Tracking And Monitoring Of Sea Fog Based On The New Generation Geostationary Meteorological Satellite

Sea fog is a kind of water vapor condensation phenomenon in the lower atmosphere of the ocean,which is a disastrous weather phenomenon.Mastering the distribution and variation of sea fog can effectively reduce the harm caused by sea fog.Satellite remote sensing technology is characterized by near real-time,wide coverage and continuous observation.In particular,the new generation of geostationary meteorological satellite observation system has the characteristics of one observation in 10 minutes.It provides high frequency remote sensing data for better tracking,monitoring and analyzing the occurrence,development and extinction of sea fog.Firstly,using Japan's new generation geostationary meteorological satellite(Himawari-8,H-8),this paper compares and analyzes the difference of brightness temperature,brightness temperature difference and brightness temperature ratio in middle and thermal infrared channels of different surface features such as sea fog,water body,low cloud,meddle cloud and high cloud.It is found that the brightness temperature of sea fog,water and low cloud is higher than that of middle and high cloud.The brightness temperature difference between 3.89?m and 9.64?m of fog is concentrated in 15 ? 30 K,which is higher than that of middle and high cloud.The brightness temperature difference between 3.89 ?m and 11.24 ?m of fog is concentrated in-10 ?-1K,which is lower than that of water and most cloud.The brightness temperature difference between 8.59 ?m and 12.38 ?m of fog is concentrated in-3.0 ?-1.5 K,which is lower than that of low cloud and water.The brightness temperature difference between 10.41?m and 11.24?m of fog is concentrated in-1.0 ? 0K,which is higher than that of low cloud.On this basis,five kinds of sea fog identification indexes,including sea fog and water separation index,sea fog and middle-high cloud separation index,sea fog and low cloud separation indexes,sea fog infrared split window feature recognition index,mid infrared brightness temperature texture index are developed.Nighttime sea fog monitoring algorithm based on multi-exponential probability distribution is proposed.The algorithm is applied to three new generation geostationary meteorological satellites:H-8,GK-2A and FY-4A.Sea fog area can be identified only by adjusting exponential probability parameters based on satellite observations,which shows that the algorithm is accuracy.Sea fog distribution monitored by different satellites at the same time is consistent,and the correlation of coverage area is more than 99%.The results show that the monitoring results have good applicability.The method has practical value.Finally,a typical advection sea fog event and a typical radiation sea fog event are selected to track and analyze the radiation characteristics during the evolution of sea fog through the fusion of H-8,GK-2A and FY-4A satellite observation data.It is found that the meteorological conditions are slightly different between advection fog and radiation fog.In the process of development,both have the same infrared radiation characteristics: the brightness temperature of 3.89?m channel decreases about 6 K,The brightness temperature of 8.59?m channel decreases about 1 K,and the radiation brightness temperature in other channels does not change obviously.