The real-time generation of visibility maps based on backscatter quantities from a Doppler Light Detection and Ranging (LIDAR) system and visibility sensor readings is revisited, considering both the plan position indicator (PPI) and range height indicator (RHI) scans of the LIDAR. The methodology of generating such maps is summarized in this paper. Their applications in two uncommon haze cases (30 December 2025 and 16 January 2026) at the Hong Kong International Airport are considered, supplemented by another case which independent visibility observations over another automatic weather station is available. The LIDAR visibility maps are found to provide signals for the spatial distribution of haze, both horizontally and vertically, in the boundary layer. They turn out to be consistent with the other independent weather observations, such as surface wind pattern, ceilometer’s backscatter power, aerosol optical depth product from meteorological satellites and another independent forward scatterometer. They are also well aligned with the PM10 forecasts from an air quality model. Based on the cases presented in this paper, the LIDAR-based visibility maps are found to be robust for visibility monitoring at an operating airport. Further research directions of such visibility maps are also discussed. • Visibility maps based on backscatter data from Doppler LIDAR provide clear pictures about the horizontal and vertical distribution of low visibility weather such as haze. • Wave features are found in the backscatter/visibility data at the shear zone of airflows of opposing directions at different heights. • The LIDAR-based visibility maps are consistent with the independent observations by a ceilometer and from meteorological satellite, as well as forecasts by an air quality model.
Chong et al. (Sun,) studied this question.