[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[IDV #UXJ-837158]: average spatial subset with ASCII output query

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 Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated.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.

  • Subject: [IDV #UXJ-837158]: average spatial subset with ASCII output query
  • Date: Mon, 14 Jul 2014 14:44:11 -0600
> Do you know if IDV can produce spatial averages at each time step? For 
> example, I have a 2D 1000hPa temperature plot at a daily time step for 100 
> days for all of North America. What I would like to do is to be able to 
> calculate an area average of the temperature for a spatial subset of a 
> specific area, say like for the southeast USA only.
> 
Teddy,
    Yes, there is a formula, savs(a),  you can use to do the area average of 
some variables. First, load your dataset, and in the Field Selector, select 
Formulas > Grids > Define a grid diagnostic, and select Color-Shaded Plan view 
as display type, click create display. When a window popup, type in savs(a). 
And then another window popup,  select the temperature field, and subset the 
area. You will see a solid color display created. Now in the display control, 
File > Save > Save data in cache .... Second, go back to the Field Selector, 
select the cached data, and Probes > Data Probe/Time Series, and create 
display, you will get the time series chart of the average field.

    It is a little trick, but it should work.
    By the way, I read the meeting notes of your trip. What a great job 
promoting IDV, many thanks.

Yuan




> I would like the output to be a single value at each time representing the 
> areal average for my defined spatial subset region. As a result, I ultimately 
> wish to have 100 average temperature values only; one for each spatial subset 
> at every time step.
> 
> Does this make sense? I think that IDV does not do things like this, but it 
> would be a dream if so. I have scoured the formula library and have had no 
> luck. Any ideas or experience with this?
> 
> In the meantime, I read in a 3D netcdf file (x,y,t) to GrADS where I use the 
> aave function to calculate spatial averages and then output ASCII data in a 
> text file. The result is a text file with only 100 values, which is what I 
> want. Ideally, I would like to do this on the IDV if possible.
> 
> As always, I remain a huge IDV user and advocate!
> Thank you,
> teddy allen
> 
> 
> ------------------------------------------------------------------------------------------
> 
> Teddy Allen, Ph.D. Student
> 
> The Rosenstiel School of Marine and Atmospheric Science
> 
> Division of Meteorology and Physical Oceanography
> 
> 4600 Rickenbacker Causeway
> 
> Miami, FL 33149
> 
> USA
> 
> 
> 
> Director of Scientific Applications
> 
> The International Environmental Data Rescue Organization (IEDRO)
> 
> www.iedro.org
> 
> 
> Office: MSC-315
> 
> Tel : +001-305-421-4275
> 
> skype: teddy.allen
> 
> web: www.teddyallen.com<http://www.teddyallen.com>
> 
> -------------------------------------------------------------------------------------------
> 
> 


Ticket Details
===================
Ticket ID: UXJ-837158
Department: Support IDV
Priority: Normal
Status: Open