Abstract:Based on the observation data of Ka band scanning millimeter-wave radar and automatic weather station, the sea fog remote sensing experiment was carried out in coastal area of Pingtan, Fujian Province. The characteristics of six sea fog processes that occurred from May 2020 to March 2021 were analyzed, and visibility inversion in fog area was carried out based on millimeter-wave radar. The results showed that the millimeter-wave radar can effectively detect the horizontal distribution and vertical structure of sea fog, and can be used to monitor the evolution of sea fog. In the flourishing stage of sea fog, the reflectivity factor of millimeter-wave radar shows a strong filamile-like echo structure extending from the top of fog layer to the surface. The radar reflectivity factor of sea fog is negatively correlated with the forward-scatter visibility, but for each sea fog process, the relation between the radar reflectivity factor and the forward-scatter visibility does not follow a clear general equation. The radar reflectivity factor of sea fog is concentrated in the range from -30 dBz to -10 dBz, and the frequency histogram accords with normal distribution. The echo of fog area is uniform on the whole, but the dynamic range of reflectivity factor is large in fog generation and dissipation stage, while the dynamic range is small in fog persistence stage. The retrieved visibility by millimeter-wave radar and the forward-scatter visibility have relatively consistent fluctuations, which could reflect the change of visibility in fog area, but different cases present different features.