J1.11 Global and regional indirect effects of aerosols appeared in modeling and satellite remote sensing

Tuesday, 11 July 2006: 4:30 PM
Ballroom AD (Monona Terrace Community and Convention Center)
Teruyuki Nakajima, Univ. of Tokyo, Kashiwa, Chiba, Japan; and T. Takemura, A. Higurashi, T. Y. Nakajima, and K. Suzuki

Various sensitivity factors, Bq, of aerosol-cloud interaction effects are studied to evaluate the strength of aerosol indirect effects, when the correlation between aerosol number, Na, and a cloud parameter, q, is expressed as dq = Bq x dNa/Na. The statistics are obtained from satellite remote sensing results of aerosol and cloud parameters such as the optical thickness and a size index, and from model simulation results using MIROC general circulation model plus SPRINTARS aerosol model and also using a non-hydrostatic bin cloud model. It is found that POLDER type remote sensing method gives us a very small sensitivity factor for radiative forcing (q= radiative forcing), Br= -0.6 W/m2, as compared AVHRR and MODIS results, Br= -4.3 W/m2. We found a similar sensitivity parameter for the cloud fraction of low-level clouds over the Atlantic Ocean as Bn= 0.15 from AVHRR, and Bn= 0.12 from MODIS given by Yoram Kaufman's group, but we have much small factor for the globe as Bn= 0.03 from AVHRR. These results suggest that there are large uncertainties in the estimation of the sensitivity factor depending on satellite observation methods, and also there is a large dependence on the location of the globe. We like to discuss implications of the large variety of values of sensitivity factors using satellite remote sensing and model simulation results.
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