ISSN 1006-9895

CN 11-1768/O4

Interdecadal Change of the Antarctic Oscillation and the Antarctic Circumpolar Wave
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    Abstract:

    The Antarctic Oscillation Index (AAOI) and the westerly index of Antarctic oscillation (Uaaoi) are defined by using the NCEP data of sea level pressure, temperature and 850-hPa westerly wind from January 1951 to December 2002. Long-term trend, interdecadal jump and cycles of AAOI and Uaaoi as well as the effect on the Antarctic circumpolar wave are discussed. Main conclusions show that the relationship between AAOI and Uaaoi is significant with the correlation coefficient of 0.218, which exceeds 99.9% confidence level. While AAOI and Uaaoi are high, the westerly wind increases, vice versa. Long-term tendency exists in AAOI and Uaaoi with trend rate of 0.01915/10 a and 0.009249/10 a respectively. A distinctive jump point happened in 1972, before and after this year the average AAOI was -3.9691 hPa and 2.9107 hPa respectively, the average AAOI is increased by 6.88 hPa, the average westerly wind was -1.09 m/s and 0.93 m/s respectively. The sea level pressure and temperature along 50°S-60°S in 50 years show clear patterns of dominating eastward propagation with 4.4 years rounding a circle before the jump year and 3.6 years after the jump year in term of the time series by filter of 3-5 years. In the first principal component of EOF, wave number 3 and wave number 2 are dominating before and after the jump year, respectively.

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  • Online: December 06,2011
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