【摘要】 基于葵花八号静止卫星多通道云辐射数据,发展一种过冲云顶轮廓的有效识别算法,并与全球降水测量卫星过境我国南部陆地与南海区域所标定的过冲云顶数据集对比,评估算法性能,其命中率为87.7%,误报率较传统单通道红外纹理算法降低62.0%。基于该算法,结合广东雷电野外综合观测试验期间混合长基线天电阵列定位的闪电数据,统计分析2019—2023年5—10月我国南部陆地与南海过冲云顶的演变特征及海陆分布差异。结果表明:南海过冲云顶主要集中于南海东北部近菲律宾海域,亮温普遍低于192 K,局地可达184 K,整体发生频次为南部陆地的2.9倍,南部陆地则以海南岛北部、广西中南部及广东西南部区域为主,亮温较高,为186～195 K;南海产生过冲云顶的雷暴云占比为8.9%,南部陆地相比较低,为6.6%; 6—10月南海过冲云顶发生频次较高,7月南部陆地最为活跃;南海过冲云顶全天分布较均匀,昼夜变化不明显,南部陆地呈午后迅速发展、夜间快速减弱特征。更多还原

【Abstract】 Overshooting tops are turret-shaped cloud structures that form when strong updrafts in deep convec-tion penetrate the tropopause and extend into the stratosphere, and they are closely associated with severe weather conditions such as heavy rainfall, hail, and strong winds. A comprehensive analysis of its spatial distribution is essential for enhancing the monitoring and early warning capabilities of severe convective systems. The southern terrestrial region of China and the South China Sea are regions with frequent severe convective activity in China, where convective and lightning activity characteristics show distinct land-sea contrasts due to variations in underlying surface conditions. Utilizing multi-spectral cloud radiative data from Himawari-8 geostationary satellite, an effective algorithm is developed to extract the contours of overshorting tops. The algorithm is evaluated using overshooting top measurements from Global Precipita-tion Measurement(GPM) radar during its overpasses of the southern terrestrial region of China and the South China Sea from 2019 to 2023, achieving a probability of detection(POD) of 87.7% and a false alarm ratio(FAR) of 31.4%. Compared to the traditional single-channel infrared texture algorithm, FAR is re-duced by 62.0%. Using this algorithm combined with lightning data located by Hybrid Lightning Sferic Array obtained during Guangdong Comprehensive Observing Experiment on Lightning Discharge, the dis-tribution and evolution of overshooting tops over the southern terrestrial region of China and the South China Sea are statistically analyzed for the period from May to October during 2019-2023, and the land-sea contrasts are also examined. Results indicate that, over the South China Sea, overshooting tops mainly concentrate in the northeastern sector, with brightness temperatures generally below 192 K and locally reaching 184 K. The occurrence frequency in this maritime region is 2.9 times higher than that over the southern terrestrial region of China, where overshooting tops are primarily distributed over northern Hain-an Island, central-southern Guangxi and southwestern Guangdong, exhibiting relatively higher brightness temperatures of 186-195 K. Statistical analysis reveals that 8.9% of thunderstorm clouds over the South China Sea develop overshooting tops, whereas the proportion decreases to 6.6% over the southern terres-trial region of China. Overshooting tops over the South China Sea maintain a relatively high occurrence frequency from June to October, whereas those over the southern terrestrial region of China are mostly ac-tive in July; overshooting tops over the South China Sea are more evenly distributed throughout the day, with no evident day-night differences, whereas those over the southern terrestrial region of China develop rapidly in the afternoon and weaken quickly during the night.更多还原