ENSO循环与低纬度大气的正压和斜压运动

Atmospheric barotropic and baroclinic modes associated with ENSO cycle

:利用一个 2层海洋模式和 GISST资料、NCEP再分析资料 ,对大气正压 /斜压运动与 ESNO循环之间的联系进行了研究。结果表明 ,在赤道中、东太平洋地区 ,大气斜压模在 ENSO时间尺度上的变化位相略超前于正压模的变化 ,正压模的变化位相超前于 SSTA变化 ,SSTA变化位相超前斜压模的变化位相。斜压纬向风异常与SSTA具有正相关关系 (西太平洋西部相反 ) ;正压模则与 Nino3区海温异常有负相关关系 (西太平洋西部相反 )。斜压模与海表异常加热相互激励 ,促进异常海温增长 ,是增长模 ;而正压模则抑制斜压模的和海温异常的增长 ,是转换模。正压模的位相超前对预测 El Nino/ L a Nina的发生发展具有参考意义。

WT5BZ]The relationships among the barotropic/baroclinioc modes of tropical wind field and ENSO cycle are investigated in the present paper using a 2 Layer regional ocean model and the NCEP/NCAR reanalysis data as well as GISST sea surface temperature data set. In the central eastern part of tropical Pacific, the phase of variations of baroclinic zonal wind is to some extent leading to the phase of barotropic mode. The phase of time change of barotropic mode is much leading to the phase of sea surface temperature anomalies (SSTA) whose phase at the same time is leading to the phase of baroclinic mode changes. The positive correlation is observed between baroclinic zonal wind and SSTA whereas the negative is observed between the barotropic zonal wind and SSTA. The baroclinic (barotropic) mode tends to increase (decrease) the magnitude of SSTA, which is useful to understand the mechanism of ENSO cycle. [WT5HZ]