This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Matt, I guess first thing is to make sure that you can use the us.west grid file that I provided in the tar file. If needed, I can make a file for another area you need. If the tercnvrt program is the culprite in creating your direct access file, then I should check what operating system you are running on, and your compiler version. I can see if I can duplicate your trouble here. Steve Chiswell Unidata User Support >From: "Matthew G. Fearon" <address@hidden> >Organization: Desert Research Institute >Keywords: 199912172159.OAA25747 >Steve, > >I tried running the program interactively and I received the following >error message. I am thinking something is wrong with the terrain.gsf >file or the tercnvrt.f program. I will continue to tinker with things, >but I thought I would send you these errors since they are >different. > >Thank you again, >Matt > > >fire:/opt/nawips-5.4/terrain 74 > gdtopo > GDFILE Grid file $GEMDATA/HRCBOB.GRD > GAREA Grid area WV > GDATTIM Grid date/time LAST > TOPOFL Topography file name > Parameters requested: GDFILE,GAREA,GDATTIM,TOPOFL. > GEMPAK-GDTOPO>gdfile=us.west > GEMPAK-GDTOPO>garea=25;-125;45;-105 > GEMPAK-GDTOPO>gdattim=990101/1200 > GEMPAK-GDTOPO>topofl=terrain.gsf > GEMPAK-GDTOPO>r > look read 80 > terrain.gsf > look access 11 0 > here 41095 > look REC 534236 1.000000 >fmt: read unexpected character >apparent state: unit 11 named terrain.gsf >last format: (2i5) >Unit 11 is a direct formatted external file >*** Execution Terminated (115) *** > > > >Unidata Support wrote: > >> Matt, >> >> the error message implies that the terrain.gsf data file >> is not being found. Since you know that the file does exist, >> you might need to verify that: >> 1) Your file permissions allow you to access the file from the >> path. >> 2) The line in your script where you define >> TOPOFL = /data1/nawips-5.4/terrain/terrain.gsf >> >> check for any typos in the path or hidden cntrl characters >> (sometimes text editors can stick in a ^H or something if you backspace >> and fudge a character). >> >> 3) try running the program interactively instead of from your redirection >> to eliminate the above possibility. >> >> Steve Chiswell >> Unidata User Support >> >> >From: "Matthew G. Fearon" <address@hidden> >> >Organization: Desert Research Institute >> >Keywords: 199912172026.NAA22512 >> >> >Steve, >> > >> >Thank you for this information. It will be very helpful to me. >> >I followed all the procedures after retrieving the terrain.tar.Z >> >file. I made a direct access binary file from the ascii as well. I >> >received the normal completion message after running >> >tercnvrt. When I run gdtopo however, I receive the following >> >error >> > >> >$GEMEXE/gdtopo << EOF >> > GDFILE Grid file $GEMDATA/HRCBOB.GRD >> > GAREA Grid area WV >> > GDATTIM Grid date/time LAST >> > TOPOFL Topography file name >> > Parameters requested: GDFILE,GAREA,GDATTIM,TOPOFL. >> > GEMPAK-GDTOPO> GEMPAK-GDTOPO> GEMPAK-GDTOPO> GEMPAK-GDTOPO> GEMPAK-GDTOPO> > [G >> > DT >> >OPO -12] Topography file does not exist. >> > Parameters requested: GDFILE,GAREA,GDATTIM,TOPOFL. >> > GEMPAK-GDTOPO> GEMPAK-GDTOPO> >> > >> >rm *.nts >> > >> >Here is my gdtopo program: >> > >> >$GEMEXE/gdtopo <<EOF >> >GDFILE = us.west >> >GAREA = 25;-125;45;-105 >> >GDATTIM = 990101/1200 >> >TOPOFL = /data1/nawips-5.4/terrain/terrain.gsf >> >r >> > >> >exit >> > >> >EOF >> > >> >#$GEMEXE/gpend >> >rm *.nts >> > >> >The terrain.gsf file does exist. Do you know what may be >> >the problem ? Please reply at your convienence. Thank you >> >again for all your help. >> > >> >Matt Fearon >> >address@hidden >> > >> > >> > >> > >> >Unidata Support wrote: >> > >> >> Matt, >> >> >> >> All models use some smoothed form of surface data since using >> >> terrain data at a higher resolution than the grid and/or large >> >> discontinuities inadjacent grid point values will cause the model >> >> to blow up with anomalous gravity waves and non-hydrostatic >> >> forcing. >> >> >> >> The ETA model employs a step terrain. There are some points about >> >> the difference in actiual station elevation and the model elevation in >> >> the 32km ETA whitepaper at: >> >> http://www.nws.noaa.gov/om/447body.htm >> >> >> >> You can also look at the FSL RUC 40km topography at: >> >> http://maps.fsl.noaa.gov/40kmtopocol.gif >> >> They also have ascii 40km and 60km topography datasets for download at: >> >> http://maps.fsl.noaa.gov/MAPS.domain.cgi >> >> >> >> We do have a 5 minute (approx 10km) gridded topography dataset for >> >> Gempak which you can use as a gridded data set (eg gdlist, gdpoint etc). >> >> >> >> To use the gempak terrain dataset, download from the gbuddy ftp account >> >> nawips-5.4/contrib/terrain.tar.Z >> >> >> >> and unpack on your system with: >> >> >> >> zcat terrain.tar.Z | tar xvf - >> >> >> >> This will create a directory called terrain which containe >> >> the ascii terrain data set (63 Mb) and a program directory called >> >> gdtopo which can be used to convert the data into a gempak >> >> grid file. >> >> >> >> First you need to convert the ascii terrain file into a direct access >> >> file (like a gempak map datafile). To do this, you need to build the >> >> tercnvrt program from the fortran code with: >> >> >> >> f77 -o tercnvrt tercnvrt.f >> >> >> >> Then run tercnvrt to create the direct access file, eg: >> >> >> >> prompt% tercnvrt >> >> >> >> Please enter name of original terrain dataset: terrain.ascii >> >> ^^^^^^^^^^^^^ >> >> Now enter name of file which will >> >> contain sector of terrain data: terrain.gsf >> >> ^^^^^^^^^^^ >> >> >> >> Now build and install gdtopo by cd'ing into the gdtopo directory >> >> and building with: >> >> >> >> make all >> >> make install >> >> make clean >> >> >> >> (This will install the gdtopo program into the $GEMEXE directory and >> >> install the ancillary pdf files as well). >> >> >> >> Now you can create a grid file for some area. Since the maximum number of >> >> grid points by default in a gempak grid file is ~97,000 points, this >> >> is approximately 311x311 grid points (for the 5 minute data set this is >> >> roughly 25 degrees x 25 degrees). In otherwords, even though the database >> >> covers the entire globe, you can only view a 25 degree square at a time >> >> as a gempak grid file. As an example, I created a file called us.west >> >> in the terrain subdirectory that is a 20x20 degree file (garea = >> >> 25;-125;45;-105) as an example which you can use. >> >> >> >> To create your own grid file area, run gdtopo: >> >> >> >> GDFILE = us.west >> >> GAREA = 25;-125;45;-105 >> >> GDATTIM = 990101/1200 >> >> TOPOFL = terrain.gsf >> >> GEMPAK-GDTOPO>r >> >> >> >> The gdattim is only used to create a grid time in the output file but >> >> really doesn't do anything else. >> >> >> >> An example of running gdcntr with the us.west grid file that is produced: >> >> GDATTIM = 990101/1200 >> >> GLEVEL = 0 >> >> GVCORD = pres >> >> GFUNC = topo >> >> GDFILE = us.west >> >> CINT = 200 >> >> LINE = 5/1/1/0 >> >> MAP = 6 >> >> TITLE = 1 >> >> DEVICE = ps >> >> SATFIL = >> >> RADFIL = >> >> PROJ = ced >> >> GAREA = grid >> >> CLEAR = y >> >> PANEL = 0 >> >> TEXT = .5 >> >> SCALE = 0 >> >> LATLON = 7/10/1//1;1 >> >> HILO = >> >> HLSYM = >> >> CLRBAR = >> >> CONTUR = 0 >> >> SKIP = 0 >> >> FINT = 200 >> >> FLINE = 30-7 >> >> CTYPE = c >> >> LUTFIL = >> >> STNPLT = >> >> GEMPAK-GDCNTR>r >> >> Creating process: ps for queue 251454 >> >> >> >> Grid file: us.west >> >> GRID IDENTIFIER: >> >> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM >> >> 990101/1200 0 PRES TOPO >> >> >> >> GAREA: grid >> >> >> >> MINIMUM AND MAXIMUM VALUES -4765.00 3790.00 >> >> >> >> LINE CONTOURS: >> >> >> >> LEVELS: -4600.00 -4400.00 -4200.00 -4000.00 -3800.00 -3600.00 -3400. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> >> >> LEVELS: -3200.00 -3000.00 -2800.00 -2600.00 -2400.00 -2200.00 -2000. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> >> >> LEVELS: -1800.00 -1600.00 -1400.00 -1200.00 -1000.00 -800.00 -600. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> >> >> LEVELS: -400.00 -200.00 0.00 200.00 400.00 600.00 800. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> >> >> LEVELS: 1000.00 1200.00 1400.00 1600.00 1800.00 2000.00 2200. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> >> >> LEVELS: 2400.00 2600.00 2800.00 3000.00 3200.00 3400.00 3600. > 00 >> >> COLORS: 5 5 5 5 5 5 > 5 >> >> LINTYP: 1 1 1 1 1 1 > 1 >> >> LINWID: 1 1 1 1 1 1 > 1 >> >> LABEL: 0 0 0 0 0 0 > 0 >> >> Enter <cr> to accept parameters or type EXIT: >> >> >> >> I hope this helps you with your work. >> >> >> >> Steve Chiswell >> >> Unidata User Support >> >> >> >> >From: "Matthew G. Fearon" <address@hidden> >> >> >Organization: Desert Research Institute >> >> >Keywords: 199912170024.RAA17299 >> >> >> >> >Steve, >> >> > >> >> >I attached my question below. I just figure I would mention briefly >> >> >what I am trying to accomplish first. >> >> > >> >> >I have created a text file of 40km eta model hght@0%none field or >> >> >what is consider the ground surface in the eta model. I have done >> >> >this for each grid point for the entire eta grid and each hght has a >> >> >corresponding latitude and longitude. I then compared the true >> >> >ground surface of certain sounding stations to the heights >> >> >from the eta model by locating the closet lat/lon relationship. From >> >> >this comparison, I am noticing that the eta heights are always quite >> >> >higher than the true ground surface of the sounding sites, except for >> >> >FSX which is lower. I attached a list below, the heights are in meters: >> >> > >> >> >stn sounding eta >> >> >RNO 1341.5 1776.8 >> >> >UIL 54.880 229.29 >> >> >OAK 3.0500 109.45 >> >> >FSX 2134.1 1740.0 >> >> >EKO 1551.8 1872.2 >> >> >BOI 871.95 1371.6 >> >> >DEN 1612.8 2238.7 >> >> >TUS 786.59 1084.6 >> >> >GGW 695.12 832.76 >> >> > >> >> >Do you know if there is a prewritten grid file containing the true >> >> >ground >> >> >surface elevation (hgt above mean sea level) that I could match to the >> >> >lat/lons that are available from the 40km eta ? >> >> > >> >> >Your suggestions would be greatly appreciated. >> >> >Thank you in advance, >> >> > >> >> >Matt Fearon >> >> >address@hidden >> >> > >> >> > >> >> >> >> ************************************************************************* > *** >> >> Unidata User Support UCAR Unidata Prog > ram >> >> (303)497-8644 P.O. Box 3 > 000 >> >> address@hidden Boulder, CO 80 > 307 >> >> ------------------------------------------------------------------------- > --- >> >> Unidata WWW Service http://www.unidata.ucar.edu/ >> >> ************************************************************************* > *** >> > >> >> **************************************************************************** >> Unidata User Support UCAR Unidata Program >> (303)497-8644 P.O. Box 3000 >> address@hidden Boulder, CO 80307 >> ---------------------------------------------------------------------------- >> Unidata WWW Service http://www.unidata.ucar.edu/ >> **************************************************************************** >