Surface waters Flashcards
What is ENSO?
periods of climate conditions centered in tropical pacific oceans.
What is the frequency of ENSO?
3-7 years
How long does ENSO lasts?
lasts 1 year
What does ENSO cause?
disruptions to normal atmosphere/ ocean interactions
What is a typical system?
movement of water from East to West.
deep water upwells to replace it keeping oceans cool along coast of South America
What is Southern Oscillation?
periodic reversal of low and high pressure areas in southern pacific
What happens to surface pressure in Indonesia?
low pressure becomes high
What happens to surface pressure in the pacific zone?
High pressure becomes low
What is El Nino?
wind driven reversal in the ocean current resulting in warm water moving toward America
What is El nina?
condition of colder than normal surface waters in the tropical pacific
What are consequences of El Nino?
decreased intensities of hurricanes in the Atlantic because jet stream is diverted South
What are global consequences of El Nino?
Northern USA has warmer winters
Dry areas of Peru and Ecuador have high rainfall
Indonesia/Austrailia/Phillipines have drought
What is MEI
Multivariate ENSO Index
How is MEI calculated?
from measurements of sea temperatures, level-pressure, and surface air temperatures to the Eastwest and North-south velocity of components of the trade winds and total amount of cloudiness
Where do currents occur?
Surface ocean= top 100m=10%
Deep Ocean=below 100m=90%
What is the driving force of currents?
Wind
What happens during the Elkman Spiral?
water is deflected by coriolis effect
Earth rotates further out from under
water appears to be deflected to a greater degree than overlying air
What is the Elkman Spiral?
Water is deflected to right in North hemisphere and left in Southern Hemisphere.
Average water motion is 90% from wind direction
How is the North Equatorial current formed?
Northeast trade winds push water toward the west.
How is the North Pacific current formed
by westerlies moving east to west
How is the California and Kuroshio Current formed?
water flows towards areas where water has been removed
What currents make the Noth Pacifc Gyre?
North Equatorial Current, North Pacific Current, California,Kuroshio current
What is the principle of the continuity of flow?
A fluid flows so the next flux of liquid in or out of a given volume within the fluid is 0
What forms the Antarctic Circumpolar Current?
Strong Westerlies
Where does the Antarctic Circumpolar Current flow?
completly around the globe without interuption
What does the Antarctic Circumpolar current provide?
mechanism of sharing and mixing among oceans
How are fronts formed?
by Ekman wind convergence which channels the current between them
What fronts are part of the Antarctic Circumpolar Current?
-Subtropical front
-Subantarctic front
-Polar/Antarctic front
How is the speed of wind compared to the speed of currents?
currents are 1/100 speed of wind
How to measure volume of water transported by currents?
1SV=1 million cubic meters per second
Geostrophic Flow?
horizontal flow of water occuring when there is a balance of coriolis and gravitational forces acting on water
What is Western Intensification?
Increase in speed of geostrophic currents along the Western boundary of an Ocean Basin
What are factors causing Western Intensification?
- Eastward turning of the Earth
- Increase of coriolis effect with latitude
- Changing direction of tradewinds and westerlies
- Friction between land masses and ocean water currents
How do western currents compare to Eastern currents?
Western currents:Fast flowing, narrow
Eastern Currents: Slow, wide
What are examples of western currents?
Gulf Stream
Kuroshio current
What are examples of Eastern currents?
Canary current
California current
What are permanent wind driven zones?
5 major convergent zones
3 major divergence zones
-related to ocean gyres and geostrophic currents
-lower productivity in downwelling areas
What are meanders?
Oscillations and waves along boundary of current
What are eddies?
Pockets of water moving in a circular motion.
What are mesoscale eddies?
10-500km in diameter and persist for day-month timescales
What do eddies do?
Stir the ocean until they dissipate due to fluid friction, loosing chemical and thermal energyand energy of motion to turbulence
How do eddies cause verdical transport in low pressure North hemisphere?
Elkman transport of water away from the center to upwelling and nutrients.
(convergence, counterclockwise)
How do eddies cause verdical transport in high pressure North hemisphere?
Elkman transport of water foward leads to downwelling
(divergence, clockwise)
What are Seasonal wind driven zones?
Seasonal changes in wind pattern affect Ekman transport
winds blowing along coastlines can generate…
Ekman transport of water foward or away from the coast
