<html><head></head><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1512489722799_3785"><span id="yui_3_16_0_ym19_1_1512489722799_3864">Dear NCL users,</span></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512489722799_3823"><span id="yui_3_16_0_ym19_1_1512489722799_3866">I am very new on NCL and I am trying to filter my rainfall data using Lanczos Filter (bandpass 10-90 day filtering). My question concerns the processing of the weights. I would like to know <br></span></div><div id="yui_3_16_0_ym19_1_1512489722799_3884" dir="ltr"><span id="yui_3_16_0_ym19_1_1512489722799_3866">1-is there any relationship between the number of weights to choose and the cutoff frequencies?</span></div><div id="yui_3_16_0_ym19_1_1512489722799_3929" dir="ltr"><span id="yui_3_16_0_ym19_1_1512489722799_3866">2-is there any practical criterion to choose the number of weights? I know that this number influences the loss of data.</span></div><div id="yui_3_16_0_ym19_1_1512489722799_4139" dir="ltr"><span id="yui_3_16_0_ym19_1_1512489722799_3866">Below is my code:</span></div><div id="yui_3_16_0_ym19_1_1512489722799_4147" dir="ltr"><span id="yui_3_16_0_ym19_1_1512489722799_3866"><br>----------------------------------------------------------------------------------------------------------------------------------------------------------------------</span></div><div id="yui_3_16_0_ym19_1_1512489722799_3965" dir="ltr"><span id="yui_3_16_0_ym19_1_1512489722799_3866">;import the file<br id="yui_3_16_0_ym19_1_1512489722799_4027">gpcp=addfile("gpcp_Sahel.nc","r")<br id="yui_3_16_0_ym19_1_1512489722799_4028">rr=gpcp->precip<br id="yui_3_16_0_ym19_1_1512489722799_4029">;filter parameters<br id="yui_3_16_0_ym19_1_1512489722799_4030">ihp=2 ;bandpass<br id="yui_3_16_0_ym19_1_1512489722799_4031">sigma=1.0 ; Lanczos sigma<br id="yui_3_16_0_ym19_1_1512489722799_4032">nWgt = 81 ; number of weights -> means 40 data lost at the beginning and 40 data lost at the end. <br id="yui_3_16_0_ym19_1_1512489722799_4033">fca = 1./90. ; start freq ;highpass= 90 days<br id="yui_3_16_0_ym19_1_1512489722799_4034">fcb = 1./10. ; last freq; lowpass= 10 days<br id="yui_3_16_0_ym19_1_1512489722799_4035">wgt = filwgts_lanczos (nWgt, ihp, fca, fcb, sigma )<br id="yui_3_16_0_ym19_1_1512489722799_4036">printVarSummary(wgt)<br id="yui_3_16_0_ym19_1_1512489722799_4037">xBPF = wgt_runave_n_Wrap ( rr, wgt, 0, 0) ; 10-90 day bp performed across time dimension(0) of rr (meaning the time dimension)<br id="yui_3_16_0_ym19_1_1512489722799_4038"></span></div><div id="yui_3_16_0_ym19_1_1512489722799_3786"><div id="yui_3_16_0_ym19_1_1512489722799_4166"> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------</div><div id="yui_3_16_0_ym19_1_1512489722799_4167"><br></div><div id="yui_3_16_0_ym19_1_1512489722799_4168"><br></div><div id="yui_3_16_0_ym19_1_1512489722799_4157"><br></div><div id="yui_3_16_0_ym19_1_1512489722799_4158"><br></div><div id="yui_3_16_0_ym19_1_1512489722799_4169"><br></div><div id="yui_3_16_0_ym19_1_1512489722799_4170">Cheers,<br></div></div><div id="yui_3_16_0_ym19_1_1512489722799_3869" class="signature"><br>GUIGMA</div></div></body></html>