斜压模、正压模和异常海温时间变化的位相关系

THE PHASE RELATIONSHIP AMONG THE TEMPORAL VARIATIONS OF BAROCLINIC AND BAROTROPIC MODES AND SSTA

利用 1958- 1997共 4 0年 NECP/ NCAR再分析大气资料和 GISST海表温度资料集 ,研究了大气斜压模、正压模与海表温度变化这三者之间位相关系 ,并从大气动力学方程组解释了这些位相关系。指出 :大气斜压西风异常时间变化的位相落略微后于 SSTA的变化位相 ,而正压西风异常的变化位相则超前于SSTA变化位相。斜压纬向风异常的变化又超前于正压异常纬向风的变化。斜压纬向风异常与海表温度异常之间存在正相关关系 ,而异常正压纬向风与异常海表温度之间则存在负相关关系。斜压模的产生联系于热力强迫 ,而正压模的产生则归因于斜压扰动间的非线性相互作用。这些由动力和热力过程控制的位相关系包含着ENSO循环的可能机制。

In the context of the 1958~1997 NCEP/NCAR reanalyses and GISST datasets,the phase relations among baroclinic/barotropic modes and SSTA have been studied,and explained by the governing equations of atmospheric dynamics.It is showed that the phase of the baroclinic anomalous westerly leads that of SSTA.In turn,the baroclinic Zonal wind anomaly changes ahead of the baroctropic zonal wind anomaly wind anomalies and SSTA.The genesis of the baroclinic mode is related to thermal heating,but that of the barotropic mode is attributed to non-linear interactions between baroclinic disturbances.These phase relations governed by the dynamic and thermal processes contain the possible mechanism of ENSO cycle.