P050-02
Canadian Atmospheric Laser Absorption Spectrometer Experiment Test-bed (CALASET): Field Measurements of CO2 and N2O with a Stratospheric Balloon-Borne Laser Spectrometer

Friday, 11 December 2020: 05:33
Virtual
Mark Panas1, John E Saunders2, William Knee-Walden2, Noah Cassidy2, Young-Min Cho2, Jack Farrell2, Alex Fogal2, Joanna Hon2, Emily Knuckey2, Pierre Fogal2, Wolfgang Jäger3, Jennifer G Murphy1 and Kaley A Walker2, (1)University of Toronto, Department of Chemistry, Toronto, ON, Canada, (2)University of Toronto, Department of Physics, Toronto, ON, Canada, (3)University of Alberta, Department of Chemistry, Edmonton, AB, Canada
Abstract:
The Canadian Atmospheric Laser Absorption Spectrometer Experiment Test-bed (CALASET) is a collaborative project to design laser spectrometers for stratospheric balloon flight. Instruments are constructed to be both highly sensitive and mechanically robust. The first generation of CALASET is an infrared laser spectrometer built for in-situ sensing of CO2 and N2O on a stratospheric balloon gondola. Wavelength modulation spectroscopy (WMS) techniques are used to collect and visualize spectra during flight and to perform post-flight analysis.

CALASET employs a quantum cascade laser within an open path Herriott multi-pass cell with an effective path length of 81 m. A software lock-in amplifier (LIA) was written in Python to process the data, and an analytical model based on WMS theory is used to retrieve trace gas mole fractions. This model uses measured laser characteristics, parameters from the HITRAN spectral database, and a least-squares fitting algorithm.

The spectrometer and key components were tested under low pressure conditions (~1 mbar) in the Space Instrument Calibration Facility at University of Toronto during development. The instrument was compared at ambient pressure and temperature in the laboratory against a Los Gatos Research Fast Greenhouse Gas Analyzer measuring CO2 mole fraction.

To date, there have been two iterations of the instrument with engineering and scientific data collected during two successful field campaigns in 2018 and 2019. Spectra were collected from ground up to float altitudes, near 35km, over an 11-12 hour period at a rate of 1-3 Hz. The results from the past two field campaigns will be discussed along with a brief introduction to the future plans of the CALASET project.

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