1997—1998年热带印度洋偶极子季节性位相锁定可能成因

POSSIBLE CAUSES FOR SEASONAL PHASE LOCKING OF 1997—1998 TROPICAL INDIAN OCEAN DIPOLE

利用改进的中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室的第三代海洋环流模式,以及1949年1月—1999年12月NCEP/NCAR月平均海表面大气距平资料,采用数值试验的方法,研究了1997—1998年热带印度洋偶极子从发展到成熟的特征,以及在相同大气异常强迫下1—12月大气气候基本态对印度洋偶极子的作用。结果表明,海洋表面的大气强迫对激发1997—1998年印度洋偶极子有重要作用;大气气候态对1997—1998年印度洋偶极子的强度有很大影响,其中9月的大气气候态最有利于印度洋偶极子达到最强;赤道印度洋上空风应力异常是1997—1998年印度洋偶极子形成的主要原因。

The characteristics of the 1997--1998 dipole event and the effect of the basic state of the atmosphere and climate on Indian Ocean dipole under the same anomaly forcing were investigated based on the numerical experiments with the use of NCEP/NCAR Jan 1949--Dec 1999 sea surface atmosphere data. To carry out the numerical experiments, the revised oceanic general circulation model developed in State Key Laboratory of Numerical Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics, Chinese Academy of Sciences （IAP/LASG L30T63 OGCM） was also employed. The results presented that the sea surface atmospheric forcing acted an important role in the 1997--1998 Indian Ocean dipole event; the basic state of the atmosphere and climate impacted greatly the intensity of the dipole and the state of the atmosphere and climate in September was the most favorable to the mature of dipole; the wind stress anomaly over the equatorial Indian Ocean was the crucial factor for the occurrence of the 1997--1998 dipole event.