El Nio事件成熟位相锁定在年底的物理过程研究

A Study of Mechanism of the Locking of El Nio Event Mature Phase to the End of the Year

用一个中等复杂程度的热带海气耦合模式研究了气候基本态的季节变化在ElNi o事件成熟位相锁定中的作用。结果表明 ,模式模拟出了ElNi o事件成熟位相锁定在年底左右的基本特征。由海洋气候基本态的季节变化所引起的平流的季节变化是ElNi o事件成熟位相锁定在年底的机制。在ElNi o事件期间 ,1～ 5月份 ,赤道中东太平洋地区的海洋气候基本态所引起的暖平流较弱 ,较弱暖平流造成海表温度异常降低 ,使海气耦合不稳定度较弱 ,从而使ElNi o事件衰减。 6～ 1 2月份 ,赤道中东太平洋地区的海洋气候基本态所引起的暖平流较强 ,较强暖平流造成海表温度异常升高 ,使海气耦合不稳定度加强 ,从而使ElNi o事件发展。这样 ,在年底左右 ,赤道中东太平洋地区形成海表温度异常的一个极值点 ,形成ElNi o事件成熟位相。海洋垂直 (经向 )平均流的季节变化产生的平流的季节变化最 (次 )强 ,因此 ,海洋垂直 (经向 )平均流是ElNi o事件成熟位相锁定在年底的主 (次 )要因子。

The role of the seasonal variation of the basic state in the locking of El Nio mature phase to the end of the year is explored by using an intermediate complex coupled atmosphere ocean model The results show that the model can simulate the basic characteristics of the mature phase locking The seasonal variation of the advection caused by the seasonal variation of the basic state is the mechanism for the mature phase locking From January to May, over the middle and eastern Pacific, the warm advection caused by the basic state is weaker, which leads surface temperature to decrease, thus the coupling atmosphere ocean instability strength decreases which in turn leads sea surface temperature to decrease But from June to December, over the middle and eastern Pacific, the warm advection caused by the basic state is stronger which leads temperature to increase, thus the coupling atmosphere ocean instability increase which in turn strengthens El Nio event Finally, a maximum of sea surface temperature anomaly over the middle and eastern Pacific area occurs at the end of the year, forming the mature phase of El Nio events The seasonal variation of the warm advection caused by the seasonal variation of the vertical (meridian) mean velocity is the strongest (stronger) Therefore, the vertical (meridian) mean velocity is the most (more) important factor for the mechanism of the locking of El Nio event mature phase to the end of the year