1. Natural Climate Variability
2. Inter-annual Variability
El Niño-Southern Oscillation (ENSO)
every 3-7 years
strong atmospheric pressure gradient across the tropical Pacific weakens
Trade Winds slacken or reverse
warm water normally piled against SE Asia (due to strong Trade Winds), migrates eastward across the tropical Pacific
global consequences/repercussions including widespread droughts in some areas, floods in other areas, severe winter coastal storms along CA, mild winters in NE U.S. p

2. L H During a normal year, there is a strong pressure gradient between
the SE Pacific High and the
Indo-Australian Low driving
strong Trade Winds and piling-up
warm water in the western Pacific H L
During an El Niño event,
Trade Winds slacken and
warm surface waters of the
Western Pacific Warm Pool
slide east over the eastern
equatorial Pacific

3. http://www. sbg. ac. at/ipk/avstudio/pierofun/atmo/el-scans/el-nino1

4. Relationship between sea-surface temperature and atmospheric pressure: interannual variability of ENSO
yellow bars = El Niño years

5. Normal year
El Niño
What’s different?

7. p. 127

8. Global climatological effects of the El Niño.
Global climatological effects of the El Niño.
(Source: PhysicalGeography.net)

9. How is southern New England affected by
El Niño?