Lecture 6

Question 1

Explain the earths energy budget

Answer 1

Energy surplus at low latitudes are equal to energy deficits at high latitudes = balanced heat budget.

As the heat is then transferred from the equator regions to the polar through wind and ocean currents.

Question 2

What drives ocean circulation?

Answer 2

Temperature
Salinity
(Cool, salty water = most dense)

Question 3

Explain thermohaline circulation

Answer 3

Warm water = lower density than cold
Cold regions - cold salty water sinks (heavy)
Evaporation increases salinity of water in warm regions
During journey to cold regions, salty water cools and sinks toward ocean floor
In contrast, diffuse upwelling occurs in warm regions
Therefore, temperature and salinity gradients drive an overturning circulation

Question 4

The North Atlantic current is responsible for…

Answer 4

The relatively mild climates of Western and Northern Europe

Question 5

What forms over the Gulf Stream?

Answer 5

Clouds, as water vapour evaporates from the ocean surface

Question 6

What probe is dropped 3500m and produces low frequency tones once a day for tracking currents?

Answer 6

SOFAR

Question 7

An example of meridonal overturning circulation:

Answer 7

Atlantic.

Being denser, Antarctic bottom water slips beneath North Atlantic deep water. The water then gradually rises across a very large area in the tropical zones, then flows poleward to repeat the cycle

Question 8

Water salinity is affected by:

Answer 8

Precipitation, run off, melting of ice + snow (decrease)
Evaporation (increase)
Input of dissolved ions is balanced by removal to sediments - global oceans in steady state

Question 9

Seawater solution =

Answer 9

Dissolved salts
Dissolved gases
Dissolved organic material
Large range of particles in suspension

Question 10

Meridonal overturning circulation is part of thermohaline circulation which can be called the:

Answer 10

‘Ocean conveyor belt’

Question 11

Thermohaline circulation

Answer 11

Driven by temperature and salinity

Contributes to the global distribution of energy in heat form

Question 12

El Niño southern oscillation

Answer 12

Abnormal weather pattern - caused by the warming of the Pacific Ocean near the equator.
Occurs when the normal trade winds weaken (or even reverse), which lets the warm water that is usually found in the western Pacific flow instead towards the east.
This warm water displaces the cooler water that is normally found near the surface of the eastern Pacific, setting off atmospheric changes that affect weather patterns in many parts of the world.
Happens usually every 2-7 years
Has to be a 0.5 degrees c change to be considered an El Niño year

Question 13

The tropical Pacific Ocean and atmosphere act as…

Answer 13

A giant heat engine that converts solar energy to kinetic energy of winds

Question 14

Walker circulation (walker cell)

Answer 14

Normal: trade winds blow towards the west across tropical Pacific = pile up of warm water in W Pacific
cold-nutrient rich water, wells up in S. American coast - supports diverse marine ecosystems, dry climate conditions
High water temperatures = extensive convection near Indonesia
Forms convective loop (important part of Hadley cell)
= formation of a zonal gradient in water temperatures

Question 15

El Niño conditions

Answer 15

Trade winds relax in central and western Pacific
Consequently, thermocline in Eastern Pacific gets depressed, W. Pacific elevated
Warm surface water moves eastwards followed by rainfall
Causes change in atmospheric circulations affecting weather even at great distances from Pacific

Question 16

Example of effects from El Niño

Answer 16

Flooding in South America

Drought in Indonesia and Australia

Question 17

La Niña conditions

Answer 17

Unusually cold sea temperatures
Trade wins strong
Sometimes follows El Niño
Opposite to El Niño (hot phase) - El Niña = cold phase

Question 18

Anthropogenic activities increasing CO2

Answer 18

Emissions from transport 
Energy generation (e.g. Coal, oil) 
Industrial and domestic heating
Cement production 
Deforestation (land use change)

Question 19

Natural sources of atmospheric CO2

Answer 19

Volcanoes (1/150th compared to anthropogenic)
Combustion processes (e.g. Wildfire)
Respiration of aerobic organisms (animals, humans)

Question 20

The average incoming solar radiation exceeds the average annual outgoing infrared radiation, emitted by the earth, between what latitudes?

Answer 20

40 N and 35 S

Question 21

What does the CO2 concentration depend on in the ocean?

Answer 21

Depends on amount of Co2 in atmosphere and temperature of water

Question 22

As water temperature increases, it’s ability to dissolve co2…

Answer 22

Decreases

Question 23

How much did CO2 increase in the atmosphere from the pre-industrial stage?

Answer 23

It doubled, which meant the oceans co2 doubled also

Question 24

Global warming reduces the oceans ability to absorb co2 leaving more in the atmosphere this will cause…

Answer 24

Higher temperatures

Question 25

Colder areas of water temp generally represent regions of…

Answer 25

Net co2 uptake

Warmer water regions = positive sea-air flux

Question 26

What is ocean acidification?

Answer 26

Uptake of increased co2 reduces surface ocean PH values, which increases the acidity of ocean water

Question 27

Increase in ocean acidification affects:

Answer 27

Coral reefs (declining calcification)
Cold water corals
Ecosystems where aragonite is essential (shell building)
Temperature increase results in coral bleaching