Interannual variability of winter precipitation linked to upper ocean heat content off the east coast of Korea

We present a link between highly variable winter precipitation (e.g. occasional heavy snow) in the mountainous cities along the east coast of Korea and upper ocean heat content (OHC) in the western part of the East Sea (Japan Sea). After removing annual climatological cycle, OHC (as well as sea surface temperature, SST) variability coherent with the winter sea surface wind (SSW) is extracted using maximum covariance analysis (MCA). The first-mode MCA pattern, explaining 68% of the total covariance, indicates that the stronger westerly (easterly) winter SSW links to larger (smaller) OHC in the upper 400 m or higher (lower) SST of the western part of the sea. Time series of the first-mode MCA are comparable to winter precipitation variability at three local cities along the coast (Gangneung, Donghae, and Uljin) with significantly high correlation coefficients (0.84, 0.68, and 0.56, respectively). The links between OHC and SSW and between SSW and precipitation are discussed because zonal contrast of OHC drives zonal tilt of northerly monsoonal wind in winter by canonical turbulent momentum exchange within the marine planetary boundary layer (MPBL). The momentum exchange within the MPBL yields the interannual variability of SSW and thus, winter precipitation in the coastal cities.