El Nino/Southern Oscillation
Description
Collapse or Relaxation of Normal Persistent East-to-West Equatorial Tradewinds in Pacific
Migration Westward of Large Atmospheric High Pressure Cell Over South Pacific From Tahiti to Australia
Migration Occurs - 3 to 7 years for 6 - 20+ months
Why? - "Southern Oscillation"
- Low Pressure Over Monsoonal Areas of Indo-Pacific Islands Displaced by Incoming High Pressure Dome
- Conversely, Area of Normal High Pressure Between Peru & Tahiti has Lower Barometric Pressure
*Map produced by the South Carolina Department of Natural Resources
Large Mass of Water Migrates Eastward Across Pacific Ocean from Formation Area Around Indonesian & Philippine Archipelagoes
Anomalously High Temperature - 29-32 Degrees Celsius
7000-7500 Mile Journey Started in Spring
4-8 Weeks to Complete
1997 Event
"El Nino" Half of the Equation of El Nino/Southern Oscillation
Global Impacts of El Nino/Southern Oscillation
Intense droughts in Australa, India, Indonesia, Philippines, Brazil, parts Africa, the Western Pacific Basin Islands, Central America
Occurs at different times (seasons) during event and varying degrees of magnitude
Milder winters in the Northeast
Wet over the south from Florida to Texas
Alaska and NW regions of Canada and US can be abnormally warm
Hurricane activity minimal in Atlantic Ocean
1997 Hurricane Season - 7 Named Storms (Average 9) 3 Hurricanes (Average 2)
Rain and flooding to California, Oregon and Washington
Impacts to South Carolina
When Large Mass of Hot Water Came to Americas
- No Big Perturbation for SC
- Several Weeks for Atmosphere to Respond to New and Increased Heat Source
- Started Doing so by Mid-July
Atmosphere Reacted by Trying to Move Heat Out in 2 ways
- Large Convective Thunderstorms
- Large Pacific Hurricanes - ie. Guillermo & Pauline
Indirect Product of Two Changes in the Atmosphere
- Generate West-to-East Flowing Winds From Pacific Across all Central America, Caribbean Sea, Gulf of Mexico, Southern and Southeast US, Western Atlantic.
- - Flowing Against Atlantic Tradewinds With Easterly Waves and Hurricanes
- - Shear Destroyed Any Convection
Mid-July - October (Drought)
Impacts and Outlook for South Carolina
During an El Nino Event, South Carolina can expect the following:
Summer Rapidly Disappearing From Memories & Thermometer
Another Part of El Nino Process Starting Up
Start as Moist, Warm, Tropical Jetstream
- Strengthen and Weaken
- Remain Moist - Carry Storm Centers Through Region
SC Can Expect Between 120 - 135% Normal Precipitation within 6 - 10 months of the onset of a typical El Nino event
Reserch on Historical Records Show 2 Worrisome Trends
- Severe ENSO Associated With More Frozen Precipiation Icestorms/Snowstorms
- Frequency Damaging Nor'easters From Gulf of Mexico Across Florida Panhandle into Southern Gulf Stream
- High Possibility of Coastal Erosion and Flooding
- 4 Events to date
