Application of lidar to atmosphere pollutant mapping: a review

Abstract

The favored scheme for the remote monitoring of atmosphere pollutants is based on the differential absorption of radiations by the target species. The sources of these radiations are the Rayleigh or Mie scattering from the distributed atmospheric aerosols at to slightly different wavelengths. This technique is known as deferential absorption lidar (DIAL) and offers the best range capability compared to other remote sensing techniques. However, the DIALs are complex and one system is dedicated to monitor only one species. The accuracy in DIAL measurements are also critically dependent on environment and instrumental parameter. The other promising technique for remote pollution monitoring is the Raman lidar. This is based on the detection of Raman back-scattered signals from the pollutant species and allows detection of several species simultaneously. However, Raman lidars do not allow long range capabilities. The application of lidars for atmosphere pollutant mapping is ultimately tied up with trade-offs between required or desired sensitivity, range capability and the data averaging time. The state-of-the-art of the two most promising lidar technologies, their limitations and recent advances in their applications are reviewed in this paper.