Numerical Simulation Of Dust Aerosol Delivery Its Radiation Feedback Effects

To study the radiative effect of dust aerosols on synoptic-scale system and the dusttransport, an interactive weather-dust model (GRAPES₂W_SDM) was developed. Themodel based on the GRAPES_DAM dust aerosol model which developed by CAMS,including the shortwave radiative transfer scheme for dust aerosols, and the dust aerosolparameterization. Based on the dust aerosol concentration which output from dust aerosolmodel, and using the new Chinese desert parameter, the radiative effects of dust aerosol wascalculated. The change of temperature caused by radiative effect of dust aerosol was returnedto the weather model on-line.According to the representative of synoptic-scale systems which caused dust weather, theduration, and the range of the dust weather process, two case happened in China were chose,one caused by the cold front happened in south of Xinjiang, the other caused by the Mongoliacyclone. Two parallel simulation, one including the radiative effects of dust aerosol (RAD)and the other without them (CTL). A comparison of the two experiments shows that:(1) GRAPES_DAM model which didn't consider radiative effects of dust aerosol, cansimulated the synoptic situation, the surface wind, and the dust aerosol transport very wellduring the 72h. It established a good foundation for the RAD experiment.(2) Radiative effects of dust aerosol impacted the solar radiation flux arrived the floor,solar heating rate, temperature, wind, and the physic quantity of boundary layer. If the dustaerosol concentration simulate very well, the experiment which consider the radiative effectsof dust aerosol can simulate the surface temperature and the pressure much better. (3) Radiative effects of dust aerosol also impacted the dust production, transport, and thedeposition. In the special terrain and weather case, radiative effects of dust aerosol can changethe wind direction, and transport the dust back.(4)The impact on weather-dust which caused by the radiative effects of dust aerosolshould be divided into different areas to discussed. In this paper, four areas was chose todiscuss, including the upper of dust body, the lower of the dust body, foreside of the dust bodyand the bottom of the dust body. Besides the dust production, it should also include the dusttransport and deposition.The simulation also shows that it existed a positive feedback mechanism caused by theradiative effects of dust aerosol: dust heating and raising effect. The mechanism happened inthe middle and upper of the sand-dust body, if there have a weak raising area. The dustaerosol over there absorbed the solar radiation, heated the layer, and then improved the raisingvertical velocity. The increase of raising vertical velocity raised more dust into the upper areain turn. Finally, both the raising vertical velocity and dust aerosol concentration increased.Along with the solar radiation cumulating, the mechanism also enhanced;and along with thesolar radiation disappearing, the mechanism also disappeared.(5) The impact on sea level pressure of Mongolia cyclone which caused by the radiativeeffects of dust aerosol not remarkable, including the route and the intensity of the cyclone.Only when there were some dust source behind the Mongolia cyclone, and the dust cantransport into the center of the cyclone, the impact would be remarkable.