>From: Robert Mullenax <address@hidden> >Organization: Universal Weather >Keywords: 200212122157.gBCLvr401500 McIDAS NEXRCOMP Robert, >I am running the nex2gini script every 10 minutes to generate U.S. base >reflectivity >composites, and have been using them in GARP/NMAP2. Everything >seems to work fine. I have occasionally looked at them in McIDAS >and they looked okay as well. However, I am thinking of making >a sort of radar cgi type thing out of them using McIDAS and >noted today that the navigation of the composite >seems to be off by approximately 45nm. The data is correctly displayed >in GEMPAK, but all the echoes are shifted ~45nm to the north of their >actual location in McIDAS. I just looked at the RTNEXRAD/N0R N0R product for ID=TWB and the NEXRCOMP/1KN0R-NAT product loaded centered on TWB and the correspondence look pretty good: NEXRAD Level III N0R for TWB: http://www.unidata.ucar.edu/staff/tom/gifs/rtnexrad_tbw.gif NEXRCOMP/1KN0R-NAT loaded with TWB at the center http://www.unidata.ucar.edu/staff/tom/gifs/nexcomp_tbw.gif The feature whose location I compared was the upper right most 55 dBZ echo to the ENE of Tampa. I then IMGCOPYied the 00:22 NEXRCOMP/1KN0R-NAT product centered on TBW, made a copy of it, and remapped the 00:20 N0R product for TBW onto the copy. The results of this operation can be seen in the following two GIFs (tm): IMGCOPYed NEXRCOMP/1KN0R-NAT with TWB at the center: http://www.unidata.ucar.edu/staff/tom/gifs/nexcomp2_tbw.gif Remapped NEXRAD Level III N0R for TWB: http://www.unidata.ucar.edu/staff/tom/gifs/rtnexrad_tbw.gif The location of the echos looks pretty consistent to me!? I animated the two displays in McIDAS and see what looks to be at most a 1 pixel shift between the two displays. A 1 pixel shift is more-or-less 1 km, so my quickie test does not replicate your 45 nm offset (which would be 83.340 km). How does your base reflectivity composite compare to ours? You can access ours on papagayo: DATALOC ADD NEXRCOMP papagayo.unl.edu >I have attached two sample images from >the same time, each app looking at the same file. You will see that >McIDAS shows precip covering Mobile Bay for example while >GEMPAK does not. GEMPAK is correct. I create the grid on >an RH Linux 7.2 box and have tried the McIDAS display on the same >box (McIDAS 2002a) and on a McIDAS 7.704 Sun SPARC with >the same result. <<gem.gif>> <<MCIDAS.GIF>> > >Here is the .nts file I use for the nex2gini: > >GRDAREA 21.8;-122;48.2;-62.5 >PROJ lcc/40;-100;40 >KXKY 4750;3020 >CPYFIL >GFUNC n0r >RADTIM current >RADDUR 15 >RADFRQ >STNFIL rad.tbl >RADMODE >SATFIL rad_YYYYMMDD_HHNN >COMPRESS no I will see if Chiz has any comments about these GEMPAK settings. Tom >From address@hidden Thu Dec 12 22:12:04 2002 I don't why it didn't occur to me to look at your NEXRCOMP stuff. Anyway, I verified tonight (at home) that while your NEXRCOMP imagery is correct, ours is shifted to the north again..roughly 45nm in McIDAS, but it does display correctly in GARP. I looked at the stuff over Florida. I did change the garea and kxky Steve had in his nex2gini example as I wanted to get more of the eastern edge of the Maine radars and a little further south and west. Tommorrow I will set my settings back to his suggested ones as a test. Thanks for the quick reply. Robert
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.