[ncl-talk] unable to extract data and plot it for a smaller domain.

Rashed Mahmood rashidcomsis at gmail.com
Thu Sep 17 12:23:04 MDT 2020


Hi Geeta,
It would be difficult to answer this question without a data file and the
script used to plot these figures. Is it possible to share data and the NCL
script?
Cheers,
Rashed

On Thu, Sep 17, 2020 at 8:05 PM Geeta Geeta via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hi.
> This issue was sorted out a few days ago. Now I  am finding a small
> problem which is the shift of the position of the clouds.
> I mean when I plot the data for regional domain, clouds seem to be shifted
> by about 2 degree compared to the original domain plot (attachments) .
>
>
> Requesting once again to sort out this issue too.
> Geeta.
>
>
>
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>
>  On Friday, 11 September, 2020, 10:10:16 pm IST, Dennis Shea <
> shea at ucar.edu> wrote:
>
>
>
>
>
>  Are the latitude and longitudes on the file?
> 1) If "yes", just read as indicated below.2) If "no",  the projection
> information must be used to generate the latitude and longitude information
> ------------------------
> The following functions may be useful when the latitudes and longitudes
> are available
>
> region_ind
>
> getind_latlon2d
>
>
> -------------------------
>  f = addfile("3DIMG_23JUN2018_0300_L1C_ASIA_MER.h5" , "r")
>
>  glon2d = f->...longitude_variable ...
>  glat2d = f->...latitude_variable...
>
>  printMinMax(glat2d, 0)
>  printMinMax(glon2d, 0)
>
>  latS = 10 ; California [*rough*]
>  latN = 20
>  lonW = 70
>  lonE = 75
>
>
>  ji = region_ind (glat2d,glon2d, latS, latN, lonW, lonE)
>
>  jStrt = ji(0) ; lat start
>  jLast = ji(1) ; lat last
>  iStrt = ji(2) ; lon start
>  iLast = ji(3) ; lon last
>
>  LAT2D = glat2d(jStrt:jLast,iStrt:iLast)
>  LON2D = glon2d(jStrt:jLast,iStrt:iLast)
>
>  printMinMax(LAT2D, 0)
>  printMinMax(LON2D, 0)
>
>  ; read data just for the region of interest
>  x = f->IMG_TIR1(0,jStrt:jLast,iStrt:iLast)
>  printVarSummary(x)
>
>
>  printMinMax(x)
>
>
>
>
>
> On Fri, Sep 11, 2020 at 8:41 AM Geeta Geeta via ncl-talk <
> ncl-talk at mailman.ucar.edu> wrote:
> the NxM grid is the larger grid,  of the size 55N and 61E.
>
> will it be minI  = 70* 61/(105.5-44.5) ??
>
>
>
> does not seem to be correct, I am not achieving anything
>
>
>
>
>
> Geeta.
>
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>
>  On Friday, 11 September, 2020, 07:48:54 pm IST, Rick Brownrigg <
> brownrig at ucar.edu> wrote:
>
>
>
>
>
>
>
>
>
>
>
>  Hi,
>
> No, not in meters -- you're trying to find the indices of the grid cells
> that correspond to the corners of your smaller domain. For instance, what
> are the values i,j that correspond to the corner (-10N,44.5E)
>
>
>
> RB
>
>
>
> On Fri, Sep 11, 2020 at 8:11 AM Geeta Geeta <geetag54 at yahoo.com> wrote:
>
> Soory Mr Rick. It is not clear to me.
>
>
>
>
>
>
>
> 4 corners of large  domain are  (-10N,44.5E) , (-10,105.5), (45.5,105.5),
> (45.5,44.5).
>
>
>
> I want small domain to be 10-20N/70-75E.
>
>
>
> So I have to calculate the X Y (distance in meters)?.
>
>
>
> kindly clarify .
>
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>
> Geeta.
>
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>  On Friday, 11 September, 2020, 07:20:57 pm IST, Rick Brownrigg <
> brownrig at ucar.edu> wrote:
>
>
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>
>  Hi,
>
>
>
> I *think* the trick here is to compute the i,j indices of the grid that
> correspond to your smaller domain. Since it's a mercator projection, and
> the original domain is relatively small (60x60 degs), I would think you
> could get decent results by using a simple linear scaling to find those
> values. So if the grid is NxM (LatxLon), and you extract the min/max
> lat/lons from the attributes into variables minLon, maxLon, etc.,  then
> something like:
>
>
>
>
>
>
>
>   minI = tointeger( minLonSmallerDomain * (M -0) / (maxLon - minLon) )  ;
> truncating
>
>
>
>   maxI = tointeger( maxLonSmallerDomain * (M -0) / (maxLon - minLon)
> )...similarly for Y...
>
>
>
> and then:
>
>
>
>  Plot(0)                           =
> gsn_csm_contour_map(wks,TIR1_INVERTED(0,minJ:maxJ,minI:maxI),rescount)
>
>
>
> and don't forget to substitute appropriate values into the
> mpLeft/RightCornerLat/LonF resources.
>
>
>
> Does that make sense?
>
>
>
> Rick
>
>
>
>
>
>
>
> On Fri, Sep 11, 2020 at 4:22 AM Geeta Geeta via ncl-talk <
> ncl-talk at mailman.ucar.edu> wrote:
>
>
>
> Hi.
>
>
>
>
>
>
>
>
> I have satellite data which has a resultion of 4 km (TIR1) and there is projection information provided in the datafile.
>
>
>
>
>
>
>
> integer Projection_Information ( DIM_000 )
>
>
>
>
>
>
>
>         DIMENSION_LIST :    <ARRAY of 0 elements>
>
>
>
>
>
>
>
>         false_easting :      0
>
>
>
>
>
>
>
>         false_northing :      0
>
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>
>
>         grid_mapping_name :    mercatorpor Brightness Temperaturerature
>
>
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>
>         longitude_of_projection_origin :      75
>
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>         lower_left_lat_lon(degrees) :    (  -10, 44.5 )
>
>
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>         lower_right_lat_lon(degrees) :    (  -10, 105.5 )
>
>
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>
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>
>         semi_major_axis :    6378137
>
>
>
>
>
>
>
>         semi_minor_axis :    6356752.3142
>
>
>
>
>
>
>
>         standard_parallel :    17.75
>
>
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>
>
>
>         upper_left_lat_lon(degrees) :    ( 45.5, 44.5 )
>
>
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>
>
>
>
>         upper_left_xy(meters) :    ( -3234623.003937, 5401854.420193 )
>
>
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>         upper_right_lat_lon(degrees) :    ( 45.5, 105.5 )
>
>
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> The lat/lon are not provided.
>
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> Plotting the TIR1 (count), radiance and Brightness temperature for the entire domain is happening by using information from the Projection info.
> This INFO is used from the Line numbers 109-114 of the code.
>
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> My questions are 1. I am Not able to plot the data for a smaller domain of
> my ineterst
>
>
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>
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>                           2. since I am unable to attch the lat/lon arrays to the variables, I am unable to plot the data for a smaller domain and unable to write the data for a smaller domain of my intererst.
>
>
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>
>
> the Images are attached.
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> Request someone to help me.
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> Geeta._______________________________________________
>
>
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