<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Arial; font-size: 12pt; color: #000000'>Hello Oli,<div><br></div><div>I can only answer your first question. I downloaded the file you mentioned, and it seems to have corrupt and/or missing GRIB2 metadata. It's not viewable in grads. There is another ftp server which has the NESDIS-IMS snow cover/sea ice data:</div><div><br></div><div><span class="Object" id="OBJ_PREFIX_DWT3065" style="color: rgb(0, 0, 139); text-decoration: none; cursor: pointer; "><a target="_blank" href="ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/dcom/us007003/20121113/wgrbbul/" style="color: rgb(0, 0, 139); text-decoration: none; cursor: pointer; ">ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/dcom/us007003/20121113/wgrbbul/</a></span><br><br></div><div>Only the most recent data is kept on the server. In the us007003 directory, there are 3 subdirectories named by date, and data is usually available only for the middle date. There are two files of interest:</div><div><br></div><div>imssnow.grb.grib2 - NESDIS-IMS snow cover/sea ice at 24km resolution</div><div>imssnow96.grb.grib2 - NESDIS-IMS snow cover/sea ice at 4km resolution</div><div><br></div><div>Each dataset is on a north polar stereographic grid. The snow cover looks OK in both files, while the sea ice looks fine in the 24km product but is zero everywhere in the 4km product. I've used WRF before (not recently) and I think WPS can handle the interpolation from the polar stereo grid to the WRF grid. In the Vtable, you need to change the parameter number from 42 to 201 in the GRIB2 section. However, converting the snow cover data into something that WRF can use (such as water equivalent accumulated snow depth) requires an empirical algorithm and is beyond my expertise.</div><div><br></div><div>Best regards,</div><span><br><br><span name="x"></span>Eric L. Altshuler<br>Assistant Research Scientist<br>Center for Ocean-Land-Atmosphere Studies<br>4041 Powder Mill Road, Suite 302<br>Calverton, MD 20705-3106<br>USA<br><br>E-mail: ela@cola.iges.org<br>Phone: (301) 902-1257<br>Fax: (301) 595-9793<span name="x"></span><br></span><br><hr id="zwchr"><b>From: </b>"Ólafur Rögnvaldsson" <or@belgingur.is><br><b>To: </b>wrf-users@ucar.edu<br><b>Sent: </b>Wednesday, November 7, 2012 5:21:30 PM<br><b>Subject: </b>[Wrf-users] How to use NESDIS snow cover data in WRF<br><br>Dear fellow WRF-users.<br><br>I was wondering if you could assist me in one matter. We would like to start using the daily (more or less) snow cover updates from NESDIS to improve (hopefully:) our operational forecasts here in Iceland.<br><br>Could you please inform me about how one should make the most of these data? In particular:<br><br>1) Is this the proper ftp-site for downloading the snow-cover (grib) files: ftp://140.90.213.161/autosnow/4kmNH/ ?<br>2) What changes should one make to the Vtable file?<br>3) Is there some code modification (and/or additions) that need to be done to WRF and/or WPS?<br><br>In particular, I was unable to ungrib this file:<br><br>ftp://140.90.213.161/autosnow/4kmNH/NH4km_autosnow_11042012.grb<br><br>using this Vtable snipped:<br><br>GRIB1| Level| From | To | metgrid | metgrid | metgrid |GRIB2|GRIB2|GRIB2|GRIB2|<br>Param| Type |Level1|Level2| Name | Units | Description |Discp|Catgy|Param|Level|<br>-----+------+------+------+----------+---------+-----------------------------------------+-----------------------+<br> 42 | 1 | 0 | | SNOWCOVER| 0/1 | Snow cover | 0 | 1 | 42 | 1 |<br><br>as I get the following error message:<br><br>or@dofri:~/dofri/wrf/V3.3.1/WPS$ ./ungrib.exe <br> *** Starting program ungrib.exe ***<br>Start_date = 2012-11-04_08:10:00 , End_date = 2012-11_04_08:20:00<br>output format is WPS<br>Path to intermediate files is ./<br> ungrib - grib edition num 2<br>ERROR: Time unit in ipdtmpl(8), 4 is not suported<br>Warning: ieee_inexact is signaling<br>FORTRAN STOP<br><br>Looking forward to read your advice.<br><br>Kind regards, Óli.<br>--<br>Kveðja/regards,<br>Ólafur Rögnvaldsson<br>Reiknistofa í veðurfræði - Belgingur<br>www.riv.is - www.belgingur.is<br><br><br>_______________________________________________<br>Wrf-users mailing list<br>Wrf-users@ucar.edu<br>http://mailman.ucar.edu/mailman/listinfo/wrf-users</div></body></html>