This paper proposes several quantitative characteristics to study convective systems using observations from Doppler weather radars and geostationary satellites. Specifically, in order to measure the convective intens...This paper proposes several quantitative characteristics to study convective systems using observations from Doppler weather radars and geostationary satellites. Specifically, in order to measure the convective intensity of each system, a new index, named the ＂Convective Intensity Ratio＂ （CIR）, is defined as the ratio between the area of strong radar echoes at the upper level and the size of the convective cell itself. Based on these quantitative characteristics, the evolution of convective cells, surface rainfall intensity, rainfall area and convectively generated anvil clouds can be studied, and the relationships between them can also be analyzed. After testing nine meso-β-scale convective systems over North China during 2006–2007, the results were as follows： （1） the CIR was highly correlated with surface rainfall intensity, and the correlation reached a maximum when the CIR led rainfall intensity by 6–30 mins. The maximum CIR could be at most ～30 mins before the maximum rainfall intensity. （2） Convective systems with larger maximum CIRs usually had colder cloud-tops. （3） The maximum area of anvil cloud appeared 0.5–1.5 h after rainfall intensity began to weaken. The maximum area of anvil cloud and the time lag between maximum rainfall intensity and the maximum area of anvil cloud both increased with the CIR.展开更多
利用中国科学院大气物理研究所发展的三维强风暴模式,对Egrett Microphysics Experiment with Radia-tion Lidar and Dynamics(EMERALD)试验期间的一次长寿命热带深对流个例进行对流产生、发展、消亡过程以及云砧的数值模拟,并与实测资...利用中国科学院大气物理研究所发展的三维强风暴模式,对Egrett Microphysics Experiment with Radia-tion Lidar and Dynamics(EMERALD)试验期间的一次长寿命热带深对流个例进行对流产生、发展、消亡过程以及云砧的数值模拟,并与实测资料[包括C波段双线偏振雷达图像资料、机载云粒子成像仪(CPI)探测的云砧卷云微物理特性以及激光雷达探测的云砧宏观特性资料]进行了细致的对比,然后通过改变模式中最大云滴数浓度进行有关云凝结核数浓度影响云砧卷云冰晶含水量和数浓度的敏感性试验。模式较好地模拟出系统的一些重要宏观特征,如爆发性增长阶段、各高度雷达水平反射率因子的最大值、对流云主体移动方向、云砧底部和顶部高度。对云砧冰相粒子含水量、数浓度以及平均直径等微观特征的模拟结果与实测也比较接近。对于本文个例而言,异质核化为冰晶形成的最主要方式,其次为过冷云滴的均质核化。敏感性试验结果表明:当云凝结核数浓度增加时,爆发性增长阶段的垂直速度减小,使得对流云从中低层向高层的水物质输送量减少,从而使云砧卷云冰晶的数量减少。展开更多
基金supported bythe National High Technology Research and Development Program of China (Grant No. 2006AA122106)the Na-tional Natural Science Foundation of China (Grant No.40875019) the Foundation of Basic Scientific Researchand Operation of Chinese Academy of Meteorological Sci-ence (Grant No. 2007Y004)
文摘This paper proposes several quantitative characteristics to study convective systems using observations from Doppler weather radars and geostationary satellites. Specifically, in order to measure the convective intensity of each system, a new index, named the ＂Convective Intensity Ratio＂ （CIR）, is defined as the ratio between the area of strong radar echoes at the upper level and the size of the convective cell itself. Based on these quantitative characteristics, the evolution of convective cells, surface rainfall intensity, rainfall area and convectively generated anvil clouds can be studied, and the relationships between them can also be analyzed. After testing nine meso-β-scale convective systems over North China during 2006–2007, the results were as follows： （1） the CIR was highly correlated with surface rainfall intensity, and the correlation reached a maximum when the CIR led rainfall intensity by 6–30 mins. The maximum CIR could be at most ～30 mins before the maximum rainfall intensity. （2） Convective systems with larger maximum CIRs usually had colder cloud-tops. （3） The maximum area of anvil cloud appeared 0.5–1.5 h after rainfall intensity began to weaken. The maximum area of anvil cloud and the time lag between maximum rainfall intensity and the maximum area of anvil cloud both increased with the CIR.
文摘利用中国科学院大气物理研究所发展的三维强风暴模式,对Egrett Microphysics Experiment with Radia-tion Lidar and Dynamics(EMERALD)试验期间的一次长寿命热带深对流个例进行对流产生、发展、消亡过程以及云砧的数值模拟,并与实测资料[包括C波段双线偏振雷达图像资料、机载云粒子成像仪(CPI)探测的云砧卷云微物理特性以及激光雷达探测的云砧宏观特性资料]进行了细致的对比,然后通过改变模式中最大云滴数浓度进行有关云凝结核数浓度影响云砧卷云冰晶含水量和数浓度的敏感性试验。模式较好地模拟出系统的一些重要宏观特征,如爆发性增长阶段、各高度雷达水平反射率因子的最大值、对流云主体移动方向、云砧底部和顶部高度。对云砧冰相粒子含水量、数浓度以及平均直径等微观特征的模拟结果与实测也比较接近。对于本文个例而言,异质核化为冰晶形成的最主要方式,其次为过冷云滴的均质核化。敏感性试验结果表明:当云凝结核数浓度增加时,爆发性增长阶段的垂直速度减小,使得对流云从中低层向高层的水物质输送量减少,从而使云砧卷云冰晶的数量减少。
