热带印度洋季节内振荡对海表温度日变化的影响

Impact of Madden-Julian Oscillation on Diurnal Variation of Sea Surface Temperature in the Tropical Indian Ocean

利用了逐时的热带印度洋浮标观测资料,采用合成分析的方法研究了大气季节内振荡(Madden-Julian Oscillation,MJO)对海表温度(Sea Surface Temperature,SST)日变化特征的影响。结果显示,SST的日变化振幅与大气对流活动存在显著的反位相关系,即在对流活动最强时,SST的日变化振幅最小,标准差为0.06℃;在对流活动最弱时,SST的日变化振幅最大,标准差为0.23℃。以浮标观测的海-气通量强迫一维海洋混合层模式可以再现SST日变化特征的季节内差异,据此诊断发现海表净热通量和混合层深度的季节内变化是MJO影响SST日变化振幅的主要途径。

Based on the hourly data from Indian Ocean buoy observation, the impact of atmosphere Mad- den-Julian Oscillation （MJO） on diurnal variations of sea surface temperature （SST） is studied by using composite analysis method. The results show that a significant anti-phase relationship occurs between the amplitude of diurnal variation of SST and the atmospheric convective activity, that is, the minimum ampli- tude of diurnal variation of SST appears at the strongest convective phase of atmosphere, with the standard deviation being 0.06 ℃, while the maximum amplitude appears at the weakest convective phase, with the standard deviation being 0.23 ℃. By using one-dimension oceanic mixed layer model which is forced by air- sea fluxes observed with buoys, the intra-seasonal variation of diurnal cycle of SST can be reproduced, which indicates that the intra-seasonal changes in the net sea surface heat flux and the mixed layer depth are the main ways through which the MJO affects the amplitude of diurnal SST.