Wednesday, 11 July 2018
Regency A/B/C (Hyatt Regency Vancouver)
Tropical Cyclone(TC) Nuri was an extensively studied storm that formed in the western Pacific and propagated into the highly polluted airmass downwind of mainland China. Previously we studied potential aerosol impacts on NURI using RAMS(Cotton et al.,2012). Satellite-derived aerosol optical depth(AOD) was used to map out the boundaries of the polluted airmass and aerosol concentrations were prescribed as high and low concentrations. It was found that if high concentrations of the polluted aerosol entered the eyewall region of the storm, the storm intensified while if the aerosol only affected the outer rainband of the storm, it weakened. There were two problems with this study. (1) The simulated storm was weaker than observed TC. The response to aerosol might be different if the full intensity of the storm was simulated. (2) The specified concentrations of aerosol were rather arbitrary.
In this study, we re-examine aerosol impacts on TC Nuri using the global nonhydrostatic model, OLAM. Using the unique TC spin-up algorithm in OLAM, a storm of the observed intensity is simulated. Moreover, OLAM has a sophisticated aerosol activation scheme which allows the competitive interaction of aerosols of differing sizes and chemistry in forming cloud droplets. Instead of arbitrarily specifying aerosol concentrations and a single aerosol chemistry in the earlier RAMS simulations, we estimate aerosol concentrations and chemistry using the global atmospheric chemistry model GEOS-Chem. GEOS-Chem is run for the period covering NURI, with no anthropogenic sources and with anthropogenic sources. The results of the analyses of those simulations will be presented at the conference.
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