Life Cycle of Precipitating Cloud Systems from Synergistic Satellite Observations: Evolution of Macrophysical Properties and Precipitation Statistics from Geostationary Cloud tracking and GPM Active and Passive Microwave Measurements

Abstract

Observations of clouds and precipitation in the microwave domain from the active radar (DPR) and the passive imager (GMI) onboard the GPM Core Observatory satellite are used in synergy with cloud tracking information derived from infrared imagery from the GOES-13 and Meteosat-7 geostationary satellites for analysis of the life cycle of precipitating cloud systems, in terms of temporal evolution of their macro-physical characteristics, in several oceanic and continental regions of the Tropics. The life cycle of each one of the several hundred thousand cloud systems tracked during the two-year (2015-2016) analysis period is divided into five equal-duration stages between initiation and dissipation. The average cloud size, precipitation intensity, precipitation top height, and convective and stratiform precipitating fractions are documented at each stage of the life cycle for different cloud categories (based upon lifetime duration). The average life cycle dynamics is found remarkably homogeneous across the different regions and is consistent with previous studies: systems peak in size around mid-life; precipitation intensity and convective fraction tend to decrease continuously from the initiation stage to the dissipation. Over the three continental regions, Amazonia, Central Africa and Sahel, at the early stages of clouds‘ life cycle, precipitation estimates from the passive GMI instrument are systematically found to be 15 to 40% lower than active radar estimates. By highlighting stage-dependent biases in state-of-the-art passive microwave precipitation estimates over land we demonstrate the potential usefulness of cloud tracking information for improving retrievals, and suggest new directions for the synergistic use of geostationary and low-Earth-orbit satellite observations.