摘要
建立一个中等复杂程度的海—气耦合模式研究东、西边界反射 ,纬向平流项 -u′ (T +T′) / x在ENSO循环位相转换中的作用及东、西边界反射与纬向异常流 (u′)符号改变的关系。结果得到 :u′超前Ni no 3区SSTA位相转变的原因是东、西边界反射造成的。Sver drup平衡时所产生的地转流 (ur)与东、西边界反射所产生的地转流 (ur)的方向在大部分时间里是相反的 ,同时ur 与风应力强迫之间大约有 9个月的滞后时间 (Kelvin波从 1 80°E出发经东边界反射产生的Rossby波到达 1 80°E时间 )。在模式ENSO事件消亡过程中的某一时刻以后 ,边界反射产生的调整过程变为主要过程 ,u′主要由ur 来决定 ,这样就造成了u′的反向先于Ni no区SSTA的反向。它实际上是海洋的调整过程与风应力强迫之间滞后关系的一种反映。敏感性数值试验表明 ,取消东边界反射 ,耦合模式能够模拟ENSO循环 ,但其周期比控制试验的周期短一年 ( 3年 )。取消 -u′ (T +T′) / x,耦合模式能够模拟ENSO循环 ,但其周期比控制试验的周期长 2年 ( 6年 )。
An immediate atmosphere-ocean coupled model is developed to study the role of eastern and western boundary reflections, zonal advection [-u′(T+T′)/x] in the ENSO cycle phase transition and the linking between reversed direction of zonal currents anomaly and eastern and western boundary reflections. The results show that the reason of the u′ leading SSTA over Nio 3 area in phase transition is caused by boundary reflection. It is almost reverse in model ENSO cycle between u d, formed by Sverdrup balance, and u r, formed by boundary reflection. Meanwhile, there is about 9 months lag time between u r and zonal wind stress anomaly (The time that Kelvin wave propagate from 180°E to eastern boundary and the time that the gravest Rossby wave propagates from the eastern boundary to 180°E). After the point during the ENSO event decaying process, model ENSO cycle is controlled by the adjustment process caused boundary reflection. During this course, u r controls u′, which causes u′ to be reverse direction early to SSTA to be. Acturelly, it shows a lag relationship between zonal wind stress anomaly forcing and oceanic adjustment process. The numerical tests of sensitivity show that when the eastern boundary reflection was removed, the model can still simulate ENSO cycle but shorter period 3 years, shorter 1 year than that in control run. When -u′(T+T′)/x is removed, the model can simulate ENSO cycle but longer period 6 years, longer 2 year than that in control run.mosphe
出处
《大气科学》
CSCD
北大核心
2003年第3期354-368,共15页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目G1 9980 4 0 90 0第一部分
中国科学院知识创新工程重要方向项目KZCX2- 2 0 8共同资助