Fwd: uv2dvF and uv2vrF NaN values

Correction on my last email on "Inf" versus "NaN":

Begin forwarded message:

> From: Dennis Shea <shea@ucar.edu>
> Subject: Re: uv2dvF and uv2vrF NaN values
> Date: February 21, 2014 2:22:45 PM MST
> To: Mary Haley <haley@ucar.edu>
>
> offline ....
>
>
> re: I'm assuming that "Inf" values will be seen as "NaN"
>
> I don't think this is true
>
> I think you need something like
>
> x = where(abs(x).gt.120, x@_FillValue, x)
>
> D
>
> On 2/21/14, 2:17 PM, Mary Haley wrote:
>> Jon,
>>
>> It would be an issue if you are passing in "Inf" or "NaN" values to *any* function in NCL, except for two special functions we have for checking this kind of thing.
>>
>> You can use the "isieee_nan" and "replace_ieeenan" functions to "fix" any data that has bad values in it.
>>
>> See the FAQ:
>>
>> http://www.ncl.ucar.edu/FAQ/#data_hand_004
>>
>> I'm assuming that "Inf" values will be seen as "NaN" values by these functions. Let me know if you try this and it doesn't work.
>>
>> --Mary
>>
>> On Feb 21, 2014, at 12:28 PM, jonathan meyer <tallj03@hotmail.com> wrote:
>>
>>> Hi Mary,
>>>
>>> I've been digging into this and believe I have found the issue with returns of NaNs.
>>>
>>> It seems that the input arrays that were being fed to these functions have some 'inf and -inf' values in a few grid cells.
>>>
>>> I re-created the input files so no 'inf' values were included and the functions seem to be working normally (although plotting even a single panel is painstakingly long which I'm guessing is a product of the very small values of vorticity and divergence and the precision of the contour levels needed????).
>>>
>>> It seems the functions saw some of these 'inf' values and choked?
>>>
>>> I can send along both versions of the input files and my working .ncl code if you feel it is necessary to look into the issue further.
>>>
>>>
>>> Thanks,
>>> Jon
>>>
>>>
>>>
>>>> Subject: Re: uv2dvF and uv2vrF NaN values
>>>> From: haley@ucar.edu
>>>> Date: Thu, 20 Feb 2014 08:53:37 -0700
>>>> CC: ncl-talk@ucar.edu
>>>> To: tallj03@hotmail.com
>>>>
>>>> Hi Jon,
>>>>
>>>> If *any* NCL function is returning NaN, this is a problem. They should be returning missing values or else issuing some kind of error.
>>>>
>>>> Can you provide the two NetCDF files online? You can use our ftp:
>>>>
>>>> http://www.ncl.ucar.edu/report_bug.shtml#HowToFTP
>>>>
>>>> --Mary
>>>>
>>>>
>>>> On Feb 19, 2014, at 3:50 PM, jonathan meyer <tallj03@hotmail.com> wrote:
>>>>
>>>>> Good afternoon NCL-ers,
>>>>>
>>>>> I am computing ageostrophic winds using actual winds and geostrophic winds. In order to convince myself the ageostrophic wind fields satisfy the mathematics of the atmosphere I am computing the divergence and vorticity of the ageostrophic winds which should equal zero everywhere.
>>>>>
>>>>> Using the uv2dvF and uv2vrF functions to compute these two fields returns NaN values for the entire array. I've confirmed there are no missing data, and the dataset is on a global fixed grid with the latitude monotonically increasing (-90 to 90).
>>>>>
>>>>>
>>>>>
>>>>> My question:
>>>>>
>>>>> Is the return of NaN an artifact of the functions where divergence/vorticity is actually zero?
>>>>>
>>>>> I've tested these functions using actual U and V winds and they return appropriate ranges of values, so something is unique to the ageostrophic winds.
>>>>>
>>>>> Thanks in advance,
>>>>> Jon
>>>>>
>>>>>
>>>>> My Code Snippet
>>>>>
>>>>> begin
>>>>> ;==================================================================
>>>>> print("ESTABLISH CCSM FILES AND RETRIEVE DIMENSION INFO")
>>>>> ; =================================================================
>>>>>
>>>>> f1_in = addfile(dir1 + "CCSM_REG_U_test1979.nc", "r")
>>>>> f2_in = addfile(dir2 + "CCSM_REG_V_test1979.nc", "r")
>>>>>
>>>>> lev = f1_in->lev
>>>>> lat = f1_in->lat2(::-1)
>>>>> lon = f1_in->lon2
>>>>>
>>>>> n_lev = dimsizes(lev)
>>>>>
>>>>> ; =================================================================
>>>>> print("READ IN CCSM DATA")
>>>>> ; =================================================================
>>>>>
>>>>> Ug = f1_in->Ug(:,:,::-1,:)
>>>>> U = f1_in->U( :,:,::-1,:)
>>>>>
>>>>> Vg = f2_in->Vg(:,:,::-1,:)
>>>>> V = f2_in->V( :,:,::-1,:)
>>>>>
>>>>> ; =================================================================
>>>>> print("COMPUTE AGEOSTROPHIC WINDS")
>>>>> ; =================================================================
>>>>>
>>>>> Ua = U-Ug
>>>>> Va = V-Vg
>>>>>
>>>>> ; =================================================================
>>>>> print("COMPUTE DIVERGENCE AND VORTICITY OF AGEOSTROPHIC WINDS")
>>>>> ; =================================================================
>>>>>
>>>>> print(num(ismissing(Ua)))
>>>>> print(num(ismissing(Va)))
>>>>>
>>>>> div = uv2dvF(Ua,Va)
>>>>> vor = uv2vrF(Ua,Va)
>>>>>
>>>>> ****RESOURCE SETTING BLAH BLAH*******
>>>>>
>>>>> do z = 0, n_lev-1
>>>>> print("Plotting level " + lev(z))
>>>>>
>>>>> resdiv@gsnCenterString = "Divergence"
>>>>> plot(0) = gsn_csm_contour_map_ce(wks, div(0,z,:,:), resdiv)
>>>>>
>>>>> resvor@gsnCenterString = "Vorticity"
>>>>> plot(1) = gsn_csm_contour_map_ce(wks, vor(0,z,:,:), resvor)
>>>>>
>>>>> resP@txString = "00Z 1 July 1979 "+ lev(z) + "-mb"
>>>>> gsn_panel(wks,plot, (/2,1/), resP)
>>>>>
>>>>> end do
>>>>>
>>>>>
>>>>> end
>>>>>
>>>>>
>>>>>
>>>>> When Running the code:
>>>>>
>>>>> See http://www.ncl.ucar.edu/ for more details.
>>>>> (0) ESTABLISH CCSM FILES AND RETRIEVE DIMENSION INFO
>>>>> (0) READ IN CCSM DATA
>>>>> (0) COMPUTE AGEOSTROPHIC WINDS
>>>>> (0) COMPUTE DIVERGENCE AND VORTICITY OF AGEOSTROPHIC WINDS
>>>>> (0) 0
>>>>> (0) 0
>>>>> (0) Plotting level 30
>>>>> warning:ContourPlotInitialize: no valid values in scalar field; ContourPlot not possible:[errno=1101]
>>>>> warning:ContourPlotInitialize: no valid values in scalar field; ContourPlot not possible:[errno=1101]
>>>>> (0) Plotting level 50
>>>>> warning:ContourPlotInitialize: no valid values in scalar field; ContourPlot not possible:[errno=1101]
>>>>> warning:ContourPlotInitialize: no valid values in scalar field; ContourPlot not possible:[errno=1101]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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Received on Fri Feb 21 14:24:13 2014