13B.4 The Boreal Winter Madden Julian Oscillation's Influence on Summertime Precipitation in the Greater Caribbean

Thursday, 26 January 2017: 11:15 AM
609 (Washington State Convention Center )
Scott Curtis, East Carolina University, Greenville, NC; and D. Gamble

Precipitation totals in the greater Caribbean are known to be affected by interannual variability.  In particular, dry conditions in the spring-summer have been physically linked to the positive phase of North Atlantic Oscillation (NAO) in the literature.    In this study, it was found through regression analysis that an active Madden-Julian Oscillation (MJO) in winter geographically focused over the Maritime Continent contributes to a positive NAO in March via the generation of Rossby waves in the Northern Hemisphere.  Specifically, a negative Pacific North American pattern develops in the winter and transitions to an Atlantic pattern in spring.  The positive NAO is a transient feature of this evolving wavetrain, but a center of significant positive 200hPa geopotential heights is entrenched over the Southeast U.S. throughout the February to May time period and is manifested as high pressure at the surface.  The southern flank of this system increases the speeds of the tradewinds and leads to a cooling of the Caribbean SSTs and thus convection suppression and reduced precipitation.  Thus, this study advances our understanding of the climate of the greater Caribbean by using climate teleconnections to relate the MJO to rainfall in the region.

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