Passage II

A study performed at a site off the Mediterranean coast examined how an ocean storm during the winter affected wave height, current speed, and the rate of sedimentation.

Study

Before the winter storm season began, 3 types of instruments were anchored to the ocean floor in water 26 m deep (see Figure 1). A wave height buoy, which was attached to its anchor with an elastic cord, contained a device that measured its vertical movements in the waves. An acoustic profiler, fixed in position 2.5 m above the ocean floor, used sound waves to measure the horizontal speed of the ocean current at that depth. A pair of sediment traps, fixed at the same distance above the ocean floor as the acoustic profiler, collected sediment that settled out of the water.

From November 4 to November 24, the average wave height, in meters (m), and the average current speed, in centimeters per second (cm/sec), were determined daily (see Figures 2 and 3, respectively). The mass of sediment, in grams (g), deposited per square meter (m²) of ocean floor per day (the sedimentation rate) was also determined daily over those 21 days (see Figure 4). A strong storm affected the site beginning the morning of November 12.

Figures adapted from Antoine Grémare et al. , "The Effects of a Strong Winter Storm on Physical and Biological Variables at a Shelf Site in the Mediterranean." ©2003 by Elsevier SAS.