NODC Standard Product: Ocean current drifter data (2 disc set) (NCEI Accession 0098060)

These CD-ROMs hold over 4 million surface current observations, almost all obtained by the ship drift method. Date, data source, position, and current direction and speed are recorded for each observation. With the exception of about 5,100 observations taken using the Geomagnetic Electrokinetograph (GEK), these are not instrument-measured current data. Rather, they are indirect determinations of ocean surface currents based on the ship drift method. In this method, the difference between a ship's dead-reckoned position (determined from its previous position determined from a navigational fix) is ascribed solely to the effect of surface currents. These data are contained on disc 1 of this set.

In addition to the data files, disc 2 of this set provides surface current data summaries in the NODC Surface Current (Ship Drift) Long Summary format. These data are summarized by Modified Canadian ten-degree square, one-degree square, and month for all years. A Postscript file showing the Modified Canadian ten-degree square numbers is also included on disc 2 of this set. Subsurface Float Trajectories: The Subsurface Float Data Set consists primarily of SOFAR (Sound Fixing and Ranging) and RAFOS (SOFAR spelled backwards) float trajectories. These floats are ballasted for a target depth and acoustically tracked. Some ALACE (Autonomous Lagrangian Circulation Explorer) float trajectories are included with this float data set. ALACE is a subsurface float that cycles vertically from a depth where it is neutrally buoyant to the surface where it is located by, and relays data to, satellites. The Subsurface Float data has approximately 475 float trajectories and 432 float-years of data. Float depths range from a few hundred meters to several thousand with most observations falling in the 700 m to 2000 m depth range. Most of the trajectories are located in the North Atlantic Ocean and were obtained as part of a variety of experiments during the years 1972-1992.