Optical parametric technology for methane measurements

Martha Dawsey; Kenji Numata; Stewart Wu; Haris Riris

doi:10.1117/12.2191615

1 September 2015 Optical parametric technology for methane measurements

Martha Dawsey, Kenji Numata, Stewart Wu, Haris Riris

Proceedings Volume 9612, Lidar Remote Sensing for Environmental Monitoring XV; 961205 (2015) https://doi.org/10.1117/12.2191615
Event: SPIE Optical Engineering + Applications, 2015, San Diego, California, United States

Abstract

Atmospheric methane (CH₄) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO₂) per molecule. Yet, lack of understanding of the processes that control CH₄ sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH₄ from orbit. Our concept for a CH₄ lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth’s surface to measure CH₄. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH₄ detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 μJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH₄ measurements with 1% precision (10-20 ppb).

Citation Download Citation

Martha Dawsey, Kenji Numata, Stewart Wu, and Haris Riris "Optical parametric technology for methane measurements", Proc. SPIE 9612, Lidar Remote Sensing for Environmental Monitoring XV, 961205 (1 September 2015); https://doi.org/10.1117/12.2191615

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