Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum

correction to RUC land-surface fields at 18z today

Posted By: Stan Benjamin
Date: 11-June-08 1452Z

Hello, A horizontal shift error of about ~3-4km in land-surface fields was found in the RUC. New, corrected fields are planned to be corrected in the operational RUC at 18z today. The fields to be corrected are: terrain elevation, vegetation type (including land-water mask), and soil type. A comparison from southern Lake Michigan for 2m temps with old and new land-surface fields is available at: http://www.emc.ncep.noaa.gov/mmb/ruc2/test/ruc2mtmi_2008060912f000.gif The correction will improve the accuracy for RUC surface forecasts, especially near coastlines. The erroneous shift put water surface type over actual land points on the W-SW sides of bodies of water (like Lake Michigan), and put land surface type over actual water points on the E-NE sides of those same bodies of water (as shown in example). In the example, the coastline appears much more reasonable with the correction. ASCII versions of the new topo, vegtype, and soiltype fields are available at http://ruc.noaa.gov/fslparms/13km/jun08/. The current (pre-18z) corresponding fields are available in http://ruc.noaa.gov/fslparms/13km/. The correction will improve the accuracy for RUC surface forecasts, especially near coastlines. Thanks to Joe Koval at the Weather Channel for his role in drawing attention to this problem. If you don't hear otherwise after 18z, you can conclude that this change went in. Stan Benjamin

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