Polar Stereographic Projections (high-level plot interface)
gsnPolar = "NH"
gsn_csm_contour_map_polar is the plot interface that draws a contour plot over a polar stereographic map.
gsn_panel is the plot interface that creates panel plots.
Draw the plot as usual, setting the resource gsnContourNegLineDashPattern.
gsn_add_polygon is the plot interface that draws polygons as part of a plot. This means the plots can be paneled.
gsFillColor="white", Changes the color of the polygon fill.
gsn_csm_vector_map_polar is the plot template that creates basic polar vector plots.
vcMonoLineArrowColor = False, Turns on color vectors.
vcMinDistanceF = 0.02, Sets a minimum distance between the vectors. This is useful near the poles where the number of vectors increases. The value is in NDC coordinates.
gsn_csm_vector_scalar_map_polar is the plot template that draws a polar vector plot over a contour plot.
vcLineArrowColor = "white", Changes the color of the vectors.
vcGlyphStyle = "CurlyVector", turns on curly vectors.
gsnScalarContour = True, Draws the contour plot under the vectors rather than have the vectors be colored by the contour plot.
the plot template that draws a polar streamline plot.
stArrowLengthF = 0.008,
controls the length of the directional arrows. The default is
stLengthCheckCount = 15, controls how frequently a new streamline is started. The value is in terms of an internal NCL loop that calculates new starts. The default is 35.
stArrowStride = 1, Controls in which grid cells an arrow head is draw. The default is every other grid cell.
stLineStartStride = 1, Controls which grid points are allowed to start new streamlines. The default is 2, which is every other grid cell.
stMinArrowSpacingF = 0.035, controls the distance between drawn arrows. The default is 0.0, which could draw arrows right on top of each other.
stStepSizeF= 0.001, Controls the basic step size used to create the streamline. The default is dynamic.
The following two resources on the ones that you will really have to tweak depending upon the field you are plotting.
Note, that at present you need to load gsn*test for this feature to work.
gsnPolarLabelFontHeightF= .025, will change the font height of the lat/long labels w/o changing the gsn* string text.
gsnPolarLabelDistance = 1.08, Controls how far away from the circle the polar labels will be drawn. These labels are not a tick mark object. They are are text that has been manually added. A determination was made as to how far away from the edge to place this text. When the ability to blow the text up was added, it ran the 0 and 180 text into the circle. Note that this resource moves all the text out, and not just the 0 and 180.
gsnPolarLabelSpacing = 90, controls how frequently to label the lat,lon lines. This is different from a tick mark resource b/c polar tickmark labels are actually added text.
mpCenterLonF controls what longitude is at the center of the plot. This resource can be used adjust what longitude is facing south.
The gsn_add_polymarker function is called twice for each range of values: once to draw a filled dot (gsMarkerIndex=16) and one to draw an outlined dot (gsMarkerIndex=4). This gives the appearance of outlined markers. The marker sizes (gsMarkerSizeF) range in value from 0.025 to 0.075.
The random_uniform function is used to generate random data.