P. Rairoux

Stratospheric aerosol size distributions from multispectral lidar measurements at Sodankylä during EASOE

This paper presents results from lidar measurements made at Sodankyla (67[degrees]N) of stratospheric aerosols during EASOE. The lidar was capable to resolving size distributions into the micron size range, and by polarization techniques distinguishing PSC formations. Volcanic gas source aerosols were observed to be .1 to .3 microns in mean radius between 17 and 22 km, and larger below this altitude.

A four-wavelength depolarization backscattering LIDAR for polar stratospheric cloud monitoring

A four wavelength backscattering depolarization LIDAR designed for polar stratospheric cloud and stratospheric aerosol measurement is described. The system uses the following wavelengths: 355 nm, 532 nm, 750 nm, and 850 nm. These wavelengths, obtained by means of the third- and second-harmonic of a Nd: YAG laser and by means of a tunable Ti: Sapphire laser, are chosen in a way to better characterize the particel size of such stratospheric aerosols. They are not emitted simultaneously as the LIDAR system is designed with only two detection channels permitting to detect, in the analog and in the photon counting mode, both the direct and the depolarized backscattered signal. The system has been operational in northern Finland since the end of November 1991.

Comparative study of nitric oxide immission in the cities of Lyon, Geneva, and Stuttgart using a mobile differential absorption LIDAR system

The immission load of nitric oxide due to traffic is investigated in the cities of Lyon, Geneva, and Stuttgart using a mobile differential absorption LIDAR system (DIAL). Horizontal and vertical maps of the NO mixing ratio, as well as 24 hour records are presented. It is shown that street canyons favor high immission values, whereas broad main axes are efficiently ventilated (Lyon); inversion conditions rise the average immission load within a city mainly independent of traffic (Geneva and Stuttgart), whereas highly frequented intersections favor high immission values regardless of weather conditions (Geneva); the observed maximum immission loads also depend on the traffic density during rush hours (Stuttgart).

Effects of stratospheric aerosols from the Mt. Pinatubo eruption on ozone measurements at Sodankylä, Finland in 1991/92

This article reports on column ozone measurements made from Sodankyla, (67[degrees]N), during the winter of 1991-1992. These measurements have been made with a Brewer spectrophotometer, and a SAOZ instrument. The results are correlated with TOMS data also. A strong sensitivity to light scattering due to atmospheric aerosols has been shown. When airmass factors are adjusted into the measurements, then the measurements are better correlated between themselves.

Remote Detection of Atmospheric Pollutants Using Differential Absorption Lidar Techniques

Air pollution is an extremely dynamic phenomenon, and this makes its understanding and, therefore, its control, more elusive. This dynamic behavior appears not only in physical terms by the diffusion and transport of emitted pollutants, but also chemically, through the many reactions occuring in the atmosphere. It is therefore of outstanding importance to be able to correlate emission and immission, and thus characterize the impact of different kinds of sources of pollution (industries, vehicles, domestic heaters) on the environment. The only way to control phenomena like acid rains or hole formation in the ozone layer, is to perform a permanent and large-scale monitoring of the air pollution. Presently existing devices, however, although they may be very sensitive like Laser Induced Fluorescence (LIF) or Differential Optical Absorption Spectroscopy (DOAS), can only provide spot measurements at ground level. Three-dimensional informations, reflecting the dynamic character of pollution, are, until now, sorely lacking.

Aerosol size distribution measurements using a multispectral lidar system

Consideration is given to a novel inversion algorithm to determine the aerosol size distribution from lidar signals obtained at several wavelengths. This algorithm is based on a nonlinear fit of the backscattered measurements using a set of predetermined functions. Size distribution profiles of tropospheric aerosols in different meteorological conditions - clear, hazy, and cloudy atmosphere - are determined on the basis of lidar measurements made in central Switzerland, which is characterized by a specific microclimate. Measurements of stratospheric clouds and aerosols created by the Pinatubo eruption were measured above Berlin and Sodankyla, Finland. These measurements are used to characterize the size distribution of these volcanic aerosols in order to estimate their influence on radiative transfer.

Ozone, VOC, NO2 and Aerosol Monitoring in Urban and Industrial Areas Using a Mobile DIAL System

We introduce a new, mobile Lidar system which is based on a flashlamp-pumped Titanium:Sapphire Laser. It is constructed on industrial standard. It allows for quasisimultaneous, spatially resolved measurements of ozone as well as VOC’s and NO2 which are known as important precursors in the formation of tropospheric ozone.

Laser Remote Sensing of Sulfur Dioxide, Nitrogen Dioxide, Toluene, Ozone, and Dust in the Industrial Area of Cubatão (Brazil)

Measurements of temporal and spatial distributions of sulfur dioxide, nitrogen dioxide, toluene, and aerosols have been made with two lidars in the industrial region of Cubatao, Brazl. Immissions, emissions and transport phenomena were investigated. The data provide a comprehensive picture of the actual situation and appear useful for future planning of new facilities in the area.

Ti:Sapphire Based Lidar Systems

Recent progress in Lidar/DIAL technology has allowed to obtain 3-dimensional mappings of the concentration of air pollutants at highest sensitivity (ppb-range) and over large distances (10 km) [1–6]. Presently, it is possible to monitor real-time distributions and dynamics of nitrogen oxides, sulfur dioxide, and ozone. Recently, also the detection of toluene and benzene in the near uv has been demonstrated [7]. Routine or fully automatic operation has been severely restricted, however, by the complexity and maintenance of the usually employed Nd:YAG or Excimer-pumped dye lasers. The advent of new tunable all-solid-state laser systems, such as vibronic lasers (Ti:Sapphire, LICAF, LISAF,...) or laser-pumped OPOs, opens a new era in the domain of userfriendly and fully automatic DIAL operation.

Error analysis of restoring stratospheric aerosol parameters from single frequency lidar sounding

An algorithm for restoring stratospheric backscatter coefficients from ground-based lidar measurement is proposed. Error sources of the algorithm are analyzed including the boundary condition, the molecular backscatter coefficients, and the influence of the aerosol light extinction.