[ncl-talk] problems with regriding

Vanúcia Schumacher vanucia-schumacher at hotmail.com
Fri Aug 22 06:33:53 MDT 2014


Hi Dennis,
I still do not understand what can I do to solve this problem, because when I change the resolution, I choose the option of lat and lon (0,358),(-87.86, 87.86), ncview and ferret programs  I can plot the data without problems (global), but when I try plot the data without changing the resolution they are confused on the map (attached).
print(var&lon)print(var&lat)
Variable: lat (coordinate)Type: integerTotal Size: 596 bytes            149 valuesNumber of Dimensions: 1Dimensions and sizes:	[lat | 149]Coordinates: Number Of Attributes: 4  units :	1  long_name :	cell index along second dimension  point_spacing :	even  axis :	Y
ncdump -h 
	time = UNLIMITED ; // (122 currently)	j = 149 ;	i = 182 ;	bnds = 2 ;	vertices = 4 ;variables:	double time(time) ;		time:bounds = "time_bnds" ;		time:units = "days since 1980-11-01" ;		time:calendar = "standard" ;		time:axis = "T" ;		time:long_name = "time" ;		time:standard_name = "time" ;	double time_bnds(time, bnds) ;	int j(j) ;		j:units = "1" ;		j:long_name = "cell index along second dimension" ;	int i(i) ;		i:units = "1" ;		i:long_name = "cell index along first dimension" ;	float lat(j, i) ;		lat:standard_name = "latitude" ;		lat:long_name = "latitude coordinate" ;		lat:units = "degrees_north" ;		lat:bounds = "lat_vertices" ;	float lon(j, i) ;		lon:standard_name = "longitude" ;		lon:long_name = "longitude coordinate" ;		lon:units = "degrees_east" ;		lon:bounds = "lon_vertices" ;	float lat_vertices(j, i, vertices) ;		lat_vertices:units = "degrees_north" ;	float lon_vertices(j, i, vertices) ;		lon_vertices:units = "degrees_east" ;	float tos(time, j, i) ;		tos:standard_name = "sea_surface_temperature" ;		tos:long_name = "Sea Surface Temperature" ;		tos:comment = "\"this may differ from \"\"surface temperature\"\" in regions of sea ice.\"" ;		tos:units = "K" ;		tos:original_name = "sosstsst" ;		tos:original_units = "degC" ;		tos:history = "2012-07-24T13:46:07Z altered by CMOR: Converted units from \'degC\' to \'K\'." ;		tos:cell_methods = "time: mean (interval: 1 month)" ;		tos:cell_measures = "area: areacello" ;		tos:missing_value = 1.e+20f ;		tos:_FillValue = 1.e+20f ;		tos:associated_files = "baseURL: http://cmip-pcmdi.llnl.gov/CMIP5/dataLocation gridspecFile: gridspec_ocean_fx_CMCC-CM_decadal1980_r0i0p0.nc areacello: areacello_fx_CMCC-CM_decadal1980_r0i0p0.nc" ;		tos:coordinates = "lat lon" ;
// global attributes:		:institution = "CMCC - Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna, Italy" ;		:institute_id = "CMCC" ;		:experiment_id = "decadal1980" ;		:source = "CMCC-CM" ;		:model_id = "CMCC-CM" ;		:forcing = "Nat,Ant,GHG,SA,TO,Sl" ;		:parent_experiment_id = "N/A" ;		:parent_experiment_rip = "N/A" ;		:branch_time = 0. ;		:contact = "Silvio Gualdi (gualdi at bo.ingv.it)" ;		:history = "Model output postprocessed with  CDO (https://code.zmaw.de/projects) 2012-07-24T13:46:07Z CMOR rewrote data to comply with CF standards and CMIP5 requirements." ;		:comment = "Decadal hindcasts/predictions, some extended to 30 years" ;		:references = "model described in the documentation at http://www.cmcc.it/data-models/models" ;		:initialization_method = 1 ;		:physics_version = 1 ;		:tracking_id = "105250cc-615d-478c-b242-b72f4735fb74" ;		:product = "output" ;		:experiment = "10- or 30-year run initialized in year 1980" ;		:frequency = "mon" ;		:creation_date = "2012-07-24T13:46:07Z" ;		:Conventions = "CF-1.4" ;		:project_id = "CMIP5" ;		:table_id = "Table Omon (27 April 2011) 340eddd4fd838d90fa9ffe1345ecbd73" ;		:title = "CMCC-CM model output prepared for CMIP5 10- or 30-year run initialized in year 1980" ;		:parent_experiment = "N/A" ;		:modeling_realm = "ocean" ;		:realization = 1 ;		:cmor_version = "2.7.1" ;


---Vanúcia SchumacherMestranda em Meteorologia - UFVMeteorologista -UFPel
Departamento de Meteorologia Agrícola - DEACel: (31) 9978 2522 DEA: (31) 3899 1890

Date: Thu, 21 Aug 2014 15:12:20 -0600
Subject: Re: [ncl-talk] problems with regriding
From: shea at ucar.edu
To: vanucia-schumacher at hotmail.com
CC: ncl-talk at ucar.edu

[1]
I would say it is highly unlikely that "NCL is not correctly plotting the data"!

NCL is plotting what you sent it. 

[2]
Did you examine the output from


printVarSummary(var)

[snip]


Dimensions and sizes:	[TIME | 360] x [lat | 149] x [lon | 182]Coordinates:             TIME: [76.5..3636.5]
            lat: [1..149]                  <================
            lon: [1..182]                <====================


The coordinates associated with 'var' are numbers spanning 1-149 and 1-182
These are *not* latitudes or longitudes. So, when you  use

new_var = linint2_Wrap(var&lon,var&lat,var,True,new_lon,new_lat,0)

You could do you own 'debugging by printing the input

print(var&lon)
print(var&lat)


Punch line ... you are inputting number 1 to 149 and 1 to 182
NCL is interpolating to those values.


Use 

ncl_filedump

or


ncdump  -h

on your source file. That should have some lat.lon info






On Thu, Aug 21, 2014 at 2:12 PM, Vanúcia Schumacher <vanucia-schumacher at hotmail.com> wrote:




Hi users,
I do regridding data for resolution of 2 degrees and the NCL is not correctly plotting the data, it is cutting the data to the new resolution as opposed to a new lat and lon.

>begin     
>var = f[:]->SST
>var!1="lat">var!2="lon"
>j=var!1>i=var!2   
newfile = "tos_90x180.nc"

file_create = addfile(newfile, "c")    
new_lon = fspan(0,358, 180)     
new_lon at units = "degrees_east"new_lon!0 = "lon"  
new_lat = fspan(-87.86, 87.86, 90)
new_lat at units = "degrees_north"new_lat!0 = "lat"        

new_var = linint2_Wrap(var&lon,var&lat,var,True,new_lon,new_lat,0)
file_create->tos = new_var


Variable: var
Type: doubleTotal Size: 78099840 bytes            9762480 valuesNumber of Dimensions: 3
Dimensions and sizes:	[TIME | 360] x [lat | 149] x [lon | 182]Coordinates:             TIME: [76.5..3636.5]
            lat: [1..149]            lon: [1..182]Number Of Attributes: 4  missing_value :	-9.999999999999999e+33
  _FillValue :	-9.999999999999999e+33  long_name :	TOS[L=3:122]
  history :	From tos_Omon_CMCC-CM_decadal1980_r1i1p1_198011-199012
Variable: new_var
Type: doubleTotal Size: 46656000 bytes            5832000 valuesNumber of Dimensions: 3
Dimensions and sizes:	[TIME | 360] x [lat | 90] x [lon | 180]Coordinates:             TIME: [76.5..3636.5]
            lat: [-87.86..87.86]            lon: [ 0..358]Number Of Attributes: 4
  missing_value :	-9.999999999999999e+33  _FillValue :	-9.999999999999999e+33
  long_name :	TOS[L=3:122]  history :	From tos_Omon_CMCC-CM_decadal1980_r1i1p1_198011-199012



---Vanúcia Schumacher
Mestranda em Meteorologia - UFVMeteorologista -UFPel

Departamento de Meteorologia Agrícola - DEA
Cel: (31) 9978 2522 DEA: (31) 3899 1890
 		 	   		  

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