印度洋海温异常对南亚区域净初级生产力影响的数值模拟

Simulation of Influence of Indian Ocean Sea Surface Temperature Anomaly on the Net Primary Production in South Asia

利用中国科学院大气物理研究所发展的全球海洋-大气-动态植被耦合气候模式(GOALS-AVIM)的模拟结果,分析了印度洋海表温度(SST)变化及其与南亚陆面净初级生产力(NPP)的关系。模式连续运行50年,取后40年结果分析。对模拟的印度洋海表温度距平(SSTA)的经验正交分解(EOF)进行分析,发现第一特征向量在全区域表现为一致变化的趋势,表明在春夏秋冬四季中印度洋海温都有一致增暖或降温的趋势,同时赤道印度洋海温一致变化与赤道太平洋Nin^o3指数有滞后的正相关,太平洋的Nin^o3指数变化超前印度洋海温一致变化8个月左右。第二特征向量则表现为热带印度洋SST存在着东西方向振荡的偶极子型振荡特征,而且偶极子强度有明显季节变化,并有很明显的季节相位锁定。印度洋SSTA的一致变化的异常趋势与南亚地区的季节和年平均NPP变化表现出很强的同期和滞后相关性;与南亚地区年平均NPP相关性较高的印度洋夏季SST的EOF第一模态正负相位对应着不同的850hPa流场、500hPa高度场以及南亚地区降水场的异常。分析表明,印度洋及南亚地区的夏季风加强或减弱导致受南亚地区降水异常,并使该地区NPP产生异常的增加或减少。

Using the global ocean-atmosphere-land coupled model （GOALS-AVIM） developed at the Institute of Atmospheric Physics （IAP） of the Chinese Academy of Sciences, the Indian Ocean sea surface temperature （SST） abnormality and its relations with the net primary production （NPP） at the land surface in South Asia are analyzed. The model is integrated for 50 years, and the integration results for the later 40 years are used in this work. Results show that there are four dominant steady patterns of annual mean Indian Ocean sea surface temperature anomaly（SSTA） in the Empirical Orthogonal Function （EOF）. The first eigenvector exhibits a trend of simultaneous changes in the whole area, which demonstrates that the Indian Ocean SST in the four seasons possesses a consistent increase or decrease. Meanwhile, the trend is consistent with the NPP change at the land surface in South Asia. A correlation analysis shows that the consistent warming or cooling in the equatorial Indian Ocean has a positive lag correlation with the Nino3 index of the equatorial Pacific Ocean, and the lag time is eight months. The second eigen- vector shows that the tropical Indian Ocean SST displays a characteristic of the Indian Ocean Dipole （IOD） oscillation with two steady shapes of west-high - east-low and east-high - west-low. The dipole has an obvious seasonal variation, and its seasonal phase locking is also obvious. The abnormal trend of consistent changes in the Indian Ocean SSTA is highly related to the changes in seasonal and annual mean NPP at the land surface in South Asia with lag or contemporary correlation. The positive and negative phases of the first EOF mode of the summer Indian Ocean SST that has a high correlation with annual mean NPP in South Asia correspond to distinct anomalies of 850-hPa wind field, 500-hPa geopotential height field and precipitation field in South Asia. The analysis indicates that the increase or decrease of summer monsoon in the Indian Ocean and South Asia causes the precipitation abnormity in South Asia, which results in the increase or decrease of NPP abnormity in this region.