As part of environmental studies of the southern atmosphere, the CEILAP Lidar Division in collaboration with the Service d'Aeronomie has developed a mobile differential absorption lidar capable of making precise and accurate measurements of the stratospheric ozone. The XeCl excimer laser emission at 308 nm is used as absorbed line in the DIAL technique and an Nd-YAG laser 355 nm third harmonic is employed as a reference wavelength. Six detected channels are used for stratospheric ozone retrieval, four of them in the high and low energy of the elastically backscattered signal of the emitted wavelengths and two corresponding to the first Stokes nitrogen Raman of the emitted wavelengths. Tropospheric Water Vapor profiles using Raman channels and Aerosol Backscatter profiles are also obtained. In this paper we present a detailed description of the instrument, a discussion of data analysis and the results of the first lidar-satellite inter-comparison of stratospheric ozone profiles measured with this instrument. We also present a description of the SOLAR campaign that will be held in the 2005 southern winter-spring period in Rio Gallegos (51° 55'S, 69° 14'W) with the objective of studying the ozone layer when the polar vortex crosses over the continental part of Argentina. This campaign will be supported by JICA (Japan International Cooperation Agency).
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.
DIAL lidars are widely used for the monitoring of stratospheric ozone in the framework of the NDSC (Network for the Detection of Stratospheric changes). Long term DIAL ozone measurements have been performed in the South of France at Observatoire de Haute-Provence (OHP - 43.91°N, 5.71°E) since 1986 and in Antarctica in Dumont d'Urville (66.4°S, 140°E) from 1991 to 2000. At OHP, the measurements allow the study of the short-term and long-term variability of stratospheric ozone in the northern mid-latitude regions. They have been used recently to evaluate the influence of Arctic ozone depletion on mid-latitude ozone amounts. In Antarctica, the lidar measurements allowed the evaluation of the air subsidence in autumn and the ozone loss linked to anthropogenic halogen compounds in spring. Due to the location of the Dumont d'Urville station close to the edge of the polar vortex, a detailed study of the permeability of the polar vortex as a function of altitude could be performed. In addition to long term measurements, an airborne ozone lidar was deployed to sample polar air filaments mixing into mid-latitude regions. These measurements validated high resolution transport models used to evaluate at global scale the influence of polar ozone depleted air on mid-latitude ozone trends.
A ground-based differential Absorption Lidar (DIAL) system has been implemented at CEILAP laboratory, located in the Buenos Aires industrial suburbs, The goal was to perform measurements of the stratospheric ozone layer. Since early 199 systematic measurements of zone concentration profiles from approximately 18 to 35 km altitude are performed. Our measurements are carried out in 5 hours in average during the night and in cloudless conditions. The DIAL system allows us to calculate directly the ozone profile from the lidar backscattering radiation since it is a self- calibrating technique. The signals processing takes into account the influence of the temperature profile on the ozone cross section. The temperature data is obtained from the radiosondes measurements performed at Ezeira International Airport. The evolution of the stratospheric ozone profile is studied for different months. Results are compared with the data obtained by different satellites like SAGE II and HALOE. The spatial and temporal range of the satellites must be taken into account.