<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div id="yui_3_16_0_ym19_1_1518843635550_3067">Dear Ncl-talk,</div><div id="yui_3_16_0_ym19_1_1518843635550_4611" dir="ltr">Is there a way to interpolate or convert as well as to plot a 4D (time,level,lat,lon) variable that is already on pressure levels (hPa) to height levels (m)? In other words, my goal is to plot the data in height levels (m) rather than in hPa. I am aware of the "gsn_csm_pres_hgt_vector" function for plotting, however, it only plots pressure levels on the Y-axis left side which it uses as the main axis for its plot and not the Y-axis right side. I even came upon an example from NCL archive (<a href="http://www.hao.ucar.edu/modeling/tgcm/NCL/Graphics/Scripts/zplat_6.ncl" id="yui_3_16_0_ym19_1_1518843635550_9393">http://www.hao.ucar.edu/modeling/tgcm/NCL/Graphics/Scripts/zplat_6.ncl</a>) which I used but to no avail. I got error messages: fatal:Undefined identifier: (halfzp) is undefined, can't continue; fatal:["Execute.c":8640]:Execute: Error occurred at or near line 16 in file zplat.ncl. I know I don't have the "halfzp" identifier. I thought it's one of NCL resources. I have attached my script and the ".nc" file for your perusal.<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1518843635550_9173">Any assistance on the best way to go would be greatly appreciated. <br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1518843635550_9651">Many thanks.</div><div dir="ltr" id="yui_3_16_0_ym19_1_1518843635550_9174">Dave <br></div></div></body></html>