-pass filter: (0.0 < fca < 0.5) > > fcb = 1./high ;A scalar used only when a band-pass filter is desired. > > ;It is the second cut-off frequency (fca < fcb < 0.5). > > ihp = 2 ;A scalar indicating the low-pass filter: > > ;ihp = 0; high-pass ihp = 1; band-pass ihp = 2. > > nsigma = 1. ;A scalar indicating the power of the sigma factor > (nsigma > >= 0). > > ;Note: nsigma=1. is common. > > > ; compute weights > > > wts = filwgts_lancos (nwt, ihp, fca, fcb, nsigma) > > > print(wts) > > > print(wts@resp+" "+wts@freq) > > > ;******************************************************** > ; apply lanczos wts to 6 hourly data -> band pass filtering > ;******************************************************** > > > eke_f = wgt_runave_n_Wrap(eke775,wts,0,0) > > > printVarSummary(eke_f) > printMinMax(eke_f,True) > > Thanks, > Soumik > > > > > _______________________________________________ > ncl-talk mailing list > List instructions, subscriber options, unsubscribe: > http://mailman.ucar.edu/mailman/listinfo/ncl-talk _______________________________________________ ncl-talk mailing list List instructions, subscriber options, unsubscribe: http://mailman.ucar.edu/mailman/listinfo/ncl-talkReceived on Fri Sep 6 11:00:05 2013

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