This image is a representation of 5 Mhz acoustic backscatter measurements of suspended sediment on the sea-floor, obtained during a winter storm on the northern California continental shelf, as part of the Sediment Transport Events on the Shelves and Slopes (STRESS) program. The water depth is approximately 90 meters and the bottom is composed primarily of fine sand and silt. Note the periodic appearance of clouds of suspended sediment, up to a height of some 25 cm, at intervals approximately equal to the dominant period of surface gravity waves (roughly 17 seconds). Also note at smaller heights (up to 10 cm) the periodic appearance of large concentrations at higher frequencies (roughly half the wave period). The rapid appearance and disappearance of sediment clouds indicates advection of a spatially inhomogenious field, rather than particle resuspension and settling.

More information about this experiment can be found in "Sediment TRansport Events on SHelves and Slopes: STRESS", a special edition of CONTINENTAL SHELF RESEARCH, Trowbridge, Nowell, editors, Volume 14, No. 10/11. 1994.

This image is featured on the cover.

Acoustic monitoring of sediment transport was also performed on the East Coast at the LEO-15 site off Atlantic City, New Jersey.

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