Variability in water properties and predictability of sea surface temperature along Sanriku coast, Japan

Abstract We investigated the main controlling factors and predictability of extreme sea surface temperature changes along the Sanriku coast (the east coast of the northern part of Japan's main island). We analyzed distributions of water properties and flow fields via intensive observations using a conductivity–temperature–depth profiler and a coastal water-temperature monitoring system from January 1998 to December 2012. Satellite altimetry and tide gauge data were also analyzed to investigate more widespread horizontal and temporal variation of the sea surface flow field. Anomalous temperature events (2 °C lower and higher than climatological monthly values) were observed in winter 2006 and fall 2010 and 2012 along the Sanriku coast. In winter (fall) 2006 (2010, 2012), we observed both unusually thick and wide cold/fresh (warm/saline) waters, corresponding to the Oyashio (Tsugaru Warm Current) waters. At that time, sea surface velocities of the Oyashio (Tsugaru Warm Current) along the Hokkaido coast (Tsugaru Strait) were also high. We propose new methods for predicting extreme temperature changes a few months in advance, based on current observations.