Diurnal Variations of CO2 Mixing Ratio in the Lower Atmosphere by Three Wavelength DIAL

Abstract

We have conducted the measurement of high accurate CO2 mixing ratio profiles by measuring the temperature profiles simultaneously using the three wavelength CO2 DIAL. The measurements of CO2 diurnal variation in the lower atmosphere were carried out on sunny and cloudy days respectively. We find out that increasing of the CO2 mixing ratio occurs over the altitude of about 2 km from the surface during nighttime. On the other hand, the CO2 mixing ratio decreases over the lower atmosphere during daytime. In particular, the CO2 mixing ratio decreases earlier on sunny days than on cloudy days after sunrise. This result suggests that CO2 absorption by photosynthesis greatly contributes to the strength of the solar radiation.