Band-by-band contributions to the longwave cloud radiative feedbacks

Cloud radiative feedback is central to our projection of future climate change. It can be estimated using the cloud radiative kernel (CRK) method or adjustment method. This study, for the first time, examines the contributions of each spectral band to the longwave (LW) cloud radiative feedbacks (CRFs). Simulations of three warming scenarios are analyzed, including +2K SST, 2xCO2, and 4xCO2 experiments. While the LW broadband CRFs derived from the CRK and adjustment methods agree with each other, they disagree on the relative contributions from the far-IR and window bands. The CRK method provides a consistent band-by-band decomposition of LW CRF for different warming scenarios. The simulated and observed short-term broadband CRFs for the 2003-2013 period are similar to the long-term counterparts, but their band-by-band decompositions are different, which can be further related to the cloud fraction changes in respective simulations and observation.