An observation of the gulf stream surface front structure by ship, aircraft, and satellite

Abstract

Observations of surface temperature and salinity along the western edge of the Gulf Stream were made from a ship while concurrent temperature observations were obtained by instrumented aircraft at six altitudes. The major feature along a five-kilometer line normal to the Stream's edge is a temperature gradient of about 0.75°C/kilometer within which are embedded two abrupt temperature increases of about 1.5°C. Temperature variations were compensated by salinity variations, yielding nearly constant density through the frontal zone; a sharp lateral current shear was associated with the thermohaline mixing region between the steps. The attenuation of surface temperature measured by the airborne radiometer was compared with a theoretical model. The analysis supports the view that a two-part correction technique is required: one part for bulk-skin temperature differences, and another for atmospheric attenuation of sea surface emission due to the mass and temperature of interfering gases. Electronic noise and scan geometry of the Nimbus II radiometer experiment prohibits any discussion of detailed oceanographic variability as seen from space, however, the gross features of the front are reproduced to a fair degree of accuracy.