MATLAB Examples

smithlakes documentation

The smithlakes function plots 124 ICESat-detected active subglacial Antarctic lakes identified in a paper by Smith et al. For details of the underlying data, read the Smith paper and data documentation on the NSIDC website.

Contents

Syntax

smithlakes
smithlakes(LakeName)
smithlakes(...,PatchProperty,PatchValue)
smithlakes(...,'label')
smithlakes(...,'label',TextProperty,TextValue)
smithlakes(...,'xy')
[hpatch,hlabel] = smithlabel(...)

Description

smithlakes plots all 124 active subglacial lakes identified by Smith et al. By default, lakes are plotted as blue patch objects in geographic coordinates.

smithlakes(LakeName) plots only lake(s) containing LakeName. Many ice streams have multiple subglacial lakes. Use 'Whillans_2' to plot only the lake identified by Smith et al. as Whillans_2, or use 'Whillans' to plot all of the Whillans lakes.

smithlakes(...,PatchProperty,PatchValue) specifies patch properties such as 'facecolor', 'facealpha', 'edgecolor', 'linewidth', etc.

smithlakes(...,'label') places a text label on each plotted lake.

smithlakes(...,'label',TextProperty,TextValue) specifies text properties such as 'fontsize', 'color', etc.

smithlakes(...,'xy') plots in polar stereographic xy coordinates in meters.

[hpatch,hlabel] = smithlabel(...) returns handles for patch and label objects.

Requirements

This function requires

The first time you run smithlakes, the function will attempt to download the necessary data from the NSIDC website.

Example 1: Continent-wide

To plot all 124 active subglacial lakes identified by Smith et all, simply type

smithlakes
close % (closes Example 1 figure)

Example 2: Regional with context

Example 1 is not terribly insightful. Typically we want to see these lakes in some sort of regional context. Zoom a 1200 km wide map to (82°S,134°W), use the ramp and basins functions to give a little context, then plot all lakes as default blue patches:

mapzoom(-82,-134,1200,'inset','sw')
ramp
basins
smithlakes
close % (closes Exampe 2 figure)

Example 3: Specify which lakes to plot and how they look.

Now let's get fancy. Start with a 350-kilometer-wide modismoa image of the area near Recovery Glacier. We'll overlay semitransparent color to indicate ice speed with measures, so I we need to freeze the current colormap with freezeColors. Below I'm specifying ice speed color with my paruly function, which mimics the new parula colormap. For added context, use the bedmap2 function to overlay gray surface elevation contour lines.

figure('position',[100 100 900 800])
modismoa('recovery glacier',350)

freezeColors
measures('speed',...
    'recovery glacier',...
    'mapwidth',350,...
    'colormap',paruly(256),...
    'colorbar','off',...
    'facealpha',0.15,...
    'inset','sw')

% Overlay gray surface contour lines:
bedmap2('surfc','zvals',100:100:1900,'color',[.7 .7 .7])

scalebar('location','se','length',50)

Now that we have our complicated map for context, let's plot a bunch of lakes. First, plot all 124 lakes as light blue patch objects. Below I'm using my rgb function, which turns intuitive color names into RGB values.

After plotting all lakes, highlight and label only the Recovery Glacier lakes using the commands below.

% Plot all lakes:
smithlakes('facecolor',rgb('light blue'))

% Plot and label only lakes starting with "Recovery":
smithlakes('recovery',...
    'facecolor',rgb('light blue'),... % make them light blue
    'linewidth',2,...                 % with a thick black edge
    'label',...                       % turn on text labels
    'fontangle','italic',...          % make 'em fancy italics
    'fontweight','bold',...           % embolden the labels
    'color','red');                   % make the text labels red
close % (closes figure from Example 3)

Example 4: Polar stereographic coordinates.

You might want to plot these lakes in polar stereographic x,y meters instead of geographic (lat,lon) coordinates. To do so, simply include 'xy' as an argument in the smithlakes function. Let's plot all the Whillans Ice Stream lakes in red using polar stereographic coordinates. For context, start by plotting the Landsat Image Mosaic with lima:

lima('whillans ice stream',700,'xy')
smithlakes('Whillans','xy','facecolor','red')
axis image % (tightens frame)

Citing this dataset

If you use this dataset for any reason, please cite the following:

Smith, B., I. Joughin, S. Tulaczyk, and H. Fricker. 2012. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N57M05WS.

I also recommend reading and citing Smith et al.'s Journal of Glaciology paper that describes this data set. It's a good read!

Author Info

This function and supporting documentation were written by Chad Greene of the University of Texas at Austin's Institute for Geophysics, July 2015.