Accession Number : ADA288579

Title :   Infrared Field Measurements of Sea Surface Temperature: Analysis of Wake Signatures and Comparison of Skin Layer Models.

Descriptive Note : Technical rept.,

Corporate Author : WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB

Personal Author(s) : Zappa, Christopher J.

PDF Url : ADA288579

Report Date : AUG 1994

Pagination or Media Count : 276

Abstract : Infrared field measurements of ocean skin temperature made aboard the R/P FLIP in January of 1992 approximately 400 nautical miles off the coast of San Diego are presented. An extensive literature review accompanies these measurements probing the fundamentals of air-sea interaction, electromagnetics, and free-surface flows. A thin layer at the air-sea interface, known as the ocean skin layer, transfers heat by molecular conduction. The skin layer is on the order of a millimeter and typically 0.1 to 0.5 deg C cooler than the water just below for conditions of net heat flux from the ocean to the atmosphere. Two surface-piercing cables hanging from FLIP's port boom, each 1 cm in diameter, provided a disturbance of the skin layer mixing the warmer water from below up to the surface. Employing an infrared imager, we detected the temperature variations, tracked the signatures and quantified the spatial and thermal changes in time of these artificial disturbances, which were on the order of a meter. This unique method of visualizing turbulence at an air-water interface provides a direct measurement of the bulk-skin temperature difference. The recovery rate of the skin layer was found to be directly related to the level, or strength, of the disruption under low wind speed conditions (approx. 2 m/s). At moderate wind speeds (approx. 7 m/s), both the natural (breaking waves) and artificial (wakes) disturbances recovered within 2 s compared to an extrapolated recovery time of up to approx. 120 s under low wind speeds for the wake signatures. The difference is primarily a function of the net heat flux and sublayer thickness, which relate directly to the existing environmental conditions (e.g., turbulence intensity, sea state, wind speed).

Descriptors :   *OCEAN SURFACE, *WAKE, *AIR WATER INTERACTIONS, THERMAL PROPERTIES, HEAT TRANSFER, INFRARED DETECTION, SPATIAL DISTRIBUTION, OCEAN WAVES, INFRARED SIGNATURES, TWO DIMENSIONAL, COMPARISON, TURBULENCE, COMPUTATIONAL FLUID DYNAMICS, FLOW VISUALIZATION, OCEANOGRAPHIC DATA, TEMPERATURE GRADIENTS, INFRARED IMAGES, THERMAL CONDUCTIVITY, WIND VELOCITY, MIXED LAYER(MARINE), HEAT FLUX, SURFACE TEMPERATURE, SEA STATES, SEA WATER, OCEAN MODELS, THERMAL BOUNDARY LAYER.

Subject Categories : Physical and Dynamic Oceanography
      Fluid Mechanics
      Thermodynamics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE