A role of the Atlantic Ocean in predicting summer surface air temperature over North East Asia?

Simulations performed with Ocean–Atmosphere General Circulation Models (OAGCM) under the Climate Model Intercomparison Project, phase 5 (CMIP5) (Taylor et al. 2012), provide climate predictions for the upcoming 100 years (the so-called radiative concentration pathways emission scenarios). However, CMIP simulations suffer from severe limitations in predicting climate at a shorttime horizon (< 10 years), as highlighted by the “hiatus” in global-mean surface temperature rise (Watanabe et al. 2013; Kosaka and Xie 2013; Meehl et al. 2014). To fill this gap, initialized near-term (or decadal) prediction systems have been developed (Meehl et al. 2009) to provide better predictions than uninitialized simulations (Bellucci et al. 2013; Karspeck et al. 2015) on seasonal-to-decadal timescales. Decadal prediction systems are initialized frequently (generally from every year to every 5 years) to improve the simulation of internal variability. The added value of the initialization stands out over the North Atlantic Ocean where an accurate initialization of the Atlantic Meridional Overturning Circulation (AMOC) is thought to allow Atlantic Multidecadal Variability (AMV) to be predicted years in advance (Griffies and Bryan 1997; Boer 2000; Collins et al. 2006; Pohlmann et al. 2013). Thus, near-term climate prediction systems are useful tools to provide predictions at interannual-to-decadal timescales, which are helpful to calibrate plans and actions related to climatic events due to Abstract We assess the ability of the DePreSys3 prediction system to predict the summer (JJAS) surface-air temperature over North East Asia. DePreSys3 is based on a high resolution ocean–atmosphere coupled climate prediction system (~ 60 km in the atmosphere and ~ 25 km in the ocean), which is full-field initialized from 1960 to 2014 (26 start-dates). We find skill in predicting surface-air temperature, relative to a long-term trend, for 1 and 2–5 year leadtimes over North East Asia, the North Atlantic Ocean and Eastern Europe. DePreSys3 also reproduces the interdecadal evolution of surface-air temperature over the North Atlantic subpolar gyre and North East Asia for both lead times, along with the strong warming that occurred in the mid-1990s over both areas. Composite analysis reveals that the skill at capturing interdecadal changes in North East Asia is associated with the propagation of an atmospheric Rossby wave, which follows the subtropical jet and modulates surface-air temperature from Europe to Eastern Asia. We hypothesise that this ‘circumglobal teleconnection’ pattern is excited over the Atlantic Ocean and is related to Atlantic multi-decadal variability and the associated changes in precipitation over the Sahel and the subtropical Atlantic Ocean. This mechanism is robust for the 2–5 year lead-time. For the 1 year lead-time the Pacific Ocean also plays an important role in leading to