Research On The Correlatioin Between Aerosol Optic Properties And Logarithmic Ratio Of Aerosol Backscatter-to-extinction

Rayleigh-Raman-Mie Lidar and Mini-Micro-Pulse Lidar located in China Meteorological Administration Nanjing Integrated Observation Base are used to observe the aerosol overhead the Nanjing northern suburb. Then the parameters and observation theories of the lidars and the sun-photometer will be introduced, so we will correct the echo observed by the lidars. Logarithmic ratio of aerosol backscatter-to-extinction called k value is usually as an assumed value in Lidar equation solving,and it will be discussed in this paper. This paper derived the relationship expression among value k,wavelength exponent, measurement wavelength and aerosol extinction coefficient, and put forward a new method to determine k value. Then we will elementarily study the k value in different weather conditions, and use the observed aerosol extinction coefficient data to verify the method proposed in the paper. At the same time, through the inversion of atmospheric aerosol characteristics, the effects of logarithmic ratio of aerosol backscatter-to-extinction (k value) on the inversion of atmospheric lidar echo signal under different weather conditions are analyzed and discussed as following, firstly, it has a big effect between the aerosol extinction coefficient calculated and k value when it is in the foggy and hazy days. Secondly,it has slight effect between the aerosol extinction coefficient calculated and k value when it is in the sunny weather.When the weather is sunny,the aerosol extinction coefficient would be closer to the result of visibility estimation if the k value is 1.0. When the weather is foggy and hazy, the difference between the aerosol extinction coefficient and the result of visibility estimation is minimum if the k value is from 0.7 to 0.9. It shows that calculating the value k using this method has certain reliability. According to analyzing the observation data by lidar and the relative humidity sounding data, we study the effect between the aerosol extinction characteristics and relative humidity in different weather conditions such as clear weather and foggy or hazy weather. It is found that with relative humidity rising, the aerosol extinction coefficient becomes increasing in these two conditional weather. In sunny weather, the aerosol extinction coefficient relies on liner growth by relative humidity increasing; In foggy weather,the aerosol extinction coefficient relies on exponential growth by relative humidity increasing. The growth tendency of aerosol extinction coefficient is outstanding when the relative humidity is bigger than 80% in two conditional weather.