摘要：We conducted a drift simulation of tsunami debris flushed out from the Tohoku district, Japan into the North Pacific in the wake of the catastrophic tsunami on March 11, 2011, to monitor and forecast the drift path over the entire North Pacific. We performed a hindcast run of the drift path to identify and characterize the distribution of tsunami debris from March 2011 to September 2013 using ocean current and ocean surface wind time-series data obtained by a three-dimensional variational data assimilation system for the ocean and atmosphere, respectively. We further performed a forecast run from October 2013 to June 2016 in which the forecasted data with a coupled ocean-atmosphere four-dimensional variational data assimilation system was used. The results showed that the tsunami debris was first transported eastward by both the intense Kuroshio Extension and westerly winds, spreading northward and southward under the influence of both an energetic ocean eddy and a storm track over the ocean. Tsunami debris with larger windage was transported over the North Pacific by ocean surface winds rather than ocean currents and arrived at the west coast of North America in the fall of 2011. Tsunami debris located near the North American Continent migrated in associa- tion with a basin-scale seasonal change in the atmospheric pressure pattern. Our forecast run suggested that a tsunami debris belt will be formed, stretching from the North American Continent in the east to the Philippines in the west.
关键词：data assimilation; drift simulation; Great East Japan Earthquake; North Pacific; tsunami debris
