[ncl-talk] ESMF regrid fails when mask applied on multiple time steps

[Dennis Shea]

Oops!


You do not need to use the 'short2flt' function. There are no scale or
add_offset attributes.

swe = infile->Snow_Water_Equivalent_with_State_Model_variable_type

is fine.

On Thu, Sep 10, 2015 at 8:09 AM, Dennis Shea <shea at ucar.edu> wrote:
> Just looking at the netCDF file,
>
>     minlon = min(lon)
>     maxlon = max(lon)
>     minlat  = min(lat)
>     maxlat = max(lat)
>
>     print("lat_range="+(maxlat-minlat))
>     print("lon_range="+(maxlon-minlon))
>
>     print("nlat="+toint((maxlat-minlat)/0.0818))
>     print("mlon="+toint((maxlon-minlon)/0.0818))
>
> (0) lat_range=0.108334
> (0) lon_range=0.508331
>
> (0) nlat=1
> (0) mlon=6
>
> ===
> Is this correct???
>
> I speculate that under-the-hood NCL's interface to the ESMF software
> is 'confused' by this.
>
> Is there something wrong with the source file?
>
> ======================
> ======================
>
> Re:
>
>    ; WORKS
>    ;swe = infile->Snow_Water_Equivalent_with_State_Model_variable_type(0,:,:)
>    ; FAILS
>    ;swe = infile->Snow_Water_Equivalent_with_State_Model_variable_type
>    ; (:,:,:)
>
> FYI:
> The most efficient way to read in a complete variable from a nc/nc4,
> hdf4/hdf5, grb1/2 files is to not use the (:,:,:).
> Use
>
>
>     swe = short2flt(infile->Snow_Water_Equivalent_with_State_Model_variable_type)
>           ; (:,:,:)
>
>     printVarSummary(swe)      ; [time | 2] x [latitude | 14] x [longitude | 62]
>     printMinMax(swe, 0)       ; min=-9999   max=2214
>
>
> Although your use of -9999 should be acceptable, I would suggest the following
>
> ; assign _FillValue
>
>     swe at _FillValue = toshort(-9999)   ; swe is type short
>     printVarSummary(swe)
>     printMinMax(swe, 0)       ;  min=0   max=2214
>
> ; subsequently
>
>    ;Opt at SrcGridMask = where(swe.eq.-9999,0,1)
>     Opt at SrcGridMask = where(ismissing(swe),0,1)
>
> D
>
>
> On Wed, Sep 9, 2015 at 9:14 PM, Neil Berg <neil.berg14 at gmail.com> wrote:
>>
>> On Sep 9, 2015, at 8:01 PM, Neil Berg <neil.berg14 at gmail.com> wrote:
>>
>> Hello all,
>>
>> I am having an issue using ESMF_regrid after masking out water grid cells
>> (marked by -9999) in my source array when ingesting all times in the 3D
>> array (ntim x nlat x nlon).  There is no issue if I only read in the first
>> time step, hence making the input 2D (nlat x nlon).  The lat/lon grid is the
>> same for all time steps and I’ve included both a small sample of the source
>> array data (snodas_tmp.nc) and the relevant code below.
>>
>> The error message when including multiple time steps is:
>>
>> fatal:Eq: Dimension size, for dimension number 0, of operands does not
>> match, can't continue
>>
>> Any tips for using ESMF_regrid with a mask over multiple time steps?
>>
>> Thanks in advance,
>>
>> Neil
>>
>>
>>
>>
>>
>>     source_file = “./snodas_tmp.nc"
>>
>>     infile = addfile(source_file, "r")
>>     ; WORKS
>>     ;swe =
>> infile->Snow_Water_Equivalent_with_State_Model_variable_type(0,:,:)
>>     ; FAILS
>>     swe =
>> infile->Snow_Water_Equivalent_with_State_Model_variable_type(:,:,:)
>>     lat = infile->latitude
>>     lon = infile->longitude
>>
>>     minlon = min(lon)
>>     maxlon = max(lon)
>>     minlat = min(lat)
>>     maxlat = max(lat)
>>
>>     Opt = True ; Regridding options
>>
>>     Opt at SrcFileName = "snodas_SrcSCRIP.nc" ; Output files
>>     Opt at DstFilename = "snodas_DstSCRIP.nc"
>>     Opt at ForceOverwrite = True
>>
>>     Opt at SrcTitle = source_file
>>
>>     Opt at DstGridType = ".0818deg" ; destination grid of 9km or .0818 degrees
>>     Opt at DstLLCorner = (/minlat, minlon/)
>>     Opt at DstURCorner = (/maxlat, maxlon/)
>>
>>     Opt at SrcRegional = True ; regional grid source
>>     Opt at DstRegional = True ; regional grid destination
>>
>>     ; need to mask out water pts, marked as -9999
>>     Opt at SrcGridMask = where(swe.eq.-9999,0,1)
>>
>>     Opt at InterpMethod = "bilinear"
>>     Opt at WgtFileName = "snodas_Swath_2_Rect_bilinear.nc"
>>
>>     swe_regrid = ESMF_regrid(swe,Opt)
>>
>>
>>
>>
>>
>>
>>
>>
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