I've been looking at ocean cycles and
got tangled up in what Wikipedia says. The problem is they are
covering their ignorance with spurious explanations. A self evident
truth need little explanation.
El Niño is associated with a band of
warm ocean water temperatures that periodically develops off the
Pacific coast of South America and in air surface pressure in the
tropical western Pacific. The warm oceanic phase accompanies high air
surface pressure in the western Pacific. The cause is unknown.
The periodic warming in the Pacific
near South America is usually at Winter Solstice. The definition is a
warming of at least 0.5 °C averaged over the east-central tropical
Pacific Ocean.
Half a degree and only at winter
solstice in the tropics?
Really?
This anomaly happens at irregular
intervals of two to seven years, and lasts nine months to two years.
The average period length is five years. Lesser periods of seven to
nine months, are classified as El Niño "conditions";
longer periods are classified as El Niño "episodes".
Weakening of the Walker circulation and
strengthening of the Hadley circulation occur with a rise in surface
pressure over the Indian Ocean, Indonesia and Australia as air
pressure over Tahiti and the rest of the central and eastern Pacific
Ocean falls.
Trade winds in the south Pacific weaken
or head east. Warm air Peru, brings to northern Peruvian deserts and
warm nutrient-poor water replaces the cold, nutrient-rich Humboldt
Current. El Niño episodes cause extensive ocean warming reducing
easterly trade winds and the upwelling of cold nutrient-rich deep
water.
The Southern Oscillation is the
atmospheric component of El Niño. This component is an oscillation
in surface air pressure between the tropical eastern and the western
Pacific Ocean waters. The strength is measured by the Southern
Oscillation Index fluctuations in the surface air pressure between
Tahiti and Darwin, Australia.
I think these are fairly easy to
explain when considering the activity of cyclones near Antarctica,
the key to it all.
El Niño episodes are negative values
of the SOI with below normal pressure over Tahiti and above normal
pressure of Darwin. Low pressure over warm water and high pressure
over cold water -the opposite of what actually occurs in the Southern
Oceans where anticyclones surrond the eaquatorial regions and deep
cyclones fence in Antarctica.
Episodes are defined as sustained
warming of the central and eastern tropical Pacific Ocean. In Non-El
Niño conditions, the Walker circulation has easterly trade winds
bringing conditions west. Ocean upwelling off the coasts of Peru and
Ecuador brings nutrient-rich cold water to the surface. The
equatorial West Pacific has warm, wet, low-pressure with typhoons and
thunderstorms.
And nobody has linked this seasonality
to the AAO?
The ocean is some 24 in higher in the
western Pacific and nobody knows why?
Really?
Increased rainfall across the
east-central and eastern Pacific Ocean, directly affects South
America are stronger than in North America. April–October the
coasts of northern Peru and Ecuador have major flooding in strong or
extreme events and may become critical from February to April.
Southern Brazil and northern Argentina
have wetter than normal conditions in spring and early summer.
Central Chile receives a mild winter with large rainfall, and the
Peruvian-Bolivian Altiplano is sometimes exposed to unusual winter
snowfall events.
Drier and hotter weather occurs in
parts of the Amazon River Basin, Colombia, and Central America. US
winters, during the El Niño effect, are warmer and drier than
average in the North-west to northern mid-east United States,
reducing snowfall. Conversely, winters are wetter in north-west
Mexico and the south-west United States, including central and
southern California, while both cooler and wetter than average
winters in north-east Mexico and the south-east United States occur
during the El Niño phase of the oscillation....
This part just got silly. What we need
is to see some weather charts here.
