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gsn_csm_contour_map_polar

Creates and draws a contour plot over a polar stereographic map.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

	function gsn_csm_contour_map_polar (
		wks [1] : graphic,  
		data    : numeric,  
		res [1] : logical   
	)

	return_val [1] :  graphic

Arguments

wks

A Workstation identifier. The identifier is one returned either from calling gsn_open_wks or calling create to create a Workstation object.

data

The data for the contour plot. It must be two-dimensional, where the leftmost dimension will be represented on the Y (latitude) axis, and the rightmost dimension represented on the X (longitude) axis.

res

A variable containing an optional list of plot resources, attached as attributes. Set to True if you want the attached attributes to be applied, and False if you either don't have any resources to set, or you don't want the resources applied.

Return value

A scalar id of the map created is returned. The id of the contour plot is returned as an attribute called contour, and the id of the data is returned as an attribute called data. This is useful if you want to use setvalues to change some data or contour options after this function has been called.

Description

This function creates and draws a contour plot over a polar stereographic map projection on the given workstation. The default is to show only the northern hemisphere, unless the special resource gsnPolar is set to "SH".

This function puts special longitude labels around the polar map. These labels can be controlled only through a limited set of gsnPolar* resources. To turn off the labels completely, set the resource gsnTickMarksOn to False.

In order for the contours to be overlaid correctly on the map, please see the document "Overlaying data on a map".

The special resource gsnAddCyclic will be set to True so that a cyclic point will be added to the data. Set this resource to False if your data is not cyclic, or if you have already added the cyclic point in another fashion. If you see this error when you run your script:

warning:ScalarFieldSetValues: 2d coordinate array sfXArray has an incorrect dimension size: defaulting sfXArray
warning:ScalarFieldSetValues: 2d coordinate array sfYArray has an incorrect dimension size: defaulting sfYArray

then try setting gsnAddCyclic to False.

If data has a _FillValue attribute, this value will be used as a missing value.

If the resource cnFillOn is set to True, then the following will happen automatically:

  • a labelbar will be automatically added (default horizontal)
  • contour line labels will be turned off
  • the contour information label will be turned off
If you want to turn the labelbar off, set lbLabelBarOn to False.

For the map, the following will happen automatically:

  • the continents will be colored gray
  • the continental outlines will be turned off
  • the longitude locations will be labeled
If data has an attribute called "long_name", and gsnLeftString hasn't explicitly been set, then the value of this attribute is used for the left string title.

If data has an attribute called "units", and gsnRightString hasn't explicitly been set, then the value of this attribute is used for the right string title.

To maximize the area that the plot is drawn in, set the special resource gsnMaximize to True.

See Also

gsn_contour, gsn_csm_contour, gsn_csm_contour_map, gsn_csm_contour_map_ce
Special gsn resources

Examples

For some application examples, see: