Deduction fo synthetic temperature profiles from SST observations in the Iceland-Faeroe frontal region

Abstract

Subsurface temperature and sound speed profiles are generated from satellite SST observations and

validated by hydrocast observations. Hydrographic data from the October 1992 Iceland Faeroe frontal

survey is used for the calculation of Empirical Orthogonal Functions (EOFs). Statistical relationships

between the EOF amplitudes and SSTs are derived and used for the construction of synthetic

temperature profiles and sound speed distributions in the ocean. Average Root-Mean Square (RMS)

errors were computed for synthetic temperature profiles in typical water categories. Corrections to the

processed satellite SST data were applied using surface drifter data and sensitivity tests. The survey

data reflects the water mass structure in three distinct regions; Atlantic, Frontal and Arctic, for which characteristic TS curves are derived. The best agreement between the synthetically generated

temperature profiles, from SST data, with CTD measurements occurs in the Arctic region where a

tendency to follow the slope and magnitude versus depth exists. The Frontal region shows

disagreements in the upper thermocline with agreement elsewhere. In the Atlantic region there is agreement only in the upper mixed layer. In the thermocline regime the slope exhibits a parallel offset relative to the data. The differences are attributed to the inherent errors of EOF reconstruction which peak in the thermocline and the scatter of EOF amplitudes versus SST measurements. The work demonstrates that it is possible to derive synthetic temperature and sound speed profiles in the ocean from SST observations of particular water mass configurations at certain times of the season.