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ISSN 1006-9585

CN 11-3693/P

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中国区域夏季地表气温与陆面过程耦合强度的分布特征
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作者单位:

1.中国科学院大气物理研究所;2.美国密歇根州立大学地理环境与空间科学系

作者简介:

通讯作者:

基金项目:

国家重点研发计划项目(2016YFC0402702)、国家自然科学基金项目(41661144032)、公益性行业气象专项(GYHY201406021)


Spatial Characteristics of Air Temperature-Land Surface Coupling Strength during summer in China
Author:
Affiliation:

1.International Center for Climate and Environment Sciences,Institute of Atmospheric Physics,Chinese Academy of Sciences;2.Department of Geography,Environment,and Spatial Sciences,Michigan State University

Fund Project:

National Key Research and Development Program of China(2016YFC0402702),Natural Science Foundation of China (41661144032) and Key Project of the Meteorological Public Welfare Research Program (GYHY201406021)

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    摘要:

    鉴于陆气相互作用对极端高温事件的重要作用,本文选取地表气温为大气关键要素,基于ERA5-Land陆面再分析资料,分析了中国区域夏季地表气温与土壤湿度、土壤温度的耦合过程及其耦合强度的多时间尺度分布特征。研究结果表明,基于不同指标定义的陆气耦合强度在中国区域呈现不同的空间分布特征,其中陆面变量-潜热通量-气温耦合的“热点”区域主要分布在我国的西北地区和长江流域,而陆面变量-感热通量-气温耦合的“热点”区域主要分布在河套-内蒙古地区、新疆西南部地区,以及长江以南部分区域。这说明夏季地表气温对陆面变量异常的敏感度的区域差异,与不同区域陆面异常影响地表气温的主导过程密切相关。此外,陆气耦合强度的大小还随时间尺度而变化,其中月平均尺度的陆气耦合强度要明显弱于日、侯及旬平均的耦合强度;就日、侯及旬时间尺度而言,陆面变量-潜热通量-地表气温的耦合强度在全国大部分地区随时间尺度的增加而逐渐减弱,基于感热通量的陆气耦合强度在南方大部分地区也随时间尺度的增加逐渐减弱,但在北方大部分地区则表现为随时间尺度增加逐渐增强。比较表层与次表层土壤温度和湿度与地表气温的耦合强度发现,不同指标的陆气耦合强度在中国大部分地区随深度的变化不大,但在中国西北地区次表层土壤湿度与地表气温的耦合强度较表层相对减弱。

    Abstract:

    Given the important role of land-atmosphere interaction in extreme hot events, the multi-timescale characteristics of the coupling strength between surface air temperature and soil moisture, as well as soil temperature during summer in China has been analyzed using the ERA5-Land reanalysis dataset. Results show that the aforementioned four indices of land-atmosphere coupling strength (LACs) vary with regions. Specifically, “hot spots”, where variation in land surface has remarkable effect on surface air temperature through the latent heat flux, are mainly found in Northwest China and the Yangtze River basin; Nevertheless, in terms of LAC defined by the sensitivity of surface air temperature to land condition anomalies through the sensible heat exchange, the “hot spots” are mainly located in Hetao-Inner Mongolia areas, southwestern Xinjiang, and part of south Yangtze River. This indicates that the differences between the spatial distributions of four LACs could be largely explained by the dominant processes responsible for impact of land conditions on surface air temperature anomalies. It’s also found that the LAC varies a lot with timescales, with the coupling strength in monthly timescale significantly weaker than that of shorter timescales (i.e., daily-pentad-ten day); Besides, the land surface-latent heat flux-air temperature coupling strength gets weaker in majority parts of China with the timescale increasing from one day to ten days, while the land surface-sensible heat flux-air temperature coupling strength gets stronger over the northern parts of China with increasing timescales, and still gets weaker in other regions. Furthermore, subsurface soil moisture-related LAC is found to be weaker compared with that of surface one in Northwest China, but changes in subsurface soil-air temperature coupling strength of other metrics are small compared with that in surface layer.

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历史
  • 收稿日期:2021-03-24
  • 最后修改日期:2021-04-22
  • 录用日期:2021-04-26
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