Collaborative Research: Observational and Modeling Studies of Overshooting Convection and Stratosphere-Troposphere Exchange

合作研究：超调对流和平流层-对流层交换的观测和模拟研究

• 批准号: 1522906
• 负责人: Kenneth Bowman
• 金额: $ 28.96万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1522906&HistoricalAwards=false
• 关键词: Collaborative; Research; Observational; Modeling; Studies

Deep convection that penetrates (overshoots) the tropopause affects the trace gas composition of the extratropical upper troposphere and lower stratosphere, which is important for global atmospheric chemistry and the Earth's radiation balance. This study will combine more than 10 year data of ground-based radar observations with numerical model simulations to study the physical and chemical characteristics of overshooting convection. Data from approximately 100 NEXRAD radars will be composited onto a three-dimensional regional grid with high spatial and temporal resolution. Climatology of the physical characteristics of overshooting convection, such as vertical extent, geographic distribution, interannual variability, and annual and diurnal cycles will be computed from the radar observations. Overshooting convection characteristics derived from the composited radar data will be compared with estimates based on satellite IR observations. To investigate the mechanisms responsible for cross-tropopause transport and to make quantitative estimates of stratosphere-troposphere exchange, numerical model simulations with explicitly resolved convection and chemistry will be carried out for case studies and for an entire warm season. The radar data will be used along with in situ trace gas observations from aircraft to evaluate the performance of the numerical simulations.Intellectual Merit: It is well known that convection in the extratropics can penetrate the tropopause and extend into the lower stratosphere, but there is little quantitative information about its geographic distribution, frequency of occurrence, or depth of penetration into the stratosphere. The radar analyses in this study will lead to a new regional climatology of overshooting convection in the midlatitudes based on direct geometric observations at high spatial and temporal resolution. The results will be compared with satellite IR estimates of overshooting, which offer the potential to extend the regional results to a global domain. High-resolution numerical simulations of overshooting convection will be used to investigate stratosphere-troposphere exchange mechanisms and to make quantitative estimates of the transport of important trace species.Broader Impacts: This research will produce a long-term, public, dataset of radar reflectivity over a large portion of the contiguous U.S. These data will be applicable to a wide range of other hydrometeorological problems. Since convection is not resolved in current global climate models, these studies will provide guidance for developing parameterizations of stratosphere-troposphere exchange due to overshooting convection. A better understanding of overshooting convection will help to reduce uncertainties in future climate projections, which is an important economic and social problem. In addition, diagnosing convective behavior and its impact on atmospheric chemistry will lead to an improved understanding of processes affecting air quality and human health, as both increases in tropospheric ozone and depletion of stratospheric ozone are possible in overshooting storms.

穿透（过冲）对流层顶的深对流影响对流层外对流层上层和平流层下层的微量气体成分，这对全球大气化学和地球辐射平衡至关重要。本研究将利用联合收割机10年以上的地基雷达观测资料，结合数值模式模拟，研究越冲对流的物理化学特征。 来自大约100个NEXRAD雷达的数据将被合成到具有高空间和时间分辨率的三维区域网格中。 超冲对流的物理特征的气候学，如垂直范围，地理分布，年际变化，以及年度和日周期将从雷达观测计算。 将把从合成雷达数据得出的过冲对流特征与根据卫星红外观测得出的估计进行比较。 为了调查跨对流层顶输送的机制，并对平流层-对流层交换进行定量估计，将对个案研究和整个暖季进行数值模式模拟，明确解决对流和化学问题。 雷达数据将沿着使用，同时从飞机上进行现场微量气体观测，以评价数值模拟的性能。智力上的优点：众所周知，热带外对流可以穿透对流层顶并延伸到平流层下部，但关于其地理分布、发生频率或穿透平流层深度的定量资料却很少。 在这项研究中的雷达分析将导致一个新的区域气候学的超冲对流在中纬度地区的基础上，在高空间和时间分辨率的直接几何观测。 结果将与卫星红外估计的过冲，这提供了潜在的扩展到全球域的区域结果。高分辨率的数值模拟的过冲对流将被用来调查平流层对流层交换机制，并作出定量估计的重要微量species.Broader影响的运输：这项研究将产生一个长期的，公共的，雷达反射率数据集超过了大部分的连续美国这些数据将适用于广泛的其他水文气象问题。 由于对流在目前的全球气候模式中没有得到解决，这些研究将为制定由于过冲对流引起的平流层-对流层交换的参数化提供指导。 更好地了解过冲对流将有助于减少未来气候预测的不确定性，这是一个重要的经济和社会问题。 此外，诊断对流行为及其对大气化学的影响将有助于更好地了解影响空气质量和人类健康的过程，因为在过度风暴中，对流层臭氧的增加和平流层臭氧的消耗都是可能的。