Meridional transports in the North Atlantic

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Meridional transports in the North Atlantic


The ocean's thermal inertia and high heat capacity is of central importance within the global climate system: at one side the ocean regulates climate variations by its ability to store a large amount of heat and at the other side the ocean balances climate differences between higher and lower latitudes by its large-scale circulation. An usefull integral parameter to determine the large-scale circulation is the advective transport of oceanic properties such as the transport of temperature, the heat transport, or the transport of heat and freshwater, respectively. Simultaneously measurements of temperature and absolute velocity are necessary to directly determine i.e. the oceanic heat transport. Direct current measurements are only available in a few regions of the world ocean. From hydrographic data - the measured distribution of temperature and salinity as a function of depth - one can estimate the transports in a quasi-direct way. But especially data sets that span the whole water column exist temporal and spatial also only in a discret form. An exception is there the transatlantic section between the English Channel and the Grand Banks of Newfoundland.

Since 1993, the BSH has routinely measured the transports of heat and freshwater in the North Atlantic Ocean across the line English Channel-Grand Banks of Newfoundland (ca. 45°N). The measurements were made according to the criteria of the World Ocean Circulation Experiment (WOCE), and partly contributed to the WOCE hydrographic programme  and since 1998 to GOOS, respectively. During the cruises of the German research vessels "Gauss" (BSH) and "Meteor" (RF) and an one-time survey of the russian research vessel "Akademik Vavilov", seven high-resolution hydrographic data sets have been obtained so far covering the so-called WOCE/A2- or "48°N"-section. Another transatlantic cruise is planned for 2002.

Including two historical cruises made in 1957 and 1982 and seven realisations of the WOCE/A2-section in the 90s (1993, 1994, 1996, 1997, 1998, 1999, 2000) a data set are presently available to determine from hydrographic observations alone the temporal and spatial variability of the thermohaline structure along ca. 45°N in the North Atlantic and of the large-scale circulation - the Meridional Overturning Circulation (MOC) on interannual and climate-relevant decadal scales.

  1957 1982  
  S S  
  T T  
1993 1994 1996 1997
1998 1999 2000 2002?
S S S  
T T T  
Vertical distribution of potential Temperature and Salinity along "48° N" in the North Atlantic 

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 © 2016 Bundesamt für Seeschifffahrt und Hydrographie Last Update: May 7, 2013 12:13:57 PM  
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