CHARM-F-a new airborne integrated-path differential-absorption lidar for carbon dioxide and methane observations: measurement performance and quantification of strong point source emissions.

The integrated-path differential-absorption lidar CHARM-F (CO2 and CH4 Remote Monitoring-Flugzeug) was developed for the simultaneous measurement of the greenhouse gases CO2 and CH4 onboard the German research aircraft HALO (High Altitude and Long Range Research Aircraft). The purpose is to derive the weighted, column-averaged dry-air mixing ratios of the two gases with high precision and accuracy between aircraft and ground or cloud tops. This paper presents the first measurements, performed in the spring of 2015, and shows performance analyses as well as the methodology for the quantification of strong point sources applied on example cases. A measurement precision of below 0.5% for 20 km averages was found. However, individual measurements still show deviations of the absolute mixing ratios compared to corresponding data from in situ profiles. The detailed analysis of the methane point source emission rate yields plausible results (26±3 m3/min or 9.2±1.15 kt CH4 yr-1), which is in good agreement with reported numbers. In terms of CO2, a power plant emission could be identified and analyzed.

Demonstration of an iron fluorescence lidar operating at 372 nm wavelength using a newly-developed Nd:YAG laser.

We report on the development of a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at a 1116 nm wavelength. Because the third harmonic is within a few gigahertz of the 372 nm absorption line of iron, this laser system represents an alternative to alexandrite lasers commonly used in iron fluorescence lidars. With our prototype, we achieved a 0.5 W at 372 nm wavelength and a 100 Hz pulse repetition frequency. As a proof of concept, we show iron density measurements, which have been acquired using the novel lidar transmitter.