Influence of interaction between aerosol and boundary-layer shallow clouds on the simulated elevated ducts associated with high-pressure over the open sea

The bottom of the trapping layer of elevated ducts in the open sea usually corresponds well to the top of boundary-layer shallow clouds. The interaction between the aerosol and boundary-layer shallow clouds and resulting radiative forcing will change the structure of elevated ducts. In this paper, we simulated and analyzed a valuable elevated duct process associated with high-pressure in the open sea observed in 2016 using the weather research and forecasting-chemistry (WRF-Chem) model. Two experiments without (EXP0, equivalent to the weather research and forecasting (WRF) model) and with the complete aerosol-cloud-radiation interactions (EXP1) were designed. The results show that cloud droplet number concentration from aerosol activation simulated in the EXP1 experiment (considered to be true value) is lower than the prescribed constant value (100 cm^-3) in the EXP0 experiment under high-pressure weather conditions in the open sea. In the EXP1 experiment, which takes into account the real aerosol-cloud-radiation interactions, the simulated duct top height and duct strength are in better agreement with observations compared to the EXP0 experiment results when accompanied by boundary-layer shallow clouds. The three observations carried out at night are located in the cloud-free area near the high pressure center. At this time, the direct and indirect effects of the aerosol are negligible, so the differences between the two experiments are very small. This result illustrates sideways that the use of the WRF-Chem model considering aerosol-cloud-radiation interactions is beneficial to improve the simulation of the characteristic quantity of elevated ducts in the open sea where shallow clouds occur in the boundary layer.