Band-by-band spectral radiative kernels based on the ERA5 reanalysis

Abstract

Radiative kernel is a widely adopted method for diagnosing radiation variability and climate feedback. However, most of the existing radiative kernels are broadband flux kernels and lack the spectral information. Motivated by the growing interest in the spectral changes of the Earth radiation budget, we generate a new set of band-by-band radiative kernels based on the fifth generation European Center for Medium-Range Weather Forecasts (ERA5) reanalysis, which can be used for analyzing the spectrally decomposed changes in the top of atmosphere, surface and atmospheric radiation. The radiative sensitivity quantified by the ERA5 band-by-band kernel is compared to another spectral kernel and validated in a spectral radiation closure test. The use and benefits of the new ERA5 kernels are then demonstrated in an analysis of spectral feedbacks of an ensemble of global climate models (GCMs).

Arctic as the ‘radiator fins’ of Earth in a warming climate

“…The spectral radiative response can be calculated using similar method but with spectral radiative kernel. Here we use a set of spectral radiative kernel based on ERA5 reanalysis [39], which is also generated by RRTMG and has the same band configurations as the simulations used in this study. The spectral noncloud radiative responses are calculated as,…”

“…If organizing the water vapor and temperatureinduced spectral OLR changes to Planck, lapse rate (LR) and relative humidity change (RH) effects (figure 3(d)), according to the decomposition Method [38] (see Data and Method section) and using the aid of spectral kernels [39], it is clear that the prominent increase of OLR in Arctic compared to tropics is largely contributed by the Planck term, which further affirms that the unique increase of OLR in the Arctic region is due to the distinct radiative sensitivity of OLR to temperature and water vapor changes in this region and not caused by different vertical patterns or non-thermodynamicallyconstrained (varying RH) changes of them.…”