title: Origin of seasonal predictability for summer climate over the Northwestern Pacific.
abstract: Summer climate in the Northwestern Pacific (NWP) displays large year-to-year variability, affecting densely populated Southeast and East Asia by impacting precipitation, temperature, and tropical cyclones. The Pacific-Japan (PJ) teleconnection pattern provides a crucial link of high predictability from the tropics to East Asia. Using coupled climate model experiments, we show that the PJ pattern is the atmospheric manifestation of an air-sea coupled mode spanning the Indo-NWP warm pool. The PJ pattern forces the Indian Ocean (IO) via a westward propagating atmospheric Rossby wave. In response, IO sea surface temperature feeds back and reinforces the PJ pattern via a tropospheric Kelvin wave. Ocean coupling increases both the amplitude and temporal persistence of the PJ pattern. Cross-correlation of ocean-atmospheric anomalies confirms the coupled nature of this PJIO mode. The ocean-atmosphere feedback explains why the last echoes of El Niño-Southern Oscillation are found in the IO-NWP in the form of the PJIO mode. We demonstrate that the PJIO mode is indeed highly predictable; a characteristic that can enable benefits to society.
authors.affiliation: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA. ykosaka@ucsd.edu
authors.forename: Yu
authors.initials: Y
authors.lastname: Kosaka
authors.forename: Shang-Ping
authors.initials: SP
authors.lastname: Xie
authors.forename: Ngar-Cheung
authors.initials: NC
authors.lastname: Lau
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Vecchi
mesh_terms: D000388:Air; D002980:Climate; D005843:Geography; D007564:Japan; D008962:Models, Theoretical; D009991:Oscillometry; D010140:Pacific Ocean; D011312:Pressure; D012044:Regression Analysis; D015203:Reproducibility of Results; D012621:Seasons; D013696:Temperature; D013997:Time Factors; D014329:Tropical Climate; D014887:Weather
keywords: East Asian summer monsoon; air–sea interaction; interbasin interaction; tropical variability