MATLAB Examples

ibcso_data documentation

The ibcso_data function returns IBCSO bathymetric data and corresponding geographic or polar stereographic cartesian coordinates. IBCSO data are described in full on the IBCSO website and the GRL paper describing the IBSCO dataset is here.

Contents

Description of files in the IBCSO Toolbox:

  • ibcso_install simply downloads and unzips IBCSO data.
  • ibcso_data returns native-resolution gridded IBCSO DEM bathymetry or gridded distance-to-nearest-measurement.
  • ibcso_interp interpolates to any arbitrary point(s) given by lat,lon or x,y.
  • ibcso plots the official IBCSO RGB image, the IBCSO DEM as a color-scaled pcolor or contour plot, or distance-to-nearest measurement.

Syntax

Z = ibcso_data
Z = ibcso_data(lati,loni)
Z = ibcso_data(xi,yi)
Z = ibcso_data(...,extrakm)
Z = ibcso_data(...,'res',resolution)
Z = ibcso_data(...,'wgs84')
[lat,lon,Z] = ibcso_data(...)
[X,Y,Z] = ibcso_data(...,'xy')
[...] = ibcso_data(...,'dist')

Description

Z = ibcso_data returns IBCSO bed elevation data at the full 500 m resolution. This is a large 13341x13335 dataset and loading may take a second or two.

Z = ibcso_data(lati,loni) returns only enough IBCSO data to fully encompass a set of points given by geo coordinates lati,loni.

Z = ibcso_data(...,xi,yi) returns only enough IBCSO data to fully encompass a set of points given by polar stereographic (-71) coordinates xi,yi.

Z = ibcso_data(...,extrakm) as above, but encompasses points xi,yi or lati,loni and adds a buffer of specified width extrakm in kilometers around all four sides of data points. This is useful when you want data surrounding a point or several measurments.

Z = ibcso_data(...,'res',resolution) specifies a resolution in kilometers. By default, this function returns the full 500 m IBCSO data set.

Z = ibcso_data(...,'wgs84') returns elevations relative to the WGS84 ellipsoid. By default, elevations are relative mean sea surface elevation, which is very close the GL04C geoid. The 'wgs84' option uses the Bedmap2 Toolbox to perform conversion.

[lat,lon,Z] = ibcso_data(...) returns a lat,lon grid of the IBCSO data set.

[X,Y,Z] = ibcso_data(...,'xy') returns polar stereographic coordinates when the 'xy' tag is included.

[...] = ibcso_data(...,'dist') returns gridded distance to data in kilometers. Data here refers to any multibeam or singlebeam data. (Requires Image Processing Toolbox). Distance calculation may 30 seconds to a minute if you're calculating the entire continental dataset.

Requirements

This function requires

  • Antarctic Mapping Tools found here.
  • A license for Matlab's Mapping Toolbox will extend some capabilities of the ibcso function, but is not required.
  • Matlab's Image Processing Toolbox is required for distance-to-data calculation.

Installation

To install the IBCSO dataset, simply run ibcso_install.

Example 1: Full dataset, downsampled

Load a whole continent of DEM data, downsampled to 5 km resolution and return an x,y grid:

[X,Y,Z] = ibcso_data('res',5000,'xy');

To create the icon used for this toolbox, I plotted the 5 km z grid with pcolor. I tried to match Figure 4 of the Arndt et al. paper using Kelly Kearney's GMT-style colormap with cptcmap and I applied a little topographic shaded relief with shadem:

pcolor(X,Y,Z)
axis image off
shading interp
cptcmap('GMT_globe','mapping','direct','ncol',10)
shadem([225 40],3)
t = text(0.5,0.5,'IBCSO','fontsize',60,...
    'units','normalized','vert',...
    'middle','horiz','center');
close

Example 2: Recreate Figure 4e1 of the Arndt et al. GRL paper.

Start by defining some place of interest. Then load IBCSO data surrounding that location. Give it 60 kilometers on each side. This will load a 240x240 DEM at full 500 m resolution. Plot using the AMT function pcolorps and add hillshading effect with the AMT function shadem. I'm using Kelly Kearney's cptcmap function to mimic the colormap in the Arndt et al. paper.

[lati,loni] = scarloc('Peter I Island');
[lat,lon,z] = ibcso_data(lati,loni,60);
pcolorps(lat,lon,z)
shading interp
cptcmap('GMT_globe','mapping','direct','ncol',10)
shadem([225 60],3)
axis image off

Citing IBCSO data

If you use IBCSO data, please cite the following:

Arndt, J. E., et al. (2013), The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0-A new bathymetric compilation covering circum-Antarctic waters, Geophys. Res. Lett., 40, 3111-3117, doi:10.1002/grl.50413.

Author Info

This function was written by Chad A. Greene of the Institute for Geophysics at the University of Texas in Austin July 2015. Updated September 2015 to allow distance-to-measured-data calculation.