Reconciling Models and Observations of Aerosol Indirect Effects: A 2004 Field Study in the Northeastern United States

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The effect of aerosols on clouds (aerosol indirect effect) has critically important relevance to radiative transfer and climate forcing. The aerosol indirect effect is still poorly understood, this aggravated by a severe paucity of high quality experimental field data required to produce accurate parameterizations and properly constrain analytical models. This project involves a series of field experiments on the Office of Naval Research Center for Interdisciplinary Remotely-Piloted Aircraft Studies (ONR/CIRPAS) Twin Otter research aircraft (with extramural funding from ONR confirmed) as part of the Intercontinental Transport and Chemical Transformation (ITCT) project during summer 2004 over the Northeastern United States. The California Institute of Technology (CalTech) group will collect a variety of meteorological, aerosol microphysical and chemical data from the Twin Otter and follow with detailed analyses and three-dimensional radiative transfer modeling. The ultimate goal of this project is a robust closure study comparing measured terms in the radiation budget to predictions of those terms from aerosol and cloud properties. Taking into account more advanced aerosol-cloud interaction parameterizations involving low-altitude clouds will lead to more representative modeling of aerosol-cloud-radiation processes on a variety of scales under a general circulation model framework. Results from this study will provide new data and improved insight to our understanding of clouds and climate, reducing present large uncertainties related to quantifying current and predicting future climate change. Broader educational impacts include support for one postdoctoral scholar and two graduate students at CalTech. Through a subcontract to Georgia Institute of Technology to incorporate field data into a general circulation model aerosol-cloud interaction module an additional graduate student will be supported.