J8.2 Rapid Acceleration of the Wyrtki Jet in the Central Indian Ocean by a Cyclone-Assisted Wind Burst Embedded withn an MJO Event

Wednesday, 11 July 2012: 1:45 PM
Essex Center/South (Westin Copley Place)
James N. Moum, College of Earth, Ocean & Atmospheric Sciences, Oregon State University, Corvallis, OR; and W. D. Smyth, J. B. Edson, S. P. DeSzoeke, and C. W. Fairall

Handout (3.6 MB)

Detailed measurements of upper ocean processes and surface fluxes at 0, 80.5E in October/November 2011 during the DYNAMO Intensive Observation Period include the passage of a major MJO event. Peak sustained winds of 23 m s-1 contributed to daily-averaged wind stress of 0.35 N m-2 immediately following passage of the first convective front. Despite considerable precipitation, the ocean surface quickly became saltier as subsurface entrainment mixed salty water up from below. During the event, mixed layer cooling was completely balanced one-dimensionally. The cooling rate of 0.4 K/day was due to -320 W m-2 from the atmosphere and -180 W m-2 from below due to subsurface mixing. To first order, the acceleration of the Wyrtki Jet from 12 Sv (+/- 1 degree from the equator) to 24 Sv, quadrupling the system kinetic energy, was balanced simply by the wind stress at the sea surface.

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