The objectives of the September, 2002 operations, preliminarily reported here, were (1) to compile a detailed bathymetric map of the lake using swath-mapping techniques, in order to provide baseline data for a variety of applications and studies, and (2) to complete a sidescan-sonar survey of the lake, providing a nearly complete acoustic image of the lake floor. Limited amounts of subbottom acoustic-reflection data (CHIRP) were also collected, along with samples of lake-floor sediments representative of different kinds of backscatter patterns. These surveys followed an earlier subbottom acoustic-reflection survey (1997), using boomer and 3.5 kHz systems (S. M. Colman, unpublished data).
Sound velocity profiles were collected in order to map the sound velocity profile of the water column. The interferometric sonar systems acquires high-resolution bathymetric measurements in a swath. However, changes in the sound velocity profile with depth will affect the acousit ray path. The acoustic ray path must be accurately modeled in order to calculate accurate depth and position of individual soundings.