Influence of Land Use and Landscape Heterogeneity on Cloud Formation and Atmospheric Circulation in Southwest Australia

澳大利亚西南部是研究土地利用对云形成和大气环流模式影响的理想试验台。为了农业目的而清除原生植被，在农田和未受干扰的植被区之间形成了一条700公里长的尖锐边界。初步研究表明，农作物取代原生植被会改变地表能量，直接影响对流云的形成。地表非均质性的剧烈性质和大的空间范围有利于二次环流的形成，而二次环流也影响云的形成。本研究将结合地面、卫星、飞机观测、空间统计分析和数值模拟实验，解决一系列与土地利用对澳大利亚西南部云形成和区域大气环流的假设影响有关的科学问题。本研究将利用这些观测来描述地表能量学和大气热力学结构作为土地利用的函数及其与云形成的关系。观测结果还将用于验证由景观异质性产生的次生中尺度环流的存在。数值模拟与观测相结合，将用于确定土地利用的差异是否导致观测到的云形成变化，以及中尺度环流是否受到景观异质性的影响。对卫星观测云量进行详细分析，确定农田和原生植被云形成差异的统计意义。该研究的独特之处在于景观异质性具有明显更高的空间尺度和剧烈的空间变化。空间异质性的尺度和性质是重要的，因为先前的研究被批评为采用空间尺度大、变化剧烈的假设景观异质性格局，而在自然界中没有对应的格局。这项研究的一个更广泛的影响是它对解决正在进行的关于景观异质性对区域气候影响的争论的潜在贡献。这项研究的结果也有望对经历剧烈土地利用变化的土地利用管理规划者有用。这项研究工作将使美国、澳大利亚和日本的研究人员能够进行国际合作，并通过研究生参加实地活动和分析项目期间产生的数据来促进研究生教育。

Southwest Australia is an ideal test bed to investigate the influence of land use on cloud formation and atmospheric circulation patterns. Clearing of native vegetation for agricultural purposes has resulted in a 700 km long sharp boundary between the croplands and the undisturbed vegetation areas. Preliminary studies suggest that replacement of native vegetation by agricultural crops alters the surface energetics, directly influencing convective cloud formation. The drastic nature and large spatial extent of the land surface heterogeneity is conducive to the formation of secondary circulations that also impact cloud formation. This investigation will address a series of scientific questions related to the hypothesized impact on land use on cloud formation and regional atmospheric circulations of southwest Australia using a combination of ground, satellite, aircraft observations, spatial statistical analysis and numerical modeling experiments. This study will utilize these observations to characterize surface energetics and atmospheric thermodynamic structure as a function of land use and its relationship to cloud formation. Observations will also be used to verify the existence of secondary mesoscale circulations generated by landscape heterogeneity. Numerical simulations, in combination with observations, will be used to determine if differences in land use are responsible for observed variations in cloud formation and if mesoscale circulations are forced by landscape heterogeneity. Detailed analysis of satellite observed cloudiness will be conducted to determine the statistical significance of differences in cloud formation over the croplands and native vegetation This study is unique in the sense that the landscape heterogeneity has significantly higher spatial scales and exhibits drastic spatial changes. The scale and nature of the spatial heterogeneity is important since prior studies have been criticized for employing hypothetical landscape heterogeneity patterns with large spatial scales and drastic changes that have no counterparts in nature. One of the broader impacts of this study is expected to be its potential contribution towards resolving the ongoing debate on the impact of landscape heterogeneity on regional climate. The results from this study are also expected to be of utility to land use management planners experiencing drastic land use change. This research effort will enable international collaboration between researchers in United States, Australia and Japan and promote graduate education through the participation of graduate students in both the field campaign and the analysis of data generated during the project.