The isopenocean function returns logical true for any locations that are neither grounded nor ice shelf according to MEaSURES Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2. The isopenocean function returns the logical NOT of the isice function.
The dataset is described on the NSIDC site here: http://nsidc.org/data/NSIDC-0709
tf = isopenocean(lati,loni) tf = isopenocean(xi,yi)
tf = isopenocean(lati,loni) returns true for all geo locations (lati,loni) for all locations that are not part of the ice sheet ice in the Mask_Antactica_v2.tif (sic) dataset.
tf = isopenocean(xi,yi) returns true for all non-ice-sheet locations in Mask_Antactica_v2.tif (sic), where input coordinates are automatically determined to be polar stereographic (true lat 71 S) meters if their values exceed the normal lat,lon range.
This example uses a Gravity Plugin for AMT to load some example data, but I'll show you how you can follow along without loading that dataset. Whether you have the gravity plugin or not, begin by creating a 300 km wide grid centered on PIG, at 0.25 km resolution:
[lat,lon] = psgrid('pine island glacier',300,0.25);
If you have the gravity plugin, interpolate gravity values to the grid like this:
FA = gravity_interp(lat,lon,'free air');
If you don't have the gravity plugin you can simply use random data like this:
FA = rand(1201);
Use isopenocean to find out which parts of the dataset are not over the ice sheet:
ocean = isopenocean(lat,lon);
Mask-out all grounded ice and ice sheets (use the tilde for NOT) by setting them to NaN:
FA(~ocean) = NaN;
Plot the gravity data corresponding to the open ocean:
pcolorps(lat,lon,FA) axis tight
For context, overlay a red grounding line and a black coastline:
If you use this dataset, please cite the following:
- The dataset: 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.
- Literature citation: Rignot, E., S. S. Jacobs, J. Mouginot, and B. Scheuchl. 2013. Ice-shelf melting around Antarctica, Science. 341. 266-270. http://dx.doi.org/10.1126/science.1235798.
- Antarctic Mapping Tools: Greene, C.A., D.E. Gwyther, and D.D. Blankenship. 2016. Antarctic Mapping Tools for Matlab. Computers and Geosciences. http://dx.doi.org/10.1016/j.cageo.2016.08.003.
This function and supporting documentation were written by Chad A. Greene of the University of Texas Institute for Geophysics (UTIG), November 2016. Updated May 2017.