88th Annual Meeting (20-24 January 2008)

Tuesday, 22 January 2008: 5:00 PM
Evidence of mineral dust altering cloud microphysics and precipitation
220 (Ernest N. Morial Convention Center)
Qilong Min, SUNY, Albany, NY; and R. Li, E. Joseph, S. Wang, Y. Hu, and V. Morris
Multi-platform and multi-sensor observations are employed to investigate the impact of Saharan dust outbreaks on cloud and precipitation processes over the eastern Atlantic Ocean. Effects of the dust on internal thermodynamic and cloud microphysical features are studied. To control for dynamic effects unique cases were selected where cloud systems were partially embedded in dust plumes having sectors with either high or low concentration of dust aerosols. Dust modified the cloud microphysical processes such that rainfall distribution shifted from heavy rain to light rain – effectively suppressing rainfall. Dust enhanced evaporation processes, which further reduced surface rainfall. Another dust induced impact on precipitation was the alteration of thermodynamic processes in the cloud system. Changes in cloud microphysices over the dusty environment altered the vertical gradient of latent heating in both convective and stratiform regions. Adjustments to these changes resulted in a weaker but longer lasting cloud system with decreased stratiform precipitation fraction.

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