Calibrated remote measurements of SO2 and O3 using atmospheric backscatter

Abstract

Remote measurements of calibrated samples of SO2 and O3 have been achieved with a lidar using ultraviolet signals produced by a tunable dye laser and a nonlinear crystal. The operating wavelengths for these measurements were 292.3 and 293.3 nm for SO2 and 292.3 and 294.0 nm for O3. The atmosphere in front of and behind the chamber acted as a distributed reflector to send laser light back through the chamber to a receiver near the laser. The laser measurements agreed well with in situ measurements. Integration of eight laser pulses at each of two wavelengths allowed the determination of SO2 concentration with an uncertainty equivalent to ±0.6 ppm in 100 m for low concentrations. For O3, the corresponding uncertainty limit was ±1.2 ppm in 100 m. The measurement errors are primarily attributable to variations in atmospheric backscattering intensity during the experiment, since the different wavelengths were radiated sequentially rather than simultaneously. The sensitivity of a system transmitting more favorable wavelengths at intervals separated by less than 1 min is estimated to be near ±0.1 ppm in 100 m for both SO2 and O3.

Development and Application of a Compact, Tunable, Solid-State Airborne Ozone Lidar System for Boundary Layer Profiling

“…(The two wavelengths are generally referred to as the online and offline wavelengths for the more absorbed and less absorbed wavelengths, respectively.) The Hartley absorption band between ;(260 and 300) nm in the near UV is the spectral region of choice for lidar measurements of tropospheric ozone, and the vast majority of past and current tropospheric ozone lidar systems use UV laser transmitters operating in this range (e.g., Grant and Hake 1975;Pelon and Mégie 1982;Browell et al 1983;Uthe et al 1992;Proffitt and Langford 1997;Richter et al 1997;Weidauer et al 1997;Alvarez et al 1998;Ancellet and Ravetta 1998;Fix et al 2002;Meister et al 2003;Machol et al 2009). Longer wavelengths are typically used for stratospheric measurements.…”

Techniques for laser remote sensing of the environment

“…In the early 1970s the DIAL system was first developed to measure NO 2 air pollution molecules using a nitrogen pumped dye laser (Rothe et al, 1974) and SO 2 and O 3 molecules using a flashlamp pumped dye laser, frequency doubled by Grant and Hake (1975). The measurement of NO 2 showed the DIAL technique could be used to measure urban or industrial area concentration of about 0.2 ppm at the range of 700 m, while the SO 2 and O 3 measurements showed that calibrated measurements could be made.…”

Applications des lasers à l'étude de l'atmosphère

“…Les énergies utilisables sont de l'ordre de 50 à 100 mJ pour une largeur spectrale de 0,1 nm et un domaine d'utilisation continu allant de 290 nm à 320 nm, qui permet de couvrir l'essentiel des transitions électroniques. Cette méthode a jusqu'à présent été employée avec succès dans la troposphère (S02, 03 [41]) (N02 [42]) (Fig. 8) et dans la stratosphère pour l'ozone [43] (Fig.…”