Land-falling typhoons are controlled by the meridional oscillation of the Kuroshio Extension
Low-frequency variations of typhoon paths are often attributed to changes in the North Pacific subtropical high and monsoon through influences on the steering wind. Evidence indicates however a strong imprint of the Kuroshio on the atmosphere. Here we show that the meridional oscillation of sea surface temperature (SST) front over the Kuroshio Extension east of Japan significantly correlates with the number of land-falling typhoons along East Asia from June to October, accounting for 70% of the low-frequency variance since 1980. We used observations and a simple model to show that when the SST front shifts poleward (equatorward), SST gradient south of the current and westerly tropospheric wind weaken (strengthen), steering more typhoons to veer toward (away from) the East Asian continent. Our analysis also indicates that long-term weakening of SST gradient and westerly wind appears to be concomitant with poleward shifting of the Kuroshio, attributed to global warming in some studies, and suggests the potential for more land-falling typhoons in East Asia in the coming decades.
KeywordsTyphoons Steering flow Kuroshio Extension SST front Air-sea coupling
We thank Bo Qiu for making his KEI time series data available. The WPSH & EASM indices were calculated from the NCEP data (below) (Wang et al. 2013). Other data are all publicly available in the following web-links: IBTrACS: https://climatedataguide.ucar.edu/climate-data/ibtracs-tropical-cyclone-best-track-data; NCEP: http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html; Niňo3.4: http://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Nino34/; PDO: https://www.ncdc.noaa.gov/teleconnections/pdo/; SRB: https://eosweb.larc.nasa.gov/project/srb/srb_table; GPCP: https://www.esrl.noaa.gov/psd/data/gridded/data.gpcp.html; NOAA: https://www.esrl.noaa.gov/psd/data/gridded/data.interp_OLR.html.
- Hansen J, Ruedy R, Sato M, Lo K (2010). Global surface temperature change. Rev Geophys, 48(4)Google Scholar
- Lau WK, Kim KM (2015), Robust Hadley Circulation changes and increasing global dryness due to CO2 warming from CMIP5 model projections. Proc Natl Acad Sci 112(12):3630–3635Google Scholar
- Qiu B, Chen S, Schneider N (2016) Inter-decadal modulations in the dynamical state of the Kuroshio Extension system 1905–2015. CLIVAR Exchang #69 20:6–9Google Scholar