NCL Plot Styles: Time vs. Longitude (Hovmueller)
gsn_csm_hov is the plot interface that creates Hovmueller diagrams.
trYReverse = True, Reverses the y-axis.
cnLineLabelAngleF = 0.0, Changes the angle of the contour labels.
gsnContourZeroLineThicknessF doubles the thickness of the zero contour.
ShadeLtGtContour is the shea utility function that shades the contours from -4 to 4. Note: ShadeLtGtContour has been superceded by the more versatile gsn_contour_shade. We recommend you use this instead.
cnFillOn = True, Turns on the color fill.
See the color example page for lots of ways of dealing with color.
gsnMajorLonSpacing = 90.
Spaces out the longitude labels every 90 degrees. The default for this plot would be 60 degrees.
In this example, the minor tickmarks are treated as major tickmarks and vice versa. Several tickmark resources are used to place month labels inbetween the minor tickmarks.