Title of Presentation: Laser Sounding Instrument using Oxygen A-Band for Atmospheric Pressure Sensing
Primary (Corresponding) Author: Mark Stephen
Organization of Primary Author: Goddard Space Flight Center
Co-Authors: Jian-Ping Mao, James B. Abshire, S. Randy Kawa
Abstract: We describe research directed toward developing a remote sensing instrument capable of measuring atmospheric pressure from a satellite. The primary focus for the authors is a calibration channel for a similar carbon dioxide sensor, however there are many other uses for such an instrument, including: weather prediction, atmospheric modeling and dynamic gravity field measurements. The CO2 measurement can be affected by changes in atmospheric properties such as humiditiy, temperature and pressure. We use spectroscopy of pressure broadened lines of the diatomic oxygen A-band as the basis for the measurement. The oxygen dry mixing ratio stays constant at 20.95% so it makes a good reference for a variable gas like CO2. We are developing a measurement technique that capitalizes on the spectroscopy work of others but uses new laser and instrument architectures. The laser developed is a frequency-doubled, DFB seeded erbium-doped fiber amplifier (EDFA). It is a tunable, narrow frequency, rugged, efficient, high peak power device capable of very high resolution spectroscopy. The instrument uses laser pulses reflecting from a hard target and measures the average atmospheric pressure of the column of air through which the laser pulses travel. The instrument design and component technology is being considered to easily extend to both aircraft and satellite but our development to date has been ground-based. We report on the basic theory behind the instrument, measurements made at a test site at Goddard, review the current state of the instrument and associated technologies and the necessary steps to improve performance.