Past shifts in the general circulation: Causation, structure, and effects on hydroclimate

摘要: There is now abundant evidence that an important consequence of recent climate change the displacement key elements within global circulation. Considerable uncertainty exists with regard to sign and magnitude these changes, it also not fully understood how roles individual anthropogenic forcings contribute toward their cause. Because potential impacts they may impose upon hydroclimate, changes in circulation, particularly causation, are high interest. Our primary goal differentiate between various driving shifts. We analyze results from long time-slice simulations performed using a stateof-the-art atmospheric general circulation model, which show features have shifted poleward since preindustrial era. Many shifts characterized by pronounced seasonality exhibit tendency be maximized during summer months each respective hemisphere. Furthermore, tends greater variability both over southern hemisphere extratropical regions. While reductions ozone increases greenhouse gas concentrations played role indirect effects feedback mechanisms been dominant. In most cases, linear addition produced those experiments prescribed nearly identical for experiment all included. This result remarkably consistent, indicating lead approximately linearly additive.