Hi Brian- > I've uploaded a zipped IDV bundle called simpledifference.zidv. The > comparison is between two precipitation fields. In this file, the fields > are unitless, but I have tried specifying mm in the text file header and > using newUnit on the vis5d file and get the same result. Thanks for the files. You definitely need to do the newUnit on the Vis5D data. I can get it to work if I subtract the v5d from the gridded point obs, but not the other way around. I'll look into that further when I get into the office. Don > -----Original Message----- > From: Unidata IDV Support [mailto:address@hidden > Sent: Wednesday, December 02, 2009 3:52 AM > To: Billings, Dr. Brian, Contractor, Code 7533 > Cc: address@hidden > Subject: [IDV #WWB-790357]: simple difference on objective analyses > > Hi Brian- > > > Full Name: Brian Billings > > Email Address: address@hidden > > Organization: Naval Research Laboratory Package Version: 2.7u2 > > Operating System: Windows Vista > > Hardware: > > Description of problem: Have any issues been reported on using the > simple difference formula where one of the fields is an objective > analysis of point data? I have been trying to use this option on a 2D > vis5d file and a text data listing. The times are the same and the units > are the same, but the results are obviously incorrect. The users guide > says that the calculation is automatically performed only on the area in > which the grids overlap, but this is not being done in my output. Is the > issue with using an objective analysis or some other possibility? > Thanks. > > If you are subtracting temperatures, the values will end up in K so if > you convert to Celsius you'll be off by a factor of 273. The IDV does > not distinguish between delta degrees K and regular K so a conversion > between units will treat them as absolute. > > If that's not what you are seeing, could you upload the vis5d file and > the text data to: > > http://motherlode.ucar.edu/repository/alias/idvupload > > so I can take a look. Let me know what field you are trying this with. > > Don Murray > > > > > > > Ticket Details > =================== > Ticket ID: WWB-790357 > Department: Support IDV > Priority: Normal > Status: Open > > Ticket Details =================== Ticket ID: WWB-790357 Department: Support IDV Priority: Normal Status: Open
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.