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Meteo 1020 – Lecture 4 The Natural Variability of the Earth-Atmosphere System. Natural variability can be classified by its forcing type (internal or external to the climate system) and whether it is periodic/cyclic or episodic. Modes of Natural Variability that we know of:

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Meteo 1020 – Lecture 4

The Natural Variability of the Earth-Atmosphere System

  • Natural variability can be classified by its forcing type (internal or external to the climate system) and whether it is periodic/cyclic or episodic.

  • Modes of Natural Variability that we know of:

  • timescale form forcing

  • Seasonal 90 days cyclic external

  • El Niño Southern Oscillation 3-5 yrs cyclic internal

  • North Atlantic Oscillation decadal cyclic internal??

  • Volcanism none episodic external

  • Ice ages 40,000 yrs cyclic internal

  • Pacific Decadal 20-50 yrs cyclic ????


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Meteo 1020 – Lecture 4

The Natural Variability of the Earth-Atmosphere System

  • Air-Sea Interactions:

  • Ocean and atmosphere communicate with one another:

  • constituents: water (precipitation and evaporation), carbon dioxide, oxygen, trace gasses, etc

  • Energy – momentum through wind stress driving the surface currents

  • Heat – sensible heat and latent heat due to evaporation

http://science.hq.nasa.gov/oceans/images/water_cycle.jpg


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Ocean structure: on average: warm and relatively fresh mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

http://www.wbgu.de/Images/sn_2006_en/2.1-4.png


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How does ocean circulation affect local climates? mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

Answer: Heat release locations are warmer!

Warm surface current- Less Dense

Cold deep water current–More Dense

Salty water anywhere- More Dense

Intergovernmental Panel on Climate Change (IPCC), "Climate Change 2001: The Scientific Basis"


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What directions do warm and cold water currents travel? mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

Animation by Jack Cook (Woods Hole Oceanographic Institute)


Is it true that the north atlantic current could shut down l.jpg
Is it true that the North Atlantic current could shut down? mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

The ocean surface transfers heat to the atmosphere!

Animation by Jack Cook (Woods Hole Oceanographic Institute)


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Meteo 1020 – Lecture 4 mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

The Natural Variability of the Earth-Atmosphere System

The global thermohaline circulation: Cold Salty water in the north Atlantic becomes dense and convects downward, spreads southward and contributes to vertical overturning of deep ocean water on millennial timescales.

Importance: Climate of northern Europe and Asia rely on heat and moisture supplied to atmosphere to keep climate habitable in extreme northern latitudes.


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What process could change the ocean circulation? mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water masshttp://www.whoi.edu/page.do?pid=12455&tid=282&cid=10046go to bookmarks


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Is freshwater increasing in the North Atlantic? mixed layer lying on top of a nearly isothermal (same temperature) cold and salty water mass

http://www.whoi.edu/templates/files/multimedia.jsp?pid=12455&cid=7466&cl=6732


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http://www.whoi.edu/institutes/occi/images/occi_abrclimate_jk_lev_en.gifhttp://www.whoi.edu/institutes/occi/images/occi_abrclimate_jk_lev_en.gif


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Meteo 1020 – Lecture 4http://www.whoi.edu/institutes/occi/images/occi_abrclimate_jk_lev_en.gif

The Natural Variability of the Earth-Atmosphere System

Even though the oceans and atmosphere are both fluids, they have a fundamental difference – their density: Atmosphere 1 kg/cubic meter, Ocean – approximately 1000 kg/cubic meter.

This density difference leads to large difference in heat capacity.

Heat capacity is defined as the amount of temperature change in kelvin degrees for a unit input of heat energy.

The ocean’s heat capacity is approximately 41 times that of the atmosphere.

A 1 degree change in atmospheric temperature is equivalent to an 0.02 change in ocean temperature change.


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Meteo 1020 – Lecture 4http://www.whoi.edu/institutes/occi/images/occi_abrclimate_jk_lev_en.gif

The Natural Variability of the Earth-Atmosphere System

El Nino is an example of air-sea interactions that occur on annual time scales

Note figures 4.8 and 4.9:

Sea surface temperature (SST) patterns change fundamentally with the el nino cycle

The atmosphere both forces and responds to the el nino cycle.

Normal sst patterns: atmospheric forcing of sst is accomplished through easterly trade winds cooling the central and eastern equatorial pacific. Atmosphere responds to warm western pacific water by the occurrence of strong thunderstorms in that region


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http://teacherresourceexchange.org/science/coriolis/index.phphttp://teacherresourceexchange.org/science/coriolis/index.php


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ENSO Animationhttp://teacherresourceexchange.org/science/coriolis/index.php

http://www.cpc.noaa.gov/products/precip/CWlink/MJO/enso.shtml#current

http://sealevel.jpl.nasa.gov/science/images/el-nino-la-nina.jpg


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ENSO Outlinehttp://teacherresourceexchange.org/science/coriolis/index.php

Mean state of the ocean and atmosphere across the tropical Pacific

Mean ocean surface temperaturesMean tropical Pacific rainfall, winds, and subsurface ocean temperaturesMean wintertime jet streams over the North Pacific and South Pacific

The ENSO cycle

El Niño and La Niña Ocean Temperature PatternsThe Southern Oscillation and its link to the ENSO cycleThe Southern Oscillation Index (SOI)

El Niño

El Niño (ENSO) related rainfall patterns over the tropical PacificEl Niño-related winds, the state of the equatorial Walker circulation, subsurface ocean structureEl Niño-related global temperature and rainfall patterns El Niño - related changes in atmospheric circulation in the subtropics and middle latitudes

La Niña

La Niña-related rainfall patterns over the tropical PacificLa Niña-related winds, the state of the equatorial Walker circulation, subsurface ocean structureLa Niña-related global temperature and rainfall patternsLa Niña- related changes in atmospheric circulation in the subtropics


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NOAA Image and texthttp://teacherresourceexchange.org/science/coriolis/index.php


2 mean tropical pacific rainfall winds and subsurface ocean temperatures l.jpg
2. http://teacherresourceexchange.org/science/coriolis/index.phpMean tropical Pacific rainfall, winds, and subsurface ocean temperatures

  • NOAA Image and text


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Summary: http://teacherresourceexchange.org/science/coriolis/index.phpNormally in the equatorial pacific

Trade winds blow from the east to the west

Warm water piles up on the western side of the equatorial pacific ocean

Cool water upwells along the coast of South America

Low pressure is observed over Indonesia and the western pacific ocean and heavy rainfall occurs there

High pressure is observed in the eastern pacific ocean.


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El Niño and La Niña Ocean Temperature Patternshttp://teacherresourceexchange.org/science/coriolis/index.php

  • NOAA Image and text


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The Southern Oscillation and its link to the ENSO cyclehttp://teacherresourceexchange.org/science/coriolis/index.php

  • NOAA Image and text



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Pressure Force winds?

More air on the left hand side (higher pressure).

The pressure difference over that distance of the sheet (the pressure gradient force), pushes the sheet to the right.


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Pressure Force winds?

More air on the left hand side (higher pressure).

The pressure difference on either side of the parcel (the pressure gradient force), pushes the parcel to the right.


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Pressure Gradient Force winds?

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/pgf.rxml


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If the earth was not spinning, winds?

air would move directly from high

to low pressure areas.

http://teacherresourceexchange.org/science/coriolis/index.php


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http://teacherresourceexchange.org/science/coriolis/index.phphttp://teacherresourceexchange.org/science/coriolis/index.php


Coriolis force http ww2010 atmos uiuc edu gh guides mtr fw gifs coriolis mpg video l.jpg

Coriolis Forcehttp://teacherresourceexchange.org/science/coriolis/index.phphttp://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/gifs/coriolis.mpgVideo


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El Nino Related Rainfallhttp://teacherresourceexchange.org/science/coriolis/index.php

  • NOAA Image and text


2 mean tropical pacific rainfall winds and subsurface ocean temperatures30 l.jpg
2. http://teacherresourceexchange.org/science/coriolis/index.phpMean tropical Pacific rainfall, winds, and subsurface ocean temperatures

  • NOAA Image and text


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El Niño-related winds, the state of the equatorial Walker circulation, subsurface ocean structure

  • NOAA Image and text


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Ocean productivity and El Ni circulation, subsurface ocean structureño

easterly trade winds weaken,

allowing warmer waters of the western Pacific to migrate eastward and eventually reach the South American Coast.

The cool nutrient-rich sea water normally found along the coast of Peru is replaced by warmer water depleted of nutrients, resulting in a dramatic reduction in marine fish and plant life.


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El Ni circulation, subsurface ocean structureño

  • NOAA Image and text


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El Ni circulation, subsurface ocean structureño


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El Ni circulation, subsurface ocean structureño


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La Niña-Related Rainfall Patterns over the Tropical Pacific circulation, subsurface ocean structure

  • NOAA Image and text


2 mean tropical pacific rainfall winds and subsurface ocean temperatures37 l.jpg
2. circulation, subsurface ocean structureMean tropical Pacific rainfall, winds, and subsurface ocean temperatures

  • NOAA Image and text


La ni a related winds walker circulation and subsurface ocean temperatures l.jpg
La Niña-Related Winds, Walker Circulation, and Subsurface Ocean Temperatures

  • NOAA Image and text



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World Connections of weather patterns Patternsshift in the distribution of heat in the atmosphere and ocean which moves things around (Boiling pot)

  • NOAA Image and text


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La Ni Patternsña

Stronger easterly (coming from the east) winds occur moving surface water away from the western coast of South America.

La Niña (female child)

La Niña occurs roughly half as often as El Niño.


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Current Data Patterns

  • NOAA Image and text


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Current La Ni Patternsña

  • NOAA Image and text


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Sea Surface Temperatures Patterns

  • NOAA Image and text


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Upper ocean heat changes Patterns

  • NOAA Image and text


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Ocean Anomalies Patterns

  • NOAA Image and text


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Meteo 1020 – Lecture 4 Patterns

The Natural Variability of the Earth-Atmosphere System

An el nino is characterized by a general warming of the water in the central and eastern pacific.

Atmosphere forces the ocean by a weakening of the easterly trades in the central and eastern pacific.

Atmosphere responds by shifting thunderstorm activity eastward to the central pacific.

Implications: Interruption of fishery along western margins of South America, failure and/or weakening of the Indian Monsoon impacting agriculture in that region.


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Meteo 1020 – Lecture 4 Patterns

The Natural Variability of the Earth-Atmosphere System

El nino remote forcing: the modulation of the normal patterns in the equatorial pacific influence weather patterns around the world:

In the U.S., the pacific storm track is shifted southward leading resulting in storminess over the southwestern U.S. and droughts over the Pacific Northwest. Precipitation is often reduced over the southeastern U.S.


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Meteo 1020 – Lecture 4 Patterns

The Natural Variability of the Earth-Atmosphere System

  • Natural variability can be classified by its forcing type (internal or external to the climate system) and whether it is periodic/cyclic or episodic.

  • Modes of Natural Variability that we know of:

  • timescale form forcing

  • Seasonal 90 days cyclic external

  • El nino 3-5 yrs cyclic internal

  • North Atlantic Oscillation decadal cyclic internal??

  • Volcanism none episodic external

  • Ice ages 40,000 yrs cyclic internal

  • Pacific Decadal 20-50 yrs cyclic ????


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North Atlantic Oscillation Patterns

The NAO index is defined as the anomalous difference between the polar low and the subtropical high during the winter season (December through March)


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The Negative NAO Patterns

The negative NAO index phase shows a weak subtropical high and a weak Icelandic low.

The reduced pressure gradient results in fewer and weaker winter storms crossing on a more west-east pathway.

They bring moist air into the Mediterranean and cold air to northern Europe

The US east coast experiences more cold air outbreaks and hence snowy weather conditions.


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Positive NAO Index Patterns

The Positive NAO index phase shows a stronger than usual subtropical high pressure center and a deeper than normal Icelandic low.

The increased pressure difference results in more and stronger winter storms crossing the Atlantic Ocean on a more northerly track.

This results in warm and wet winters in Europe and in cold and dry winters in northern Canada and Greenland

The eastern US experiences mild and wet winter conditions


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Meteo 1020 – Lecture 4 Patterns

The Natural Variability of the Earth-Atmosphere System

  • Natural variability can be classified by its forcing type (internal or external to the climate system) and whether it is periodic/cyclic or episodic.

  • Modes of Natural Variability that we know of:

  • timescale form forcing

  • Seasonal 90 days cyclic external

  • El nino 3-5 yrs cyclic internal

  • North Atlantic Oscillation decadal cyclic internal??

  • Volcanism none episodic external

  • Ice ages 40,000 yrs cyclic internal

  • Pacific Decadal 20-50 yrs cyclic ????


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Volcanic eruptions and climate: Patterns

The present atmospheric composition, Nitrogen-78%, Oxygen-21%, Argon-<1%, water vapor-0.4%, carbon dioxide-0.036%

How did the present atmospheric composition evolve?

Assume outgassing from early volcanoes provided the first atmosphere.

Composition of volcanic gasses: Water vapor-80%, Nitrogen-1%, Oxygen-0%, carbon dioxide-12%, sulphur compounds and others-7%


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  • Volcanism and the early atmosphere: Patterns

  • So how did the atmosphere evolve from the volcanic composition to our present composition?

  • Water began to precipitate early – forming oceans

  • Carbon Dioxide dissolved rapidly in the early oceans reaching saturation and leading to precipitate of Calcium carbonate to the deep ocean

  • Nitrogen and argon built up slowly since it does not dissolve in sea water

  • Oxygen built up in the atmosphere due to by product of photosynthesis.


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Earth’s Atmosphere Develops Patterns

http://www.globalchange.umich.edu/globalchange1/current/lectures/first_billion_years/first_billion_years.html


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Volcanic Patternsemissions

N2

CO2

H2O

remains

photosynthesis

condensation

N2

O2

oceans

99% of atmosphere

Volcanoes produced the atmosphere and the oceans


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EFFECTS OF LARGE EXPLOSIVE TROPICAL Patterns

VOLCANOES ON WEATHER AND CLIMATE


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EFFECTS OF LARGE EXPLOSIVE TROPICAL Patterns

VOLCANOES ON WEATHER AND CLIMATE


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Tambora in 1815 Patterns, together with an eruption from an unknown volcano in 1809, producedthe “Year Without a Summer” (1816)


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Mary Shelley Patterns

Percy Bysshe Shelley

George Gordon,

Lord Byron

Tambora, 1815, produced the “Year Without a Summer” (1816)


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“The Scream” Patterns

Edvard Munch

Painted in 1893 based on Munch’s memory of the brilliant sunsets following the 1883 Krakatau eruption.


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Pinatubo Patterns

June 12, 1991

Three days before major eruption of

June 15, 1991

Photo from USGS.


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  • These two photos show the Earth’s limb at sunset before and after the Mt. Pinatubo eruption. The first view (STS41D-32-14) shows a relatively clear atmosphere, taken August 30, 1984. Astronauts were looking at the profiles of high thunderstorms topping out at the tropopause at sunset; different atmospheric layers absorbed the last rays of light from the sun as the spacecraft moved eastward.

  • The same type of photograph (STS043-22-23) was taken August 8, 1991, less than two months after the Pinatubo eruption. Two dark layers of aerosols make distinct boundaries in the atmosphere. The estimated altitude of aerosol layers in this view is 20 to 25 km.

From http://earthobservatory.nasa.gov/Study/AstronautPinatubo/astronaut_pinatubo2.html


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Casadevall et al. (1996) and after the Mt. Pinatubo eruption. The first view (STS41D-32-14) shows a relatively clear atmosphere, taken August 30, 1984. Astronauts were looking at the profiles of high thunderstorms topping out at the tropopause at sunset; different atmospheric layers absorbed the last rays of light from the sun as the spacecraft moved eastward.

Bataan


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After Pinatubo, Clark Air Force Base 25 km from volcano and after the Mt. Pinatubo eruption. The first view (STS41D-32-14) shows a relatively clear atmosphere, taken August 30, 1984. Astronauts were looking at the profiles of high thunderstorms topping out at the tropopause at sunset; different atmospheric layers absorbed the last rays of light from the sun as the spacecraft moved eastward.

Photo by R. P. Hoblitt, June 15, 1991


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After Pinatubo, Cubi Point Naval Air Station, 40 km from volcano

U.S. Navy photograph by R. L. Rieger



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The climate effects of volcanic eruptions: volcano

  • What makes an eruption climatically significant?

  • nature of the eruption – lava vs. ash (ash is more significant)

  • composition – need high sulfur dioxide gas content

  • location – Tropical eruption spread globally

In most eruptions, the particulates have only a minor effect. If the sulfur dioxide gas can reach the stratosphere, it converts to small sulfuric acid droplets that have long residence times in the stable stratosphere. It is this cloud of particles that spread and influence climate over long periods. Note Figure 4.3 in the book.


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  • Natural variability can be classified by its forcing type (internal or external to the climate system) and whether it is periodic/cyclic or episodic.

  • Modes of Natural Variability that we know of:

  • timescale form forcing

  • Seasonal 90 days cyclic external

  • El nino 3-5 yrs cyclic internal

  • North Atlantic Oscillation decadal cyclic internal??

  • Volcanism none episodic external

  • Ice ages 40,000 yrs cyclic internal

  • Pacific Decadal 20-50 yrs cyclic ????


Pacific decadal oscillation l.jpg
Pacific Decadal Oscillation (internal or external to the climate system) and whether it is periodic/cyclic or episodic.


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warm phase             cool phase (internal or external to the climate system) and whether it is periodic/cyclic or episodic.

Pacific Decadal Oscillation


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