Coupling an advanced land surface-hydrology model with the Penn State-NCAR MM5 modeling system. Part I: Model implementation and sensitivity
Coupling an advanced land surface-hydrology model with the Penn State-NCAR MM5 modeling system. Part I: Model implementation and sensitivity
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DOI：
10.1175/1520-0493(2001)129
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发表时间：
2001-01-01
影响因子：
3.2
通讯作者：
Dudhia, J
中科院分区：
文献类型：
--
作者：
Chen, F;Dudhia, J
本文讨论并记录了一些与宾夕法尼亚州立大学NCAR第五代中尺度模式（MM 5）中先进的地表水文模型的实施有关的问题。这里采用的概念是，陆面模式不仅应该能够提供合理的日变化的表面热通量耦合模式的表面边界条件，但也正确的土壤水分的季节演变的背景下，长期的数据同化系统。与NCEP全球和区域预报模式中使用改进的俄勒冈州州立大学陆面模式（LSM）的方式类似，在MM 5中实施该模式以促进土壤湿度的初始化。此外，1公里分辨率的植被和土壤质地图中引入耦合MM 5-LSM系统，以帮助识别植被/水/土壤特性在细尺度上，并捕捉这些陆面强迫的反馈。一个月变化的气候0.15度× 0.15度的绿色植被部分被用来代表植被对地表蒸发的年度控制。各种植被和土壤参数的规格进行了讨论，并在LSM的可用水容量扩展到亚网格尺度的异质性。耦合的LSM到MM 5也是敏感的表面层的处理，特别是热/湿的粗糙度长度的计算。考虑分子亚层的影响可以改善表面热流的模拟。结果表明，土壤热传导率、导水率和地表能量平衡对土壤水分变化非常敏感。因此，有必要建立一个合适的土壤湿度资料同化系统，以提高土壤湿度初始化的细尺度。
This paper addresses and documents a number of issues related to the implementation of an advanced land surface-hydrology model in the Penn State-NCAR fifth-generation Mesoscale Model (MM5). The concept adopted here is that the land surface model should be able to provide not only reasonable diurnal variations of surface heat fluxes as surface boundary conditions for coupled models, but also correct seasonal evolutions of soil moisture in the context of a long-term data assimilation system. In a similar way to that in which the modified Oregon State University land surface model (LSM) has been used in the NCEP global and regional forecast models, it is implemented in MM5 to facilitate the initialization of soil moisture. Also, 1-km resolution vegetation and soil texture maps are introduced in the coupled MM5-LSM system to help identify vegetation/water/ soil characteristics at fine scales and capture the feedback of these land surface forcings. A monthly varying climatological 0.15 degrees x 0.15 degrees green vegetation fraction is utilized to represent the annual control of vegetation on the surface evaporation. Specification of various vegetation and soil parameters is discussed, and the available water capacity in the LSM is extended to account for subgrid-scale heterogeneity. The coupling of the LSM to MM5 is also sensitive to the treatment of the surface layer, especially the calculation of the roughness length for heat/moisture. Including the effect of the molecular sublayer can improve the simulation of surface heat flux. It is shown that the soil thermal and hydraulic conductivities and the surface energy balance are very sensitive to soil moisture changes. Hence, it is necessary to establish an appropriate soil moisture data assimilation system to improve the soil moisture initialization at fine scales.