Observation and Measurement of Shallow Marine Clouds

Observations of shallow marine cloud drop spectra from several recent projects show significant variability as a function of geographic location (Caribbean, SE Pacific and NE Pacific), cloud type (stratus vs. cumulus), aerosol concentration (pristine and polluted), altitude above cloud base, etc. This variation has important impacts on the ability of such clouds to precipitate and on the radiative properties of the clouds.

In this study we examine aircraft observations from the 2004-2005 RICO project near Antigua, the 2011 DOMEX project near Dominica, the 2008 VOCALS project off the coast of northern Chile, and the 2015 CSET project between California and Hawaii.

A key aspect is to relate observations of cloud droplet spectra (obtained with single particle spectrometers such as FSSP and CDP) to assumptions about drop spectral shapes used in numerical models, e.g. gamma distributed drop size distributions. While this has been done in some past studies, here we utilize new measurements obtained with better instrumentation to further compare observations and model assumptions.