EAS 1540 Lecture Notes - Lecture 8: Heat Flux, Ocean Current, Ekman Transport
15 Dec 2016
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Document Summary
Salt concentration and water temperature jointly determine seawater density. Adding heat warms ocean, removing head cools ocean. Sunlight energy always adds heat to the ocean. Direct solar heating takes place near surface (0-30m) Vertical mixing of near surface water (up to 500m deep) Water below 500m is uniformly cold - permanent thermocline. Seasonal thermocline - forms in summer and erased in winter. Stably stratified ocean - less dense water floats. Seasonal pycnocline - seasonal density change of density. Permanent pycnocline - around 500m, long term balance between heat/mixing of warm and cold surface. Annual range of sea surface temperature - cold waters stay cold, warm waters stay warm; mid- latitude ocean temperature varies more. Ekman transport & geostrophic currents --> wind drives surface ocean currents. Due to wind force, friction force and coriolis force. Ekman spiral = spiraling of thin ocean currents within the ekman layer. Top most current moves at 45 degrees because of wind + coriolis + friction.
