Fog is one of the most common hazardous weather conditions on expressways. With advancing urbanization and growing road network density, the adverse impacts of fog on highway traffic safety have become increasingly severe. Among the weather phenomena triggering severe traffic accidents across most regions of China, low-visibility conditions such as heavy fog, dust and sandstorms exert the greatest influence. In particular, dense fog with visibility below 50 meters is a major cause of serious traffic accidents. Failure to efficiently and accurately monitor patchy fog on expressway pavements and issue timely early warnings to running vehicles will lead to large-scale traffic congestion and even complete traffic paralysis.

Marine operating conditions change rapidly. Under extreme harsh weather, vessels are often unable to berth at ports or offshore platforms. For port authorities, sea fog ranks among the most critical marine hazardous weather and poses a major threat to navigation safety. Sea fog significantly reduces horizontal visibility in coastal waters, preventing vessels from identifying navigation beacons and greatly increasing the risks of yawing, reef collision, stranding and even ship collisions that lead to maritime accidents.

Current understanding of sea fog distribution mainly relies on observations from coastal stations, ships and buoys. However, such data is scarce, insufficiently representative and unstable in quality, resulting in a long-term lack of comprehensive and accurate knowledge of sea fog spatial distribution.