Digital bathymetry for the Southern Ocean GLOBEC study area

A new digital bathymetric database has been developed for the Marguerite Bay and adjacent shelf area of the West Antartic Penisula as part of the planning for the U.S. Southern Ocean GLOBEC program.

This new database represents a merger of depth data from navigational charts with the most recent version of the Sandwell and Smith 2-min global ocean digital bathymetry ETOPO2. Sandwell and Smith obtained all digital ship trackline bathymetry/position data that had been submitted to the National Geophysical Data Center by July 15, 2000, and then combined this in situ data with satellite-derived bathymetry to produce ETOPO2-v8.2. The positions of individual sounding data on four navigational charts that cover the study area were determined using an xy digitizing table, and the resulting digital xyz data were combined with ETOPO2-v8.2 using the GMT tool surface. The resulting digital bathymetry shows more spatial structure around Adelaide Island and within Marguerite Bay as a result of the addition of the navigational chart data, which are not part of the NGDC archive.

The navigational charts used are listed in Table 1. The original ETOPO2-v8.2 bathymetry is shown in Figure 1. The distribtution of the NGDC ship trackline data used in ETOPO2-v7.2 is shown in Figure 2. The distribution of navigational chart depth data is shown in Figure 3. The combined bathymetry (labeled ETOPO2-v8.2A) is shown in Figure 4.

The new database is available online as a netcdf file: etopo8.2a.grd, an ASCII file: etopo8.2a.asc or a Matlab file: etopo8.2a.mat

We plan to continue to update this new bathymetry as additional digital depth data are acquired during the SO GLOBEC field program. Please contact us if you have any questions about this new database, or know of additional navigational charts that could be added. Note that there are considerable discrepancies east of Adelaide Island that have not been addressed in this version of the data. These discrepancies are beyond the region shown in figure 4.

Bob Beardsley, Mike Caurso, Jan 12, 2001

Table 1. Navigational charts used to augment ETOPO2-v8.2
 
 
 

Map	Description
GB 3571	Lavoisier Island to Alexander Island British Hydrographic Office (fm) 1:500 000 10/1/1998
GB 3577	Adelaide Island, South Western Approaches British Hydrographic Office (fm) 1:75 000 3/1995
US 29142	Alexander Island to Square Bay, including Marguerite Bay National Imagery and Mapping Agency (m) 1:200 000 11/2/1996
US 29141	Square Bay to Matha Strait, including Adelaide Island Defense Mapping Agency (m) 1:200 000 8/6/1988