Estimation of the radiative effect of stratospheric aerosols using a new set of radiative kernels

We have developed a new set of radiative kernels to facilitate the quantification of the stratospheric aerosol direct radiative effect. The multi-dimensional kernel dataset quantifies the radiative sensitivity, which varies with latitude, longitude, time, and wavelength, to stratospheric aerosol optical depth (AOD), distinguishing absorptive and scattering aerosol types. Besides the geographical varying band-by-band kernels, we also introduce an analytical method that emulates the kernel values as a function of environmental control factors, including top-of-atmosphere insolation and reflectance. Applying these kernels, we estimate the stratosphere aerosol radiative effects of the 2022 Hunga volcanic eruption and the 2020 Australian wildfire. The Hunga eruption resulted in a global mean cooling effect of approximately -0.4 W/m² throughout 2022. In contrast, the Australian wildfire induced a global mean instantaneous ARE of +0.3 W/m² and a stratosphere-adjusted ARE of -0.04 W/m². Validation against radiative transfer model calculations confirms the accuracy of the kernel-based estimates. Our findings underscore the significance of spectral dependencies in stratospheric aerosol radiative effect and highlight the distinct radiative sensitivities of stratospheric aerosols compared to their tropospheric counterparts. The radiative kernels afford an efficient and versatile tool for assessing the climatic impacts of stratospheric aerosols.