The hydroxyl radical, OH, controls the lifetime of atmospheric gases like ozone, methane and halogenated hydrocarbons that impact human health and climate. Despite its importance, remote measurements of OH in the lower atmosphere are extremely limited. We propose to perform a proof of concept to demonstrate a new laser-based capability to measure OH with long path absorption spectroscopy.
We will build a proof of concept demonstration of an active laser system to detect OH with long path absorption. The concept is similar to the differential hard-target LIDARS that measure CO2 and CH4 in the near-infrared. In these experiments a narrow linewidth laser is directed at a partially reflective surface in the far-field and a small fraction of the reflected light is detected. The laser is scanned to provide the differential absorption spectrum for a Beer's Law analysis that yields the column abundance of OH.More »
Improved understanding of the coupled chemistry-climate system is a key component of NASA Earth Science objectives. In particular, NASA seeks to understand how changes in the chemical makeup of the atmosphere impact human health and the Earth's climate. Central to this theme is the oxidative photochemistry that controls the lifetime of greenhouse gases like methane, the production and loss of ozone, and the production of organic aerosols. As the primary oxidizer in the atmosphere, OH is a critical player in these processes that control the chemical evolution of the atmosphere.
Despite the importance of OH in atmospheric photochemistry, the remote sensing of the tropospheric column of OH is limited to just a few measurements using high-resolution ultraviolet spectrometers. These spectrometers, such as the UV Fourier transform spectrometer at Table Mountain, CA operated by JPL, measure column abundance of OH above an observatory. What NASA needs to advance the science in the coming decade is regional to global measurements with a portable instrument, preferably aircraft-based and ideally space-based.More »
|Organizations Performing Work
|Goddard Space Flight Center (GSFC)