[pyngl-talk] reading wrf output without lat lon variables
huseyin at envs.au.dk
Sun Nov 4 17:07:08 MST 2018
Thanks a lot for your answer. I tried the first one and it gave an error because of the lack of xlat variable, then tried the second routine with giving the parameters, and it is working now.
I am now wondering if i will be able to plot my wrf outputs with wrf-python, because I noticed that getvar routine doesn’t work due to missing lat-lon variables, do you have any advice for this?
All the best,
Bill Ladwig <ladwig at ucar.edu<mailto:ladwig at ucar.edu>> şunları yazdı (29 Eki 2018 17:40):
Without that information in the files, you're going to have to calculate the latitude and longitude values. Since you're using Python, you can use wrf-python which contains a xy_to_ll routine that converts grid points to latitude and longitude points, as long as you're using one of the standard WRF projections, which it looks like you are (https://wrf-python.readthedocs.io/en/latest/user_api/generated/wrf.xy_to_ll.html#wrf.xy_to_ll)
Note that this will only work if you have the map projection global parameters still in your file. If not, there is an xy_to_ll_proj version where you can specify the parameters yourself. (https://wrf-python.readthedocs.io/en/latest/user_api/generated/wrf.ll_to_xy_proj.html#wrf.ll_to_xy_proj).
Hope this helps,
On Mon, Oct 29, 2018 at 7:17 AM Huseyin Ozdemir via pyngl-talk <pyngl-talk at ucar.edu<mailto:pyngl-talk at ucar.edu>> wrote:
I have a problem with reading wrf output file (Projection is Polar Stereographic); i want to compare wrf model output with observations at specific latitude-longitude coordinates, but output netcdf file has no latitude and longitude variables.
I am using my python environment for reading this netcdf file, where PyNGL and PyNIO are already installed. As an example, temp variable in this output has attributes below:
short T2 [ Time|1, south_north|150, west_east|150 ]
FieldType : 104
MemoryOrder : XY
description : TEMP at 2 M
units : K
coordinates : XLONG XLAT XTIME
add_offset : 273.8086
scale_factor : -0.0005068767
Here, T2 variable has “Time", “south_north" and “west_east” dimensions and “south_north" and "west _east" dimensions have both 150 grids. There is no XLAT and XLONG variables in the netcdf output, so how can i get the temperatures at any lat-lon points with just grid numbers?
Thanks in advance,
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