Document Title - Geoscience Australia

Lord Howe High Resolution Grids
COMPARISON OF THE FOUR GRIDS
The Lord Howe Island region as represented by the global and Australian bathymetry grids are
shown in Figure 5.
Major differences in the representation of the Lord Howe Island region by the four datasets include:
Only the GA grid has detail on the volcano.
The number and size of seamounts differs greatly.
The location and size of the land component differs greatly.
30.63 o S
160.2 o E
30.63 o S
160.2 o E
32.6 o S
158.13 o E
30.63 o S
160.2 o E
32.6 o S
158.13 o E
30.63 o S
160.2 o E
32.6 o S
158.13 o E
32.6 o S
158.13 o E
Figure 5: Comparison of 4 widely used bathymetry grids. Clockwise from the top left: the GA
grid, GEBCO, ETOPO1, and DBDB2 (position markers approximate only).
Dataset Discussion
All four grids were produced using relatively sparse data. The Australian grid seems to be the most
accurate, largely due to its higher resolution through the incorporation of more survey data,
including multibeam sonar bathymetry data. However, even the Australian grid is heavily
interpolated on the upper portion of the Lord Howe volcano due to the low density of data in this
shallow area. The ETOPO1 grid appears 150 m too shallow when compared to the other grids and
actual survey soundings.
There is also inconsistency in the positioning of the seamounts and islands. The purpose of this study
is to improve on the Australian bathymetry grid in this area with the inclusion of new bathymetric
data, topographic data and a thorough assessment of the quality of the data employed.
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