Historical Trends in North Pole Hydrography since the 1950s

A comparison of profiles of ocean temperature and salinity at the North Pole shows the extent of recent Arctic oceanic change. Values for the 1950s through the 1980s are obtained from mean fields of the Environmental Working Group Winter Atlas (EWG,1997). Each of these values is a decadal mean for those depth levels. Each sample from the 1990s is an individual cast, either Conductivity-Temperature-Depth (CTD) or Expendable CTD (XCTD). Each of these is a snapshot in both time and space, as near to the Pole as the particular expedition could reach, and may not be completely representative of local geographic or seasonal variation. Profiles for the years 2000 through 2008 and for 2010 are Seacat CTD casts obtained during North Pole Environmental Observatory deployment operations, during April of each year. The 2009 profile was a Seacat CTD-Chemistry cast made by Lamont-Doherty Earth Observatory in May 2009 as part of the Switchyard project.   (Click to view in PDF format)