Cloud-Climate Feedbacks due to Extra-Tropical Clouds Systems

这项研究的主要目标是通过提高我们对云反馈效应以及液态云和冰相云中气溶胶-云相互作用的理解来减少气候变化预测中的不确定性。该提案侧重于太平洋的额外热带云系，这是造成负全球平均净云强迫的主要因素之一，并审查了它在全球和北美气候变化中的作用。它将研究气溶胶的作用，特别是来自亚洲的尘埃和烟尘，以及大尺度动力学在调节太平洋上空的云反照率方面的作用。由于极端热带云系由液态云和冰相云组成，拟议中的研究将为气候变化研究开辟新的途径。这项研究由两部分组成：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)和由于气溶胶引起的地面变暗的垂直分布，重点是尘埃-烟尘混合物；云辐射强迫也是如此；为区域尺度上的低云和高云提供人为的和可能的生物云凝结核(CCN)的输入；发展一个区域模式，对气溶胶、云、化学和天气尺度动力学之间的相互作用具有明确的参数化。这项研究包括三个部分：a.建立气溶胶-云-动力学-辐射强迫的综合观测数据集。这些数据将包括来自实地项目的观测数据，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；c.发展气溶胶-云-化学-传输-辐射模式，说明观测到的场和强迫。2.气候影响研究：利用A部分下制定的数据和模式方案，进行下列影响研究：烟尘和尘埃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；以及太平洋气溶胶云对过去和未来气候趋势的反馈影响。这一部分将使用国家大气研究中心(NCAR)的气候模型来估计对气候变化的影响和气候反馈。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3-D数据集。由于它将是以观测为基础的，它将对验证大气环流模型对气溶胶和云对气候影响的处理非常有用。强迫估计和气候影响研究将用于国家和国际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新研究途径，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.