Researchers confirm existence of North Icelandic Jet current; implications for ocean response to climate change

Read the full post at Green Car Congress.

An international team of researchers has confirmed the presence of a deep-reaching ocean circulation system off Iceland—the North Icelandic Jet (NIJ)—that could significantly influence the ocean’s response to climate change in previously unforeseen ways.

Full citation for the research article: Kjetil Våge, Robert S. Pickart, Michael A. Spall, Héðinn Valdimarsson, Steingrímur Jónsson, Daniel J. Torres, Svein Østerhus & Tor Eldevik (2011) Significant role of the North Icelandic Jet in the formation of Denmark Strait overflow water. Nature Geoscience. doi: 10.1038/ngeo1234.

Abstract: The Denmark Strait overflow water is the largest dense water plume from the Nordic seas to feed the lower limb of the Atlantic Meridional Overturning Circulation. Its primary source is commonly thought to be the East Greenland Current. However, the recent discovery of the North Icelandic Jet—a deep-reaching current that flows along the continental slope of Iceland—has called this view into question. Here we present high-resolution measurements of hydrography and velocity north of Iceland, taken during two shipboard surveys in October 2008 and August 2009. We find that the North Icelandic Jet advects overflow water into the Denmark Strait and constitutes a pathway that is distinct from the East Greenland Current. We estimate that the jet supplies about half of the total overflow transport, and infer that it is the primary source of the densest overflow water. Simulations with an ocean general circulation model suggest that the import of warm, salty water from the North Icelandic Irminger Current and water-mass transformation in the interior Iceland Sea are critical to the formation of the jet. We surmise that the timescale for the renewal of the deepest water in the meridional overturning cell, and its sensitivity to changes in climate, could be different than presently envisaged.

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