Possible predictability in overflow from the Denmark Strait

摘要: The overflow and descent of cold dense water from the Denmark Strait sill-a submarine passage between Greenland Iceland-is a principal means by which deep ocean is ventilated, an important element in global thermohaline circulation. Previous investigations its variability-in particular, direct current measurements(1,2) core since 1986-have shown surprisingly little evidence long-term changes now speed. Here we report significant characteristics during winter 1996-97, measured using two current-meter moorings inverted echo sounder located at different depths fastest part now. warmed to highest monthly value yet recorded (2.4 degrees C), showed pronounced slowing thinning lower margin. We believe that extreme warmth caused it run higher on continental slope off east Greenland, so meters were temporarily outside deeper than fast-flowing core; model simulations appear confirm this interpretation, suggest lagged response warming upstream Fram three years earlier (caused exceptional amplification North Atlantic Oscillation). If so, over-now may be predictable.