NCL Home > Documentation > Graphics > Graphical Interfaces

gsn_csm_vector_scalar_map_polar

Creates and draws a vector plot over a polar stereographic map projection, and uses a scalar field to draw a separate contour plot or color the vectors.

Prototype

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

	function gsn_csm_vector_scalar_polar (
		wks     [1] : graphic,  
		u    [*][*] : numeric,  
		v    [*][*] : numeric,  
		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.

u
v

The u and v data for the vector plot; must be two-dimensional.

data

The data for which to create a separate contour plot or color the vectors by; must be two-dimensional.

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

Description

This function creates and draws a vector plot over a polar stereographic map 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 vectors and contours to be overlaid correctly on the map, please see the document "Overlaying data on a map".

By default, the scalar field is used to color the vectors, unless the special resource gsnScalarContour is set to True, then a separate contour plot is created.

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 u, v, or data have a _FillValue attribute, these values will be used as missing values.

If the resource vcMonoLineArrowColor is set to False, then a labelbar is created. If you want to turn this 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 u 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 u 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.

If you need more control over the individual vector and contour plots, then it may be easier to create the vector plot with gsn_csm_vector, the contour/map plot with gsn_csm_contour_map_polar, and then use the overlay procedure to overlay the two. See example "lcnative_overlay_5.ncl" on the Lambert Conformal Native Grid Projection examples page.

See Also

gsn_vector_scalar, gsn_csm_vector_scalar, gsn_csm_vector_scalar_map, gsn_csm_vector_scalar_map_ce
Special gsn resources

Examples

For some application examples, see: