Jeffrey C. Mast

The spectroscopic foundation of radiative forcing of climate by carbon dioxide

Abstract The radiative forcing (RF) of carbon dioxide (CO2) is the leading contribution to climate change from anthropogenic activities. Calculating CO2 RF requires detailed knowledge of spectral line parameters for thousands of infrared absorption lines. A reliable spectroscopic characterization of CO2 forcing is critical to scientific and policy assessments of present climate and climate change. Our results show that CO2 RF in a variety of atmospheres is remarkably insensitive to known uncertainties in the three main CO2 spectroscopic parameters: the line shapes, line strengths, and half widths. We specifically examine uncertainty in RF due to line mixing as this process is critical in determining line shapes in the far wings of CO2 absorption lines. RF computed with a Voigt line shape is also examined. Overall, the spectroscopic uncertainty in present‐day CO2 RF is less than 1%, indicating a robust foundation in our understanding of how rising CO2 warms the climate system.

Far-Infrared Spectroscopy of Water Vapor: Results from Deployment of FIRST to Cerro Toco and Requirements for Future Experiments in Extremely Dry Environments

Radiative transfer measurements in extremely dry environments offer fundamental tests of water vapor spectroscopy. For such studies instrument and water vapor input to radiative transfer models need to be known to within 2%.

Observations Of Downwelling Far-Infrared Radiance At Earth’s Surface with FIRST

Far-infrared radiance from the atmosphere was observed at Earth’s surface at Cerro Toco, Chile, and Table Mountain, CA with the NASA FIRST instrument. Measurements are compared with model calculations, showing agreement within their combined uncertainty.