<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jun 2, 2015 at 7:14 PM, LI Qi <span dir="ltr"><<a href="mailto:liqi123sh@qq.com" target="_blank">liqi123sh@qq.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">Dear grads community,</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><br></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">I don't really understand how the wrfout projection works in grads.</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">Below is a descriptor file from ARWpost as an example.</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">The model domain is using lambert conformal projection with grid spacing of 30 km.</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><div style="line-height:21px">title OUTPUT FROM WRF V3.7 MODEL</div><div style="line-height:21px">pdef 231 171 lcc 35.178 110.000 116.000 86.000 60.<span data="https://ci5.googleusercontent.com/proxy/4AIRDujH04wILi5eDSi5L1pSO6piiiwBHvDNZrI53oOSyw=s0-d-e1-ft#http://00000" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">00000</span> 30.<span data="https://ci5.googleusercontent.com/proxy/4AIRDujH04wILi5eDSi5L1pSO6piiiwBHvDNZrI53oOSyw=s0-d-e1-ft#http://00000" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">00000</span> 110.<span data="https://ci5.googleusercontent.com/proxy/4AIRDujH04wILi5eDSi5L1pSO6piiiwBHvDNZrI53oOSyw=s0-d-e1-ft#http://00000" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">00000</span> <span data="https://ci6.googleusercontent.com/proxy/riJaSKlkOdWvFX7X1wsCGVDecaoU0IcE7WDdNZgQ08Z24g=s0-d-e1-ft#http://30000" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">30000</span>.000 <span data="https://ci6.googleusercontent.com/proxy/riJaSKlkOdWvFX7X1wsCGVDecaoU0IcE7WDdNZgQ08Z24g=s0-d-e1-ft#http://30000" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">30000</span>.000</div><div style="line-height:21px">xdef 783 linear 57.<span data="https://ci3.googleusercontent.com/proxy/ghA1DDxOOyDGER-n8_iAB28M73YFZs9O_v_8JvrV3kswJg=s0-d-e1-ft#http://03648" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">03648</span> 0.<span data="https://ci5.googleusercontent.com/proxy/JEzJaWAhAxks6vnvEDGQVU6xwCgxcIxxxeoeStU809ASQOznjw=s0-d-e1-ft#http://13513513" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">13513513</span></div><div style="line-height:21px">ydef 392 linear 7.<span data="https://ci5.googleusercontent.com/proxy/UemK70PEmsnU6CMf5IIbzhBHHCao6e5fMBtM3pn30wmASA=s0-d-e1-ft#http://01026" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">01026</span> 0.<span data="https://ci5.googleusercontent.com/proxy/JEzJaWAhAxks6vnvEDGQVU6xwCgxcIxxxeoeStU809ASQOznjw=s0-d-e1-ft#http://13513513" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">13513513</span></div><div style="line-height:21px">zdef 19 levels </div></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><br></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">My question is:</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">[1] Do "xdef" and "ydef" mean the data have been interpolated with resolution of 0.<span data="https://ci5.googleusercontent.com/proxy/JEzJaWAhAxks6vnvEDGQVU6xwCgxcIxxxeoeStU809ASQOznjw=s0-d-e1-ft#http://13513513" style="border-bottom-width:1px;border-bottom-style:dashed;border-bottom-color:rgb(204,204,204)">13513513</span> deg? But the original resolution is approximately 0.27 deg.</div></blockquote><div>Yes. XDEF and YDEF can be whatever value you want. XDEF and YDEF control the resolution of the plotted data, but do not change the resolution of the raw model output. Think of it as a sampling rate. You can sample a signal more frequently to get smoother looking data, but the data themselves are not changed.<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">[2] How are the xsize of 783 and ysize of 392 derived?<br></div></blockquote><div>In ARWpost, the code finds the maximum and minimum latitude and longitude value in your model grid and divide the distance by some arbitrary fraction (hard-coded within the program) <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">[3] If I would like to remap observations onto the wrf model output to facilitate comparisons, should I remap the obs onto the original 0.27deg-resolution grid, or the interpolated 0.135deg-res grid? Is the latter feasible?</div></blockquote><div>That's your call, but you'll get "the right" kind of comparison if you stick to the native model grid.<br><br></div><div>You can set the namelist parameter to grads_low_res to .true. to tell the program to ignore these arbitrary settings and just stick to your raw model grid for the control file XDEF and YDEF entries. If you want to use ARWpost, I recommend doing that.<br><br></div><div>ARWpost is somewhat outdated software, however. I would recommend using the Unified Post Processor software. There are no weird issues about different grid settings when you use it.<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><span style="line-height:23.7999992370605px"><br></span></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><span style="line-height:23.7999992370605px">Your reply would be much appreciated!</span></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px"><br></div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">Best,</div><div style="font-family:'lucida Grande',Verdana,'Microsoft YaHei';line-height:23.7999992370605px">Qi</div><br>_______________________________________________<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature">Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br></div>
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