The Madden Julian oscillation (MJO) is the primary mode of intraseasonal variability in the tropics. The MJO often couples with convection as it moves over the Indian Ocean and decouples as it leaves the west Pacific Ocean. The association between convection coupled to the MJO and the midlatitude flow pattern has been the primary focus of numerous studies. In particular, it has been shown that there is a statistical relationship between the position and strength of the MJO and anticyclonic wavebreaking (AWB). This study expands on this statistical relationship by examining, in detail, the two-way relationship between the MJO and AWB.
Using a climatology of AWB during an extended boreal cold season, we demonstrate that there is enhanced AWB over the central North Pacific when the MJO is in its middle phases. Convection associated with the MJO can induce AWB when active MJO convection is over the Indian Ocean. Once the wave breaks over the central North Pacific, the residual cut-off low phases with the MJO circulation to enhance it as it propagates eastward, resulting in a higher amplitude MJO than when no AWB occurs.
AWB over the North Pacific also has significant impacts on the temperature composites associated with MJO phase, which are often used to make intraseasonal temperature forecasts. It is shown that considering AWB, along with the phase of the MJO, results in more specific information on which to base intraseasonal temperature forecasts. Additionally, it is shown that MJO events with AWB are associated with half a day of enhanced model skill over the Northern Hemisphere.
|Advisor:||Roundy, Paul E.|
|Commitee:||Bosart, Lance F., Kiladis, George N., Molinari, John|
|School:||State University of New York at Albany|
|Department:||Earth and Atmospheric Sciences-Athmospheric Science|
|School Location:||United States -- New York|
|Source:||DAI-B 76/05(E), Dissertation Abstracts International|
|Keywords:||Equatorial waves, Kelvin waves, Madden Julian oscillations, Rossby wavebreaking|
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