![Page 1: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/1.jpg)
Ocean Gyres
- combine knowledge of global winds and Ekman flow
- surface transport can be determined from wind direction/velocity
- surface transport alters ocean surface dynamic height
- dynamic height differences => geostrophic flow in ocean
Geography 104 - “Physical Geography of the World’s Oceans”
![Page 2: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/2.jpg)
Ekman transport is 90° to right (NH) of the wind
![Page 3: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/3.jpg)
global atmospheric circulation
tropical
![Page 4: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/4.jpg)
Global Atmospheric Pressure and Winds
July
January
![Page 5: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/5.jpg)
cyclonic & anti-cyclonic wind effects
L H
![Page 6: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/6.jpg)
cyclonic & anti-cyclonic wind effects
Ekman transport
convergence, downwelling
Ekman transport
divergence, upwelling
generally cooler water from upwelling
generally warmer surface waters
![Page 7: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/7.jpg)
cyclonic & anti-cyclonic wind effects
Ekman transport
convergence, downwelling
Ekman transport
divergence, upwelling
![Page 8: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/8.jpg)
![Page 9: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/9.jpg)
Global Winds and Atmospheric Pressure
July
January
TradeWinds
Westerlies
Westerlies
![Page 10: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/10.jpg)
= High Pressure
Geostrophic Currents
![Page 11: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/11.jpg)
Ekman transport alters sea level (dynamic topography)
![Page 12: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/12.jpg)
Sloped sea surface => pressure gradient
Geostrophic Flow in Ocean – Pressure and Coriolis force balance
![Page 13: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/13.jpg)
Subtropical Gyre Circulation from Figure in Text
![Page 14: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/14.jpg)
Subtropical Gyre Circulation from Figure in Text
Southern Hemisphere Subtropical Gyre going
wrong direction!!!!
![Page 15: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/15.jpg)
geostrophic subtropical gyres
![Page 16: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/16.jpg)
major ocean gyres and currents
![Page 17: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/17.jpg)
global chlorophyll & primary productivity - Aug. 2004
lowest chlorophyll concentration in center of sub-tropical gyres
![Page 18: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/18.jpg)
measuring dynamic height by satellite
deviation due to ocean currents
geoid
![Page 19: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/19.jpg)
global dynamic height – satellite measurements
![Page 20: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/20.jpg)
global dynamic height
![Page 21: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/21.jpg)
Global Surface Currents from Altimetry
![Page 22: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/22.jpg)
http://argo.colorado.edu/~realtime/gifs_tmp/global_ssh/gmt.13083.gif
dynamic height in the Gulf of Mexico
![Page 23: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/23.jpg)
Mapped SSH in California Current
geostrophic flow direction is along lines of constant SSH
![Page 24: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/24.jpg)
CTD deployment for dynamic height measurement
![Page 25: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/25.jpg)
global dynamic height – shipboard measurements units: meters
5.3
4.1
5.6
5.0
6.35.6
4.4
5.5
Differences in dynamic height are important, not absolute values
![Page 26: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/26.jpg)
Ocean Currents Associated with Dynamic Height Contours
![Page 27: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/27.jpg)
major ocean gyres and currents
![Page 28: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/28.jpg)
trash in the North Pacific subtropical gyre
Curtis C. Ebbesmeyer
~ 6 years to orbit N Pacific subtropical gyre
![Page 29: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/29.jpg)
Summary
- cyclonic winds => surface divergence, upwelling
- anticyclonic winds => surface convergence, downwelling
- direct wind driven Ekman transport sets up sea level variations
- sea level variations (dynamic height) => geostrophic circulation
- for geostrophic flow currents are along lines of constant sea level (dynamic height)
- subtropical gyres are primary characteristic of ocean circulation
![Page 30: Ocean Gyres - combine knowledge of global winds and Ekman flow - surface transport can be determined from wind direction/velocity - surface transport alters](https://reader030.vdocuments.us/reader030/viewer/2022032800/56649d435503460f94a1fada/html5/thumbnails/30.jpg)
Readings (Surface and Deep Circulation):Text Chapter 9 (pgs 170 – 172)Reader pgs. 131 - 132