Ship-based oceanographic surveys typically operate several data-collection systems: navigation, bathymetry, camera, seismic-reflection, sidescan sonar, and physical sampling. All data gathered during the survey are geographically located by referencing their time of collection with the time of a navigational "fix" from satellites (GPS) and/or transponders. After the field activity is completed, time is also used to annotate interpreted data, for example, geologic structures from seismic-reflection profiles or sidescan-sonar images, or seafloor features from photographs. With time as the measure, routes and related events are used to extract and analyze data along segments of tracklines (line events) or at discrete points (point events). In addition to enabling time as the primary measure, route treatment of tracklines preserves the start-to-end continuity that is ordinarily fragmented by building arc topology. Depending on the data set, the event tables may be converted to standard line and point coverages.
Oriented bottom photographs that are time-referenced are one product of this study. Bottom current direction and bottom roughness were determined from the appearance of the seafloor in each photograph. A plot of the inferred current directions as a function of time along the camera tracklines reveals a complex pattern with a dominant northwest-trending swath through the area. Sediment textures were determined from the photographs and also from sample grain-size analyses. These textures provide confirmation, along survey tracks, of the textures interpreted from the sidescan-sonar image of the area. Correlation of observed sediment textures with image data paves the way for construction of a sediment map of the whole area, both along- and between-track.
Table 1. Navigation log.
Table 2. Equipment on/off times.
Table 3. Observations from
photographs.
Table 4. Measure at change of hour or day.
Table 5. Excerpts of AMLs.
Figure 1. Shaded relief map of Mamala Bay.
Figure 2. Sonar mosaic of Old Honolulu
site.
Figure 3. 1994 USGS tracklines.
Figure 4. Annotated camera
tracklines.
Figure 5. Photographs of sea floor.
Figure 6. Sea-floor morphology.
Figure 7. Current directions.