International Research Fellowship Program: Development of a Metropolis-Hastings Algorithm for Retrieving Aerosol Properties and Their Uncertainties from High Spectral Resolution

0856648赫尔曼该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。 该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。这个奖项将支持20-Benjamin赫尔曼博士与Johanna Tamminen博士和Gerrit de Leeuw博士在芬兰气象研究所进行为期四个月的研究。大气气溶胶对我们的环境有重要影响，因为它们产生的过程与云的形成相互作用以及它们如何反射和吸收太阳和热辐射。 它们通过其对辐射收支的影响来影响气候变化，既直接来自其自身的影响，也间接来自其对云动力学的影响。 气溶胶在云动力学中的作用也对降水产生影响，从而也对水循环产生影响，水循环除了在水资源中的重要性之外，还对气候产生影响。 美国国家航空航天局兰利研究中心已经开发出一种高光谱分辨率激光雷达（HSRL）仪器，可以测量距离分辨气溶胶的光学特性，特别是红外（1064 nm）和可见光（532 nm）波长的后向散射和去偏振系数，以及532 nm波长的消光系数（光衰减的程度）。 该项目解决了如何确定其他气溶胶特性的问题，特别是体积和表面积浓度，光吸收，并从这些测量总散射。 气溶胶的复杂性意味着这种激光雷达仪器测量的五种光学特性不能给出气溶胶的单一明确描述。 相反，可用的是代表不确定性的概率分布，并且基于测量误差和在没有测量的情况下可能的气溶胶状态的知识。 该项目的目标是开发马尔可夫链蒙特卡罗算法和气溶胶模型，用于处理HSRL仪器的数据，以估计气溶胶特性并评估其不确定性。 该项目与芬兰气象研究所和赫尔辛基大学的Johanna Tamminen博士和Gerrit de Leeuw博士合作。 他们的综合专业知识是对这些数据处理算法的开发的杰出贡献。 Tamminen博士在马尔可夫链蒙特卡罗方法方面经验丰富，而de Leeuw？的经验是在气溶胶的光学传感。 该项目也与芬兰气象研究所的研究兴趣平行，芬兰气象研究所拥有一台拉曼激光雷达仪器，可以进行类似于HSRL的测量。最终，这些算法可以为构建其他算法提供基础，这些算法可以分析全球地球观测系统中多台仪器的数据，从而更好地了解环境过程。

0856648HermanThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Benjamin Herman to work with Drs. Johanna Tamminen and Gerrit de Leeuw at the Finnish Meteorological Institute in Finland.Atmospheric aerosols have an important impact on our environment due to processes that result from their interaction with cloud formation and how they reflect and absorb solar and thermal radiances. They affect climate change through their affects in the radiation budget both directly from their own influence and indirectly from their effects in cloud dynamics. The role of aerosols in cloud dynamics also has an influence on precipitation and thus also the water cycle, which has its own effect on climate in addition to its importance in water resources. A high spectral resolution lidar (HSRL) instrument has already been developed at NASA-Langley that can measure range-resolved aerosol optical properties, specifically back-scattering and depolarization coefficients at infrared (1064nm) and visible (532nm) wavelengths, and extinction coefficient (the degree to which light is attenuated) at 532nm. This project addresses the problem of how to determine other aerosol properties, specifically volume and surface area concentrations, optical absorption, and total scattering from these measurements. The complexity of aerosols means that the five optical properties measured by this lidar instrument cannot give a single definitive description of an aerosol. Instead what is available is a probability distribution that represents uncertainty and is based on measurement errors and knowledge of probable aerosol states in the absence of measurements. The goal of this project is to develop Markov chain Monte Carlo algorithms and aerosol models for processing data from the HSRL instrument to estimate aerosol properties and assess their uncertainties. The project is in collaboration with Dr. Johanna Tamminen and Dr. Gerrit de Leeuw at the Finnish Meteorological Institute and the University of Helsinki. Their combined expertise is an excellent contribution to the development of these data processing algorithms. Dr. Tamminen is experienced in Markov chain Monte Carlo methods while Dr. de Leeuw?s experience is in optical sensing of aerosols. This project is also parallel with the research interests of the Finnish Meteorological Institute, which has a Raman lidar instrument that takes measurements similar to the HSRL.Ultimately, these algorithms may provide the foundation for constructing additional algorithms that analyze data from multiple instruments in the worldwide earth observing system, enabling a better understanding of environmental processes.