The use of infrared imagery to quantify near-surface thermal and hydrodynamic features on bodies of water

Abstract

Infrared imaging has proven to be an invaluable tool for remotely detecting and tracking coupled near-surface thermalhydrodynamic structures such as foam patches of breaking waves, Langmuir circulation and convective cells, thermal impressions of water mass movement and pollutant effluxes. The ability to quantify such characteristics is vital to determining the complex nature of heat transport, gas entrainment and momentum exchange across air-water interfaces. These physical processes play an important role in determining global climate and their accurate description is necessary for consistent weather modeling. In this presentation, we focus on a laboratory scale subsurface turbulent water jet that serves as a canonical near surface event. The jet liquid has a slightly elevated temperature and is placed in close proximity to the air-water interface of a quiescent water basin into which it flows. Infrared image sequences of the surface thermal field were collected for various water jet flow rates and used to examine the detailed statistical nature of the resulting coupled thermal-hydrodynamic field. We discuss the similarities of the spatial structure of the surface thermal field in light of observations made with other sensing techniques, the relevant length and thermal scales present and the order of the fluctuating surface thermal field using Karhunen-Loeve analysis.