Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 7 13 2007 10.5194/acp-7-3411-2007 http://www.atmos-chem-phys.net/7/3411/2007/ http://www.atmos-chem-phys.net/7/3411/2007/acp-7-3411-2007.html http://www.atmos-chem-phys.net/7/3411/2007/acp-7-3411-2007.pdf 3411 3424 2007-07-02 Simulation of hurricane response to suppression of warm rain by sub-micron aerosols D. Rosenfeld daniel.rosenfeld@huji.ac.il A. Khain B. Lynn W. L. Woodley Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel Woodley Weather Consultants, 11 White Fir Court, Littleton 80127, USA The feasibility of hurricane modification was investigated for hurricane Katrina using the Weather Research and Forecasting Model (WRF). The possible impact of seeding of clouds with submicron cloud condensation nuclei (CCN) on hurricane structure and intensity as measured by nearly halving of the area covered by hurricane force winds was simulated by "turning–off" warm rain formation in the clouds at Katrina's periphery (where wind speeds were less than 22 m s^−1). This simplification of the simulation of aerosol effects is aimed at evaluating the largest possible response. This resulted in the weakening of the hurricane surface winds compared to the "non-seeded" simulated storm during the first 24 h within the entire tropical cyclone (TC) area compared to a control simulation without warm rain suppression. Later, the seeding-induced evaporative cooling at the TC periphery led to a shrinking of the eye and hence to some increase in the wind within the small central area of the TC. 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