Characterisation and Modelling of Climatically Relevant Primary Biogenic Ice Nuclei in the BEACHON Southern Rocky Mountain Project

该提案是为2011年美国西部半干旱地区（包括南落基山脉研究区）碳和水的生物地球化学循环之间的联系的国际多学科，多研究者的国际研究邀请书。核心假设是，植物和土壤中活性碳气体的生物源排放，以及孢子、花粉和细菌细胞等初级碳质颗粒的风运输，导致云凝结核（CCN）和冰核（IN）的形成，这反过来影响区域降水模式，从而将碳和水循环的组成部分联系起来。从概念上讲，生物源性排放、CCN的形成以及碳和水循环动力学之间的潜在联系和反馈一直存在广泛的争论，尽管过去已经研究了耦合系统的各个方面，例如，来自植被的生物源性挥发性有机化合物（VOC）的排放和来自生物源性二次有机气溶胶（SOA）的CCN形成，但绝对没有研究可以定量地追踪整个过程。源到受体时尚——从排放，经过沉淀，再回到排放。长期以来，一直需要进行多学科研究工作，以量化和评估这些过程之间联系的相对重要性，以实现区域耦合的地表-大气模式。国际地圈-生物圈计划-陆地生态系统-大气过程综合研究（IGBP-iLEAPS）的战略计划和NCAR生物-水-大气相互作用的能量、气溶胶、碳、水、有机物、和氮（BEACHON）项目都高度重视研究工作，以加强对生物气溶胶在连接和调节生物地球化学和水循环中的作用的理解，而BEACHON SRM 2011为开发这种综合方法提供了理想的机会。BEACHON-SRM的中心目标是利用观测来评估生态系统过程及其对气候的响应对与气候相关的生物源气溶胶的数量和组成的影响，以及它们作为CCN和IN功能的潜力，并改变降水，而降水反馈完成循环并改变生态系统过程。BEACHON-SRM将重点研究生物源CCN和IN的形成和修饰。IN是那些在大气中引发冰核的粒子。虽然IN通常占大气气溶胶颗粒的不到1 / 10^5，但它们在高于-36℃的温度下启动冰的形成是重要的，这是大多数降水形成的关键第一步。除粉尘外，氨的来源还包括初级生物颗粒。生物素在中高纬度地区降水中的普遍存在已被详细记录，生物素已被直接从气溶胶和云颗粒残留物中测量出来。生物素，通常也代表了所有初级生物颗粒的一小部分，包括冰核活性（INA）细菌、真菌孢子、花粉、凋落叶和由这些颗粒的细菌分解产生的IN。生物氮在较温暖的过冷温度下特别有效，因此在中度过冷云（高于-4.5至- 10摄氏度）中可能发挥特别重要的作用。目前，大气中INA生物颗粒的浓度有很大的不确定性，由于缺乏关于这类颗粒的空间和季节分布的数据，任何估计都是有限的。该提案将为这一雄心勃勃的项目提供实地测量和建模专业知识，该项目将首次为生物气溶胶-云相互作用和对水文循环的影响提供定量和深远的结果。

This proposal is for an invited UK contribution to an international multidisciplinary, multi-investigator study of the connections between biogeochemical cycling of carbon and water in semi-arid regions of the Western U.S comprising the Southern Rocky Mountain study region in 2011. The central hypothesis is that biogenic emission of reactive carbon gases from plants and soil, and wind transport of primary carbonaceous particles such as spores, pollen and bacterial cells, lead to the formation of cloud condensation nuclei (CCN) and ice nuclei (IN) which, in turn, influence regional precipitation patterns and thus link components of the carbon and water cycles. Conceptually, the potential linkages and feedbacks among biogenic emissions, the formation of CCN, and dynamics in the carbon and water cycles have been debate extensively and while various aspects of the coupled system have been studied in the past, e.g., emissions of biogenic volatile organic compounds (VOC) from vegetation and CCN formation from biogenic secondary organic aerosol (SOA), there are absolutely no studies that have traced the entire process in a quantitative, source to receptor fashion -- from emissions, through precipitation and back to emissions. A multidisciplinary research effort aimed at quantifying and assessing the relative importance of links among these processes has long been needed to enable regional coupled surface-atmosphere models. The strategic plans of the International Geosphere Biosphere Program - Integrated Land Ecosystem Atmosphere Processes Study (IGBP-iLEAPS) and the NCAR Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen (BEACHON) project both place a high priority on research efforts that will enhance understanding of the role of biogenic aerosols in linking and regulating the biogeochemical and water cycles and BEACHON SRM 2011provides an ideal opportunity to develop this integrative approach. The central aim of BEACHON-SRM is to use observations to assess the influence of ecosystem processes, and their responses to climate, on the number and composition of climatically-relevant biogenic aerosols and their potential to function as CCN and IN, and to modify precipitation, which feeds back to complete the loop and alter ecosystem processes. BEACHON-SRM will focus on the formation and modification of CCN and IN from biogenic sources. IN are those particles that initiate ice nucleation in the atmosphere. Although IN typically represent lessthan 1 in 10^5 of atmospheric aerosol particles, they are important in initiating ice formation at temperatures warmer than -36 C, a critical first step in most precipitation formation. In addition to dust, sources of IN include primary biological particles. The ubiquity of biological IN in precipitation from mid- to high-latitude locations has been well documented recently and biological IN have been measured directly from aerosol and cloud particle residuals. Biological IN, which again typically represent a small fraction of all primary biological particles, include ice nucleation active (INA) bacteria, fungal spores, pollen, leaf litter , and IN derived from bacterial decomposition of these particles. Biological IN are particularly efficient at warmer supercooled temperatures, and thus may play an especially important role in modestly supercooled clouds (warmer than -4.5 to - 10C. At the moment there is enormous uncertainty regarding number concentrations of INA biogenic particles in the atmosphere, and any estimates are limited due to the scarcity of data regarding the spatial and seasonal distributions of these types of particles. This proposal will contribute field measurement and modelling expertise to this ambitious project which will deliver quantitative and far reaching results for biogenic aerosol-cloud interactions and impacts on hydrological cycling for the first time.