The MODIS instrument on Terra and Aqua is ideally suited for investigations into the interaction of aerosol and cloud because an extensive suite of cloud, aerosol and atmospheric properties can be retrieved from this multi-channel system. In this study, we present a technique for obtaining cloud microphysical properties of water clouds, including cloud drop concentration, over the North Pacific Ocean, which is a maritime region that is episodically influenced by air pollution from East Asia. We limit our investigation to obtaining radiative and microphysical properties of single layer water clouds which could be influenced by aerosols through the first and second indirect effects. A method of obtaining cloud droplet concentration is presented, which in principle could be applied globally. It relies on isolating portions of cloud fields that experience close to adiabatic vertical growth and estimating the geometrical cloud thickness. The results can then be used in conjunction with aerosol loading obtained from MODIS or chemical transport and transformation models to investigate aerosol-cloud interactions.

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