Effects of Space-Time Dynamics of Surface Processes on Land-Atmosphere Interactions at the Mesoscale

本建议的目的是在中尺度上研究陆面过程对陆-气相互作用的时空动力学。为了实现这一目标，将采取协调一致的观测数据分析和数值模拟方法。本研究的主要任务如下：*探索利用MM5作为大气模块对陆-气耦合模式进行细化*比较陆-气耦合模式与FIFE数据的陆面响应。*建立一个自旋上升时间尺度，作为初始大气状态和初始陆地表面状态的函数。检查自旋启动时间对强迫数据性质的依赖性。*发展一种方法来评估空间异质性对近地表大气过程响应的影响。评估土壤湿度变化特征尺度与蒸散发时空动态和近地表大气变量之间的关系。确定控制土壤湿度异常时空尺度的物理机制。利用陆地-大气耦合模型和FIFE和Washita '92站点的实测数据集，研究地表水文和大气响应的时空动态特征。这项研究所得的信息将为陆地-大气相互作用研究中尺度模式和实地试验的准确解释和广泛应用提供所需的增量知识。它们将有助于解决中尺度模式的自旋上升和尺度特性，并有助于为大气模式开发现实的陆地表面水文参数化。此外，这项工作与GCIP GEWEX（全球能源和水循环实验）大陆尺度国际项目和EOS（地球观测系统）科学计划的水和能量通量的标度以及陆地-大气耦合模式段的测试和评估直接相关。

9526628 Islam The goal of this proposal is to investigate the space-time dynamics of land-surface processes on land-atmosphere interactions at the mesoscale. The achieve this goal, a well coordinated observational data analysis and numerical modeling approach will be pursued. Following are the main tasks of this research: *Explore the use of MM5 as the atmospheric module to refine the coupled land-atmosphere model *Compare the land surface response of the coupled land-atmosphere model with the FIFE data. *Establish a spin-up time scale as a function of initial atmospheric states and initial land surface states. Examine the dependence of spin-up time on the nature of forcing data. *Develop a methodology to asses the effects of spatial heterogeneity on the response of near-surface atmospheric processes. Evaluate the relationships between characteristic scales of variabilities in soil wetness and space time dynamics of evapotranspiration and near-surface atmospheric variables. Identify the physical mechanisms that control the space-time scales of soil wetness anomalies. This proposal is designed to characterize the space-time dynamics of land surface hydrology and atmospheric response by using a coupled land-atmosphere model and measured datasets from the FIFE and Washita '92 sites. Resulting information from this research would provide the incremental knowledge needed for accurate interpretation and widespread application of mesoscale models and field experiments for land-atmosphere interaction studies. They will aid in addressing the spin-up and scaling properties of mesoscale models and in developing realistic land-surface hydrology parameterizations for atmospheric models. In addition, this effort is directly relevant to scaling of water and energy fluxes and testing and evaluation of coupled land-atmosphere model segments of the GCIP GEWEX (Global Energy and Water Cycle Experiment) Continental-Scale International Project and EOS (Earth Observing System) science plans.