ENSO Flashcards
Southern oscillation: occurs in
Eastern Pacific, near Peru and Ecuador.
Southern oscillation: coastal temperature increase forms a
Warm current and leads to strong flooding.
Southern oscillation: a large scale variation in mean sea level pressure, associated
With a change in weather patterns in the pan-tropical Pacific.
Southern oscillation: related to changes in pressure across the
Low over N Aust & Indonesia and the high over the tropical S Pacific.
Southern oscillation: warm water migrates east,
The ocean around N Aust cools, leading to dry conditions.
ENSO: is a combination of
Warm current and variation in mean sea level pressure.
ENSO: (3)
Leads to unseasonably dramatic weather.
Happens once / twice a decade.
Weather anomalies may occur a few months after the event.
ENSO: at times the high can weaken (pressure falls) whilst the
Low fills (pressure increases); this is a low index phase, the trades become weaker or even reverse W to E.
SO index (SOI): is the difference between
Monthly average mean sea level pressure at two locations.
When the SOI is high,
Trade winds blow strongly across the S Pacific E to W.
ENSO: the reverse in trade winds during a low-index phase leads to
Eastward migration of warm water across the Pacific Ocean.
The eastward migration of warm water across the Pacific Ocean is followed by deep
Cumulonimbus cloud, produced from surface heating. This produces torrential rainfall in usually dry areas, leading to dramatic flooding.
ENSO: Tall thunder clouds take heat into upper troposphere, this
Enhances horizontal temperature gradients, strengthening the jet streams and extending them eastwards.
