Pacific western boundary currents and their roles in climate

Abstract

Pacific Ocean western boundary currents and the interlinked equatorial Pacific circulation system were among the first currents of these types to be explored by pioneering oceanographers. The widely accepted but poorly quantified importance of these currents-in processes such as the El Niño/Southern Oscillation, the Pacific Decadal Oscillation and the Indonesian Throughflow-has triggered renewed interest. Ongoing efforts are seeking to understand the heat and mass balances of the equatorial Pacific, and possible changes associated with greenhouse-gas-induced climate change. Only a concerted international effort will close the observational, theoretical and technical gaps currently limiting a robust answer to these elusive questions.

Marine projections of warming and ocean acidification in the Australasian region

“…Figure 2 shows that in terms of SST, the ESMs show reasonable agreement across much of north Australia but not at higher latitudes where, near southern Australia and in the Tasman Sea, differences of more than +8 K are simulated. This large range in the Tasman Sea likely reflects the variability in the strength of Pacific Western Boundary currents in the ESMs (Hu et al, 2015), which influences the southward extension of the East Australian Current (Ridgway, 2007). In contrast, the differences near southern Australia likely reflect differences in the location of isotherms related to the coarse resolution of current ESMs (Lenton et al, 2013).…”

State Space Analysis of Ocean Surface Warming on Decadal Scale

“…The strength of these boundary currents depends on the location of the point where the North or South Equatorial Current bifurcates on reaching the coast. There is evidence to show that this bifurcation point has moved over 60 years, suggesting a multi-decadal variation in the northward or southward flow 19 and consequently multi-decadal variation of the oceanic heat transport from TOR.…”

Global and regional surface cooling in a warming climate: a multi-model analysis

“…A large suite of possible factors influencing the recent hiatus in the global surface temperature have been identified, including: the possibility of too-high model sensitivity to increased greenhouse gas (GHG) forcing (Flato et al 2013); decadal-scale ocean uptake and storage of heat in the Pacific Ocean (e.g., Meehl et al 2011;Kosaka and Xie 2013;Meehl et al 2013;Trenberth and Fasullo 2013;England et al 2014;Hu et al 2015), in the Atlantic Ocean Abstract Instrumental temperature records show that the global climate may experience decadal-scale periods without warming despite a long-term warming trend. We analysed 17 global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), identifying the likelihood and duration of periods without warming in the four Representative Concentration Pathway (RCP) scenarios RCP2.6, RCP4.5, RCP6.0 and RCP8.5, together with the preindustrial control and historical simulations.…”

“…This paradox has generated a lot of attention among researchers (e.g., Easterling and Wehner 2009;Foster and Rahmstorf 2011;Katsman and van Oldenborgh 2011;Santer et al 2011Santer et al , 2014Trenberth and Fasullo 2013;Huber and Knutti 2014;Maher et al 2014;Risbey et al 2014;Watanabe et al 2014) and the general public (Tollefson 2014). It has also been used to cast doubts about the reliability of climate research in general and climate models in particular (Showstack 2014) since the ensemble mean of the models do not reproduce the so-called surface temperature hiatus.A large suite of possible factors influencing the recent hiatus in the global surface temperature have been identified, including: the possibility of too-high model sensitivity to increased greenhouse gas (GHG) forcing (Flato et al 2013); decadal-scale ocean uptake and storage of heat in the Pacific Ocean (e.g., Meehl et al 2011;Kosaka and Xie 2013;Meehl et al 2013;Trenberth and Fasullo 2013;England et al 2014;Hu et al 2015), in the Atlantic Ocean Abstract Instrumental temperature records show that the global climate may experience decadal-scale periods without warming despite a long-term warming trend. We analysed 17 global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), identifying the likelihood and duration of periods without warming in the four Representative Concentration Pathway (RCP) scenarios RCP2.6, RCP4.5, RCP6.0 and RCP8.5, together with the preindustrial control and historical simulations.…”