caa a22 4500 605473978 CHVBK 20210128100345.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s00382-014-2315-1 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2315-1 Resolving the upper-ocean warm layer improves the simulation of the Madden-Julian oscillation [Elektronische Daten] [Wan-Ling Tseng, Ben-Jei Tsuang, Noel Keenlyside, Huang-Hsiung Hsu, Chia-Ying Tu] Here we show that coupling a high-resolution one-column ocean model to an atmospheric general circulation model dramatically improves simulation of the Madden-Julian oscillation (MJO) to have realistic strength, period, and propagation speed. The mechanism for the simulated MJO involves both frictional wave-convective conditional instability of the second kind (Frictional wave-CISK) and air-sea convective intraseasonal interaction (ASCII). In particular, better resolving the fine structure of upper ocean temperature, especially the warm layer, produces more vigorous atmosphere-ocean interaction and strengthens intraseasonal variations in both SST and atmospheric circulation. This helps organize and strengthen deep convection, inducing a stronger Kelvin-wave like perturbation and frictional near-surface convergence to the east. In addition, the warmer SST ahead of the MJO also acts to destabilize the boundary layer and enhance frictional convergence. These lead to a more realistic eastward-propagating MJO. A suite of sensitivity experiments were performed to show the robustness of the mechanisms and to demonstrate: (1) that mean state differences are not the main contributors to the improved simulation of our coupled model; (2) the role of SST variability in enhancing frictional convergence and intraseasonal variations in precipitation, and (3) that the simulation is significantly degraded when the first ocean model layer is thicker than 10m. Our coupled model results are consistent with observations and demonstrate a simple but effective means to significantly improve MJO simulation and potentially also forecasts. Springer-Verlag Berlin Heidelberg, 2014 MJO nationallicence Coupling nationallicence Warm layer nationallicence One column ocean model nationallicence Tseng Wan-Ling Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut Tsuang Ben-Jei Department of Environmental Engineering, National Chung-Hsing University, Taichung, Taiwan aut Keenlyside Noel Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway aut Hsu Huang-Hsiung Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut Tu Chia-Ying Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut Climate Dynamics Springer Berlin Heidelberg 44/5-6(2015-03-01), 1487-1503 0930-7575 44:5-6<1487 2015 44 382 https://doi.org/10.1007/s00382-014-2315-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2315-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tseng Wan-Ling Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut NATIONALLICENCE 700 1- Tsuang Ben-Jei Department of Environmental Engineering, National Chung-Hsing University, Taichung, Taiwan aut NATIONALLICENCE 700 1- Keenlyside Noel Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway aut NATIONALLICENCE 700 1- Hsu Huang-Hsiung Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut NATIONALLICENCE 700 1- Tu Chia-Ying Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 44/5-6(2015-03-01), 1487-1503 0930-7575 44:5-6<1487 2015 44 382