Collaborative Research: Understanding the Role of Landcover and Landform in the Spatial Organization of Orographic Clouds and Rainfall

合作研究：了解土地覆盖和地貌在地形云和降雨空间组织中的作用

• 批准号: 0711414
• 负责人: Miles Silman
• 金额: $ 12.73万
• 依托单位: Wake Forest University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711414&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Role; Landcover

Mountains supply freshwater for over 60% of the world's population making the location and timing of orographic precipitation crucial in determining the availability and utility of water resources and ecosystem services. Montane systems also harbor Earth's most important biodiversity hotspots, and species and ecosystem responses to climate variability and change in these regions are critically dependent on cloud and precipitation regime. The objective of this proposal is to investigate whether and how landform and landcover modulate the spatial and temporal variability of orographic clouds and precipitation in tropical high mountains, a high priority area for biodiversity conservation and human water supply. The central research hypothesis is that evapotranspiration is a critical source of moisture to the atmospheric boundary layer (ABL) either locally and, or remotely via moist transport by diurnal mountain-valley circulations, lowering the cloud base at high elevations during the afternoon, and enhancing thermodynamic instability at locations in the landscape where precipitable water and CAPE (Convective Available Potential Energy) attain collocated night-time maxima. Spatial patterns in the organization of clouds and precipitation should therefore be explained by the spatial variability of vegetation and soil moisture patterns on altitudinal gradients, and by how this translates into the spatial variability of the diurnal cycle of latent heating fluxes between the land surface and the lower troposphere. To evaluate this hypothesis, the research will focus on a tropical montane cloud forest in the Central Andes in Peru, leveraging on ongoing multidisciplinary, multi-institutional ecological research by the Andes Biodiversity and Ecosystem Research Group (ABERG) that includes the University of Edinburgh and Oxford University in the UK, and FIT, Wake Forest and Duke Universities among others in the US.ABERG has installed a large array of vegetation plots and associated ecosystem function measurements centered on the Kosnipata Valley, extending from the high Andes into the Amazonian lowlands. The plot network is anchored by a series of 21 mapped, measured, and vouchered 1 ha tree plots comprising ~15,000 stems. These plots are embedded in an array of existing weather stations and data loggers ranging from 3450m to 250m. The hectare plots also form the basis of an intensive ecosystem function experiment, with plots along the main transect having dendrometers on 20% of the trees chosen in a stratified random sample. Subsets of plots are also studied for leaf, fruit, and fine root productivity, forest structure and leaf area index, and are instrumented to log soil moisture, understory and canopy light levels, rainfall, winds velocity and direction. Carbon-cycle measurements on photosynthesis, leaf, stem, and soil respiration are also taken at these plots. An intensive hydrological study plot at 3000m is also instrumented for throughfall, stemflow, and cloud interception measurements. The investigation relies on diagnostic process studies integrating satellite products and surface observations from existing and augmented networks to survey the space-time relationships between hydro-eco-geomorphologic regimes and cloudiness. High-resolution simulations (1km or less) using a coupled land-atmosphere, non-hydrostatic, cloud-resolving model will be used to investigate the physical linkages among the spatial patterns of topography, vegetation, soil moisture and the diurnal cycle of monsoon rainfall in the central Andes at the valley-ridge scale. Specifically, the following science questions will be addressed: (1) What is the contribution of evapotranspiration to the diurnal cycle of the energy budget of the lower troposphere in tropical mountainous regions? How does it vary spatially with elevation and landform (ridges versus valleys, windward versus leeward slopes, foothills versus high peaks)? (2) How does transversal (lateral) mountain variability in the spatial arrangement of landform and vegetation affect the diurnal cycle of convective activity and precipitation during the monsoon? (3) What is the relationship between the observed multi-scaling behavior of cloud fields from satellite imagery and the dominant spatial scales of convective activity associated with topography and, or land-use/land-cover patterns? (4) How can the current trends of land-use/land-cover change, and in particular deforestation and extension of agricultural activity to the highlands, change the water cycle in tropical mountainous regions? What are the consequences of these changes for the long-term sustainability of tropical mountain ecosystems and water resources? Though in the tropics, the outcomes of this work are relevant for mid-latitude mountainous regions, especially the western US where orographic precipitation (rain and snowfall) is the dominant freshwater resource. Finally, the study area is undergoing strong land-use change from anthropogenic eradication of the natural tree line, and from the construction of the inter-oceanic highway. The research findings should lead to an improved science basis for sustainable environmental planning and adaptation to climate climate variability and change in mountainous regions.

山区为全球60％以上的人口提供淡水，这是确定水资源和生态系统服务的可用性和实用性至关重要的地形降水的位置和时间。 山地系统还具有地球最重要的生物多样性热点，物种和生态系统对气候变异性和这些地区变化的反应在关键取决于云和降水状态。 该提案的目的是研究地形云的空间和时间变化以及热带高山的降水的空间和时间变化，这是生物多样性保护和人类水供应的高优先区域。 中心研究假设是，蒸散量是对大气边界层（ABL）的关键水分来源，要么是在当地或通过昼夜山山谷循环进行潮湿的运输，在下午降低了高海拔的云基群，并增强了可用的水和斗篷的高度动力学能力（增强了可用的水平）。 因此，应通过高度梯度上植被和土壤水分模式的空间变异性来解释云和降水的空间模式，以及如何转化为潜热磁通量的局限性周期的空间变异性。 为了评估这一假设，该研究将集中于秘鲁中部安提斯中部的热带山地云森林，并利用安妮斯生物多样性和生态系统研究小组（ABERG）正在进行的多学科的多学科，多机构的生态研究（ABERG），其中包括Edinburgh大学和牛津大学在英国和Fit for，Wake Fornity and Fit，Wake Fornity和Due eus.usab in. wake and for abtere in.以及以Kosnipata山谷为中心的相关生态系统功能测量值，从高安第斯山脉延伸到亚马逊低地。 该情节网络由一系列的21映射，测量和凭证1公顷的树木图组成，其中包括约15,000个茎。这些地块嵌入了一系列现有的气象站和范围从3450m到250m不等的数据记录仪中。公顷地块也构成了密集生态系统功能实验的基础，沿着主要样带的图在分层随机样品中选择的20％的树木上具有树枝状仪。 还研究了地块的子集，用于叶子，水果和细根生产率，森林结构和叶子面积指数，并可以仪器记录土壤水分，林下和冠层光线，降雨，风速和方向。 在这些图上还进行了光合作用，叶子，茎和土壤呼吸的碳周期测量。 在3000m处的密集水文研究图还可以进行贯穿，茎流和云拦截测量值。该研究依赖于整合卫星产品和现有网络和增强网络的表面观察的诊断过程研究，以调查水力 - ECO-ECO-GEOMORPHOLOLOGIC SERMIMES和DUSTIMESS之间的时空关系。 使用耦合的陆地大气，非静态，云分辨模型的高分辨率模拟（1公里或更少）将用于研究瓦利 - 里奇 - 里奇尺度中季中心和季中心季风降雨的平均空间模式之间的物理联系。 具体而言，将解决以下科学问题：（1）蒸散量对热带山区下对流层的能源预算的昼夜周期的贡献是什么？ 它如何随着高程和地形（山脊与山谷，风向与背风斜率，山麓与高峰）的空间变化？ （2）地面和植被的空间排列中的横向（横向）变异性如何影响季风期间对流活动和降水的昼夜周期？ （3）从卫星图像中观察到的云场的多尺度行为与与地形和土地使用/土地覆盖模式相关的对流活动的主要空间尺度之间的关系是什么？ （4）目前的土地使用/土地覆盖的趋势如何改变农业活动到高地的森林砍伐和扩展，改变热带山区的水周期？ 这些变化对热带山区生态系统和水资源的长期可持续性的后果是什么？尽管在热带地区，这项工作的结果与中纬度的山区地区有关，尤其是美国西部，那里的地面降水（雨水和降雪）是主要的淡水资源。最后，研究区域正在经历大量的土地利用变化，这是由于自然树线的人为根除，以及构造海洋间高速公路。研究结果应为可持续的环境计划和适应气候气候变化和山区变化的适应性提供改善的科学基础。