Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis...Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis. It is shown that there is a 2-6 year oscillation at the interannual time scales and a quasi-30 year oscillation at the decadal time scales. These periodic oscillations relate to the distribution of tropical heat content. When the precipitation is much more (less) than normal, the upper seawater is colder (warmer) in almost all the tropical Indian Ocean, and warmer (colder) in the western Pacific as well as colder (warmer) in the eastern Pacific. The key areas of the anomaly heat content distribution that have significant correlation to the Yunnan precipitation in rainy season are in the southern hemispheric Indian Ocean with a dipole pattern in the winter as well as in the deep basin of the South China Sea (SCS) before the Yunnan rainy season begins. Therefore, the anomalous distributions of the heat content in the southern Indian Ocean and the SCS In winter are good indicators for predicting drought or flood in Yunnan Province in the following rainy season.展开更多
文摘Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis. It is shown that there is a 2-6 year oscillation at the interannual time scales and a quasi-30 year oscillation at the decadal time scales. These periodic oscillations relate to the distribution of tropical heat content. When the precipitation is much more (less) than normal, the upper seawater is colder (warmer) in almost all the tropical Indian Ocean, and warmer (colder) in the western Pacific as well as colder (warmer) in the eastern Pacific. The key areas of the anomaly heat content distribution that have significant correlation to the Yunnan precipitation in rainy season are in the southern hemispheric Indian Ocean with a dipole pattern in the winter as well as in the deep basin of the South China Sea (SCS) before the Yunnan rainy season begins. Therefore, the anomalous distributions of the heat content in the southern Indian Ocean and the SCS In winter are good indicators for predicting drought or flood in Yunnan Province in the following rainy season.
文摘利用雷电定位资料、多普勒雷达资料和FY-2E卫星红外资料对2010年6月25—26日发生在马龙的一次局地特大暴雨过程进行分析,结果表明:高层冷空气和低层暖湿气流在滇中以东地区交汇,形成明显的辐合是本次局地特大暴雨过程的主要影响系统.多普勒雷达上表现为2条带状回波合并加强,后部小单体快速东移合并入同一地点,在马龙上空形成明显的"列车效应",中尺度低空急流和逆风区的出现使得抬升辐合运动加强,触发了马龙上空对流不稳定能量的释放,产生了特大暴雨.卫星云图上,多个MCS合并为中-β尺度对流云团再发展为中-β尺度对流云带,产生强降水的过程始终保持较大面积的低于-60℃的冷中心,冷中心长时间在马龙上空维持.暴雨过程伴随着频繁的地闪活动,地闪密集地出现在单体回波合并后的强回波区域、对应着径向速度≤10 m/s的辐合区和逆风区后部及≥15 km的回波顶高位置,TBB和地闪的峰值超前于强降水1～2 h.
