doi:  10.3878/j.issn.1006-9895.1807.18134
近46年京津冀地区“夏雨秋下”现象及其成因初探

A study on the phenomenon of precipitation-delaying from midsummer to early autumn and associated reasons in Beijing-Tianjin-Hebei Province during 1970-2015
摘要点击 103  全文点击 40  投稿时间:2018-03-05  修订日期:2018-07-05
查看HTML全文  查看全文  查看/发表评论  下载PDF阅读器
基金:  天津市应用基础与前沿技术研究计划一般项目(15JCYBJC22300);公益性行业(气象)科研专项(重大专项)(GYHY201506001-1);天津市气象局博士基金项目 (201628bsjj01)
中文关键词:  京津冀  降水 盛夏  初秋 东亚夏季风
英文关键词:  Beijing-Tianjin-Hebei Province  precipitation  midsummer  early autumn  East Asian summer monsoon
              
作者中文名作者英文名单位
梁苏洁Liang Sujie天津市气候中心
丁一汇Ding Yihui国家气候中心
段丽瑶Duan Liyao天津市气象台;天津市气象台
郝立生Hao Lisheng
李明财Li Mingcai天津市气候中心
引用:梁苏洁,丁一汇,段丽瑶,郝立生,李明财.2019.近46年京津冀地区“夏雨秋下”现象及其成因初探[J].大气科学
Citation:Liang Sujie,Ding Yihui,Duan Liyao,Hao Lisheng,Li Mingcai.2019.A study on the phenomenon of precipitation-delaying from midsummer to early autumn and associated reasons in Beijing-Tianjin-Hebei Province during 1970-2015[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      基于京津冀地区逐日和逐时降水资料,分析了1970年以来变暖背景下该地盛夏(7月和8月)和初秋(9月)降水的变化特征,经初步分析后,得到了如下结论:近46年京津冀地区盛夏降水显著减少,在1990s末由多雨转为少雨位相,降水日变化上,不同时段的降水皆明显减少,其中持续性降水事件的变化对总降水量减少的贡献更大。而初秋降水明显增加,且在2000s初发生跃变,由少雨转为多雨位相,夜间降水明显增加,并且持续性降水的增加和跃变是初秋降水增加的主要原因。进一步分析发现,日最高气温的变化与短时降水有较好的时间关系,盛夏时最高气温在1997年发生跃变,从较低位相跃变为较高位相,对应的,盛夏短时降水也同年发生跃变,由多雨转为少雨位相。而初秋的最高气温变化不明显,短时降水也没有发生跃变,无明显的变化趋势。此外,在环流场上,2000s后,盛夏时欧亚中高纬阻高活动加强,阻碍了中纬度西风扰动输送水汽到京津冀地区,东亚急流偏南,京津冀地区上升气流受到抑制,不利于降水产生;而初秋时,输送至京津冀地区的水汽增加,东亚急流偏北,京津冀地区上升气流加强,贝加尔湖地区低槽受到东部高压阻挡,经向环流加强,有利于冷空气的活动,同时,西太平洋副高强度增强位置偏北偏东,有利于降水的形成。东亚海陆热力差指数的在初秋的增强反映出东亚夏季风在夏末秋初的南撤过程发生延迟,形成了以上有利于初秋降水的环流形势,导致了“夏雨秋下”的现象的出现。
Abstract:
      Based on the daily and hourly precipitation data of 33 meteorological observation stations in Beijing-Tianjin-Hebei Province from 1970~2015, the spatial and temporal characteristics of midsummer (July and August) and early Autumn (September) precipitation are analyzed. It is found that midsummer precipitation amount decreases significantly during the past 46 years, and shifts from rainy phase to rainless phase at the end of 1990s. From the point of view of precipitation diurnal variation, accumulated precipitation amounts and hours at each hour of day have decreased since the late 1990s. The decreasing precipitation amounts of long-duration rain make more contribution to the decreasing trend of total midsummer precipitation. On the other hand, the early autumn precipitation amount exhibits an increasing trend, and shifts from rainless phase to rainy phase at the beginning of 2000s. There is an obviously increase of nocturnal precipitation during the recent decade. And the increase precipitation amount of long-duration rain is largely responsible for the shift and increase of total precipitation amount in early autumn. Further analysis reveals that the monthly mean of daily maximum temperature shifts from low temperature phase to high temperature phase at 1997, accordingly, the precipitation amounts of short-duration rain shifts rainy phase to rainless phase at the same in midsummer. While the monthly mean of daily maximum temperature and precipitation amounts of short-duration rain in early autumn show no obvious trend. Also, it is found that the decaying of East Asian summer monsoon delays during late summer and early autumn leading to the phenomenon of precipitation-delaying from midsummer to early autumn in Beijing-Tianjin-Hebei Province. The results show that blocking high has been strong over mid-high latitudes in Eurasia in midsummer since early 2000s resulting in less water vapor transport by westerly jet in mid-latitudes to Beijing-Tianjin-Hebei Province, corresponding with southern location of East Asia jet and weak upward motion in Beijing-Tianjin-Hebei Province, which lead to less precipitation in midsummer. In contrast, there have been more water vapor transport to Beijing-Tianjin-Hebei Province in early autumn, corresponding with northern location of East Asia jet and strong upward motion in Beijing-Tianjin-Hebei Province since early 2000s. Also the meridional circulation is strong because of trough in Lake Baikal and high in Northeastern China in favor of cold air activity, and strong western Pacific subtropical high is located further north and east, which lead to more precipitation in early autumn in Beijing-Tianjin-Hebei Province. Besides, early autumn index of land-sea thermal difference show significant increasing trend, which may reflect delayed decaying procedure of East Asian summer monsoon.
主办单位:中国科学院大气物理研究所 单位地址:北京市9804信箱
联系电话: 010-82995051,010-82995052传真:010-82995052 邮编:100029 Email:dqkx@mail.iap.ac.cn
本系统由北京勤云科技发展有限公司设计
京ICP备09060247号