Mooring adrift

How much heat does the ocean supply to the atmosphere? And how much water evaporates in the Bay of Bengal? Both are critical for the dynamics of the monsoon, and the rainfall over land. One of the instrument platforms deployed to answer these questions is a drifting “mooring”: a floating buoy tethered to a long line with a weight at the end. The buoy is decked out with gauges measuring weather conditions at the surface. Below the water, attached to the long line, are instruments measuring ocean currents, temperature, salinity, and turbulence at many different depths, from right at the surface to 200 m below. Normally such a mooring is held in place by a heavy weight sitting at the bottom of the ocean (often old railroad wheels!) for a year. However this mooring needs not to stay for an entire year, and also not stay precisely at one point. So a much easier solution was found: instead of anchored to the seafloor, it is “anchored” to the slow currents at 200 m depth, by large x-shaped wings that get dragged by the water. So even if the winds are howling at 15 m/s, or 30 knots, the buoy won’t be sailing away, but is stuck in place with the much slower moving deep ocean. Check out its current location and live data, courtesy of the Upper Ocean Processes group at the Woods Hole Oceanographic Institution: http://uop.whoi.edu/currentprojects/MISO/misodata.html

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