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Science Frontiers ONLINE No. 90: Nov-Dec 1993 |
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Band Of Turbulence
That the ocean deeps also have their "weather" is evident in the following report. While reading it, be aware that it is only the surface manifestation of larger phenomenon which, like the bulk of an iceberg, is concealed from the observer.
July 29, 1992. Equatorial Atlantic.
Aboard the m.v. Enterprise enroute from Saldanha Bay to Las Palmas.
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"At 1930 UTC a bold linear echo was suddenly noted on the radar screen, as if from a singular, large swell wave running along a line bearing approximately 290�-110� and moving towards the ship in a south-southwesterly direction, see sketch. Although it was night-time, it was light enough to determine visually at a distance of about 1 n.mile, that it was not a large swell wave. At 1947 the vessel was passing through the echo which extended out to 4 n.mile on either side of it and, on observing the water around the ship with the aid of an Aldis lamp, it was noted that there was a great deal of turbulence present. The Enterprise, fully laden with iron ore, suddenly veered 6� to port of her heading of 325�, indicating the strength of the turbulence. The sea prior to this point was only slightly rippled by a light SW'ly wind, force 1-2. The band of turbulence was approximately 20 m wide and the sea beyond it was once again only slightly rippled."
(Harris, P.C.; "Radar Echo," Marine Observer, 63:111, 1993.)