Extended Abstract (800K)13.1
Why was September 2001 to September 2002 a year of anomalously low pressures over the Tasman Sea?
Michael J. Revell, National Institute of Water and Atmospheric Research, Wellington, New Zealand; and J. A. Renwick
During the period September 2001 to September 2002, 500 hPa heights over the Tasman Sea region were anomalously low compared to the NCEP 50 year climatology. The summer period was the most disturbed (in terms of passage of rapidly moving fronts) for 20 years. In this paper we look for reasons for these events. We calculate a global streamfunction anomaly pattern for the relevant period and show that the Tasman Sea anomaly is part of a larger scale wavelike signal which extends from the Australasian tropics across New Zealand and down towards South America. Considering this signal as a streamfunction anomaly about the year average mean flow we solve for the divergence field that would make this anomaly a solution of the linearised barotropic vorticity equation. We compare this tropically dominated divergence field with OLR anomalies for the same period and comment on the relevance of the MJO, ENSO and IPO in producing this unusual weather.
Session 13, Tropical-extratropical interactions and teleconnections over the Southern Hemisphere II
Thursday, 27 March 2003, 9:00 AM-11:30 AM
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