Mie lidar observations of lower tropospheric aerosols and clouds.

Mie lidar system is developed at Laser Science and Technology Centre, Delhi (28.38°N, 77.12°E) by using minimal number of commercially available off-the-shelf components. Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser operating at 1064nm with variable pulse energies between 25 and 400 mJ with 10 Hz repetition rate and 7ns pulse duration is used as a transmitter and off-axis CASSEGRAIN telescope with 100mm diameter as a receiver. Silicon avalanche photodiode (Si-APD) module with built-in preamplifier and front-end optics is used as detector. This system has been developed for the studies of lower tropospheric aerosols and clouds. Some experiments have been conducted using this set up and preliminary results are discussed. The characteristics of backscattered signals for various transmitter pulse energies are also studied. Atmospheric aerosol extinction coefficient values are calculated using Klett lidar inversion algorithm. The extinction coefficient, in general, falls with range in the lower troposphere and the values lie typically in the range 7.5×10(-5) m(-1) to 1.12×10(-4) m(-1) in the absence of any cloud whereas this value shoots maximum up to 1.267×10(-3) m(-1) (peak extinction) in the presence of clouds.

[1]  Vladimir A. Kovalev,et al.  Elastic Lidar: Theory, Practice, and Analysis Methods , 2004 .

[2]  Rain, rainclouds and climate , 1990 .

[3]  Glenn E. Shaw,et al.  Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze , 2001 .

[4]  K Sassen,et al.  Lidar depolarization from multiple scattering in marine stratus clouds. , 1986, Applied optics.

[5]  J. Nee,et al.  Lidar Observation of the Cirrus Cloud in the Tropopause at Chung-Li (25°N, 121°E) , 1998 .

[6]  W. Carnuth,et al.  Cloud extinction profile measurements by lidar using Klett's inversion method. , 1986, Applied optics.

[7]  P. Pierrard,et al.  Cloud-Base Height Measurements with a Single-Pulse Erbium-Glass Laser Ceilometer , 1998 .

[8]  J. Coakley,et al.  Climate Forcing by Anthropogenic Aerosols , 1992, Science.

[9]  Y. Kumar,et al.  MST radar and polarization lidar observations of tropical cirrus , 2001 .

[10]  James D. Spinhirne,et al.  Micro pulse lidar , 1993, IEEE Trans. Geosci. Remote. Sens..

[11]  Satyanarayana Malladi,et al.  Laser radar characterization of atmospheric aerosols in the troposphere and stratosphere using range dependent lidar ratio , 2010 .

[12]  C. Weitkamp.  Lidar, Range-Resolved Optical Remote Sensing of the Atmosphere , 2005 .

[13]  K. Sassen.  The Polarization Lidar Technique for Cloud Research: A Review and Current Assessment , 1991 .

[14]  P. Devara,et al.  Lidar measurements of aerosols in the tropical atmosphere , 1993 .

[15]  Steven A. Ackerman,et al.  Radiative Effects of Airborne Dust on Regional Energy Budgets at the Top of the Atmosphere , 1992 .

[16]  J. Klett.  Stable analytical inversion solution for processing lidar returns. , 1981, Applied optics.

[17]  Andrew G. Glen,et al.  APPL , 2001 .