Sampling Representativeness of Oceanographic Surveys Using Ship-Based Instruments

Publication Type:Journal Article
Year of Publication:2003
Authors:Chang, Y-H, Wen, L-S
Journal:Journal of Coastal Research
Date Published:2003
ISBN Number:07490208
Keywords:Calidris, Calidris canutus, Scolopacidae
Abstract:The representativeness of sample collection from an oceanographic survey using ship-based instruments is crucial for providing basic oceanographic information in either global or local scales, and forms the backbone for the following reconnaissance investigation. However, those data often were collected for convenience, without any consideration to the sampling coverage and representativeness. In this study we examine the impact of using grid, parallel, diagonal (W) and random sampling strategies with different sampling densities on an exhaustive data set. The result shows that the diagonal sampling strategy has the best performance to achieve the goal of collecting a representative sample with the resolution of 0.5 km and may be collected within a reasonable time of 6.1 hours in a hypothesized study area of 100 m2 with a ship speed of 7 knots. Although the random sampling strategy could have a similar result with fewer samples, its sampling time is much longer than those of the diagonal sampling strategy. The grid and parallel sampling strategies achieve the goal of collecting a representative sample only when the sample ratios between shipping course and its vertical direction are within 1 to 9 and 1 to 2.9 respectively. The sampling time for these two frequently used strategies are 5.4 hours (parallel) and 4.6 hours (grid) with a 1 km resolution. The 1 km resolution is, however, similar to those of many satellite images such as the Seawifs.
Short Title:Journal of Coastal Research
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith