[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