MATLAB Examples

measures documentation

This function plots Antarctic surface velocity or grounding line data in a coordinate system that requires Matlab's Mapping Toolbox. If you don't have Matlab's Mapping Toolbox, or even if you do, I recommend using measuresps instead--it's a better-written function and does not require any toolboxes.

Contents

Syntax

measures 'gltype'
measures('gltype','markerProperty',markerValue)
measures 'speed'
measures('speed',lat,lon)
measures('speed','locationString')
measures('speed',...,'mapwidth',mapwidth_km)
measures('speed',...'alpha',alphaValue)
measures('speed',...'colormap',cmap)
measures('speed',...'colorbar',ColorbarOption)
measures('vel',lat,lon)
measures('vel','locationString')
measures('vel',...,'mapwidth',mapwidth_km)
measures('vel',...,'quivermcProperty',quivermcValue)
measures(...,'inset','insetLocation')
h = measures(...)

Description

measures 'gltype' plots grounding lines specified by 'gl', which plots all grounding line data from the Measures project, or any of the following strings to specify a grounding line from a specific year: 'gl1992', 'gl1994', 'gl1995', 'gl1996', 'gl1999', or 'gl2007'.

measures('gltype','markerProperty',markerValue) formats the grounding line markerstyle properties with name-value pairs.

measures 'speed' plots a full continentsworth of ice speed data, downsampled to 4.5 km resolution.

measures('speed',lat,lon) plots a 500-kilometer-wide map of ice speed at 450 meter resolution, centered at the location given by lat,|lon|.

measures('speed','locationString') plots a 500-kilometer-wide map of ice speed at 450 meter resolution, centered at the location given by 'locationString'. With this syntax, measures uses the scarloc function to search the SCAR database for 'locationString'.

measures('speed',...,'mapwidth',mapwidth_km) specifies the map width in kilometers.

measures('speed',...'alpha',alphaValue) sets transparency of speed plot to an alpha value of 0 to 1. 0 is fully transparent; 1 is fully opaque.

measures('speed',...'colormap',cmap) specifies a colormap (e.g., autumn(256) )

measures('speed',...'colorbar',ColorbarOption) turns off colorbar if 'colorbar', 'off' is declared. Alternatively, colorbar placement may be specified with any of the following ColorbarOption arguments:

  • 'EastOutside', 'vertical', or 'on' Outside right
  • 'SouthOutside' or 'horizontal' Outside bottom
  • 'North Inside' plot box near top
  • 'South Inside' bottom
  • 'East Inside' right
  • 'West Inside' left
  • 'NorthOutside' Outside plot box near top
  • 'SouthOutside' Outside bottom
  • 'WestOutside' Outside left

measures('vel',lat,lon) plots velocity vectors using the quivermc function.

measures('vel','locationString') specifies map center location by its SCAR name.

measures('vel',...,'mapwidth',mapwidth_km) specifies width of a velocity map.

measures('vel',...,'quivermcProperty',quivermcValue) formats velocity vectors with quivermc name-value pairs.

measures(...,'inset','insetLocation') places an inset in a corner of the map given by cardinal location string (e.g. 'northwest' places an inset in the upper left hand corner of the map.)

h = measures(...) returns handles(s) h of plotted object(s).

Requirements

This particular function requires Matlab's Mapping Toolbox and the Antarctic Mapping Tools package.

Example 1: Mimic that plot we see all over the place

Plotting continent-scale ice speed is simple (albeit somewhat slow). You can do it just like this:

measures speed

If you'd like to mimic Rignot et al.'s plot from their 2011 Science paper, you can do it with rgbmap and the basins function from the Bedmap2 Toolbox. Note that measures plots ice speed on a log10 scale, so the color bar needs some maual tweaks to get it right. In my use of the rgbmap function below, please note that I'm guessing Rignot's colors the best that a colorblind person can...

rgbmap('pinkish brown','tan','light yellow','light grass green',...
    'aqua','dark blue','magenta','red',455);
basins

% fix the colorbar tick marks:
cb = colorbar;
set(cb,'location','north','position',[.15 .9 .35 .04],...
    'xtick',[log10(1.5) 1 2 3]','xticklabel',{num2str([1.5 10 100 1000]')},...
    'xgrid','on','gridlinestyle','-')
xlabel(cb,'velocity magnitude [m/yr]')

Example 2: Plot the speed of a specific region

How fast is Totten Glacier moving?

close % closes the plot we made in Example 1

measures('speed','totten glacier')

Now let's overlay some velocity vectors

measures('velocity','totten glacier','units','m/a','inset','northwest')

Example 3: Overlay measures velocity vectors on a modismoa image

The measures function was designed to mate with the functions in the Bedmap2 Toolbox as well as modismoa. Here we plot a 200-km-wide MODIS MOA image of Mertz Glacier Tongue and overlay velocity vectors. For information on formatting velocity vectors, see the documentation for quivermc.

close % closes the plot we made in Example 2

modismoa('mertz glacier tongue',200)
measures('velocity','mertz glacier tongue','mapwidth',200,...
    'colormap',jet(256),'arrowdensity',8)
scalebar('length',50,'color','w')

Example 4: Overlay semitransparent speed data on a MOA image

The modismoa function takes over a figure's colormap with its grayscale, so overlaying another colormap requires help from the freezeColors function. Here we overlay semitransparent speed data and some green velocity vectors on a modismoa image:

figure
modismoa('pine island glacier',150)
freezeColors;
measures('speed','pine island glacier','mapwidth',150,'alpha',.15)
measures('vel','pine island glacier','mapwidth',150,'density',6,'color','g');
scalebar('length',25,'location','southeast','color','w')

Citing these datasets:

VELOCITY DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2017. MEaSUREs InSAR-Based Antarctica Ice Velocity Map, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/D7GK8F5J8M8R.

TWO LITERARY REFERENCES 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.

Mouginot, J., B. Scheuchl, and E. Rignot. 2012. Mapping of Ice Motion in Antarctica Using Synthetic- Aperture Radar Data, Remote Sensing. 4. 2753-2767. http://dx.doi.org/10.3390/rs4092753 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. doi:10.1016/j.cageo.2016.08.003

Author Info

This function was written by Chad A. Greene of the Institute for Geophysics at the University of Texas in Austin (UTIG), July 2014. Updated August 2014 as a plugin for Antarctic Mapping Tools.