Autonomous Differential Absorption Laser Device for Remote Sensing of Atmospheric Greenhouse Gases

Panagiotis Siozos,Peter C Samartzis,Giannis Psyllakis,Michalis Velegrakis

doi:10.3390/rs14030460

Abstract

A ground-based, integrated path, differential absorption (IPDA) light detection device capable of measuring multiple greenhouse gas (GHG) species in the atmosphere is presented. The device was developed to monitor greenhouse gas concentrations in small-scale areas with high emission activities. It is equipped with two low optical power tunable diode lasers in the near-infrared spectral range for the atmospheric detection of carbon dioxide, methane, and water vapors (CO2, CH4 and H2O). The device was tested with measurements of background concentrations of CO2 and CH4 in the atmosphere (Crete, Greece). Accuracies in the measurement retrievals of CO2 and CH4 were estimated at 5 ppm (1.2%) and 50 ppb (2.6%), respectively. A method that exploits the intensity of the recorded H2O absorption line in combination with weather measurements (water vapor pressure, temperature, and atmospheric pressure) to calculate the GHG concentrations is proposed. The method eliminates the requirement for measuring the range of the laser beam propagation. Accuracy in the measurement of CH4 using the H2O absorption line is estimated at 90 ppb (4.8%). The values calculated by the proposed method are in agreement with those obtained from the differential absorption LiDAR equation (DIAL).

Highlights

The recorded signal of the amplifier increased proportionally to the laser power; sharp drops of the signal were observed at wavelengths resonant with the three absorption lines of CO2 (Figure 3a, black line)
The CO2 pressure in the chamber was calculated from the recorded spectrum using the Beer–Lambert equation and it was found to be 800 ± 20 mbar, which is the same value provided by the pressure sensor of the chamber
The atmospheric background concentration of these two greenhouse gas (GHG) was measured with an accuracy of 5 ppm and 50 ppb, respectively

Summary

Introduction

Academic Editors: Hanlim Lee and Fred Moshary. The reduction in greenhouse gases (GHGs) atmospheric concentration requires accurate measurements of their global emissions. A combination of satellite observatories and ground-based stations operate to provide global coverage [1]. Detailed GHG emission estimation requires extensive atmospheric concentration measurements of regions with high GHG emissions (cities, airports, power plants, oil and natural gas production and distribution facilities, landfills, cultivated fields, etc.). Calculation of the emissions from these specific locations have large uncertainties due to insufficient emission monitoring [2,3,4,5]. The installation and operation of ground-based stations are considered an optimal solution for the detection and monitoring of GHG concentration measurement [6,7,8] from such locations

Methods

Results

Conclusion