This graph and text illustrates the types of oceanographic background information that BBSR scientists would provide to the FIU teachers to help them most effectively use the BATS data.

Oceanographers usually graph their data with depth plotted downward on the y-axis , so that the graphed data provide a cross-sectional view of the actual ocean.

 peter@tmn.com August 17, 1997

The oceans have a well-mixed surface layer where the water temperatures are relatively constant.  Below the mixed layer is the thermocline, a zone where temperature changes rapidly with depth.  Below the thermocline the temperature is relatively uniform with depth, showing only a small decrease to the ocean bottom. 

The temperature structure of the upper ocean varies during the year.  The density of water varies with temperature and salinity;  with cold water denser than warm, and highly saline water denser than less saline.  During the summer the surface water warms.  As warmer water is less dense than cold, this warm water remains at the surface and the water column is “stable”. There is little wind so the mixed layer is shallow, as is the thermocline.  During the fall and winter,  cooler temperatures and wind from storms cool the surface waters.  This increases the density of the surface water, which then sinks to a level of similar density. This combination of cooling and wind mixing causes a deep mixed layer.  In  the spring, the water warms again and the thermocline reforms.