Measurements of Temperature Fluctuations in Breaking Surface Waves

Abstract

Measurements of temperature fluctuations and air entrainment within the upper 1 m of the surface caused by breaking surface waves have been acquired with a novel surface-following sensor array. Brief temperature fluctuations of order 20 mK?100 mK lasting up to 1.5 s and coincident with wave breaking are observed. Although a few of the temperature fluctuations represent direct measurements of the temperature of entrained air in large bubbles, it appears that in many cases the disruption of the ocean thermal boundary layer and its vertical mixing is observed. The observations suggest that wave breaking may play a role in the vertical mixing of warm or cool water stored in the top few centimeters near the ocean surface to depths at which more persistent structures continue the process. Only about 30% of whitecaps exhibit this temperature fluctuation. The authors hypothesize that measurable thermal injections tend to be concentrated in Langmuir convergence zones, which accentuate the thickness of the ocean thermal boundary layer.