el niño & la niña - palomar college · el niño/la niña & weather in southern california...
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Carlsbad Dive Club Meeting
March 12, 2015
by Al Trujillo Professor of
Oceanography Dept. Earth Sciences
Palomar College
El Niño & La Niña
Lead Author of Best-Selling Oceanography Textbook
Working as a Naturalist for Lindblad Expeditions/National Geographic
My Hobby Is Sand Collecting
Sea urchin spines
Green sand
Black sand
Star sand
Topics tonight:
• Ekman Spiral and Ekman Transport
Then on to answer these questions…
• What does an El Niño have to do with the price of eggs?
• What is La Niña?
• What kind of weather does El Niño bring to Southern California?
• Is this an El Niño year?
Tonight’s Topics & Questions
Ekman Spiral and Ekman Transport
Figure 7.7, page 205
• Ekman transport = average of all layers, oriented 90 degrees to wind direction
Northern Hemisphere
Ekman Spiral and Coastal Upwelling/Downwelling
Coastal Upwelling
Figure 7.12, page 211
El Niño and La Niña
Chris Farley: What Is El Niño?
• El Niño (Spanish for “the Child” in reference to baby Jesus) = warm surface current in equatorial Pacific Ocean that occurs periodically (every 2-12 years) around Christmastime
• Southern Oscillation = change in atmospheric pressure over Pacific Ocean accompanying El Niño
• ENSO describes a combined oceanic-atmospheric disturbance (warm and cold phases)
El Niño Definitions
Normal Surface Circulation in the Pacific Ocean
Figure 7.21,
Page 219
“Normal” Conditions in the Pacific Ocean
Figure 7.22a,
page 220
Q: How are El Niño Conditions (ENSO warm phase) different than normal?
Figure 7.22, page 220
Q: How are La Niña Conditions (ENSO cold phase) different than normal?
Figure 7.22, page 220
• Anomaly (a = without, nomos = law) maps show the difference from “normal” conditions
• Sea Surface Temperature (SST) anomaly maps are useful for identifying unusually warm or cold water: Positive SST anomaly values = water warmer
than normal
Negative SST anomaly values = water colder than normal
El Niño Anomaly Maps
January 1998 SST Anomaly Map
Figure 7.23a,
page 221
January 2000 SST Anomaly Map
Figure 7.23b,
page 221
Figure 7.26, page 224
West Coast SST Anomaly Maps
North America
North America
Pacific Ocean
Pacific Ocean
El Niño/La Niña & Weather in Southern California
• Typical weather during El Niño?
Strong El Niños: Lots of powerful storms (good waves), lots of rain (1997-1998 = more than 2X normal rainfall), but not always…
Moderate/Weak El Niños: can have drought conditions or lots of rain or no effect at all
• Typical weather during La Niña?
Extremely dry conditions (2000-2001 = 1/3 of normal rainfall)
Figure 7.24, page 222
El Niño Recurrence Interval
• Typical recurrence interval for El Niños = 2-12 years
• Note how Pacific has alternated between El Niño and La Niña events since 1950
Effects of Severe El Niños
Figure 7.25, page 223
El Niño Visualizations: What’s Happening Now?
• JPL Ocean Surface Topography from Space Latest El Niño/La Niña Watch
El Niño Visualizations: What’s Happening Now?
• Tropical Pacific real-time SST anomalies from NOAA’s Tropical Atmosphere Ocean Project (buoy data)
Data from NOAA Climate Prediction Center
Forecast SST Anomalies: Is this an El Niño Year?
• El Niño “Quick Look” from the International Research Institute for Climate Change
Carlsbad Dive Club Meeting
March 12, 2015
End
by Al Trujillo Palomar College
El Niño and La Niña
Al Trujillo’s e-mail: [email protected] This presentation is available online at:
http://www2.palomar.edu/users/atrujillo/