Xu, X., & Chassignet, E. P., Wang, F. (2018). On the variability of the Atlantic meridional overturning circulation transports in coupled CMIP5 simulations.
Clim Dyn., 51(11), 6511–6531.
Abstract: The Atlantic meridional overturning circulation (AMOC) plays a fundamental role in the climate system, and long-term climate simulations are used to understand the AMOC variability and to assess its impact. This study examines the basic characteristics of the AMOC variability in 44 CMIP5 (Phase 5 of the Coupled Model Inter-comparison Project) simulations, using the 18 atmospherically-forced CORE-II (Phase 2 of the Coordinated Ocean-ice Reference Experiment) simulations as a reference. The analysis shows that on interannual and decadal timescales, the AMOC variability in the CMIP5 exhibits a similar magnitude and meridional coherence as in the CORE-II simulations, indicating that the modeled atmospheric variability responsible for AMOC variability in the CMIP5 is in reasonable agreement with the CORE-II forcing. On multidecadal timescales, however, the AMOC variability is weaker by a factor of more than 2 and meridionally less coherent in the CMIP5 than in the CORE-II simulations. The CMIP5 simulations also exhibit a weaker long-term atmospheric variability in the North Atlantic Oscillation (NAO). However, one cannot fully attribute the weaker AMOC variability to the weaker variability in NAO because, unlike the CORE-II simulations, the CMIP5 simulations do not exhibit a robust NAO-AMOC linkage. While the variability of the wintertime heat flux and mixed layer depth in the western subpolar North Atlantic is strongly linked to the AMOC variability, the NAO variability is not.
Xu, X., Rhines, P. B., & Chassignet, E. P. (2016). Temperature-Salinity Structure of the North Atlantic Circulation and Associated Heat and Freshwater Transports.
J. Climate, 29(21), 7723–7742.
Xue, W., Xin, X., Zhang, J., Zhang, W., Wu, H., Huang, Z., et al. (2016). Development and Testing of a Multi-model Ensemble Coupling Framework. In
Development and Evaluation of High Resolution Climate System Models (pp. 163–208). Springer.
Yatagai, A., Krishnamurti, T. N., Kumar, V., Mishra, A. K., & Simon, A. (2014). Use of APHRODITE Rain Gauge-Based Precipitation and TRMM 3B43 Products for Improving Asian Monsoon Seasonal Precipitation Forecasts by the Superensemble Method.
J. Climate, 27(3), 1062–1069.
Yin, J., Griffies, S. M., & Stouffer, R. J. (2010). Spatial Variability of Sea Level Rise in Twenty-First Century Projections.
J. Climate, 23(17), 4585–4607.
Zhang, M., Wu, Z., & Qiao, F. (2018). Deep Atlantic Ocean Warming Facilitated by the Deep Western Boundary Current and Equatorial Kelvin Waves.
J. Climate, 31(20), 8541–8555.
Abstract: Increased heat storage in deep oceans has been proposed to account for the slowdown of global surface warming since the end of the twentieth century. How the imbalanced heat at the surface has been redistributed to deep oceans remains to be elucidated. Here, the evolution of deep Atlantic Ocean heat storage since 1950 on multidecadal or longer time scales is revealed. The anomalous heat in the deep Labrador Sea was transported southward by the shallower core of the deep western boundary current (DWBC). Upon reaching the equator around 1980, this heat transport route bifurcated into two, with one continuing southward along the DWBC and the other extending eastward along a narrow strip (about 4 degrees width) centered at the equator. In the 1990s and 2000s, meridional diffusion helped to spread warming in the tropics, making the eastward equatorial warming extension have a narrow head and wider tail. The deep Atlantic Ocean warming since 1950 had overlapping variability of approximately 60 years. The results suggest that the current basinwide Atlantic Ocean warming at depths of 1000-2000 m can be traced back to the subsurface warming in the Labrador Sea in the 1950s. An inference from these results is that the increased heat storage in the twenty-first century in the deep Atlantic Ocean is unlikely to partly account for the atmospheric radiative imbalance during the last two decades and to serve as an explanation for the current warming hiatus.
Zheng, Y., Shinoda, T., Lin, J. - L., & Kiladis, G. N. (2011). Sea Surface Temperature Biases under the Stratus Cloud Deck in the Southeast Pacific Ocean in 19 IPCC AR4 Coupled General Circulation Models.
J. Climate, 24(15), 4139–4164.
Zheng, Y., Zhang, R., & Bourassa, M. A. (2014). Impact of East Asian Winter and Australian Summer Monsoons on the Enhanced Surface Westerlies over the Western Tropical Pacific Ocean Preceding the El Niño Onset.
J. Climate, 27(5), 1928–1944.
Zhu, J., Huang, B., & Wu, Z. (2012). The Role of Ocean Dynamics in the Interaction between the Atlantic Meridional and Equatorial Modes.
J. Climate, 25(10), 3583–3598.
Zou, S., Lozier, M. S., & Xu, X. (2020). Latitudinal Structure of the Meridional Overturning Circulation Variability on Interannual to Decadal Time Scales in the North Atlantic Ocean.
J. Climate, 33(9), 3845–3862.
Abstract: The latitudinal structure of the Atlantic meridional overturning circulation (AMOC) variability in the North Atlantic is investigated using numerical results from three ocean circulation simulations over the past four to five decades. We show that AMOC variability south of the Labrador Sea (53°N) to 25°N can be decomposed into a latitudinally coherent component and a gyre-opposing component. The latitudinally coherent component contains both decadal and interannual variabilities. The coherent decadal AMOC variability originates in the subpolar region and is reflected by the zonal density gradient in that basin. It is further shown to be linked to persistent North Atlantic Oscillation (NAO) conditions in all three models. The interannual AMOC variability contained in the latitudinally coherent component is shown to be driven by westerlies in the transition region between the subpolar and the subtropical gyre (40°–50°N), through significant responses in Ekman transport. Finally, the gyre-opposing component principally varies on interannual time scales and responds to local wind variability related to the annual NAO. The contribution of these components to the total AMOC variability is latitude-dependent: 1) in the subpolar region, all models show that the latitudinally coherent component dominates AMOC variability on interannual to decadal time scales, with little contribution from the gyre-opposing component, and 2) in the subtropical region, the gyre-opposing component explains a majority of the interannual AMOC variability in two models, while in the other model, the contributions from the coherent and the gyre-opposing components are comparable. These results provide a quantitative decomposition of AMOC variability across latitudes and shed light on the linkage between different AMOC variability components and atmospheric forcing mechanisms.