降水的时间随机性对月总降水量的影响
投稿时间:2018-09-29  修订日期:2018-09-29  点此下载全文
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作者单位E-mail
苏京志 中国气象科学研究院 sujz@cma.gov.cn 
基金项目:国家重点基础研究发展计划(973计划);国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:受降水事件的随机性影响,月初(月末)几天之内的累积降水量很可能会超过当月总降水量的50%乃至更多。本文统计分析结果发现,月初(月末)几天累积降水量对当月总降水量显著影响的事件出现频次在季节和空间分布上都有鲜明特征,主要包括:(1)月初累积降水量对秋冬季中各月的总降水量影响程度更大,而月末累积降水量对1—4月份的月总降水量影响较大;(2)受月初累积降水量影响显著站点数在某些年份的某些月份出现极大值,受单次事件显著影响的站点数能全国总站点数的30%—50%,此即对应着一次全国大范围的极端强降水事件;(3)受月初(月末)累积降水量显著影响的站点空间分布随季节月份变化呈现出明显空间集聚特征,例如在9月份,受月初5天累积降水量显著影响的事件发生频次极大值集中在山东省和河北省附近,该区域的此类事件在过去57年间共出现频次达到20次左右。
中文关键词:月总降水量,月初/月末累积降水量,极端降水事件
 
The influence of timely-random precipitation on monthly total precipitation
Abstract:Due to the random nature of precipitation events, the accumulated precipitation within the first (last) several days of certain month is likely to exceed 50% or more of the total precipitation in that month. Statistical analyses in this paper show that such events occur with significant features in both the seasonal and the spatial distribution: (1) the cumulative precipitation in the first several days can influence the monthly precipitation during the fall and winter months, and the cumulative precipitation in the last several days can influence the monthly precipitation during the period of January-April. (2) the number of stations significantly affected by accumulated precipitation of the first several days has a maximum value in some years and some months. The number of stations significantly affected by such event reaches about 30%-50% of the total number of all the stations, which corresponds to a large-space extreme heavy precipitation event. (3) the stations with significant effect by such events show features of spatial concentration in September. For example, the stations affected by first several days mainly concentrate around Shandong and Hebei provinces, and such events in those regions has occurred about 20 times during the past 57 years.
keywords:Monthly total precipitation, accumulated precipitation of the first (last) several days of certain month, extreme precipitation events
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