Disentangling physical and dynamical drivers of the 2016/17 record-breaking warm winter in China

Abstract

Understanding the physical and dynamical origin of regional climate extremes remains a major challenge in our effort to anticipate the occurrences and mitigate the adverse impacts of these extremes. China was hit by a record-breaking hot winter in 2016/17 with remarkable surface warming over the northern and southeastern regions. Here we made a quantitative attribution of this 2016/17 winter’s surface temperature anomalies utilizing an updated version of the coupled atmosphere-surface climate feedback response analysis method (CFRAM), that recently incorporates the effect of aerosols and more species of trace gases (CFRAM-A). The CFRAM-A analysis reveals that the overall warming pattern may be largely attributed to the effects of anomalous water vapor, atmospheric dynamics, and aerosols, followed by anomalies of surface albedo, clouds, solar irradiance, ozone, and carbon dioxide. The effect of methane turns out to be negligible. Anomalies in surface dynamics provides an overall cooling effect, compensating the warming associated with other processes to some extent. Among the three major positive contributors, effects of water vapor and atmospheric dynamics prevail over both northern and southeastern China while the impact of anthropogenic aerosols appears much more pronounced over southeastern China, likely due to the implementation of highly effective emission reduction policies in China since 2013. The CFRAM-A thus provides an efficient, model-free approach for quantitatively understanding sources of regional temperature extremes and for assessing the impacts of environmental policies regulating anthropogenic emissions of aerosols and atmospheric trace gases.

An energetics tale of the 2022 mega-heatwave over central-eastern China

“…Considering the dominance of the anthropogenic aerosols (i.e., black carbon and sulfate) in the total effects of aerosols, a lower level of aerosol concentration during the 2022 summer is possibly linked to the highly effective policies of emission reduction implemented since 2013 in China. A recent study also reported a positive contribution of reduction in anthropogenic aerosols to the 2016/17 record-breaking warm winter in China 37 . It highlights an important implication that the reduction in anthropogenic aerosols associated with the effective pollution mitigation measures (if taken) could actually facilitate the occurrence of regional heatwaves.…”

“…Furthermore, the interactions among different radiative-active species are relatively small as proposed by the partial radiative perturbation method 30 (PRP) and the coupled atmosphere-surface climate feedback-response analysis method (CFRAM) 31,32 . Through linearizing the radiative energy perturbations, we may express the changes in net shortwave and longwave radiative fluxes in each layer as the sum of the changes in partial net radiative energy fluxes due to individual radiative processes (details referred to Zhang et al 37 ):…”

“…According to the total energy balance equation, the temperature change-induced longwave cooling is balanced by multiple physical processes in an equilibrium state. In light of such a premise, several climate attribution methods including but not limited to the partial radiative perturbation method 30 (PRP) and the coupled atmosphere-surface climate feedback-response analysis method 31,32 (CFRAM), have been developed to quantify the contributions from individual processes to radiative forcings at the top of the atmosphere/surface and to air/surface temperatures changes from seasonal to decadal time scales [33][34][35][36][37] . However, these methods are not applicable in a non-equilibrium state, where weather and climate extreme events lie in.…”

Extreme warm spells may facilitate the new temperature record in 2023

“…Previous climatic studies on record-breaking temperatures have mainly focused on the seasonal time scale, such as the warmest winter in 2016 [2], the hottest summer in 2018 [3], and the exceptional summer temperatures in 2022 [4]. Mechanism diagnoses of the external forcing and internal atmospheric circulations of these record-breaking temperatures have also been focused on the seasonal scale.…”

An energetics tale of the 2022 mega-heatwave over central-eastern China

“…al. (2022)35 , the Rapid Radiative Transfer Method for general circulation model version 558 and the Monte Carlo integration of the Independent…”