Cloud-Climate Feedbacks due to Extra-Tropical Clouds Systems

本研究的主要目标是通过提高我们对云反馈效应和气溶胶-云在液态云和冰相云中相互作用的理解来减少气候变化预测的不确定性。该提案侧重于太平洋的热带外云系统，这是负全球平均净云强迫的主要贡献者之一，并研究其在全球和北美气候变化中的作用。它将研究气溶胶的作用，特别是来自亚洲的灰尘和烟灰，以及调节太平洋云层反照率的大尺度动力学。由于热带外云系统既包括液态云，也包括冰相云，因此本研究将为气候变化研究开辟新的途径。该研究包括两个组成部分：1 .气溶胶和云强迫和气溶胶-云参数化：PI将估计大气辐射加热（或冷却）和大气表面变暗的垂直分布，重点是尘埃-烟尘混合物；云辐射强迫也一样；在区域尺度上为低云和高云的人为和可能的生物云凝结核（CCN）提供输入；为气溶胶、云、化学和天气尺度动力学之间的相互作用建立一个具有明确参数化的区域模式。本研究包括三个部分：A.建立气溶胶-云动力学-辐射强迫的综合观测数据集。这些数据将包括实地项目的观测结果，包括高空研究飞机数据、卫星和地面数据；B.估计云和气溶胶辐射强迫的三维结构；发展气溶胶-云-化学-输运-辐射模型来解释观测到的场和强迫。气候影响研究：利用根据A部分制定的数据和模式方案，开展以下影响研究：烟灰和粉尘的远距离输送对太平洋和北美气溶胶负荷的影响，以及太平洋和北美上空的气溶胶和云辐射强迫；气溶胶和云强迫对太平洋海面温度趋势和北美气候的影响；太平洋气溶胶云对过去和未来气候趋势的反馈效应。本部分将采用美国国家大气研究中心（NCAR）的气候模型来估计对气候变化和气候反馈的影响。更广泛的影响。这项研究将产生关于太平洋上空气溶胶和云强迫的新的综合三维数据集。由于它将以观测为基础，对于验证一般环流模式对气溶胶和云对气候的影响的处理将有很大的用处。强迫估算和气候影响研究将用于国家和国际上人类对气候影响的评估。与东亚科学家的合作将对获得亚洲地区的可靠数据具有重要价值。最后，参与该项目的学生和博士后将有一个独特的机会接触到一个具有挑战性的研究新途径，并参与国际合作。

SummaryThe main goal of this research is to reduce the uncertainty in climate change predictions by improving our understanding of cloud feedback effects and aerosol-cloud interactions in liquid as well as ice phase clouds. The proposal focuses on the extra tropical cloud systems of the Pacific Ocean, one of the major contributors to the negative global mean net cloud forcing, and examines its role in global and in North American climate change. It will investigate the role of aerosols, particularly dust and soot from Asia, and large scale dynamics in regulating cloud albedo over the Pacific Ocean. Since the extra tropical cloud systems consist of liquid as well as ice phase clouds, the proposed research will open new avenues of research in climate change. The research consists of two components: I. Aerosol and Cloud forcing and aerosol-cloud parameterization: The PI will estimate the vertical distribution of atmospheric radiative heating (or cooling) and surface dimming due to aerosols with a focus on dust-soot mixtures; same for cloud radiative forcing; provide input for anthropogenic and possibly biogenic cloud condensation nuclei (CCN) for both low and high clouds on regional scales; develop a regional model with explicit parameterizations for interactions between aerosols, clouds, chemistry and synoptic scale dynamics. The research consists of three parts: A. creating an integrated observational data set of aerosol-cloud-dynamics-radiative forcing. The data will include observations from field projects, including high altitude research aircraft data, satellite and surface data; B. estimating the 3-D structure of the radiative forcing of clouds and aerosols; and, C. developing an aerosol-cloud-chemical-transport-radiation model that accounts for the observed fields and forcing.II. Climate Impact Studies: Using the data and model schemes developed under Part A, conduct the following impact studies: the effect of long range transport of soot and dust on the Pacific and N. American aerosol loadings, and aerosol and cloud radiative forcing over the Pacific and N America; the effect of aerosol and cloud forcing on Pacific sea surface temperature trends and N American climate; and, the feedback effects of Pacific aerosol-clouds on the past and future climate trends. This part will employ National Center for Atmospheric Research (NCAR) climate models for estimating the impact on climate change and climate feedback. Broader Impacts. The research will generate new integrated 3-D data sets on aerosol and cloud forcing over the Pacific Ocean. Since it will be observationally based, it will be of great use for validating general circulation models' treatment of aerosol and cloud impacts on climate. The forcing estimates and climate impact studies will be used in national and international assessments of human impact on climate. The collaborations with East Asian scientists will be of great value for obtaining reliable data for the Asian region. Lastly, the students and post docs involved in the project will have a unique opportunity to get exposed to a challenging new avenue of research and participate in international collaborations.