P16 Characterizing seasonal and spatial variations of East Asian dust: Budget and radiative forcing

Chen, Siyu, Lanzhou University, China, and Pacific Northwest National Laboratory (PNNL), Chun Zhao, Yun Qian, L. Ruby Leung, PNNL, and Jianping Huang, Lanzhou University, China

The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the budget and radiative forcing. The simulated aerosol properties, including mass loading, optical depth (AOD), size distributions and extinction coefficient profiles, are evaluated with the in-situ and satellite observations. The model well captures the seasonal and annual variations of dust AOD over source regions Taklimakan Desert (TD) and Gobi Desert (GD), while it overestimates the aerosol extinction coefficient and PM10 concentration in spring. We conduct a budget analysis of the physical processes (e.g. emission, transport, and deposition) to investigate the dust lifecycle and determine the factors controlling the seasonal and spatial variations of dust over seven sub-regions of East Asia, i.e. source region, Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that over source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~25% and ~35% of the sink over the TD and GD, respectively. The maximum dust radiative forcing is about 20 and 18 W m-2 in the atmosphere over the TD and GD, respectively. Over the Tibetan Plateau, transport is the dominant source with a maximum magnitude in summer. Over identified outflow regions, maximum dust loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but dry deposition is larger than wet deposition over Northern China. The simulation also shows the annual mean net radiative forcing of mineral dust in East Asia is about -0.9, 1.3, and -2.2 W m-2 at the top of the atmosphere (TOA), in the atmosphere, and at the surface, respectively. The impacts of East Asian dust on the regional climate are also analyzed.