globestipple documentation

The globestipple function creates a hatch filling or stippling over a region of a globe. This function is designed primarily to show regions of statistical significance in spatial maps.

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h = globestipple(...)


globestipple(lat,lon,mask) plots black dots on a globe at locations defined by lat and lon wherever mask contains true values. The globe has radius of 6371, where 6371 corresponds to the average radius of the Earth in kilometers. Dimensions of lat, lon, and mask must all match.

globestipple(...,MarkerProperty,MarkerValue,...) specifies any marker properties that are accepted by the plot function (e.g., 'Color', 'Marker', 'MarkerSize', etc).

globestipple(...,'radius',GlobeRadius) specifies the radius of the globe as GlobeRadius.

globestipple(...,'density',DensityValue) specifies density of stippling markers. Default density is 100, but if your plot is too crowded you may specify a lower density value (and/or adjust the 'MarkerSize').

globestipple(...,'resize',false) overrides the 'density' option and plots stippling at the exact resolution of the input grid. By default, the grids are resized because any grid larger than about 100x100 would produce so many stippling dots it would black out anything under them.

h = globestipple(...) returns a handle of the plotted stippling objects.

Example 1

Plot high-density stippling where topography is above sea level. To do this, we'll use cdtgrid to create a 1-degree global grid, and island to determine which of those grid cells corresponds to land:

[lat,lon] = cdtgrid;
mask = island(lat,lon);

axis tight

% Set the globe color to azure:

Example 2

Most places on Earth tend to change temperature between February and August. Load the example monthly gridded global temperature data from 2017, and we'll figure out where those temperature trends are significant.

filename = '';
T = ncread(filename,'t2m');
lat = double(ncread(filename,'latitude'));
lon = double(ncread(filename,'longitude'));

% Grid the lat,lon arrays:
[Lat,Lon] = meshgrid(lat,lon);

% Calculate February-to-August temperature trend:
[tr,p] = trend(T(:,:,2:8));

First, plot the temperature trend with globepcolor and set the colormap with cmocean:

axis tight
cb = colorbar;
ylabel(cb,'temperature trend (\circC/month)')
globeborders('color',rgb('gray')) % plots political boundaries
view(55,10) % sets viewing angle

Unsurprisingly, the northern hemisphere tends to heat up from February to August, while the southern hemisphere does the opposite. But where is the trend significant?

Add stippling stippling wherever the trend is significant to p<0.001

   'color',rgb('dark green'),...

Author Info

This function and supporting documentation were written by Natalie S. Wolfenbarger and Chad A. Greene for the Climate Data Toolbox for Matlab, 2019.