Do We Observe Aerosol Impacts on DSDs in Strongly Forced Tropical Thunderstorms?

P. T. May Centre for Australian Weather and Climate Research, Melbourne, Victoria, Australia

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V. N. Bringi Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

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M. Thurai Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

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Abstract

Rain drop size distributions retrieved from polarimetric radar measurements over regularly occurring thunderstorms over the islands north of Darwin, Australia, are used to test if aerosol contributions to the probability distributions of the drop size distribution parameters (median volume diameter and normalized intercept parameter) are detectable. The observations reported herein are such that differences in cloud properties arising from thermodynamic differences are minimized but even so may be a factor. However, there is a clear signature that high aerosol concentrations are correlated with smaller number concentrations and larger drops. This may be associated with enhanced ice multiplication processes for low aerosol concentration storms or other processes such as invigoration of the updrafts.

Corresponding author address: Peter May, Centre for Australian Weather and Climate Research, GPO Box 1289, Melbourne, 3000, VIC, Australia. E-mail: p.may@bom.gov.au

Abstract

Rain drop size distributions retrieved from polarimetric radar measurements over regularly occurring thunderstorms over the islands north of Darwin, Australia, are used to test if aerosol contributions to the probability distributions of the drop size distribution parameters (median volume diameter and normalized intercept parameter) are detectable. The observations reported herein are such that differences in cloud properties arising from thermodynamic differences are minimized but even so may be a factor. However, there is a clear signature that high aerosol concentrations are correlated with smaller number concentrations and larger drops. This may be associated with enhanced ice multiplication processes for low aerosol concentration storms or other processes such as invigoration of the updrafts.

Corresponding author address: Peter May, Centre for Australian Weather and Climate Research, GPO Box 1289, Melbourne, 3000, VIC, Australia. E-mail: p.may@bom.gov.au
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