doi:  10.3878/j.issn.1006-9895.1909.19177
局地蒸发和外部水汽输送对松花江流域夏季降水的贡献

Contributions of Local and Remote water vapor transport to Precipitation variations over Songhua River BasinYongsheng Li1, Lixia Zhang2 and Bo Wang1
摘要点击 70  全文点击 13  投稿时间:2019-06-17  修订日期:2019-06-17
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基金:  (YSZD201701)
中文关键词:  松花江流域  降水 蒸发  水汽输送 年际变化 #$NP
英文关键词:  Songhua  River Basin, precipitation, evaporation, water  vapor transport, interannual  variation 1 引言
        
作者中文名作者英文名单位
李永生liyongsheng黑龙江省气候中心
张丽霞zhanglixia中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室LASG
王波黑龙江省气候中心
引用:李永生,张丽霞,王波.2020.局地蒸发和外部水汽输送对松花江流域夏季降水的贡献[J].大气科学
Citation:liyongsheng,zhanglixia.2020.Contributions of Local and Remote water vapor transport to Precipitation variations over Songhua River BasinYongsheng Li1, Lixia Zhang2 and Bo Wang1[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文基于Brubaker二元模型,采用JRA-55再分析资料定量研究了局地蒸发和外部水汽输送对松花江流域夏季气候态降水及其年际变率的相对贡献,并探讨了相应的物理机制。气候平均而言,外部水汽输送是松花江流域初夏(5-6月)和盛夏(7-8月)降水的最主要水汽源。受西风带影响,初夏自西边界进入松花江流域的水汽贡献占主导,外部水汽输送对当地降水的贡献为78.9%,源自蒸发的水汽贡献为21.1%。较之初夏,由于盛夏来自南边界的水汽输送加倍,外部水汽输送贡献增加,外部水汽输送和蒸发对降水贡献分别为86%和14%。JRA-55再分析资料可以合理再现观测降水演变,1961-2016年二者在初夏与盛夏的相关系数分别可以达到0.73和0.83,因此可以用于分析局地蒸发和外部水汽输送对松花江流域夏季降水贡献的年际变率。研究发现,初夏由于西南季风异常导致的南边界进入的水汽输送异常是松花江流域降水年际变率的主要原因,自西边界、北边界进入的水汽输送与降水呈现显著负相关,该水汽输送异常对应的环流型易发生在El Ni?o衰减年初夏,局地蒸发对降水年际变率的贡献不显著。盛夏由于副高和西南季风异常造成的来自南边界的水汽输送异常对降水的年际变率起主导作用,局地蒸发贡献与降水变化显著负相关,海温强迫作用对该环流异常的强迫并不显著,中高纬度大气内部变率影响占主导。由于盛夏降水与地表温度在盛夏期间显著负相关,盛夏时期降水偏少时,温度偏高,蒸发偏强,进而蒸发水汽对降水贡献增加。
Abstract:
      The relative contributions of the local and remote atmospheric moisture fluxes to summer precipitation over Songhua River Basin and its interannual variability are investigated using Brubaker model in this study. Climatologically, due to the prevailing westerly wind in early summer (May-June), the remote atmospheric moisture is the dominant contributor to early summer precipitation, which accounts for 78.9%. Accordingly, the local evaporation contribution is 21.1%. In late summer (July-August), the East Asian summer monsoon brings more moisture via the south boundary, the contribution of the remote moisture increases to 86%, and the contribution of the local evaporation reduces to 14%. JRA-55 can well capture the interannual variation of summer precipitation over Songhua River basin, with the correlation coefficients of precipitation in early summer and late summer for 1961-2016 at 0.73 and 0.83, respectively. It shows that the moisture flux via the southern boundary caused by stronger southwest monsoon plays the dominant role in early summer, and the moisture fluxes via the western and northern boundary are significantly negatively correlated with the early summer precipitation. The contribution of local evaporation is not statistically significant. The moisture fluxes anomalies tend to occur in the early summer with El Ni?o decaying. In late summer, the significantly positive contribution is from the moisture flux via the southern boundary and negative contribution from the local evaporation. The oceanic forcing on late summer precipitation anomaly is not significant, and internal atmospheric variability dominates. The significant negative contribution of local evaporation is due to significant negative correlation between surface temperature and precipitation. When precipitation is less than normal, surface temperature is warmer than normal, thus more evaporation and more contribution from local evaporation to precipitation.
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