Collaborative Research: Scientific Program Overview--Convective Transport of Active Species in the Tropics (CONTRAST)

本项目将测量在北纬冬季，西太平洋暖池区对流层气团优先向平流层下层输送时，反应性化学物质向热带对流层顶过渡层（TTL）的输送。该地区微量气体及其降解产物的来源、化学演化和输送对平流层下层的化学性质有重大影响，但迄今为止进行的测量相对较少，因此，我们对相关过程和反馈的理解和预测能力尚不确定。用臭氧探测仪测量的极低臭氧浓度预计会导致OH自由基水平极低，因此，其主要汇是涉及OH的氧化途径的活性气体的寿命更长。深层对流的同时发生和TTL中有机化合物寿命的延长会显著影响平流层卤素收支。由于该地区的化学和辐射特性是联系大气成分和气候强迫机制的关键因素，因此CONTRAST实验将提供诊断、约束和改进化学-气候模式所需的测量数据。NSF GV飞机将在现场测量一系列气体、粒子和气象参数，并对其进行解释，以阐明活跃对流和远程输送对热带大气垂直分解化学成分的作用，特别是在主导对流外流的高度区域（12-14 km）。此外，CONTRAST将与计划在同一时间和同一地理位置进行的其他两个机载研究合作进行计划和协调：NASA EV1项目ATTREX（机载热带对流层顶实验）和欧洲CAST（热带协调机载研究）。借助互补的仪器有效载荷，GV、NASA全球鹰和英国Bae146的协同飞行将对热带西太平洋上空从地表到19公里的整个大气柱进行前所未有的检查。在CONTRAST的支持下，独特的基准测量套件将提高对热带对流输送过程的基本理解，并提高我们在化学-气候相互作用中模拟深层对流作用的能力。该项目将培训大气化学方面的学生，他们将直接参与部署和随后的数据分析和建模活动。将利用网络工具和媒体开展更广泛的教育和外联活动。

This project will measure the transport of reactive chemical species into the tropical Tropopause Transition Layer (TTL) over the Western Pacific warm pool region during boreal winter when tropospheric air masses in this region are preferentially transported into the lower stratosphere. The sources, chemical evolution, and transport of trace gases and their degradation products in this region can substantially impact the chemistry of the lower stratosphere but, to date, relatively few measurements have been made and, consequently, our understanding of and ability to predict the associated processes and feedbacks are uncertain. The extremely low ozone concentrations measured with ozonesondes are expected to result in very low levels of OH radicals and, thus, longer lifetimes for reactive gases whose primary sinks are oxidation pathways involving OH. The simultaneous occurrence of deep convection and prolonged lifetime of organic compounds in the TTL can significantly impact the stratospheric halogen budget. Because the chemical and radiative properties of this region are key factors in the mechanisms that link atmospheric composition and climate forcing, the CONTRAST experiment will provide measurements necessary to diagnose, constrain, and improve chemistry-climate models. A suite of gases, particles, and meteorological parameters will be measured in situ from the NSF GV aircraft and interpreted to elucidate the roles of active convection and long-range transport on the vertically resolved chemical composition of the tropical atmosphere particularly in the altitude region that dominates convective outflow (12-14 km). Moreover, CONTRAST will be scheduled and coordinated in collaboration with two other airborne studies planned for the same time and geographic location: The NASA EV1 project ATTREX (Airborne Tropical Tropopause Experiment) and the European CAST (Coordinated Airborne Studies in the Tropics). With complementary instrument payloads, coordinated flights of the GV, the NASA Global Hawk, and the UK Bae146 will provide an unprecedented examination of the full atmospheric column, from surface to 19 km, over the tropical western Pacific Ocean.The unique suite of benchmark measurements under the auspices of CONTRAST will improve fundamental understanding of convective transport processes in the tropics and our ability to model the role of deep convection in chemistry-climate interactions. The project will train students in atmospheric chemistry who are directly involved in the deployment and subsequent data analysis and modeling activities. Broader education and outreach activities will be developed using web-based tools and media.