Impacts of Anomalies of Thermal State over the Qinghai‐Xizang Plateau and Sea Surface Temperature on Interannual Variability of the Asian Monsoon Seasonal Transition
Impacts of Anomalies of Thermal State over the Qinghai‐Xizang Plateau and Sea Surface Temperature on Interannual Variability of the Asian Monsoon Seasonal Transition
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DOI：
10.1002/cjg2.940
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
J. Mao;Guoxiong Wu
中科院分区：
文献类型：
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作者：
J. Mao;Guoxiong Wu
基于亚洲副热带反气旋脊面附近对流层中上层经向温度梯度在季节转换期间的反转，通过相关分析和综合分析，探讨了亚洲季风季节转换的年际变化及其与外强迫的关系。结果表明，厄尔尼诺/南方涛动（ENSO）和青藏高原前冬春季热状态是亚洲季风季节转换年际变化的两个主导因素。冬春季厄尔尼诺事件发生时，沃克环流减弱，西太平洋暖池上空深层对流受到抑制，而赤道东太平洋对流增强，导致赤道印度洋上空绝热下降运动。受此影响，赤道印度洋海域气温偏暖，亚洲地区经向气温梯度变大，季节转换较常年偏晚。相反，拉尼娜事件通常会导致提前的季节转换。早春青藏高原对流层中上层温度异常是预测季节转换异常的良好指标。
Based on the reversal of the middle and upper tropospheric meridional temperature gradient near the ridge surface of the Asian subtropical anticyclone during seasonal transition, the interannual variability of the Asian monsoon seasonal transition and its relation to external forcing are examined by applying correlation and composite analyses. Results show that the El Nino/Southern Oscillation (ENSO) and thermal state over the Qinghai-Xizang Plateau in the preceding winter and spring are two dominant factors responsible for the interannual variability of the Asian monsoon seasonal transition. When the El Nino event occurs during winter and spring, Walker circulation is weakened so that deep convection is suppressed over the western Pacific warm pool, while enhanced convection over the eastern equatorial Pacific induces adiabatic descending motion over the equatorial Indian Ocean. Consequently, air temperature over the equatorial Indian Ocean gets warmer, meridional temperature gradient over Asian sector becomes larger, and the seasonal transition is later than normal. Contrarily, La Nina event usually leads to an early seasonal transition. The middle and upper tropospheric temperature anomalies over the Qinghai-Xizang Plateau in early spring are good indicative of predicting abnormal seasonal transition.