MATLAB Examples

dist2mask returns the distance in kilometers from given datapoints to any mask type (grounded, iceshelf, etc.) according to MEaSURES Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2. This function is similar to the bedmap2_dist function in the Bedmap2 Toolbox.

The Antarctic Boundaries dataset is described on the NSIDC site here. An overview of the tools in this AMT plugin can be found here.

## Syntax

```d = dist2mask(masktype,lati,loni)

## Description

d = dist2mask(masktype,lati,loni) gives the distance d from the geo locations (lati,loni) to the nearest mask type, which can be any of the following:

• 'grounded' all ice or rocks on the landward side of the InSAR-detected landward limit of flexure.
• 'iceshelf' all the bits of the ice sheet (not sea ice) on the seaward side of the landward limit of flexure.
• 'ice' any part of the ice sheet (not sea ice).
• 'openocean' any part of the open ocean (not ice shelves or sea ice).
• 'tidal' everything seaward of the landward limit of flexure, including ice shelves.

d = dist2mask(masktype,xi,yi) is the same as above, except coordinates are polar stereographic meters (ps71), which are automatically parsed by the islatlon function.

## Example

Given these scattered points, let's say it's mooring data:

```lat = -70+4*randn(50,1); lon = -45+6*randn(50,1); plotps(lat,lon,'ko'); antbounds('coast','poly','facecolor',0.5*[1 1 1],'facealpha',1) ```

Suppose you want to know the distance of each mooring to the nearest bit of ice sheet:

```d = dist2mask('ice',lat,lon); scatterps(lat,lon,50,d,'filled') cb = colorbar; ylabel(cb,' distance from coast (km) ') mapzoomps('ne','frame','off') % places an inset map in the corner ```

## Contouring distances from the coast

Sometimes you might want to plot a line a given distance from the coast, say, to show effects within 100, 500, and 1000 km from the coast. To do that, make a grid that fills your domain. Let's make a grid that fills the current axis limits, then calculate the distance to the coast for each grid point:

```xl = xlim; % limits of current axes yl = ylim; [X,Y] = meshgrid(xl(1):1000:xl(2),yl(1):1000:yl(2)); D = dist2mask('ice',X,Y); ```

Now contour the 100, 500, and 1000 km distances from the coast:

```hold on [C,h] = contour(X,Y,D,[100 500 1000],'k'); clabel(C,h) % labels the contours ```

## Citing this dataset

If you use this dataset, please cite the following:

• Dataset citation: Mouginot, J., B. Scheuchl, and E. Rignot. 2017. MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. http://dx.doi.org/10.5067/AXE4121732AD.
• Antarctic Mapping Tools: Greene, C. A., Gwyther, D. E., & Blankenship, D. D. Antarctic Mapping Tools for Matlab. Computers & Geosciences. 104 (2017) pp.151-157. doi:10.1016/j.cageo.2016.08.003.

## Author Info

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