NCL Graphics: Masked Lambert Conformal Projections

A masked Lambert Conformal map is a regular Lambert Conformal map that has a particular area masked out so you can focus on an area of interest.

lcmask_1.ncl: Unmasked and masked lambert conformal projection.

mpProjection = "LambertConformal" turns on the correct projection.

gsnMaskLambertConformal = True will turn on the projection masking.

To mask the projection, you must set the boundaries with the following resources:
mpMinLonF
mpMaxLonF
mpMinLatF
mpMaxLatF

It is also required to set gsnAddCyclic to False whenever you plot a non-global domain.

A Python version of this projection is available here.

lcmask_2.ncl: Maximized example with outline turned on.

gsnMaximize enlarges the plot to the point where the fonts are legible. For this type of plot, you will probably want to always have this resource turned on.

gsnMaskLambertConformalOutlineOn turns off a border around the plot

lcmask_3.ncl: Vectors on masked grid

lcmask_4.ncl: Shows how to add your own longitude/latitude labels to a masked Lambert Conformal plot. The gsn_add_text function is use to attach the labels. The angle of the strings is calculated by converting lat/lon values to NDC space (datatondc) and then using atan to get the angle.

This script uses a procedure called "add_lc_labels" to add the lat/lon labels. You may need to increase or decrease the lat_spacing or lon_spacing arguments if you are not satisfied with the results.