Controls on the Redistribution of Coastal Zone Aerosols in Convective Clouds Associated with Sea Breeze Circulations

The land use changes and population growth in coastal areas can result in significant degradation of air quality at the sub-kilometer scale. Diurnal sea breeze circulations can modulate the air pollution in coastal zones where nearly a half of the world’s population resides. The overall objective of this study is, therefore, to better predict the spatial distributions and temporal variability of aerosols that occur in association with the sea breeze regime. The prediction of the aerosol distributions in coastal zones is challenging as various meteorological and topographical factors coexist and can interact nonlinearly to the influence the sea breeze distribution of aerosols. Some of the factors assessed include background horizontal wind speed, boundary layer height, temperature, and relative humidity, as well as the depth and strength of inversion layer.

Using the Regional Atmospheric Modelling System (RAMS), we carried out idealized sea breeze convection simulations. The simulations conducted were guided by using Latin Hypercube Sampling which allows simultaneous variation of all the factors and their interactions. The simulations take a broad but appropriate range of thermodynamic, land surface, and aerosol conditions into account.

Sensitivity analysis of the simulation results exhibits contributions of individual factors to the variability of three-dimensional aerosol distribution. We also demonstrate the importance of nonlinear interactions among these factors. The processes driving the predominant factors governing the strength and intensity of the sea breeze and its role in coastal aerosol optical depths will be presented.