- 2008-06-17T00:00:00 - All datasets obtained by NGDC were converted to common horizontal and vertical datums of WGS 84 and sea level, respectively, using FME. They were also converted to common file format, ESRI point shapefiles, for visualization and inspection.

- 2008-06-25T00:00:00 - Datasets were visually inspected with ArcGIS for identification and editing of data anomalies. Datasets were then compared with overlapping datasets to ensure data consistency.

- 2008-06-30T00:00:00 - Coastline datasets were adjusted to fit satellite imagery.

- 2008-07-10T00:00:00 - xyz files of the Measured and Estimated Seafloor Topography data (between -500 m and 0 m) were surfaced using GMT's 'surface' tool onto a 1 arc-minute cell size grid that interpolated to fill empty cells. Points extracted along the GSHHS coastline were also included, at -1 m elevation, to force bathymetric interpolation into the coastal zone. The resulting Arc ASCII grid was clipped to the coastline and the -120 m contour to remove values over land and non-coastal waters.

- 2008-07-18T00:00:00 - xyz files for each input dataset were gridded using MB-System's 'mbgrid' tool, which utilizes a high-tension spline interpolation method to fill grid cells with no input elevation values. Preferential weighting was given to the NSIDC Antarctica RAMP topography dataset. Least weight was given to the global datasets and the interpolated bathymetric surface. Gridding was performed in 16 regional tiles, each with a 5% data buffer. The grids were imported in ArcGIS and seamlessly merged to create the final global relief model.

- 2008-07-31T00:00:00 - ETOPO1 was bult as a global, grid-registered, 1 arc-minute grid that spans from pole to pole and from -180 degrees to 180 degrees in longitude. It is 21601 cells by 10801 cells in dimension, with multiple duplicate cells sitting atop the North and South poles and on the -180 degrees and 180 degrees longitude line. A cell-registered version (21600 by 10800 cells) was created from the grid-registered version by resampling, using GMT's 'grdsample' tool. This resampling introduces some flattening of relief, due to averaging of four grid-registered cell vlaues to produce one cell-registered value. Both types are global, though the grid-registered version should be considered the authoritative version. The cell-registered version may be more appropriate for creating maps and images.