Characteristics of Vertical Circulation in the Convective Boundary Layer over the Huaihe River Basin in China in the Early Summer of 2004
Characteristics of Vertical Circulation in the Convective Boundary Layer over the Huaihe River Basin in China in the Early Summer of 2004
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DOI：
10.1175/2008jamc1769.1
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发表时间：
2008-11
影响因子：
3
通讯作者：
S. Endo;T. Shinoda;Hiroki Tanaka;T. Hiyama;K. Tsuboki;H. Uyeda;K. Nakamura
中科院分区：
文献类型：
--
作者：
S. Endo;T. Shinoda;Hiroki Tanaka;T. Hiyama;K. Tsuboki;H. Uyeda;K. Nakamura
本文的目的是阐明中国淮河流域这一湿润的陆地地区的对流边界层（CBL）的特征。数据收集在2004年初夏使用32米通量塔和1290兆赫风廓线雷达。当成熟麦田或裸地占主导地位时（第一阶段），地表感热通量（SHF）与潜热通量（LHF）接近。在植被转变为水田后（第二阶段），LHF远大于SHF。从第一和第二时段中选择两个晴天，分别称为干情况和湿情况。在干燥的情况下，一个深CBL迅速发展，从清晨CBL的热上升气流是强烈的。在潮湿的情况下，从上午晚些时候开始，一个浅的CBL缓慢发展，热气流很弱。为了研究CBL中的热力过程，进行了大涡模拟（LES）。模拟充分再现了表面热通量和CBL发展的干的情况下，湿的情况下。对于干燥的情况下，感热贡献了几乎所有的浮力通量。相反，对于潮湿的情况下，热量和水分作出了同等的贡献。湿度对浮力的贡献较大是湿润陆地地区CBL的主要特征之一。
The purpose of this study is to clarify the characteristics of the convective boundary layer (CBL) over a humid terrestrial area, the Huaihe River basin in China, which is covered by a large, nearly flat plain with uniform farmland. Data were collected in early summer 2004 using a 32-m flux tower and a 1290-MHz wind profiler radar. When mature wheat fields or bare fields dominated (the first period), the sensible heat flux (SHF) from the land surface was nearly equal to the latent heat flux (LHF). After vegetation changed to paddy fields (the second period), the LHF was much larger than the SHF. Two clear days from the first and second periods were selected and are referred to as the dry case and wet case, respectively. For the dry case, a deep CBL developed rapidly from the early morning, and thermal updrafts in the CBL were vigorous. For the wet case, a shallow CBL developed slowly from late morning, and thermals were weak. To study the thermodynamic process in the CBL, a large-eddy simulation (LES) was conducted. The simulation adequately reproduced the surface heat flux and the CBL development for both the dry case and the wet case. For the dry case, sensible heat contributed to nearly all of the buoyancy flux. In contrast, for the wet case, heat and moisture made equal contributions. The large contribution of moisture to the buoyancy is one of the main characteristics of the CBL over humid terrestrial areas.