The Antarctic oscillation-East Asian summer monsoon connections in NCEP-1 and ERA-40
- First Online:
- 98 Downloads
Connections between the spring Antarctic Oscillation (AAO) and the East Asian summer monsoon (EASM) in two reanalysis datasets—NCEP-1 (NCEP/NCAR Reanalysis 1) and ERA-40 (ECMWF 40-year Reanalysis)—are investigated in this study. Both show significant correlation between AAO and EASM rainfall over the Yangtze River valley, especially after about 1985. Though ERA-40 shows weaker anomalous signals connecting AAO and EASM over southern high latitudes than NCEP-1, both datasets reveal similar connecting patterns between them. A wave-train-like pattern appears in the upper levels, from southern high latitudes through east of Australia and from the Maritime Continent to East Asia. In positive AAO years, the cross equatorial southeasterly flow over the Maritime Continent in the lower levels is strengthened, the specific humidity of the whole atmosphere over East Asia increases, and convective activity is enhanced; thus the summer rainfall over East Asia increases. The spring AAO-EASM connection may be better represented in ERA-40.
Key wordsAntarctic Oscillation East Asian summer monsoon NCEP-1 ERA-40
Unable to display preview. Download preview PDF.
- Fan, K., and H. J. Wang, 2006: Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring. Science in China(D), 49(5), 554–560.Google Scholar
- Huang, R. H., and F. Y. Sun, 1994: The impact of thermal state in the western Pacific warm pool and the convective activity above the warm pool on the East Asian climate anomalies. Chinese J. Atmos. Sci., 18, 141–151. (in Chinese)Google Scholar
- Krishnamurti, T. N., 1979: Tropical meteorology. Compendium of Meteorology, A. Wan-Nielsen, Ed., WMO No. 364, 428pp.Google Scholar
- Nitta, T., 1987: Convective activities in the tropical western Pacific and their impact on the northern hemisphere summer circulation. J. Meteor. Soc. Japan, 65, 373–390.Google Scholar
- Sun, J. Q., H. J. Wang, and W. Yuan, 2008: A possible mechanism for the co-variability of the boreal spring Antarctic Oscillation and the Yangtze River valley summer rainfall. International Journal of Climatology, doi: 10.1002/joc.1773.Google Scholar
- Sun, S. Q., and S. J. Ma, 2001: Anomalies of the western Pacific subtropical high and its relation to the flood in Yangtze River Valley in 1998. Acta Meteorologica Sinica, 59, 719–729. (in Chinese)Google Scholar
- Tao, S. Y., and L. X. Chen, 1987: the East Asian summer. Review in Monsoon Meteorology., Oxford University Press, 60–92.Google Scholar
- Uppala, S., and Coauthors, 2004: ERA-40: ECMWF 45-year reanalysis of the global atmosphere and surface conditions 1957–2002. ECMWF Newsletter Meteorology, 101, 2–21.Google Scholar
- Wang, B., 2006: The Asian Monsoon. Springer, in association with Praxis Publishing, 268–279.Google Scholar