[ncl-talk] Masking

Wed Nov 8 00:35:31 MST 2017

Hi Mary

Thank you for the reply. The adjustment works perfectly to mask the data. I have another question related to this. When I use the wrfoutput file and use the commands lat2d I get this output

Variable: data3

Type: float

Total Size: 108360 bytes

27090 values

Number of Dimensions: 2

Dimensions and sizes: [south_north | 129] x [west_east | 210]

Coordinates:

Number Of Attributes: 8

lon2d : <ARRAY of 27090 elements>

lat2d : <ARRAY of 27090 elements>

coordinates : XLONG XLAT XTIME

stagger :

units : K

description : TEMP at 2 M

MemoryOrder : XY

FieldType : 104

When I use this to a sliced file from nco which has changed the attributes of the file I get the following output.

Variable: data2

Type: float

Total Size: 108360 bytes

27090 values

Number of Dimensions: 2

Dimensions and sizes: [y | 129] x [x | 210]

Coordinates:

Number Of Attributes: 9

lon2d : <ARRAY of 210 elements>

lat2d : <ARRAY of 210 elements>

stagger :

description : TEMP at 2 M

MemoryOrder : XY

FieldType : 104

coordinates : XLONG XLAT

units : K

time : 40320

Also when I use the sliced  file to mask the data I get the error

(0) shapefile_mask_data:Error: not a valid rectilinear,curvilinear, or unstructured grid.

I will appreciate your help

Muhammad Omer Mughal
MSc BSc Mechanical Engineering
PhD  Research Scholar
Remote Sensing and Satellite Research Group
Department of Imaging and Applied Physics
Curtin University

Curtin University
Tel | +61 8 9266 7962
Fax | +61 8 9266 2377
Mobile | 0470 237 525

Email | m.mughal1 at postgrad.curtin.edu.au<mailto:m.lynch at curtin.edu.au>
Web | http://curtin.edu.au<http://curtin.edu.au/>

Curtin University is a trademark of Curtin University of Technology.
CRICOS Provider Code 00301J (WA), 02637B (NSW)

________________________________
From: Mary Haley <haley at ucar.edu>
Sent: Wednesday, 8 November 2017 12:42:12 AM
To: Muhammad Omer Mughal
Cc: ncl-talk at ucar.edu
Subject: Re: [ncl-talk] Masking

Muhammad,

It looks like you are trying to use a rectilinear lat/lon grid for masking rather than the original lat/lon data associated with your "T2" variable.

If your file is indeed a WRF output file, then you should use the XLAT/XLONG variables on the file, rather than trying to create your own lat/lon arrays.

Your code would look something like this:

 nt = 0
 data

= wrf_user_getvar(a, "T2",

nt)
 data at lat2d = wrf_user_getvar(a, "lat", nt)
 data at lon2d = wrf_user_getvar(a,

"lon",

nt)
 data at _FillValue = -9999

 opt       = True
 opt at debug = True
 data_mask = shapefile_mask_data(data,"Shapefile/malay.shp",opt)

For an example that masks a WRF output file, see example shapefile_14_mask.ncl

at:

http://www.ncl.ucar.edu/Applications/shapefiles.shtml#ex14

Note that this example is specifying "Ohio" as the specific area in the shapefile to mask against, but if you simply want to use the whole shapefile, then you do not need to set "shape_var" or "shape_names" as this script is doing.

--Mary

On Tue, Nov 7, 2017 at 6:48 AM, Muhammad Omer Mughal <m.mughal1 at postgrad.curtin.edu.au<mailto:m.mughal1 at postgrad.curtin.edu.au>> wrote:

Hi

I am using a WRF output file and I did the following changes "ONLY" to the code[ https://www.ncl.ucar.edu/Applications/Scripts/mask_9.ncl] . I want to  mask the temperature in Malaysia using the shape file malay.shp. Can you kindly tell me what else do  I need to change as currently I am not able to see the data masked within Malaysia. I will be grateful for your help

load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"

begin
  MASK_INSIDE = True

  a = addfile("./UTC_0.nc","r")
   lat=a->XLAT
   lon=a->XLONG

  minlat=min(lat)
  maxlat=max(lat)
  minlon=min(lon)
  maxlon=max(lon)

 nlat=129
 nlon=210

  lat1d       = fspan(minlat,maxlat,nlat)
  lon1d       = fspan(minlon,maxlon,nlon)

 data = wrf_user_getvar(a, "T2", 0)
 data at _FillValue = -9999

  lat1d       = fspan(minlat,maxlat,nlat)
  lon1d       = fspan(minlon,maxlon,nlon)
  lat1d at units = "degrees_north"
  lon1d at units = "degrees_east"

;---Attach lat/lon coordinate array information.
  data!0      = "lat"
  data!1      = "lon"
  data&lat    = lat1d
  data&lon    = lon1d

  f       = addfile("Shapefile/malay.shp", "r")
  mrb_lon = f->x
  mrb_lat = f->y
  nmrb    = dimsizes(mrb_lon)

  min_mrb_lat = min(mrb_lat)
  max_mrb_lat = max(mrb_lat)
  min_mrb_lon = min(mrb_lon)
  max_mrb_lon = max(mrb_lon)

www.ncl.ucar.edu<https://www.ncl.ucar.edu/Applications/Scripts/mask_9.ncl>
www.ncl.ucar.edu<http://www.ncl.ucar.edu>
;***** ; mask_9.ncl ; ; Concepts illustrated: ; - Drawing the Mississippi River Basin using data from a shapefile ; - Masking a data array based on a geographical ...

Muhammad Omer Mughal
MSc BSc Mechanical Engineering
PhD  Research Scholar
Remote Sensing and Satellite Research Group
Department of Imaging and Applied Physics
Curtin University

Curtin University
Tel | +61 8 9266 7962
Fax | +61 8 9266 2377
Mobile | 0470 237 525

Email | m.mughal1 at postgrad.curtin.edu.au<mailto:m.lynch at curtin.edu.au>
Web | http://curtin.edu.au<http://curtin.edu.au/>

Curtin University is a trademark of Curtin University of Technology.
CRICOS Provider Code 00301J (WA), 02637B (NSW)

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