Journal of Arid Meteorology

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Effects of Qinghai-Xizang Plateau’s Spring Surface Diabatic Heating#br# Anomalies on the East Asian Summer Monsoon Intensity

CUI Yang, CHANG Zhoulin, YU Lian, WANG Chenghai   

  1. 1. Key Laboratory of Meteorological Disaster Preventing and Reducing in Ningxia, Yinchuan 750002, China;
    2. Institute of Plateau Meteorology, CMA, Chengdu 610072, China;
    3. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
  • Received:2016-07-12 Revised:2016-11-14 Online:2017-02-28 Published:2016-11-14

青藏高原春季地表非绝热加热异常对东亚夏季风强度的影响

崔洋常倬林余莲王澄海   

  1. 1.宁夏气象防灾减灾重点实验室,宁夏 银川 750002;2.中国气象局成都高原气象研究所,
    四川 成都 610072;3.兰州大学大气科学学院,甘肃 兰州 730000
  • 作者简介:崔洋(1982-),男,宁夏吴忠人,博士,高级工程师,主要从事旱区寒区气候变化、数值模拟、大气边界层研究. E-mail:cuiyang@cma.gov.cn
  • 基金资助:

    国家自然科学基金项目(41440035,91437217,41275061)

Abstract:

The monthly average zonal wind, sensible and latent heat fluxes reanalysis data of the NCAR/NCEP Reanalysis I (NCEP-I) and European Centre for Medium-Range Weather Forecasts Center(ERA-interim), and the 723 stations observational precipitation and temperature data from 1961 to 2014 over China, were used to investigate the effects of Qinghai-Xizang Plateau’s (QXP) spring surface diabatic heating anomalies, which were associated with snowmelt and thawing processes, on the East Asian summer monsoon intensity changes. Firstly, the inter-annual variation characteristics of QXP surface diabatic heating in spring that closely related with the thawing of snow and thawing-freezing processes of soil were analyzed and diagnosed. Meanwhile, a new East Asian summer monsoon index (EASMI) was defined, which has intimately associated with the spring surface diabatic heating and large-scale atmospheric circulation over QXP. Based on the above, the relationships between EASMI and the summer precipitation over China were researched, and the effects of QXP’s spring surface diabatic heating anomalies on the East Asian summer monsoon intensity change were also investigated and analyzed. The results are as follows: (1) Due to the atmospheric outgoing long wave radiation decreasing and the surface-atmosphere temperature difference (Ts-Ta) mutation, the spring surface sensible and latent heat fluxes had successively experienced significant mutation from increasing to decreasing around 1997, 2003 during the past 36 years. (2) The new EASMI that was defined by the 200 hPa zonal wind speed in this paper had a good, wide representation and application. It showed a weakening tendency in recent 50 years with the rate of -0.73(10a)-1. (3)There was a significant negative correlation between the new EASMI and the entire Yangtze River basin’s summer precipitation, i.e. when the new EASMI appeared a positive (negative) anomalies, the entire Yangtze River basin’s summer precipitation from June to August would appear an abnormal decrease (increase). (4) The early spring surface latent heat flux positive (negative) anomalies of QXP, which linked to the snow melting and soil thawing processes, would cause the followed establishment of the East Asian summer monsoon anomalously weakened (enhanced). It also showed that the quasi-three-year cycle of QXP’s spring surface sensible and latent heat fluxes had the inhibitory effect to the EASMI’s quasi-three-year cycle, but the strengthening effect to the quasi-three-year cycle of summer precipitation in eastern China.

Key words: Qinghai-Xizang Plateau, snow and frozen soil, sensible heat flux, latent heat flux, East Asian summer monsoon

摘要:

为了探究与融雪、融冻过程相联系的青藏高原春季地表非绝热加热异常对东亚夏季风强度变化的影响,利用NCEP/NCAR Reanalysis I(NCEP-I)和欧洲中心(ERA-interim)全球月平均感、潜热通量等再分析资料,以及1961—2014年全国723个气象站逐月历史观测资料,首先定义一个与青藏高原地表非绝热加热相联系的新东亚夏季风指数,并分析新夏季风指数与中国夏季降水的关系,进而探讨青藏高原春季地表非绝热加热异常对东亚夏季风强度变化的影响。结果表明:(1)受青藏高原春季大气射出长波辐射减弱、地气温差发生突变影响,近36 a青藏高原春季地表感热、潜热通量先后在1997年、2003年左右经历了一次由增大转为减小的明显突变;(2)采用200 hPa水平风速新定义的东亚夏季风指数具有良好、广泛的代表性和适用性,近50 a来新东亚夏季风指数强度呈减弱趋势,减弱速率为-0.73/10 a;(3)新东亚夏季风指数与长江流域夏季6—8月降水之间存在极为显著的负相关关系,即东亚夏季风出现增强(减弱)异常时,长江流域夏季6—8月降水会异常减少(增多);(4)融雪、融冻过程引起的青藏高原春季前期地表潜热通量正(负)异常,会引起随后建立的东亚夏季风强度的减弱(增强)。与融雪、融冻过程联系紧密的青藏高原春季地表感、潜热通量存在显著的准3 a左右周期,其年代际变化对随后爆发的东亚夏季风和我国东部地区夏季降水准3 a左右周期的变化具有重要影响。

关键词: 青藏高原, 积雪冻土, 感热通量, 潜热通量, 东亚夏季风

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