AEROSOLS AND CLOUDS IMPACT ON THE DIURNAL TEMPERATURE RANGE IN THE ATMOSPHERIC BOUNDARY LAYER

An analysis of long-term measurements of meteorological parameters and a one-dimensional (1D) model are applied to unravel the complex causes and effects of the observed trend of decrease in diurnal temperature range (DTR) over Taiwan. We apply the Fu-Liou radiation scheme to provide profiles of radiation fluxes and heating rates in the coupled atmosphere-plant-soil model (the CAPS model). In the initial stage of this study, aerosols and clouds are prescribed to evaluate the radiative forcing in the 1D model. Aerosol optical properties are derived primarily based on the Mie theory. The issues of aerosol mixing state and hydroscopic growth on radiative forcing are addressed as well. In addition, the impacts of clouds on the observed DTR are evaluated by means of prescribed clouds at different heights. The preliminary result shows that low and middle clouds can significantly decrease daytime temperature while increase nighttime temperature, resulting in a decrease of DTR. Aerosols of different compositions and mixing states may also induce significant temperature perturbation. In the near future, when our atmospheric boundary layer model is fully coupled with a photochemical-aerosol-cloud model, the complex feedback processes of aerosol, cloud and climate can be better addressed