<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div><div><div>I am regridding a mask from coarse to fine resolution. The mask is a monthly binary field developed to remove spurious ice from certain satellite products (<a href="http://nsidc.org/data/docs/daac/nsidc0622-valid-ice-masks/">http://nsidc.org/data/docs/daac/nsidc0622-valid-ice-masks/</a>). Mask = 1 where ice is valid, and Mask = 0 where ocean is valid. There are other flags for land/coastal land that I can ignore as well with the following command:</div></div></div><span id="OLK_SRC_BODY_SECTION"><span style="mso-bookmark:_MailOriginalBody"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div><br></div><div>NIC_mask<span class="Apple-tab-span" style="white-space:pre"> </span>= where (NIC_Flag.ne.1, default_fillvalue("integer"), NIC_Flag)</div></div></span></span><span id="OLK_SRC_BODY_SECTION"><span style="mso-bookmark:_MailOriginalBody"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div><br></div><div>As an interim step, I spit out “NIC_mask” to it’s own NC file and opened with NC View. Please see “OriginalMask.png” attached. </div><div><br></div><div>Later on in the code, I chose Opt@InterpMethod = “bilinear” as I figured it was quickest and didn’t matter much since I’m dealing with 1’s and fill values. However, it looks like there is a not so insignificant amount of information being lost near the coastlines in the resulting interpolation. Please see a similar screen grab “BilinearInformationLoss.png” attached for the result generated by ESMF_Regrid. </div><div><br></div><div>Since the regridding takes a while (20+ minutes) on my desktop for bilinear, and an unknown time for other interpolation methods, I have not tested each one. I figured running “neareststod” could produce more accurate results but I’ve let the code run for hours and it seems to be getting hung up…somewhere. </div><div><br></div><div>I was wondering if the folks have some explanation as to why bilinear would smearing the coastlines, or recommendations for avoiding this.</div><div><br></div><div>I suppose I can try to regrid a small subset that includes coastal regions with different methods as a next step to save time….</div><div><br></div><div>Thank you for the discussion,</div><div>Greg</div><div><br></div><div>--</div><div><div id=""><div><div><br></div></div><div><div style="font-family: -webkit-standard;"><b>Greg Deemer</b></div><div style="font-family: -webkit-standard;">User Services Office</div><div style="font-family: -webkit-standard;">National Snow and Ice Data Center</div><div style="font-family: -webkit-standard;">(303) 735-8068</div><div style="font-family: -webkit-standard;"><a href="http://nsidc.org/">http://nsidc.org</a></div><div style="font-family: -webkit-standard;">Twitter: @NSIDC</div></div></div></div></div></span></span></body></html>