HR: 1615h
AN: OS44A-02    [Abstracts]
TI: Tropical-Extratropical Interaction and Intraseasonal Rainfall Variability within the SPCZ
AU: * Kiladis, G N
EM: george.kiladis@noaa.gov
AF: Physical Sciences Division ESRL/NOAA, 325 Broadway, Boulder, CO 80305,
AB: The South Pacific Convergence Zone (SPCZ) is within a region characterized by strong atmospheric tropical-extratropical interactions. The northwest-southeast oriented portion of the SPCZ shares many of the same characteristics as other diagonal convergence zones across the globe, namely, a dominance of transient precipitation events linked to frontal and Rossby wave activity originating within the midlatitude westerlies. We show that deep convection within the diagonal portion of the SPCZ is controlled primarily by the impingement of upper level troughs embedded within Rossby wave trains propagating into the western Pacific from the extratropical Indian Ocean. This interaction is favored by the existence of a wave guiding due to the large scale basic state flow over the region. As a contrast, the dominant mode of precipitation variability in the more zonally-oriented tropical portion of the SPCZ, equatorward of around 10S latitude, is linked to equatorial Rossby (ER) wave activity propagating westward. This equatorial wave activity is in turn frequently triggered by extratropical wave activity propagating into the east Pacific from the Northern Hemisphere. Both types of synoptic scale activity is significantly modulated by the Madden-Julian Oscillation (MJO), through its intraseasonal alteration of the lower frequency background basic state flow.
DE: 3314 Convective processes
DE: 3319 General circulation (1223)
DE: 3354 Precipitation (1854)
DE: 3364 Synoptic-scale meteorology
DE: 3374 Tropical meteorology
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting