[ncl-talk] impact of missing values

[Adam Phillips]

Hi Laura,
I don't believe you received an answer to your question. You asked whether
setting cnFillMode = "RasterFill" will change the number of grid cells that
are filled when there is missing data. The answer is yes. When you set
cnFillMode = "RasterFill", every grid cell that is not set to _FillValue
will be filled. When cnFillMode = "AreaFill" (the default), NCL will look
at the values of the neighboring grid cells when shading the center grid
cell. If not enough neighboring grid cells have data then NCL will not fill
the center grid cell. Thus, if you want to color fill all valid grid cells
you should set cnFillMode = "RasterFill".
Adam

On Thu, Sep 20, 2018 at 2:22 PM Laura Fowler <laura at ucar.edu> wrote:

> Hello:
>
> I am trying to plot the index level of the cloud base of shallow
> convection for one time step. In my netCDF file, there is no convection
> when the index level is equal to 55 (which is the total number of layers in
> my experiments).
>
> First, I plot the incidence of shallow convection defined as equal to 1.
> when the cloud base is defined, and 0. otherwise (see kbcon_inc.pdf). Then,
> I plot the actual value of the index level after defining the grid-point as
> a missing value if the cloud base is equal to 55 (see kbcon.pdf). Missing
> values are plotted in gray.
>
> When I compare the two plots, some grid-points are missing in kbcon.pdf
> compared to kbcon_inc.pdf, as for instance over the tropical Pacific Ocean.
> I know that the incidence filed is correct after comparing it against an
> other diagnostics. I do not understand the differences between the 2 plots
> and why some grid cell are missing. It it the impact of missing values. Is
> it the impact of setting res at cnFillMode = "RasterFill"?
>
> If interested, the ncl script test.ncl is in
>
>
> /gpfs/fs1/work/laura/MPASprojects2018/MPAS.cu_shallow.diagnostics/run3.40962.cu_gf/temp
>
>
>
>
>
>
>
>
>
> --
>
> !-------------------------------------------------------------------------------------------------------------
> Laura D. Fowler
>
> Mesoscale and Microscale Meteorology Division (MMM)
> National Center for Atmospheric Research
> P.O. Box 3000, Boulder CO 80307-3000
>
> e-mail: laura at ucar.edu
> phone: 303-497-1628
>
>
> !-------------------------------------------------------------------------------------------------------------
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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