The Detection Of Temperature And Aerosol Profiles In Middle And Lower Atmosphere Using Raman Lidar

In recent years, unrestrained destruction of nature due to the activities of human led to the deterioration of ecological environment. The incidence of the extreme weather phenomena including greenhouse effect, droughts, snowstorms, sandstorms and so on is increasing. A study of the laws of the lower atmosphere is very important to explain the continuous occurrence of extreme weather phenomena, and to improve the accuracy of region’s weather forecast.Lidar with the characteristics of high spatial and temporal resolution was applied more and more in atmospheric sounding. Using the Rayleigh-Raman-Mie (RRM) lidar of Nanjing University of Information Science and Technology (NUIST), the detection and the invertion of temperature profile was studied. Longer integration time, background correction, wavelet transform and slide average are employed to denoise the Raman backscattering signal. It can effectively improve the SNR of the original signal. In respect of temperature invertion algorithm, the effect of aerosols to temperature profile was analyzed, extinction profiles were used to correct Raman signals, so the effect of aerosols to temperature inversion results was reduced. To verify the temperature invertion algorithm, Raman lidar temperature inversion results were compared with both the sounding data above Nanjing and the atmospheric model. Based on the studies of the temperature inversion algorithm, Raman lidar was used for routin observation of temperature profiles above Nanjing. The results of long-term observation were statistical analysed. The results showed that:the difference between the average monthly temperature from Raman lidar and that from sounding was1-2K during November2010. The average temperature profiles of three ten days during November2010show that:at altitude of10km, temperature of first ten days was4K higher than that of the third ten days. With winter approaching, the temperature lapse rate had significantly increased in low-altitude section. These results not only verified the Raman lidar’s ability of long-term observation to lower atmospheric, but also highlight the characteristics of low-cost, high spatial and temporal resolution comparing with sounding balloons. In addition to studies of temperature using Raman lidar, the aerosol characteristic profiles was also invert from Raman lidar signals. The results showed that:the aerosol retrieval results from differential method is very sensitive to high frequency noise, so aerosol profiles fluctuated in condition of fewer aerosol. But when the attenuations were the same to Raman lidar and aerosol lidar, Raman lidar can detect aerosol layer at higher altitude. The invertion results will be better if high frequency noise is reduced.