We report a Compact Eye-Safe Backscatter Lidar (CESBL) system conceived for tropospheric aerosol research in the Arctic environment. The instrument will play an active role in the investigation of Arctic Haze and Ice Fog during winter time; intercontinental transport of Asian dust during springtime; and Aerosol plumes released from forest fires during summer time. In addition the system will perform systematic observations of Arctic Boundary Layer dynamics and Cirrus clouds. The lidar works at 1.574 μm and delivers 200 mJ maximum per pulse at 10 Hz prf. The output beam is conveniently expanded to yield an Eye-Safe factor greater than 250 suitable to operate in Urban Environments. The receiver is aimed with a Cassegrain telescope F/10, 20 cm primary diameter. The collimation and focusing were designed using commercial optics to holds approximately 1mrad field of view over a detector surface of 0.2 mm diameter. Signal detection is made by an InGaAs-APD followed by amplifiers. The Lidar system is mounted on an optical breadboard on a steerable platform and integrated into a PXI National Instrument data acquisition computer providing two acquisition channels at 200 MS/s maximum; 200 MHz of maximum bandwidth; and 12 bits vertical resolution. The acquisition code runs in a Lab-View platform with visualization interface and acquisition options optimized for field work. In this article the lidar system characteristics and the concept design are discussed. Initial geophysical results are shown.
The lidar systems contribute with privileged information to study environmental pollution due to its capacity to discriminate different atmospheric parameters in time and space. In this work, three of those system were developed at CEILAP laboratory in Argentina (34° 33' S, 58° 30' W): 1) a Multiwavelength lidar to characterized the atmospheric boundary layer and tropospheric aerosols using a Nd:YAG laser (10 Hz, 650 mJ @ 1064 nm); 2) a Raman lidar to measure night-time water vapor profiles, useful as a tracer of air parcel and in understanding energy transport within the atmosphere. This system utilizes an excimer laser (XeCl) (100 Hz, 300 mJ @ 308 nm), and 3) a differential absorption lidar (DIAL) to measure the stratospheric ozone profile. Two laser are used, the same excimer laser of Raman lidar and a Nd:YAG laser (30 Hz, 950 mJ @ 1064 nm). Complementary in situ measurements are also performed with a sun-photometer (AERONET-NASA); UVA, UVB and GUV radiometers (Argentina Solar Monitoring Network), pyranometer and a pyrgeometer. Recent results and the synergy between the actives and passives instruments are showed.
An analysis of aerosols optical parameters is made using the sun photometer measurements taken at CEILAP in 2000. The sun photometer deployed in the Buenos Aires suburb is part of AERONET. Using the present data set, time series of key optical parameters such as the optical depth at 500 nm and Angstrom coefficient of the wavelength scaling law are derived. Clustering the observations by mean of a statistical analysis we can infer the pollution episodes in the Buenos Aires area. They can be either of local or regional origins, depending on the meteorological conditions prevailing over central Argentina.
Since 1996 a lidar station is operated routinely at CEILAP (CITEFA-CONTCET), located in Buenos Aires suburb. The scientific objectives are related to environmental and atmospheric radiative budget studies. Two backscatter lidars operating at 532 nm and 308 nm are used to document the atmospheric boundary layer dynamics, and cirrus clouds and tropospheric aerosols radiative properties. The lidar measurements are made in conjuction with visible radiometer measurements on the same site and radiosoundings made twice daily at the nearby meteorological station. Atmospheric boundary layer measurements during daytime are conducted since 1996 on a regular basis using the backscatter lida.r operating at 532 nm, and more recently using a second lidar on the same site operating at 308 nm. Similarly, cirrus clouds and tropospheric aerosols measurements are conducted during clear days (e.g. without low clouds) since 1996 using the backscatter lidars. Since the late 1997 more interest is given to urban ABL dynamics in connection with pollution events, and biomass burning taking place in the tropical South America. It happened that such plumes can be frequently transported over the Buenos Aires area by large scale circulation
Conference Committee Involvement (2)
Lidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing
17 September 2007 | Florence, Italy
Lidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing II