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Lecture 13
Ocean Surface Currents

Animation courtesy of D. Reed, San Jose State Geology

Main points of today's lecture:



Other goodies
Antarctic circumpolar current
- no land masses blocking
- tremendous wave activity there

Edges of basins are where currents are strongest, especially on the western side of the basin (e.g., Gulf Stream going up the western Atlantic)

- 1 Sv is all the water in all of the world's rivers!
- Imagine 55 million cubic meters of water flowing past you!
- That's the Gulf Stream (55 Sv)!

Does water just follow the wind?
- No! See above on Ekman transport. Surface currents are driven by the wind but also by Ekman transport
- Ekman was a graduate student for Nansen and was charged with figuring out why icebergs always moved to the RIGHT of the wind up in the Arctic Sea.

- the "mound" in the middle of ocean gyres is maintained by a balance between the Coriolis force and the pressure gradient (aka geostrophic flow)
- related to that, westward intensification of ocean boundary currents is maintined by the Coriolis force

Upwelling is the key to phytoplankton happiness and productivity!

Biggest waves on the planet found at the southern tip of Africa
- large freighters broken up by these waves
- phenomenal surf and surfers

Trash from 2011 Japanese tsunami
- estimate is that it will take 2 years to get from Japan to US west coast (730 days)
- some of it will sink
- a lot of it will be dispersed throughout the gyre
- so we will NOT have piles of trash from Japan appearing on our beaches


Have you thought about...? (answers need not be submitted!)

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