Development of an atmospheric CO2 sensor based on TDLAS-WMS

Abstract

Greenhouse gases (GHG) have negative impacts on the climate changes. Carbon dioxide (CO2), one of the dominant GHG, comes mainly from the anthropogenic emissions in urban areas. In this work, we develop a CO2 sensor based on TDLAS-WMS (tunable diode laser absorption spectroscopy – wavelength modulation spectroscopy) to detect the daily CO2 concentration in the atmosphere. Firstly, the residual amplitude modulation (RAM) in the first harmonic is eliminated using the phasor decomposition method. Then, the multi-harmonic detection is employed to improve the precision of the sensor. It reveals that the precision can reach 0.02 ppm for CO2 measurement. The atmospheric CO2 measurement is conducted in urban area for a whole year. The results indicate that the anthropogenic activities can be observed in the diurnal CO2 cycles, especially in the wintertime. The developed sensor has a great potential for the air quality monitoring in urban areas.