Characteristics of Yellow Sea Fog Under Varying Aerosol Conditions

Abstract

Sea fog usually refers to a fog that occurs under the influence of the ocean, and the Yellow Sea is a region where sea fog regularly occurs. Fog occurrence and structure is impacted by aerosol concentration in the air where the fog forms. Along with industrial development, air pollution, and thus aerosol concentration has increased and become a serious environmental problem in Northeastern China. These higher pollution levels are confirmed by various satellite remote sensing instruments including Moderate Resolution Imaging Spectroradiometer (MODIS) aboard on the Aqua satellite, Ozone Monitoring Instrument (OMI) aboard on the EOS-Aura satellite, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite which observe aerosol, ozone and cloud properties. These observations show a clear influence of aerosol loading over the Yellow Sea region which can have an impact on the regional sea fog. High-resolution data sets from MODIS Aqua L2 are used to investigate the relationships between cloud properties, aerosol (AOD, aerosol optical depth), and SST features. The result of the bi-variate comparison method shows that for most of the cases, larger values of COT (Clout Optical Thickness) are related to both smaller ER (Droplet Effective Radius) and higher CTH (Cloud Top Height). However, for the cases where fog is relatively thinner with many zero values in CTH, the larger COT is related to both smaller ER and CTH. For the fog cases where AOD is dominated by smoke (e.g. confirmed fire activities in the East China Plain) the Semi Direct Effect/Cloud Burning of Soot likely plays a role in determining fog structure. The large amount of absorbing aerosol caused by fires can absorb sunlight and increasing the temperature of the air near surface, which can burn away clouds and result in a relationship where smaller ER corresponds with thinner fog and smaller COT values.