Comparison of CO2 Vertical Profiles in the Lower Troposphere between 1.6 µm Differential Absorption Lidar and Aircraft Measurements Over Tsukuba.

A 1.6 µm differential absorption Lidar (DIAL) system for measurement of vertical CO2 mixing ratio profiles has been developed. A comparison of CO2 vertical profiles measured by the DIAL system and an aircraft in situ sensor in January 2014 over the National Institute for Environmental Studies (NIES) in Tsukuba, Japan, is presented. The DIAL measurement was obtained at an altitude range of between 1.56 and 3.60 km with a vertical resolution of 236 m (below 3 km) and 590 m (above 3 km) at an average error of 1.93 ppm. An in situ sensor for cavity ring-down spectroscopy of CO2 was installed in an aircraft. CO2 mixing ratio measured by DIAL and the aircraft sensor ranged from 398.73 to 401.36 ppm and from 399.08 to 401.83 ppm, respectively, with an average difference of -0.94 ± 1.91 ppm below 3 km and -0.70 ± 1.98 ppm above 3 km between the two measurements.

Development of 1.6 µm DIAL using an OPG/OPA transmitter for measuring atmospheric CO2 concentration profiles.

An experiment for the measurement of atmospheric CO2 vertical profiles up to a 7 km altitude was successfully conducted using a 1.6 µm ground-based differential absorption Lidar developed by Tokyo Metropolitan University. To achieve a high pulse repetition rate, large power output, and high frequency stabilization, we developed a new 1.6 µm Lidar system using an optical parametric generator (OPG) transmitter. Unlike the previous system's transmitter, OPG does not need a resonator. We amplified its output with two optical parametric amplifiers. We validated our system against an in situ sensor and found the difference between their CO2 concentration measurements to be 0.06 ppm.

Mesopause-region temperature and wind measurements with pseudorandom modulation continuous-wave (PMCW) lidar at 589 nm.

A study on the feasibility of using pseudorandom modulation continuous-wave (PMCW) Na lidar for mesopause-region temperature and horizontal wind measurements is presented with a number of specific geometries and associated beam-telescope overlap functions, suitable for ground-based and airborne deployments. The performance of these deployment scenarios is analyzed by scaling from the received signal and sky background and the measurement uncertainties in temperature and horizontal wind of the well-tested Colorado State University pulsed Na lidar. Using currently available high-power (~20 W) continuous-wave Na narrowband lasers, a compact PMCW bistatic Na lidar system can indeed be deployed to simultaneously measure mesopause-region temperature and horizontal winds on a 24 h continuous basis, weather permitting.

Development of a 1.6 microm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile.

We have developed a 1.6 microm carbon dioxide (CO(2)) differential absorption lidar utilizing a quasi-phase-matching optical parametric oscillator (OPO) and a photon-counting detector. The operating wavelengths were chosen based on their low interference from water vapor and low temperature sensitivity. The online wavelength was in the (30012<--0001) band of CO(2), which was insensitive to atmospheric temperature. The established OPO laser achieved a 10 mJ, 200 Hz repetition rate at the online and offline wavelengths. Our observations confirmed the statistical error of 2% with 5 h of accumulation for the CO(2) density profile less than 5.2 km. Also, the statistical error of 1% at an altitude of 2 km was demonstrated. The results of the vertical CO(2) concentrations acquired using a 1.6 microm wavelength are presented.