The 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.
