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Small-scale Temperature Variability Affected by Rain Events During SPURS-2
[24-May-2017] Chickadel, C., Drushka, K., Asher, W., Thompson, E., Gaube, P., and Jessup, A.
Presented at the Global Ocean Salinity and the Water Cycle Workshop
High-resolution thermal imagery captured from a shipboard infrared camera during the SPURS 2 experiment shows development of small-scale skin temperature variability. These centimeter to meter wavelength features are typically elongate and linear, similar to classic Langmuir cells. They were observed over a range of wind and rain events, though their character varied. Previously, the characteristics and kinematics of these small features have been studied only from a small set of ocean and laboratory experiments. Our aim is to understand the significance of these small-scale features in upper ocean mixing, and to examine the degree they are affected by mechanical mixing of rain and shallow rain-caused stratification in open ocean conditions. Thermal imagery is analyzed to determine the skin temperature variability, and spectral analysis is used to estimate the strength, scale, and orientation of the skin temperature features. Comparison of these derived parameters preliminarily reveals that the occurrence and orientation of the linear features is driven by the wind. However, the presence and degree of precipitation appears to modulate the relative feature strength (temperature signal above a background). We further explore the dependence of the feature length scales with ocean conditions and attempt to derive surface energy dissipation estimates associated with the features from the spatial content of the thermal imagery.

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