[ncl-talk] ESMF regrids data with missing values

[Zhifeng Yang]

Hi Dennis,

Sorry for late reply. I just missed your email and didn't respond it.

Here are the variables that I interpolate using ESMF.

Variable (CALIOP_cf_yearly) before using ESMF:

Variable: CALIOP_cf_yearly
Type: float
Total Size: 259200 bytes
            64800 values
Number of Dimensions: 2
Dimensions and sizes:    [180] x [360]
Coordinates:
Number Of Attributes: 1
  _FillValue :    -9999
(0)    min=0.00341297   max=1

----------------------------------------------------------------------------------------------------
Variable (CALIOPg_cf_yearly) after using ESMF:

Variable: CALIOPg_cf_yearly
Type: float
Total Size: 65884 bytes
            16471 values
Number of Dimensions: 2
Dimensions and sizes:    [91] x [181]
Coordinates:
Number Of Attributes: 1
  _FillValue :    -9999
(0)    min=0.0176868   max=1

Both of them have the attribute "_FillValue: -9999". Actually what I am
doing is to interpolate the 1*1degree grids to 2*2 degree grids.

Thank you
Zhifeng

On Thu, Sep 3, 2015 at 10:31 AM, Dennis Shea <shea at ucar.edu> wrote:

> As we always request .... please include a
>
>    printVarSummary(temp)
>    printMinMax(temp,0)
>
> Does 'temp' have an _FillValue attribute?
>
> On Wed, Sep 2, 2015 at 9:15 PM, Zhifeng Yang <yangzf01 at gmail.com> wrote:
> > Hi
> >
> > I am using the ESMF to regrid an array including missing values. The
> > interpolation method is "bilinear". In order to distinguish the
> positions of
> > missing value, I add
> >
> > Opt at SrcGridMask    = where(.not.ismissing(temp),1,0)
> >
> > in my code. Unfortunately, it seems that NCL still uses the missing
> values
> > to calculate the interpolation, and my destination array is full of
> missing
> > value.
> >
> > Since I interpolate 1deg*1deg to 2deg*2deg, the four 1deg*1deg grids can
> get
> > one 2deg*2deg grid. It seems that if I have one missing value in these
> four
> > 1deg*1deg grids, my interpolated 2deg*2deg grid will be a missing value,
> no
> > matter of other 3 1deg*1deg grids.
> >
> > So how can I ignore the influence from the missing values while I
> > interpolate the 1deg*1deg grid to the 2deg*2deg grid?
> >
> > Thank you
> > Zhifeng
> >
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