Measurements of water vapor, surface ozone, and ethylene using differential absorption lidar

Abstract

The measurement of various minor constituents in the atmosphere is of great significance to understand physics, Chemistry and dynamics of the atmosphere. Ozone in the troposphere is one of the most important trace species as it is a greenhouse gas trapping the longwave radiation in 9.6 p.m band affecting the energy budget of the earthatmosphere system. It is also a pollutant produced as a result of anthropogenic activities such as fossil fuel burning and has potential to affect human health and vegetation if it is allowed to attain high concentrations. Water vapour also plays a significant role in climate studies and the chemistry of the atmosphere. Ethylene is an urban pollutant and its concentration as low as 10 ppb is toxic to plants. A differential absorption lidar system using a tunable CO2 laser has been designed and developed at National Physical Laboratory, New Delhi, to monitor various minor constituents in the atmosphere. Some times ethylene concentration was found to be more than 20 ppb while that of surface ozone was more than 140 ppb which is a health hazard. In this paper salient features of experimental set up and results obtained will be presented in detail.

Surface ozone measurements using differential absorption lidar

“…The accurate and real time measurement of water vapour is therefore significant for better understanding of hydrological cycle. The measurement of water vapour has been made using DIAL [17][18][19][20][21] by tuning CO 2 laser on "ON" resonance line R (20) at 975.9304 cm -1 and "OFF" resonance line R(18) at 973.28848 cm -1 . The measurements of ethylene were made by tuning the CO 2 laser on "ON" resonance line P (14) and "OFF" resonance line P(22).…”

“…This technique was first developed by Schotland 13 using a ruby Lidar for measurement of water vapour and was used by various investigators [14][15][16][17][18][19][20][21] successfully for atmospheric probing. Tunable infrared CO 2 lasers have been widely used to monitor various trace atmospheric gases [15][16][17][18][19][20][21] because there is a good spectral coincidence between laser emission lines and the absorption lines of various trace constituents in the atmosphere. In view of the above, a Differential Adsorption LIDAR using a tunable CO 2 laser has been designed and developed at National Physical Laboratory, New Delhi (28.7 o N, 77.2 o E), to monitor various minor constituents in the atmosphere [18][19][20][21] .…”

“…Tunable infrared CO 2 lasers have been widely used to monitor various trace atmospheric gases [15][16][17][18][19][20][21] because there is a good spectral coincidence between laser emission lines and the absorption lines of various trace constituents in the atmosphere. In view of the above, a Differential Adsorption LIDAR using a tunable CO 2 laser has been designed and developed at National Physical Laboratory, New Delhi (28.7 o N, 77.2 o E), to monitor various minor constituents in the atmosphere [18][19][20][21] . In the present communication experimental set up and results obtained are discussed in details.…”

Evaluation of the performance of DIAL system for the determination of ethylene concentration in an agricultural area

“…In 2000, Ivashchenko et al [16] proposed a numerical approach for designing a DIAL system with the operating range as a parameter. In a vertical application for atmospheric monitoring, Jain et al [17] measured ethylene, water vapor, and surface ozone using a DIAL system. Recognizing the importance of considering water vapor and common chemical species in the atmosphere for horizontal environmental applications, Rossi et al [18], [19] employed a multiwavelength approach to increase measurement accuracy.…”