<div dir="ltr">Dear NCL experts,<div><br></div><div>I'm looking for a method of band-pass filtering on a shpere using NCL.</div><div>"<a href="https://mailman.ucar.edu/pipermail/ncl-talk/2019-May/014800.html" target="_blank">https://mailman.ucar.edu/pipermail/ncl-talk/2019-May/014800.html</a>"<br></div><div>The above URL is the advice of that in ncl-talk.</div><div>Following the advice, I'm trying as below.</div><div>***------- ncl scripts</div><div>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp = f->Z_GDS0_ISBL ; geopotential in ERA5(GRIB)<br></p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue";min-height:15px"><br></p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">lon = tofloat(Gp&g0_lon_2)</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp_w1<span>  </span>= Gp</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp_w5<span>  </span>= Gp</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp_a <span>  </span>= Gp</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue""><br></p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">spec_harmonics = shaeC(Gp) ; to spherical harmonics domain</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">spec_w1<span>  </span>= tri_trunC(spec_harmonics,1) ; truncate </p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">spec_w5<span>  </span>= tri_trunC(spec_harmonics,5) ; truncate</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">spec_a <span>  </span>= where(spec_w1.eq.spec_w5,0,spec_w5) ; band-pass filtering (1<n<=5)  </p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue";min-height:15px"><br></p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue";min-height:15px">Gp_w1<span>    </span>= shseC(spec_w1,dimsizes(lon)) ; return to physical domain<br></p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp_w5<span>    </span>= shseC(spec_w5,dimsizes(lon)) ; return to physical domain</p>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Gp_a <span>    </span>= shseC(spec_a ,dimsizes(lon))    ; return to physical domain</p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue""><span style="font-family:Arial,Helvetica,sans-serif;font-size:small">***-------</span><br></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue""><span style="font-family:Arial,Helvetica,sans-serif;font-size:small">I want to remain only the wavenumber from 2 to 5 of geopotential(so consider about n=2,3,4,5). </span></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue"">Is this the right process for band-pass filtering on a sphere?</p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:13px;line-height:normal;font-family:"Helvetica Neue""><br></p></div><div>Thank you,</div><div>Minwoo Kim</div><div><div><div dir="ltr" data-smartmail="gmail_signature"><div dir="ltr"><div><p style="color:rgb(17,17,17);font-family:"line-height:1.5;position:relative;top:-3px;padding-bottom:8px;font-weight:bold;";font-size:inherit;margin:0px;padding:0px;word-break:break-all">---------------</p></div>김 민우<div><span style="color:rgb(136,136,136);font-family:"line-height:17px;";font-size:12px">연구원</span><span style="font-family:"line-height:17px;";font-size:12px;padding:0px 6px;color:rgb(215,215,215)">|</span><span style="color:rgb(136,136,136);font-family:"line-height:17px;";font-size:12px">공주대학교 종관기상연구실</span><br></div><div><table cellspacing="0" cellpadding="0" border="0" style="color:rgb(17,17,17);font-family:"Apple SD Gothic Neo","Malgun Gothic","\00b9d1\00c740  \00ace0\00b515",sans-serif;font-size:13.3333px;width:568px"><tbody><tr><td style="color:rgb(136,136,136);font-size:12px;font-family:"line-height:17px;";line-height:1.5"><p style="margin:0px;padding:0px"><span style="font-weight:bold;color:rgb(17,17,17)">m</span> 010-7708-9120<span style="padding:0px 6px;color:rgb(215,215,215)">|</span><span style="font-weight:bold;color:rgb(17,17,17)">e</span> <a href="mailto:minwookim.9120@gmail.com" target="_blank">minwookim.9120@gmail.com</a></p></td></tr><tr><td style="color:rgb(136,136,136);font-size:12px;font-family:"line-height:17px;";line-height:1.5"><table cellspacing="0" cellpadding="0" border="0" style="width:568px"><tbody><tr><td style="font-family:"line-height:17px;";line-height:1.5"><p style="margin:0px;padding:0px"><span style="font-weight:bold;color:rgb(17,17,17)">a</span> 충청남도 공주시 공주대학로 56, 자연과학대학 445호</p></td></tr></tbody></table><p style="margin:0px;padding:0px"><br style="color:rgb(17,17,17);font-family:"Apple SD Gothic Neo","Malgun Gothic","\00b9d1\00c740  \00ace0\00b515",sans-serif;font-size:13.3333px"></p></td></tr></tbody></table></div></div></div></div></div></div>