Based on the historical records of the drought and flood disasters during 1480-1940AD, this paper reconstructs the sequences of wetness index (WI) and drought and flood disasters. We find a good identical relationsh...Based on the historical records of the drought and flood disasters during 1480-1940AD, this paper reconstructs the sequences of wetness index (WI) and drought and flood disasters. We find a good identical relationship between the fluctuation of WI sequence and the δ^18O record of the GISP2 ice core in Greenland, which shows an apparent monsoonal disposal pattern of moisture and temperature. By applying the Morlet Wavelet Transform Method to deal with the data, several apparent periodicities, such as 7-8a, 11-15a, 20-23a and ca 50a, are revealed, among which some can be attributed to the solar forcing. Based on results of Cluster Analysis of dry-wet changes, we resume the regional differentiation pattern of flood-drought disasters all over Guangdong during different climatic intervals in the LIA and, find the western and northern parts of Guangdong have undergone drastic changes in drought-flood regional differentiation, but the eastern part is relatively stable, and the area of the Pearl River Delta shows stable condition of more flood disasters.展开更多
2022年7月内蒙古中西部地区降水明显偏少,且呈前期偏多、后期偏少的涝—旱转折性分布特征,分析不同阶段环流分布差异和影响系统间的配置对进一步做好内蒙古汛期降水预测具有重要作用。利用内蒙古116站逐日降水量、国家气候中心130项气...2022年7月内蒙古中西部地区降水明显偏少,且呈前期偏多、后期偏少的涝—旱转折性分布特征,分析不同阶段环流分布差异和影响系统间的配置对进一步做好内蒙古汛期降水预测具有重要作用。利用内蒙古116站逐日降水量、国家气候中心130项气候指数、美国国家环境预报中心/国家大气科学研究中心(National Center for Enviromental Prediction/National Center for Atmospheric Research,NCEP/NCAR)逐日再分析资料和美国国家海洋和大气管理局(National Oceanic and Atmospheric Admin⁃istration,NOAA)逐月海表温度资料,分析2022年7月内蒙古中西部地区涝-旱转折事件的成因。结果表明:(1)2022年7月内蒙古中西部地区降水量严重偏少,为该地区1991年以来同期降水最少、气象干旱最为严重。(2)7月1—11日降水相对偏多,冷空气路径偏北且强度较弱,西太平洋副热带高压强度偏弱,位置偏北、偏西,冷暖空气在内蒙古中西部地区交绥,加之这一时段高空西风急流位置偏北,内蒙古中西部位于急流轴以南,有利于高层辐散和上升运动发展。7月12—31日降水明显偏少,环流经向度加大,冷空气活动路径偏南且强度增强,西太平洋副热带高压强度偏强且位置明显偏南,不利于水汽输送,加之高空西风急流位置偏南,内蒙古中西部位于急流轴以北,不利于高层辐散和上升运动发展;7月中旬后期至下旬高空西风急流南北向扰动偏强有利于激发东亚—西北太平洋经向遥相关波列,使得西太平洋副热带高压位置偏南从而导致降水偏少。(3)日本海至北太平洋西北部地区的海温异常是影响内蒙古中西部地区降水多寡的重要外强迫信号之一。2022年7月该海区海温异常偏高,其上空激发的气旋式环流减弱了南方暖湿水汽的经向输送,是导致内蒙古中西部降水由涝转旱的原因之一。展开更多
基金N aturalScience Foundation ofG uangdong Province,N o.031522Fok Y ing Tung Education Foundation,N o.91021
文摘Based on the historical records of the drought and flood disasters during 1480-1940AD, this paper reconstructs the sequences of wetness index (WI) and drought and flood disasters. We find a good identical relationship between the fluctuation of WI sequence and the δ^18O record of the GISP2 ice core in Greenland, which shows an apparent monsoonal disposal pattern of moisture and temperature. By applying the Morlet Wavelet Transform Method to deal with the data, several apparent periodicities, such as 7-8a, 11-15a, 20-23a and ca 50a, are revealed, among which some can be attributed to the solar forcing. Based on results of Cluster Analysis of dry-wet changes, we resume the regional differentiation pattern of flood-drought disasters all over Guangdong during different climatic intervals in the LIA and, find the western and northern parts of Guangdong have undergone drastic changes in drought-flood regional differentiation, but the eastern part is relatively stable, and the area of the Pearl River Delta shows stable condition of more flood disasters.
文摘2022年7月内蒙古中西部地区降水明显偏少,且呈前期偏多、后期偏少的涝—旱转折性分布特征,分析不同阶段环流分布差异和影响系统间的配置对进一步做好内蒙古汛期降水预测具有重要作用。利用内蒙古116站逐日降水量、国家气候中心130项气候指数、美国国家环境预报中心/国家大气科学研究中心(National Center for Enviromental Prediction/National Center for Atmospheric Research,NCEP/NCAR)逐日再分析资料和美国国家海洋和大气管理局(National Oceanic and Atmospheric Admin⁃istration,NOAA)逐月海表温度资料,分析2022年7月内蒙古中西部地区涝-旱转折事件的成因。结果表明:(1)2022年7月内蒙古中西部地区降水量严重偏少,为该地区1991年以来同期降水最少、气象干旱最为严重。(2)7月1—11日降水相对偏多,冷空气路径偏北且强度较弱,西太平洋副热带高压强度偏弱,位置偏北、偏西,冷暖空气在内蒙古中西部地区交绥,加之这一时段高空西风急流位置偏北,内蒙古中西部位于急流轴以南,有利于高层辐散和上升运动发展。7月12—31日降水明显偏少,环流经向度加大,冷空气活动路径偏南且强度增强,西太平洋副热带高压强度偏强且位置明显偏南,不利于水汽输送,加之高空西风急流位置偏南,内蒙古中西部位于急流轴以北,不利于高层辐散和上升运动发展;7月中旬后期至下旬高空西风急流南北向扰动偏强有利于激发东亚—西北太平洋经向遥相关波列,使得西太平洋副热带高压位置偏南从而导致降水偏少。(3)日本海至北太平洋西北部地区的海温异常是影响内蒙古中西部地区降水多寡的重要外强迫信号之一。2022年7月该海区海温异常偏高,其上空激发的气旋式环流减弱了南方暖湿水汽的经向输送,是导致内蒙古中西部降水由涝转旱的原因之一。