Thermal Infrared Spectroscopy of Atmospheric Species Critical to Radiative Forcing of Earth’s Climate

Abstract:

Thermal-infrared (from about 6 to 100 or more microns wavelength), emission-mode Fourier transform spectrometer (FTS) systems acquire radiometric spectra for diurnal diagnostics of atmospheric properties. We have been funded through NASA’s Planetary Instrument Definition and Development Program (PIDDP) to develop CIRS-lite as a lightweight successor to the Goddard-developed Cassini CIRS FTS currently operating in Saturn orbit. CIRS-lite also has promise for Earth science due to its modest mass, power and volume requirements and novel technical capabilities.

For Earth, CIRS-lite supports the characterization of climate radiative forcing, including trace species measurements such as methane. Detection capability beyond the typical limit of HgCdTe focal planes (about 16 microns wavelength) enables a more complete characterization of the greenhouse effect. As for trace-species quantification, a beyond-HgCdTe focal plane permits characterization of water without overlapping lines from other species, enabling better measurements of these other species such as methane at wavelengths reachable by HgCdTe.