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 adjust method. This study, for the first time, examines the contributions of each spectral band to the longwave (LW) cloud radiative feedbacks (CRF). Both the CRK and adjust methods are used to derive the CRF. Simulations of three warming scenarios are analyzed, including +2K SST, 2xCO₂, and 4xCO₂ experiments. While the LW broadband CRFs derived from the two 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, with the far-IR and the window bands each contributing ~ 33-40% to the LW CRF. However, for the simulated and observed short-term CRF for the 2003-2013 period, the far-IR band contributes much less than the window band.