ABSTRACT
This section presents an examination of laser remote sensing of ozone in the Earth’s atmosphere. Three main topics have been studied by means of ozone vertical profiles: • seasonal and year-to-year variability to detect planetary scale changes both in the troposphere (altitude
range 0-15 km) and in the stratosphere (altitude range 15-40 km); • photochemical ozone production/destruction assessment near sources of primary pollutants; and • transport estimates for which ozone is considered a quasi-passive tracer (mass flux across the planetary
boundary layer top and across the boundary between the stratosphere and the troposphere). One consequence is that various spatial and temporal scales must be addressed by field measurements
of ozone and this is why lidar remote sensing is well suited for this task, compared with balloon-borne or airborne in situ measurements. Early work with lidar systems to monitor ozone in the atmosphere has shown that the differential absorption lidar (DIAL) technique is the most efficient way to derive an ozone profile with good range and sensitivity [1-3]. Fluorescence or Raman scattering measurements of pollutants are restricted to pollution-source monitoring where long range and good sensitivity are not so important. The optimization of the measurement by the DIAL technique involves the selection of the appropriate spectral domain (ultraviolet (UV) and infrared (IR)) to measure the ozone absorption, the treatment of atmospheric interference by other atmospheric species (molecules or particles) and the use of lasers with a suitable output energy and repetition rate for the measurements. This is reviewed in section D7.2.2, while the selection of the appropriate laser source is described in section D7.2.3. Designing a DIAL instrument is obviously not only a problem of identifying the best laser source but also a careful optimization of the detection system (optical receiver and signal processing). This is discussed in section D7.2.4. Finally, some results from ozone measurements obtained up to now with the DIAL technique are presented in section D7.2.5.
