A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km-60 km away from ground.Before the inversion of the Doppler shift due ...A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km-60 km away from ground.Before the inversion of the Doppler shift due to wind,the Rayleigh response function should be calculated,which is a convolution of the laser spectrum,Rayleigh backscattering function,and the transmission function of the Fabry-Perot interferometer used as the frequency discriminator in the lidar.An analysis of the influence of the temperature on the accuracy of the Une-of-sight winds shows that real-time temperature profiles are needed because the bandwidth of the Rayleigh backscattering function is temperature-dependent.An integration method is employed in the inversion of the temperature,where the convergence of this method and the high signal-to-noise ratio below 60 km ensure the accuracy and precision of the temperature profiles inverted.Then,real-time and on-site temperature profiles are applied to correct the wind instead of using temperature profiles from a numerical prediction system or atmosphere model.The corrected wind profiles show satisfactory agreement with the wind profiles acquired from radiosondes,proving the reliability of the method.展开更多
The sensitivity of Doppler wind lidar is an important parameter which affects the performance of Doppler wind lidar. Aerosol scattering ratio, atmospheric temperature, and wind speed obviously affect the measurement o...The sensitivity of Doppler wind lidar is an important parameter which affects the performance of Doppler wind lidar. Aerosol scattering ratio, atmospheric temperature, and wind speed obviously affect the measurement of Doppler wind lidar with iodine filter. We discuss about the relationship between the measurement sensitivity and the above atmospheric parameters. The numerical relationship between them is given through the theoretical simulation and calculation.展开更多
The nightly mean mesospheric temperature profiles between 80 and 107 km, observed by Na lidar, over Fort Collins, Colorado （41°N, 105°W） from 1990 to 2010, are employed to research the temporal and spatial...The nightly mean mesospheric temperature profiles between 80 and 107 km, observed by Na lidar, over Fort Collins, Colorado （41°N, 105°W） from 1990 to 2010, are employed to research the temporal and spatial variations and mesopause. We find that the maximum mean temperature is in summer months above 95 kin, but reverse below 95 kin, and there is a cooler region below 185 K around 97 km in August. The largest seasonal variation is 39.2 K at 81 kin, and the minimum is 6.5 K at 96.5 km. The maximum standard derivation in spring and autumn months are larger than other seasons above 105 kin, but the temperatures in March, June and September are lower than the other months between 82 km and 100 km where winter is the largest season. Moreover, the seasonal variations of the temperature are about 36, 8 and 21 K at 85, 95 and 105 km, respectively, winter is colder and summer is warmer above 97.5 km, but reverse below 92 km. The mesopause height is around 102 km in winter, but 84 km in summer, and the mean speed of decreasing or increasing of the mesopause height is about 5 km/month in spring and autumn months which are about 90 km. The lasting time of the mesopause in winter is near 6 months, longer than other seasons, and the mesopause temperature is about 165 K in cool summer, and 185 K in warm winter.展开更多
A transition zone near cirrus lateral boundaries can be detected by CALIOP （cloud-aerosol lidar with orthogonal polarization）. In the present study, for such transition zones over China, a number of optical properti...A transition zone near cirrus lateral boundaries can be detected by CALIOP （cloud-aerosol lidar with orthogonal polarization）. In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55-1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise hori- zontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability dens- ity distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3-5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direc- tion of the vertical and horizontal winds. These observations implied that the transitional features were caused by ma- terial exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase trans- formation of particles, such as sublimation.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41174130,41174131,41274151,and 41304123)
文摘A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km-60 km away from ground.Before the inversion of the Doppler shift due to wind,the Rayleigh response function should be calculated,which is a convolution of the laser spectrum,Rayleigh backscattering function,and the transmission function of the Fabry-Perot interferometer used as the frequency discriminator in the lidar.An analysis of the influence of the temperature on the accuracy of the Une-of-sight winds shows that real-time temperature profiles are needed because the bandwidth of the Rayleigh backscattering function is temperature-dependent.An integration method is employed in the inversion of the temperature,where the convergence of this method and the high signal-to-noise ratio below 60 km ensure the accuracy and precision of the temperature profiles inverted.Then,real-time and on-site temperature profiles are applied to correct the wind instead of using temperature profiles from a numerical prediction system or atmosphere model.The corrected wind profiles show satisfactory agreement with the wind profiles acquired from radiosondes,proving the reliability of the method.
基金the National Natural Science Foundation of China under Grant No.40427001,60578038,and 40505003
文摘The sensitivity of Doppler wind lidar is an important parameter which affects the performance of Doppler wind lidar. Aerosol scattering ratio, atmospheric temperature, and wind speed obviously affect the measurement of Doppler wind lidar with iodine filter. We discuss about the relationship between the measurement sensitivity and the above atmospheric parameters. The numerical relationship between them is given through the theoretical simulation and calculation.
基金supported by the National Natural Science Foundation of China(Grant Nos.40505005,41304146)the Specialized Research Fund for State Key Laboratories of China
文摘The nightly mean mesospheric temperature profiles between 80 and 107 km, observed by Na lidar, over Fort Collins, Colorado （41°N, 105°W） from 1990 to 2010, are employed to research the temporal and spatial variations and mesopause. We find that the maximum mean temperature is in summer months above 95 kin, but reverse below 95 kin, and there is a cooler region below 185 K around 97 km in August. The largest seasonal variation is 39.2 K at 81 kin, and the minimum is 6.5 K at 96.5 km. The maximum standard derivation in spring and autumn months are larger than other seasons above 105 kin, but the temperatures in March, June and September are lower than the other months between 82 km and 100 km where winter is the largest season. Moreover, the seasonal variations of the temperature are about 36, 8 and 21 K at 85, 95 and 105 km, respectively, winter is colder and summer is warmer above 97.5 km, but reverse below 92 km. The mesopause height is around 102 km in winter, but 84 km in summer, and the mean speed of decreasing or increasing of the mesopause height is about 5 km/month in spring and autumn months which are about 90 km. The lasting time of the mesopause in winter is near 6 months, longer than other seasons, and the mesopause temperature is about 165 K in cool summer, and 185 K in warm winter.
基金Supported by the National Natural Science Foundation of China(41405031 and 41475037)China Meteorological Administration Special Public Welfare Research Fund(GYHY201506013)+1 种基金Sichuan Youth Fund(2014JQ0019)Scientific Research Fund of Chengdu University of Information Technology(KYTZ201504 and J201519)
文摘A transition zone near cirrus lateral boundaries can be detected by CALIOP （cloud-aerosol lidar with orthogonal polarization）. In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55-1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise hori- zontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability dens- ity distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3-5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direc- tion of the vertical and horizontal winds. These observations implied that the transitional features were caused by ma- terial exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase trans- formation of particles, such as sublimation.
