A Land-Atmosphere Coupling Model and Mechanism of the Crust Layer and the Evolution of Canopy in Artificial Vegetation Area of Shapotou
A Land-Atmosphere Coupling Model and Mechanism of the Crust Layer and the Evolution of Canopy in Artificial Vegetation Area of Shapotou
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发表时间：
2002
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通讯作者：
Y. De-liang;Li Jiachun;Du Yue;Li Xinrong;Zhang Jingguang
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作者：
Y. De-liang;Li Jiachun;Du Yue;Li Xinrong;Zhang Jingguang
众所周知，陆气相互作用对全球和区域环境有很大的影响。为了确定陆气界面的通量和参数化方案，有必要研究典型下垫面上的陆地过程。近年来，人们逐渐认识到陆气界面水热交换过程与冠层的密切关系，越来越多地关注冠层覆盖率及其形状的变化对气候的影响。陆气相互作用主要有：一是辐射交换；二是地表粗糙度对大气运动的摩擦；三是感热和潜热的交换。自20世纪70年代以来，对陆气相互作用和陆面参数化方案的认识有了很大的进步。根据其复杂程度，可以将其分为简单模型和复杂模型。一般而言，简单模型忽略了冠层在水循环中的影响。地表水控制方程主要是“水桶模型”或对Budyko提出的“水桶模型”的修正。地表能量控制方案是一个忽略土壤下能量传输的地表瞬时能量平衡方程。自20世纪80年代以来，地表能量控制方案是一个忽略土壤下能量传输的地表瞬时能量平衡方程。从20世纪80年代以来，地面水控制方程主要是“水桶模型”或对Budyko提出的“水桶模型”的修正。地表能量控制方案是一个忽略土壤下能量传输的地表瞬时能量平衡方程。自20世纪80年代以来，地表能量控制方案主要是忽略土壤下能量传输的地表瞬时能量平衡方程对冠层水热循环的生物物理和生理过程进行了广泛的研究。已经提出了几个SPAC系统的模型，如BATS模型(Dickinson 1986)和SIB模型(Sell 1986)。作为结果，科学家们关注耦合模型来模拟陆地-大气相互作用。同时，大气湍流输送在界面上的动量、质量和能量交换中起着决定性的作用。1989年，Naot利用新的湍流模型进一步发展了陆地-大气相互作用耦合模型。1990年，NAOT利用新的湍流模型进一步发展了陆地-大气相互作用耦合模型。应用湍流理论建立了反映裸露土壤和低层大气水热交换的土壤-大气耦合模式(SALSA)。近年来，人们越来越关注土壤-大气传输过程，以及IGBP、UNEP和GEWEX等项目，陆气相互作用的研究也在不断深入。本文阐述了陆面-大气相互作用研究对人类生存环境保护和地方经济发展的重要性及其现状。在前人工作的基础上，建立了腾格里沙漠麦田SPAC系统的微气象耦合模式。该模式具有较高的精度和较高的实用价值考虑叶片气孔非饱和条件计算蒸散量，并对根系吸收模型进行修正。微生物结皮的存在改变了土壤导水率，改变了沙层有限降水的时空分布，导致深层灌木退化。将冠层划分为多层，旨在揭示冠层内平均量的垂直分布，为地面过程的参数化提供科学依据。模型能够很好地模拟小麦冠层微环境，与实测平均温度、特定湿度和潜热通量等符合得很好。并进行了敏感度试验，分析了冠层的影响。
It is well-known that land-atmosphere interaction exerts great influences on global and regional environment.In order to determine the fluxes and parameterization scheme at the land-atmosphere interface,it is necessary to investigate terrestrial processes on typical underlying surface.In recent years,people have come to recognize the close relationship between the water-heat exchange process in the land-atmosphere interface and the canopy,more and more attention has been paid to the influence on the climate by the change of the canopy coverage ratio and their form.The main interactions of the land-atmosphere are:firstly,the radiation exchange;secondly,the friction of the surface roughness against the movement of the atmosphere;and the third is the exchange of the sensible heat and the latent heat.A great improvement was made to understand land-atmosphere interaction and land-surface parameterization scheme since 1970s.The model can be clsasified as simple model and complex model according to its complicated degree.Generally speaking,the simple model ignores the effect of the canopy in water cycling.The surface water governing equation is mainly the “bucket model” or the revision of the “bucket model” developed by Budyko.The surface energy control scheme is a surface instant energy balance equation which ignores the energy transmission under the soil.Since 1980s,canopy biophysical and physiological processes for water and heat cycling are extensively studied.A few model for SPAC system,such as BATS model(Dickinson 1986) and SIB model(Seller 1986) have been proposed.scientists have paid attention to coupling models for simulating the land-atmosphere interaction as a result.At the mean time,the atmosphere turbulence transfer plays a decisive role in the momentum,quality and energy exchange above the interface.In 1989,the land-atmosphere interaction coupling model was further developed by Naot using the new trubulence model.In 1990,the soil-atmosphere coupling model(SALSA)which reflects the water-heat exchange of the bare soil and the lower atmosphere was established by Berge applying the turbulence theory.In recent years,people are more concerned with land-atmosphere transfer process and projects such as IGBP,UNEP and GEWEX.The land-atmosphere interaction is being intensively studied.In the present paper,we have elucidated the importance of investigation on land surface-atmosphere interaction for mankind's living environment protection and local economics development as well as its present state.Based on the previous work,a coupling micrometeorological model for SPAC system over wheat field in the Tengger desert is presented.Especially,the leaf stoma non-saturation condition is considered to calculate the evapotranspiration,and the root absorption model is revised as well.The presence of microbiotic crust changes the soil hydraulic conductivity,alters the temporal and spatial distribution of limited precipitation in sand layer and leads to the degradation of deep-rooted shrubs.The canopy is divided into several layers,aiming at revealing the vertical profiles of mean quantities within it and providing scientific basis for parameterization of terrestrial processes.The model is shown capable of well simulating the microenvironment of wheat canopy in good agreement with measured mean temperature,specifie humidity and latent heat fluxes et al. And the sensitivity test is carried out as well to analyze canopy's influence.