Anthropogenic aerosols are effective radiative forcing agents that perturb the Earth’s climate. Major emission sources shifted from the western to eastern hemisphere around the 1980 s. An ensemble of single-forcing s...Anthropogenic aerosols are effective radiative forcing agents that perturb the Earth’s climate. Major emission sources shifted from the western to eastern hemisphere around the 1980 s. An ensemble of single-forcing simulations with an Earth System Model reveals two stages of aerosol-induced climate change in response to the global aerosol increase for 1940–1980 and the zonal shift of aerosol forcing for 1980–2020, respectively. Here, using idealized experiments with hierarchical models, we show that the aerosol increase and shift modes of aerosol-forced climate change are dynamically distinct, governed by the inter-hemispheric energy transport and basin-wide ocean–atmosphere interactions, respectively.The aerosol increase mode dominates in the motionless slab ocean model but is damped by ocean dynamics. Free of zonal-mean energy perturbation, characterized by an anomalous North Atlantic warming and North Pacific cooling, the zonal shift mode is amplified by interactive ocean dynamics through Bjerknes feedback. Both modes contribute to a La Ni?a-like pattern over the equatorial Pacific. We suggest that a global perspective that accommodates the evolving geographical distribution of aerosol emissions is vital for understanding the aerosol-forced historical climate change.展开更多
By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in dis...By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagrazn, Lyapunov exponent spectrum, time- domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2016R1A1A3A04005520 and 2017K2A9A1A06056874)supported by the National Science Foundation (AGS-1934392)+1 种基金The Community Earth System Model project is supported primarily by the National Science Foundation (NSF)supported by the National Center for Atmospheric Research, which is a major facility sponsored by the NSF under Cooperative Agreement (1852977)。
文摘Anthropogenic aerosols are effective radiative forcing agents that perturb the Earth’s climate. Major emission sources shifted from the western to eastern hemisphere around the 1980 s. An ensemble of single-forcing simulations with an Earth System Model reveals two stages of aerosol-induced climate change in response to the global aerosol increase for 1940–1980 and the zonal shift of aerosol forcing for 1980–2020, respectively. Here, using idealized experiments with hierarchical models, we show that the aerosol increase and shift modes of aerosol-forced climate change are dynamically distinct, governed by the inter-hemispheric energy transport and basin-wide ocean–atmosphere interactions, respectively.The aerosol increase mode dominates in the motionless slab ocean model but is damped by ocean dynamics. Free of zonal-mean energy perturbation, characterized by an anomalous North Atlantic warming and North Pacific cooling, the zonal shift mode is amplified by interactive ocean dynamics through Bjerknes feedback. Both modes contribute to a La Ni?a-like pattern over the equatorial Pacific. We suggest that a global perspective that accommodates the evolving geographical distribution of aerosol emissions is vital for understanding the aerosol-forced historical climate change.
基金Project supported by the National Natural Science Foundations of China (Grant Nos 50677056 and 60472059)
文摘By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagrazn, Lyapunov exponent spectrum, time- domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.
