March 27th lecture

Question 1

What does ENSO stand for?

Answer 1

El Nino Southern oscillations

Question 2

What is walker circulation? ( what it is and thwo points )

Answer 2

its a East-West Atmospheric Cell

• High pressure and sinking in the east Pacific
• Low pressure and rising ( and precipitation) in the west pacific

Question 3

What helps drive SEC to the West, what does it cause?

Answer 3

Easterlies help drive SEC to the west, causing warm water to pile up in the western Pacific (Pacific Warm Pool)

Question 4

What are “normal” Pacific Conditions? ( two things )

Answer 4

• Coastal winds along south america produce string upwelling
• This is associated with a strong thermocline slope across the basin, with the thermocline deep in the west and shallow in the east.

resulting in lots of fish near south ameraica

Question 5

What is ENSO?

Answer 5

It is a phenomenon that is related to coupled atmospheric-ocean process,

The Southern Oscillation and the Oceanic El Nino process

Question 6

Why is it called El Nino in ENSO?

Answer 6

Since this process starts in September (in most years when it occurs) and reaches the Peru coast by December (Christmas), the local named it El Nino, which is Spanish for Christ Child

Question 7

What is the ENSO atmospheric process? How does it affect the pacific ocean?

Answer 7

Atmospheric Processes (details of which are still under study) can cause bursts of westerly winds to occur at times along the
equator

This weakens or even reverses the WALKER circulation.

Question 8

What happens to the pacific warm pool when the trade winds are interrupted or halted due to ENSO?

Answer 8

The warm pool is no longer held against the western side of the basin and sloshes back to the central pacific.

It also triggers Kelvin waves, that travel across the tropical pacific eastward

Question 9

What do Kelvin waves strengthen?

Answer 9

They strengthen the EUC

Question 10

What does a Strengthened EUC result in?

Answer 10

the thermocline slope being flattened

Question 11

What happens when the Thermocline off peru is flattened due to EUC?

Answer 11

The thermocline off of peru gets depressed, warming up the ocean and reducing upweling of deep water, thus resulting in less fish.

Question 12

What happens to the waves that relfect off of south america? ( two things )

Answer 12

– 1) Travel north and south
along the coastlines of
North and South America,
bring water water to higher
latitudes (as far north as
British Columbia)
– 2) Also produce waves that
reflect back across the
tropical Pacific, that
eventually help end the
ENSO event

Question 13

What does NAO stand for?

Answer 13

North Atlantic Oscillation (NAO)

Question 14

What is NAO?

Answer 14

it is a component of the Arctic oscillation, it is the sea level pressure (SLP) difference between

Ponta Delgada
Azores
and Stykkisholmur in Iceland

it measures aspects of variability

Question 15

What are the impacts of NAO?

Answer 15

The Iceland low semi-permanent low pressure area and the Azores (Bermuda) high semi-permanent high pressure area fluxuate in strength an position over a period of months or years, they can shit the location of the jet stream, affecting weather in the northern hemisphere.

Question 16

What happens during the postive phase of a NAO?

Answer 16

During the positive phase there is a strengthening of both the semi-permanent pressure centers resulting in a increased pressure gradient across the north Atlantic.

Question 17

What is the result of the heighten pressure gradient of the north Atlantic during the positive phase of NAO?

Answer 17

the westerlies increase in speed, allowing the cold air to drain off the North American continent rather than letting it build up and move south.

Question 18

What happens during the negitive phase of the NAO?

Answer 18

Both semi-premient pressures weaken, causing a drecrese in pressure gradient across the north Atlantic

Question 19

What is the result of the weakend pressure gradient of the north Atlantic during the positive phase of NAO?

Answer 19

This results in the weakening of the westerlies which allows cold air to build up over Canada and move south via a deepening trough which affects the eastern US.

Question 20

What happens when a NAO goes through a postive phase and there is a strong ENSO happening?

Answer 20

the combination of effects means that temperatures will more than likely be much warmer in the Southeast than what they would be if only affected by the NAO.