Measurement-model intercomparison of long-term spectral and broadband infrared measurement trends at the ARM SGP site
Authors
Daniel Feldman — Lawrence Berkeley National Laboratory
Margaret S. Torn — Lawrence Berkeley National Laboratory
William D. Collins — Lawrence Berkeley National Laboratory
Jonathan Gero — University of Wisconsin
Description
Trends and associated statistics in both spectral and broadband downwelling longwave radiation are determined from the atmospheric emitted radiance interferometer and the broadband radiometer station, respectively, at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site. These measurements are compared against spectral and broadband simulations based on historical forcing runs from the Community Climate System Model (CCSM), versions 3 and 4. We find that the phase and amplitude of trends as measured and from the climate models do not differ statistically. In the spectra, we find that the increase in CO2 over the time-span of the measurements can be detected in the wings of the R-branch of v2 absorption feature around 13.5 μm. Additionally, the contributions of water vapor and clouds to trends in downwelling longwave radiation are compared between measurement and model using the differential sensitivity of the mid-infrared window band (8–12 μm). Finally, we discuss prospects for comparing long-term spectral and broadband measurements at ARM against the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive.
