MATLAB Examples

measuresps documentation

The measuresps function plots Antarctic ice surface speed as an imagesc plot in polar stereographic coordinates (meters, true lat 71 S) or velocity vectors as a quiver plot.

Contents

Syntax

measuresps('gl')
measuresps('gl',PropertyName,PropertyValue)
measuresps('speed')
measuresps('speed','log')
measuresps('speed','alpha',AlphaValue)
measuresps('velocity')
measuresps('velocity',QuiverProperty,QuiverValue)
measuresps(...,'autoscale',false)
measuresps(...,'km')
h = measuresps(...)

Description

measuresps('gl') plots the InSAR-derived point of surface flexure, which is one way to interpret the grounding line.

measuresps('gl',PropertyName,PropertyValue) formats the grounding line with any properties recognized by the plot function (e.g., linewidth, markerstyle, color, etc.)

measuresps('speed') plots gridded surface speed as an imagesc plot.

measuresps('speed','log') plots surface speed as an imagesc plot using log base 10.

measuresps('speed','alpha',AlphaValue) plots surface speed as a semitransparent imagesc plot, which can be useful when overlaying.

measuresps('velocity') plots quiver arrows of velocity.

measuresps('velocity',QuiverProperty,QuiverValue) specifies quiver properties such as color, linewidth, etc.

measuresps(...,'autoscale',false) turns off automatic downsampling of large datasets. The full MEaSUREs grid is over 12,000 x 12,000 grid cells, which is probably more pixels than your screen can depict, so by default the measuresps function scales the dataset to be closer to about 3000x3000 pixels. You're welcome to turn off the autoscaling, but plotting may be real slow.

measuresps(...,'km') plots in polar stereographic kilometers rather than meters.

h = measuresps(...) returns a handle h of plotted objects.

Example 1: Whole continent

It's real easy make a continent-wide map of ice speed. This should do it:

measuresps speed

And you can overlay things like the grounding line just as easily. We'll make it a red grounding line by specifying 'r':

measuresps('gl','r')

Example 2: Small region

If you try to zoom in on the map created in Example 1, you'll see that the resolution is low. If you have a small region of interest, zoom a map to the region before calling measuresps, and that way measuresps will know to plot high-res data. You can initialize a map like this:

figure
mapzoomps('george vi ice shelf')

Or if you happen to have the lima plugin for Antarctic Mapping Tools, you can use LIMA as a base layer:

lima('george vi ice shelf','xy')

Add a layer of semitransparent (alpha = 0.5) ice speed, log-scaled:

measuresps('speed','log','alpha',0.5)

Overlay a black grounding line:

measuresps('gl','k')

Add red velocity vectors and a scalebar

measuresps('velocity','color','r')
scalebarps('location','nw')

Citing these datasets:

VELOCITY DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011. MEaSUREs InSAR-Based Antarctica Ice Velocity Map. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. doi:10.5067/MEASURES/CRYOSPHERE/nsidc-0484.001

A LITERARY REFERENCE FOR THE VELOCITY DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011.Ice Flow of the Antarctic Ice Sheet, Science, Vol. 333(6048): 1427-1430. doi:10.1126/science.1208336.

GROUNDING LINE DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011. MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0498.001.

A LITERARY REFERENCE FOR THE GROUNDING LINE DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011. Antarctic Grounding Line Mapping from Differential Satellite Radar Interferometry. Geophyical Research Letters 38: L10504. doi:10.1029/2011GL047109.

ANTARCTIC MAPPING TOOLS: Greene, C.A., Gwyther, D.E. and Blankenship, D.D., 2016. Antarctic Mapping Tools for Matlab. Computers & Geosciences. http://dx.doi.org/10.1016/j.cageo.2016.08.003

Author Info

The measuresps function and supporting documentation were written by Chad A. Greene of the University of Texas Institute for Geophysics (UTIG), October 2016.