Observation of vertcal CO2 concentration profiles in the lower-atmosphere using a compact direct detection 1.6 μm DIAL

Abstract:

Knowledge of present carbon sources and sinks including their spatial profile and their variation in time is one of the essential informations for predicting future CO₂ atmospheric concentration levels. Moewover, for the detailed analysis of forest carbon dynamics and CO₂ fluxes of urban area, the CO₂ concentration measurement techniques with high spatial and temporal resolution are required in the lower atmosphere. A differential absorption lidar (DIAL) is expected to measure atmospheric CO₂ concentration profiles in the atmospheric boundary layer from a ground platform. We have succeeded to develop a compact direct detection 1.6 μm DIAL system for measuring CO₂ concentration profiles in the lower atmosphere. This DIAL system consists of the optical parametric generator (OPG) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate and the receiving optics that included the near-infrared photomultiplier tube operating at the analog mode and the 25 cm telescope. We have succeeded in observing the daytime temporal change of vertical CO2 concentration profiles for the range from 0.25 to 2.5 km with integration time of 30 minutes and range resolution of 300 m. This compact direct detection CO2 DIAL is usefull for the estimation of CO₂ flux.

This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.