Topography and Coastline [10] The Shuttle Radar Topography Mission (SRTM) onboard the Space Shuttle Endeavour obtained the most complete near-global high-resolution data set of the Earth’s topography during its 10 day operation [Farr and Kobrick, 2000; Rabus et al., 2003]. The topographic data were derived by radar interferometry and covers 90% of the Earth’s land surface at 300 (90 m) resolution. The cell size of the SRTM data was less than that of the new grid (300
compared to 3.600, respectively) therefore there were no gaps in the data coverage for all subaerial areas. [11] High-resolution vector coastlines were obtained for both Papua New Guinea (1:50000 Coastline of Papua New Guinea, available at http://gis.mortonblacketer.com.au/ upngis/downloads.htm) and Australia (GEODATA Coast 100k 2004, available at http://www.ga.gov.au/nmd/ products/thematic/coast.jsp). The coastlines were used in two ways: (1) the vector files were used to clip the SRTM topographic data, and remove any data that occurred outside the areas defined as land by the coastline file; and (2) both vector coastlines were converted to a grid with 3.600 reso- lution grid and converted to an XYZ ASCII text file, each latitude/longitude pair being given a depth value of 0. The coastline ASCII file ensured that a cell value of 0 m would mark a coastline around all topographic data, and that the topographic data did not ‘‘bleed out’’ into the bathymetry during the gridding process.