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1/25/13
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Short-Term* Dynamic Changes in Sea Level
* Hours to Decades
Temperature Effects – The Gulf Stream
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Pressure Effects – Storm Surge
El Niño and the Southern Oscillation (ENSO)
208˚ W
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Warmer water extends to eastern Pacific
El Niño
La Niña Warmer water mostly in western Pacific
El Niño and La Niña
El Niño
La Niña
La Nada
Mechanics of ENSO
http://www.esrl.noaa.gov/psd/people/joseph.barsugli/anim.html
http://www.youtube.com/watch?v=DbNzw1CCKHo
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SST anomalies - El Niño
SST anomalies - La Niña
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frequency = 2-7 years
Southern Oscillation Index or Multivariate ENSO Index
Wet winter in N.A. - decreased snowpack - water supply Warmer in midwest, cooler in southwest Decreased Atlantic Hurricane Activity Very wet in S. America Drying in S.E. Asia and Australia - numerous brush fires - air quality West of Antarctic peninsula - more sea ice
El Niño - driven Events
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Higher sea level - from thermal expansion of water Huge waves - massive sediment transport Wet conditions - sea cliff failures
Severe Beach Loss in Southern California
Seasonal Cycles
Typically, the effects of variation in sea surface temperature, barometric pressure, and strength/orientation of ocean currents. Note magnitude of variation. ~1 cm wse change per 1 mb (0.1 kPa) change in atmospheric pressure
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Storm surge – Hurricanes (localized)
Components: 1. Barometric 2. Wind Stress 3. Coriolis 4. Wave Setup
Storm surge – Nor’Easters (large regional extent)
Components: 1. Barometric 2. Wind Stress 3. Coriolis 4. Wave Setup
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Examples of storm surge
The onshore wind component of storm surge
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The size of the storm: Hurricanes vs. Nor’Easters
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