Albedo, albedo susceptibility, and cloud-aerosol interactions in the Southeast Pacific stratocmulus deck

Uncertainties in the magnitude and sign of the cloud-aerosol indirect effect have been a topic of debate due to its potential climatic impact. This study aims to better understand the role of the changes in aerosol concentration and microphysics to alter the cloud albedo in the Chile-Peru stratocumulus deck. Cloud-aerosol interactions are investigated by using information collected during the Variability of the American Monsoon Systems' (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), in October-November 2008. Estimates of albedo and cloud optical thickness will be obtained by using a technique that combines millimeter-wavelength-derived liquid water path and downward shortwave fluxes from a pyranometer gathered during the sub-cloud aircraft traverses, along with 1D radiative transfer simulations. We will also derive an adiabatic cloud droplet number concentration (Nd) by blending the microwave liquid water path with the retrieved cloud optical thickness, which then allows us to examine the albedo susceptibility, defined as the differential change in albedo due to changes in the adiabatic Nd, is also analyzed. These results will be interpreted in a broader context by analyzing Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals and NCEP/NCAR reanalysis.