Seasonal Variability Of Clouds and Precipitation in the Southern Oceans as Diagnosed from A-Train Data

Abstract:

Cloudiness in the Southern Oceans is predominantly due to ubiquitous low-level clouds. These clouds are a predominant cause of the high albedo of this region. Since these clouds are linked to the surface through fluxes of heat, moisture, and aerosols, they are quite sensitive to the large seasonal variability in meteorology and biology that tend to drive large swings in seasonal aerosol concentrations, cloud condensation nuclei concentrations, and cloud droplet number concentrations. The A-Train has created a reliable and long-term measurement data record of these clouds that includes vertical profiles of radar reflectivity and microwave brightness temperature from CloudSat and solar reflectances from MODIS. We are examining this data record for seasonal swings in cloud properties that are obvious in the measurements. In addition we have implemented a unique cloud and precipitation property retrieval algorithm that allows us to examine, for instance, the covariance of the albedo and precipitation susceptibility as a function of season. We are finding that the measurements support the idea of large seasonal oscillations in cloud properties.