A new 30-arc second resolution global topography/bathymetry grid (SRTM30_PLUS) has been developed from a wide variety of data sources. Land and ice topography comes from the SRTM30 and ICESat topography, respectively. Ocean bathymetry is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings. The main contribution of this study is the compilation and editing of the raw soundings, which come from NOAA, individual scientists, SIO, NGA, JAMSTEC, IFREMER, GEBCO, and NAVOCEANO. The gridded bathymetry is available for ftp download in the same format as the 33 tiles of SRTM30 topography. There are 33 matching tiles of source identification number to convey the provenance of every grid cell. The raw sounding data, converted to a simple common format, are also available for ftp download.

The research in this paper focuses on the I/O problem associated with a parallel application writing to a single physical disk. Included in our research are the original ideas that led to the first version of the parallel software, subsequent versions of the software derived from lessons learned from benchmark results, and speedup results of each version. The underlying purpose of this software is to process hydrographic data having a complicated, multi-tiered format. The data processing involves reading tens to hundreds of files containing raw data, filtering out extraneous data values, and writing the filtered data to a single file used in additional processing. The problem is not computationally intensive, but bound by the system's file writing capability. Results show that the more responsible the software was for organizing the data before writing, the better the speedup. The critical factor for writing data efficiently involved the limitation of writing data over a single I/O controller. Our parallel software has fantastic utility where system specifications do not allow for the use of parallel file systems, or writing data over multiple I/O controllers.

The Digital Mapping, Charting and Geodesy Analysis Program (DMAP) of the Naval Research Laboratory (NRL), in an effort to aid Naval Oceanographic Office (NAVO) data processing needs, has developed a system to spatially index and query bathymetric data stored in generic sensor format (GSF) data files. The GSF data file format has the ability to store various types of data, but in this system only bathymetry, specifically, single-beam and multi-beam bathymetry, is indexed. Bathymetric data is used by NAVO to generate various oceanographic information products. Presently, to obtain bathymetric data for a particular area of interest (AOI) for product generation, NAVO personnel must determine which oceanographic surveys generated bathymetric data files in the AOI and where these files are physically located. Next, they have to download all of these files and process them. Each of these files may have large amounts of data (potentially hundreds of megabytes) that are outside of the given AOI. It is also possible that some files may not have any data in the AOI. Using the spatial indexing ability of Oracle, the NRL-developed system allows NAVO to quickly determine and retrieve only the bathymetric data that are relevant to the AOI, completely automating the process of data acquisition. This system provides benefits by substantially reducing the amount of data that must be considered when producing a product and also by providing users with an intuitive interface to use for data retrieval purposes. This paper discusses the spatial indexing scheme, spatial querying, the interface for retrieving data, and other components of the NRL system. In addition, problems that were encountered and the time savings provided by this system are discussed.