doi:  10.3878/j.issn.1006-9895.1808.18123
1961-2015年中国地区冰雹持续时间的时空分布特征及影响因子研究

The Characteristics of Spatial and Temporal Distribution of Hail Duration in China during 1961-2015 and its Possible Influential Factors
摘要点击 199  全文点击 44  投稿时间:2018-02-05  修订日期:2018-07-16
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基金:  国家自然科学基金
中文关键词:  冰雹  持续时间  时空分布  影响因子
英文关键词:  hail  duration  temporal and spatial distribution  potential influential factors
     
作者中文名作者英文名单位
赵文慧ZhaoWenhui中国气象科学研究院
姚展予Yao Zhanyu中国气象科学研究院
引用:赵文慧,姚展予.2019.1961-2015年中国地区冰雹持续时间的时空分布特征及影响因子研究[J].大气科学
Citation:ZhaoWenhui,Yao Zhanyu.2019.The Characteristics of Spatial and Temporal Distribution of Hail Duration in China during 1961-2015 and its Possible Influential Factors[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文利用中国地区577个地面观测站1961-2015年共55a的冰雹资料,本文应用统计学方法,分析了1961-2015年期间中国冰雹持续时间的空间分布、年际变化以及日变化特征,包括站点降雹累积持续时间、平均单次降雹持续时间、区域平均单次降雹持续时间、小时降雹累积持续时间和总降雹累积持续时间,结果表明:中国地区1961-2015年站点降雹累积持续时间空间分布与海拔高度、地形等性质关系密切,总的分布特征主要呈现为高原和高山多,而平原、河谷少。55a最大站点降雹累积持续时间出现在青藏高原地区,累积持续时间高达250分钟,其次为内蒙古中部以及东北部的山区地带(累积持续时间约为150分钟)。站点降雹累积持续时间与海拔高度呈现较高的正相关关系,相关系数高达0.99。主要考虑为在海拔高地势复杂的山区地带,由于地形影响导致上升气流旺盛,极易触发局地对流,从而产生冰雹天气过程。平均单次降雹持续时间在1961-2015年期间呈现上升趋势,55a冰雹累积持续时间大约增长1分钟,且通过了95%显著性水平的显著性检验。西北地区、北部平原地区和东南地区在1961-1980年期间,区域平均单次降雹持续时间都有显著的下降趋势,而在1970-2015年期间西北地区和青藏高原地区呈现显著的上升趋势。1961-1980年期间区域平均单次降雹持续时间在西北地区的的长期趋势变化主要受到日最低气温以及温度日较差长期年际变化的影响,在北部平原地区仅与温度日较差相关,而在东南地区与三个对流参数都有较好的相关性。1970-2015年和1961-2015年期间西北地区和青藏高原地区的区域平均单次降雹持续时间的上升趋势与分别这两个区域的区域平均日最高气温、日最低气温呈正相关。单次降雹持续时间的日变化特征为午后至夜间出现的冰雹持续时间长于凌晨和上午的冰雹过程,持续时间峰值出现在当地时间午后17时和18时。通过利用探空资料对两个对流参数的分析,结果表明中国地区20时的对流参数值均大于08时,表明午后的平均对流潜能均大于上午值。因此午后持续时间较长的冰雹天气过程可能主要是由于午后较大的对流潜能激发影响,也就是说午后20时的对流有效势能和Totals-totals指数可能是冰雹持续时间日变化的影响因子之一。
Abstract:
      Based on 55-year (1961 to 2015) ground-based hail and atmospheric sounding observations, the climatological characteristics of hail duration in mainland China, along with convective parameters, were analyzed. The duration of a single hail case is counted based on the record of the beginning and the ending time of the hail case. Hail duration of each station is defined as accumulation of all duration of single hail case for each station for a total period of 55 years from 1961 to 2015; average single hail duration is defined as the sum of the duration of all hail cases of 577 stations per year divided by the total number of hail cases; the region average single hail duration is defined as the sum of the duration of all hail cases of stations in certain region per year divided by the total number of hail cases; hourly hail duration is defined as the sum of the duration of all hail cases occur in each hour for a total period of 55 years from 1961 to 2015, we always round the time down to the nearest hour proceeding the actual time of occurrence. For example, if the starting time of hailstorm in data is 1432 local solar time (LST), then we will classify it as 1400 LST; while we define the whole hail duration as the sum of duration of all hail cases during the period of 1961-2015 of 577 stations.The results showed that the spatial distribution of hail duration of each station in China is closely related to the altitude, topography and other properties,including hail duration of each station, average single hail duration, the region average single hail duration, hourly hail duration and whole hail duration. The hail duration of each station in the plateau and mountains are longer than that in plains and valleys overall. The largest hail duration tended to appeared in the Tibetan Plateau, which was about 250min for the period 1961-2015, followed by the mountainous areas in central Inner Mongolia and northeast (about 150 min for 55a). We found that the hail duration of each station showed a high positive correlation with altitude, the correlation coefficient was as high as 0.99. The spatial distribution of hail duration was mainly due to the influence of high altitude and complex terrain, which may cause the strong updrafts that can easily trigger local convection, which may contribute to hail cases. Overall, the average single hail duration increased by 1 minute from 1961 to 2015, and the trend is statistically significant at the 95% confidence level. The region average single hail duration in NWC(Northwest China), NCP(the North China Plain) and SEC(Southeast China) showed downward trends in 1961-1980, while that in NWC and TTP(the Tibetan Plateau) increased. There are positive relationships between the region average single hail duration trend in NWC and the trend of Tmin and DTR(daily temperature range), and the correlation between hail duration trend in NCP and DTR trend. While the hail duration trend in SEC is well correlated with all convective parameters. The upward trends of region average hail duration in NWC and TTP in 1970-2015 and 1961-2015 are both positively related with the trend of Tmax and Tmin. In terms of diurnal variability, hail duration of hail cases that appeared during afternoon and night were longer than that appeared in the morning, with hail duration peaking at 17:00LST (local solar time) and 18:00 LST. The analysis of two convective parameters by using long-term sounding data showed that the convective parameters at 20BJT (BeiJing time) in China were greater than that at 08BJT, indicating that the mean convective potential in the afternoon is greater than the morning value. Therefore, the longer hail weather process in the afternoon may be mainly influenced by the greater impact of convective potential in the afternoon; that is to say, CAPE and TT index at 20:00BJT may be two of the influential factors of the diurnal cycle of hail duration.
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