Oceanography 10 Ocean Circulation PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons PART 2: Measuring Ocean Currents and Structure PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses Figure 8.8 Gulf Stream flows at 55 million cubic meters/sec, 500 times the flow of the Amazon River Figure 8.14 1
Sea Surface Temperatures in Celsius during the Northern Hemisphere Summer (25 degrees C = 77 degrees F, 15 degrees C = 59 degrees F) Top picture is July, bottom is January, green and blue indicate temperatures below 0 Celsuis and warmer temperatures are shown in red and black Oceanography 10 Ocean Circulatio PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons https://www.youtube.com/watch?v=ccmty0pkgds (NASA Perpetual Ocean) PART 2: Measuring Ocean Currents and Structure PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses Part 2 Measuring Ocean Currents and Structure: Seasoar, a modified CTD meter can be used at the surface to ~350 meters CTD Sensors Satellites Bouys ARGO: free floating profile floats Current Meters Doppler Meters Spills, Accidents 2
Fig. 9.17 Part 2 Measuring Ocean Currents and Structure: ARGO = Array for Real-Time Geostrophic Oceanography Argo is a global array of 3,000 free-drifting profiling floats that measures the temperature and salinity of the upper 2000 m of the ocean. This allows for continuous monitoring of the temperature, salinity, and velocity of the upper ocean, with all data being relayed and made publicly available within hours after collection. CTD Sensors Satellites Bouys ARGO: free floating profile floats Current Meters Doppler Meters Spills, Accidents Part 2 Measuring Ocean Currents and Structure: CTD Sensors Satellites Bouys ARGO: free floating profile floats Current Meters Doppler Meters Spills, Accidents 3
Doppler Current Meter Doppler Effect Drift Bottles 1956 1959: 33,800 bottles released Flotsam: floating wreckage of a ship or its cargo. Jetsam: part of a ship, its equipment, or its cargo that is purposely cast overboard or jettisoned to lighten the load in time of distress and that sinks or is washed ashore. The Hansa Carrier / May 1990 4
Figure 8 p.236 (figure 2) Figure 8 p.237 (figure 3) http://www.islandnet.com/~see/weather/elements/shoes.htm http://www.dailymail.co.uk/news/article-1374520/japan-earthquake-tsunami-debris-floating-us-west-coast.html The Ital Florida following an encounter with large waves on its maiden voyage, lost 40 containers Between 5 6 million containers move on the oceans daily Some cargo ships are so big, 3 football fields could fit on them One ship can hold up to 3.5 million barrels of crude oil Estimated between 2,000 10,000 metal containers end up in ocean/yr, or 5 25/day In spring 2014 the Danish ship Svendborg Maersk lost 487out of 500 containers A 20ft container can float up to 2 months, a 40ft container floats up to 6 months 5
Japan--- START POINTS ---North America Japan--- START POINTS ---North America Japan--- START POINTS ---North America Japan--- START POINTS ---North America Oceanography 10 Ocean Circulation PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons Coriolis Effect PART 2: Measuring Ocean Currents and Structure PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses Gapard Coriolis 1792 1843 French Mathematician 6
Coriolis Effect: the apparent deflection of moving unattached objects relative to the Earth s surface. Oceanography 10 Ocean Circulation PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons PART 2: Measuring Ocean Currents and Structure Notice the change between 0-30 degrees = 140mph and between 30-60 degrees = 380mph! PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses Figure 6.19 7
Oceanography 10 Ocean Circulation PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons PART 2: Measuring Ocean Currents and Structure PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses Part 3: General Surface Current Patterns Ekman Spiral & Transport, Gyres, Zones of Divergence and Convergence, Upwelling and Downwelling, Geostrophic Flow, & Boundary Currents Figure 8.1 Ekman Transport Vagen Walfrid Ekman 1874 1954 Swedish Oceanographer 8
Why Low Pressure spins in a counter-clockwise direction Low Pressure Practice Problems If strong steady winds are blowing from the north to the south off the coast of California, which of the following will result? A. Downwelling B. Upwelling C. A zone of convergence D. Both A and C If strong steady winds are blowing from the south to the north off the east coast of Southern South America, which of the following will result? A. Upwelling and a zone of divergence B. Downwelling and a zone of convergence C. El Nino D. Both B and C Geostrophic Flow 9
Eastern Boundary Currents & Western Intensification Boundary Current Characteristics Notice the change between 0-30 degrees = 140mph and between 30-60 degrees = 380mph! 30-60 degrees changes 380mph or 613 Km/hr 0-30 degrees changes 140mph or 224 Km/hr 10
The Cromwell Current: Flows eastward~ 100 meters deep, 400Km wide, 6,000Km long, flowing at ~ 3 knots, flow volume ~ 1,000 X Mississippi River, discovered in 1952 Oceanography 10 Ocean Circulation PART 1: Introduction General types of Ocean Currents Solar Energy and the Seasons PART 2: Measuring Ocean Currents and Structure PART 3: General Surface Currents and their Patterns Effects of the Earth rotation; Coriolis Effect Earth s changing rotational velocities Earth s major wind patterns Gryres and effects of currents PART 4: Ocean Structure & Water Masses 11
Figure 7.4 Part 4 Perpetual Ocean http://video.mit.edu/watch/perpetualocean-10824/ Ocean Structure and Water Masses Surface Zone, Pycnocline Zone & Deep Zone El Niño 12
Part 4 Ocean Structure and Water Masses Surface Zone, Pycnocline Zone & Deep Zone El Niño El Niño / ENSO This slide shows normal atmospheric conditions called La Niña (not an El Niño event) High air pressure in eastern Pacific, low air pressure in western Pacific. Surface topography and temperature is measured by satellites and subsurface temperatures are measured by buoys. Red is 30 degrees Celsius (86F) and blue is 8 degrees Celsius (46.4F). http://www.cpc.ncep.noaa.gov/products /analysis_monitoring/enso_advisor y/index.shtml El Niño / warm phase = high pressure in western Pacific, low in eastern Pacific. La Niña / cold phase = low pressure in western Pacific, high in eastern Pacific 13
Atlantic Multidecadal Oscillation variability in the North Atlantic SST, defined in 1994 There is also a North Atlantic Oscillation (1920 s) involving changes of atmospheric Pressure and a Pacific Decadal Oscillation (1997), effects climate and SST. Mechanisms causing oscillations remain under study Figure 8.8 https://www.youtube.com/watch?v=b-tswthjpye https://www.youtube.com/watch?v=vp4qtyvqtuo 14