Multi-Sensor Diagnostics of the Large-Scale Factors Influencing the Onset of Precipitation in Warm Clouds

Warm rain can have a significant impact on the climate system through its roles in modulating the radiative properties of low clouds and redistributing moisture in the tropical atmosphere. Previous work has shown that as much as half of the rainfall occurrence in the tropics may originate from warm rain processes but global observations of warm rain are complicated by its shallow, isolated nature, low water content, and small constituent raindrops. This presentation will discuss recent efforts to exploit the enhanced sensitivity of the spaceborne cloud radar aboard CloudSat to document the global distribution of warm rain systems and their properties. Analysis of global cloud, precipitation, sea surface temperature, water vapor, and aerosol datasets from sensors in the A-Train constellation suggest that precipitation development in warm clouds varies considerably as a function of several commonly used metrics for describing the large-scale environment including aerosol concentration and atmospheric stability. Though it is challenging to establish causality from such statistical comparisons, the findings highlight the value of multi-sensor satellite observations for testing the complex relationships between aerosols, clouds, precipitation, and the large-scale environment in numerical models.