Extended Abstract (236K)P2.11
Does the Antarctic Oscillation Modulate Tropical Cyclone Activity in the Northwestern Pacific
Joo-Hong Kim, Seoul National University, Seoul, Korea; and C. H. Ho
In this study, we present the evidence of relationship between tropical cyclone(TC) activity and Antarctic Oscillation(AAO) phase for austral winter (July, August, and September), based on analyses of AAO index, wind, outgoing longwave radiation(OLR), and TC data. The TC passages revealed significant difference between high AAO periods and low AAO periods. The primary change is observed over the East China Sea, Japan, and Philippine. The change is as large as 2 and matches a 50-100% increase from the climatology during high AAO period compared to low AAO period. It is suggested that the relation AAO-TC activity in the East China Sea and Japan may be understood by changes in large-scale circulation over the region. The 850 hPa horizontal wind difference clearly indicates two anomalous anticyclonic circulations in the southern hemisphere(SH) and northern hemisphere(NH) midlatitudes: a huge anticycloe in south of Australia and a relatively small anticyclone in East China Sea. In association with the formation of two anticyclonic anomalies, the convection activity which is represented by OLR increases in the vast areas along the equator and decreases in the NH subtropics and SH midlatitude. This physically coherent event is possibly due to enhanced local Hadley circulation induced by high AAO activity.
Poster Session 2, Atmospheric Oscillations and Boundary Layer Processes (Hall 4AB)
Wednesday, 14 January 2004, 2:30 PM-4:00 PM, Hall 4AB
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