10.2
Projecting the Madden-Julian Oscillation (MJO) modulation of atmospheric circulation onto Chilean winter precipitation
Bradford S. Barrett, U.S. Naval Academy, Annapolis, MD
The Madden-Julian Oscillation (MJO) is the leading intraseasonal mode of tropical atmospheric variability. While a planetary scale circulation, it has been shown to modulate both synoptic and mesoscale precipitation and circulation. Winter precipitation in Chile has been connected to both synoptic- and mesoscale forcing mechanisms, including those from traveling mid-latitude cyclones, flow blocking, and local barrier jets. This study explored the links between the two, first examining the variability of Chilean precipitation using a sampling of different surface and remote-sensing datasets (surface gauges, the Tropical Rainfall Measuring Mission TRMM, and a proxy from outgoing longwave radiation) and then examining the variability of mesoscale-scale forcing and circulation. Particular attention was paid to how the MJO modulates flow blocking and the development of low-level wind maxima upstream and parallel to the Andes. These barrier jet phenomena have been shown to be important contributors to total precipitation during the winter season in central Chile.
Session 10, Special sessions on the study of multiscale interactions
Wednesday, 3 August 2011, 1:15 PM-2:00 PM, Marquis Salon 456
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