770 The Role of Vertical Wind Shear at Different Levels in Determining Aerosol Effects on Deep Convection

Wednesday, 9 January 2013
Exhibit Hall 3 (Austin Convention Center)
Jiwen Fan, PNNL, Richland, WA; and Q. Chen

Aerosols could invigorate or suppress convection by serving as cloud condensation nuclei. Our previous studies indicated that vertical wind shear plays a key role in determining whether aerosols enhance or suppress convective intensity. That is, aerosols generally enhance convection under weak wind shear condition for warm-based deep convective clouds; increasing wind shear dampens aerosol invigoration effect and even leads to a suppression effect. However, the vertical wind shear at the different levels should have very different impact on cloud dynamics, which could lead to significantly different aerosol effects on convection. In this study, we conduct the sensitivity study by changing the wind shear intensity at the lower-level (0-5 km), the middle level (5-10 km) and the upper level (above 10 km) using the Weather Research and Forecasting (WRF) model with spectral-bin microphysics (SBM), to look into how aerosol impact on deep convective clouds changes with the different levels of wind shear and which level of wind shear plays a more significant role in terms of aerosol effects on cloud dynamics, macro- and micro-physical properties, and radiative forcing.
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