feb. 2, 2005 1 the atmosphere and atmospheric ozone dr. paul a. newman nasa’s goddard space...

1

Feb. 2, 2005

The Atmosphere and Atmospheric OzoneThe Atmosphere and Atmospheric Ozone

Dr. Paul A. Newman

http://code916.gsfc.nasa.gov/People/Newman/

NASA’s Goddard Space Flight Center

2005 NASA Earth System Science Teacher Workshop

NASA GSFC

April 22, 2005

Dr. Paul A. Newman

http://code916.gsfc.nasa.gov/People/Newman/

NASA’s Goddard Space Flight Center

2005 NASA Earth System Science Teacher Workshop

NASA GSFC

April 22, 2005

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Feb. 2, 2005

What are the main issues in atmospheric physics?

What are the main issues in atmospheric physics?

• Ozone depletion

• Atmospheric pollution

• Climate change

All 3 issues are related to changing atmospheric composition

• Ozone depletion

• Atmospheric pollution

• Climate change

All 3 issues are related to changing atmospheric composition

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Feb. 2, 2005

OutlineOutline

• Atmospheric Basics & Solar Radiation

• Ozone: basics and photochemistry

• Ozone loss in the atmosphere• Summary• Educational activities

• Atmospheric Basics & Solar Radiation

• Ozone: basics and photochemistry

• Ozone loss in the atmosphere• Summary• Educational activities

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Feb. 2, 2005

Atmospheric Basics

Atmospheric Basics

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Feb. 2, 2005

180 200 220 240 260 280 300Temperature (K)

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Alti

tude

(km

)

Troposphere

Stratosphere

Mesosphere

Thermosphere

Atmospheric StructureAtmospheric StructureA

ltitude (miles)

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0

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30

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81oF45oF9oF-27oF-63oF-99oF-135oF

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Feb. 2, 2005

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Alti

tude

(km

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Troposphere

Stratosphere

Mesosphere

Thermosphere


ltitude (miles)

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50

60

Airliners fly at 30,000-40,000 feet

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Feb. 2, 2005

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Alti

tude

(km

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Troposphere

Stratosphere

Mesosphere

Thermosphere


ltitude (miles)

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ER-2 flies at 70,000 feet

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Feb. 2, 2005

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Alti

tude

(km

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Troposphere

Stratosphere

Mesosphere

Thermosphere


ltitude (miles)

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0

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30

40

50

60

Oxygen (21%) Nitrogen (78%)

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Feb. 2, 2005

Atmospheric CompositionAtmospheric Composition

• Nitrogen 0.781• Oxygen 0.209• Argon 0.009• Water 0.014 (tropics) 0.002 (poles) 0.000004 (stratosphere)• CO2 0.000360 • O3 0.0000100 (stratosphere) 0.0000001 (troposphere)

• Nitrogen 0.781• Oxygen 0.209• Argon 0.009• Water 0.014 (tropics) 0.002 (poles) 0.000004 (stratosphere)• CO2 0.000360 • O3 0.0000100 (stratosphere) 0.0000001 (troposphere)

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Feb. 2, 2005

Solar Radiation: The photochemistry

driver

Solar Radiation: The photochemistry

driver

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Feb. 2, 2005

The Electromagnetic SpectrumThe Electromagnetic Spectrum

10-1210-12 10-1010-10 10-810-8 10-610-6 10-410-4 10-210-2 11

-ray-ray X-rayX-ray UltraVioletUltraViolet VisVis InfraRedInfraRed RadioRadioMicrowaveMicrowave

Scale (meters)Scale (meters)

BaseballBaseballFleaFleaCellCellE. ColiE. ColiVirusVirusProteinProteinH2OH2O

Higher EnergyHigher Energy Lower EnergyLower Energy

1 nm = 1x10-9 m =1 billionth of a meter1 nm = 1x10-9 m =1 billionth of a meter

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Feb. 2, 2005

Solar Energy Outside Earth’s Atmosphere(from space)

1 m = 1x10-6 m =1 millionth of a meter

Solar Energy at Earth’s Surface

UV IR

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Feb. 2, 2005

Absorption of UV by ozoneAbsorption of UV by ozone

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Feb. 2, 2005

UV radiationUV radiation• Solar radiation exists at a variety of wavelengths, most commonly visible

radiation from 400 nm (nanometers or billionths of a meter) to about 700 nm.

• UV radiation extends from 1-400 nm (invisible to the human eye).• http://sohowww.nascom.nasa.gov/data/realtime-images.html Extreme UV

images from the Extreme ultraviolet Imaging Telescope (EIT), and the Michelson Doppler Imager (MDI)

• A UV photon is more energetic than a visible photon, and the UV photon can break the bonds of biological molecules such as proteins and DNA.

• Solar radiation exists at a variety of wavelengths, most commonly visible radiation from 400 nm (nanometers or billionths of a meter) to about 700 nm.

• UV radiation extends from 1-400 nm (invisible to the human eye).• http://sohowww.nascom.nasa.gov/data/realtime-images.html Extreme UV

images from the Extreme ultraviolet Imaging Telescope (EIT), and the Michelson Doppler Imager (MDI)

• A UV photon is more energetic than a visible photon, and the UV photon can break the bonds of biological molecules such as proteins and DNA.

30.4 nm UV radiation 60,000-80,000 K30.4 nm UV radiation 60,000-80,000 K

04/18/2003images

04/18/2003images

677 nm visible radiation

677 nm visible radiation

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Feb. 2, 2005

What is ozone?What is ozone?

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Feb. 2, 2005

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Mesosphere

Thermosphere


ltitude (miles)

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Oxygen Ozone

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Feb. 2, 2005

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Ozone (parts per million)

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20

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80

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Alti

tude

(km

)

Troposphere

Mesosphere

Thermosphere

Ozone FactsOzone FactsA

ltitude (miles)

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0

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30

40

50

60

90% of ozone is in the stratosphere

0 2 4 6 8

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Feb. 2, 2005

Ozone (parts per million)

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Alti

tude

(km

)

Stratosphere

Mesosphere

Thermosphere


ltitude (miles)

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0

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40

50

60

0 2 4 6 8

10% of ozone is in the troposphere

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Feb. 2, 2005

What does ozone do?Absorbs UV radiationWhat does ozone do?Absorbs UV radiation

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Feb. 2, 2005

Ozone (part per million)

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Alti

tude

(km

)

Stratosphere


ltitude (miles)

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0 2 4 6 8

UVc - 100% AbsorptionUVb - 90% Absorption

UVa - 50% Absorption & Scattering

Ozone is the Earth’s natural sunscreen

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Feb. 2, 2005

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80

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Alti

tude

(km

)

Troposphere

Stratosphere

Mesosphere

Thermosphere

Ozone FactsOzone Facts

Altitude (m

iles)

10

0

20

30

40

50

60

Ozone is a pollutant, lung and esophagus

irritant

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Feb. 2, 2005

UV Health FactsUV Health Facts

• UV pluses: produces vitamin D in the skin - necessary to maintain levels of calcium and phosphorus (10-15 minutes twice a week)

• UV minuses:– Eye damage: cataracts, photokerititus

(snowblinding), ocular cancers – Skin cancers: basal, squamous,

melanoma– photoaging– Damage to various land speciesDamage

to aquatic species– Increased pollution levels in urban

environments

• UV pluses: produces vitamin D in the skin - necessary to maintain levels of calcium and phosphorus (10-15 minutes twice a week)

• UV minuses:– Eye damage: cataracts, photokerititus

(snowblinding), ocular cancers – Skin cancers: basal, squamous,

melanoma– photoaging– Damage to various land speciesDamage

to aquatic species– Increased pollution levels in urban

environments





Cataract

Melanoma

Mexico City

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Feb. 2, 2005

Ozone Photochemistry

Ozone Photochemistry

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Feb. 2, 2005

Ozone Absorption of UVOzone Absorption of UV

UV radiation (200-300 nm) converted to heatNet: O3 + h O3

At 30 km, this reaction takes 0.1 seconds

1. O3 is split by UV radiation

1. O3 is split by UV radiation

2. An O2 reacts withAn O atom to reform O3

2. An O2 reacts withAn O atom to reform O3

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Feb. 2, 2005

Ozone ProductionOzone Production

UV < 240 nm

O2 + h 2 O

O + O2 + M O3 + M

Ozone is created by oxygen molecules and energetic UV radiation

Net: O2 + h 2 O3

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Feb. 2, 2005

Catalytic Ozone LossCatalytic Ozone Loss

Principal ingredients for ozone loss:UV radiation and a free radical

X = OH, NO, Cl, Br

1. O3 + h O2 + O2. O3 + X O2 + XO3. XO + O O2 + X

Net: 2 O3 3 O2

1.

2.

3.

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Feb. 2, 2005

Photochemical balance

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Feb. 2, 2005

Source gases for ozone lossSource gases for ozone loss

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Feb. 2, 2005

16%

32%

23%

12%

7%5%

1%4%

0

3400

3000

2000

1000

(CH3CCl3)

(e.g., HCFC-22 = CHClF2)

(CCl2FCClF2)

Naturalsources

Other gasesMethyl chloroform

HCFCs

CFC-113

Carbon tetrachloride (CCl4)

CFC-11 (CCl3F)

CFC-12 (CCl2F2)

Methyl chloride (CH3Cl)

0

20

15

10

5

15%

27-42%

5-20%20%

14%

4%

Methyl bromide (CH3Br)

Halon-1211 (CBrCIF2)

Halon-1301 (CBrF3)

Other halons

Very-short lived gases (e.g., bromoform = CHBr3)

Source Gases

• Cl is much more abundant than Br• Br is about 50 times more effective at O3 destruction

From Ozone FAQ - see http://www.unep.org/ozone/faq.shtml

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Feb. 2, 2005

Atmospheric Chlorine Trends from NOAA/CMDL -HATS Group


Figure from Trends of the Commonly Used Halons Below Published by Butler et al. [1998]

CFC-12

50 years

102 years

5 years

42 years

85 years

Steady growth of CFCs up to 1992

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Feb. 2, 2005

Photochemical balance

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Feb. 2, 2005

What’s happened to polar ozone?

What’s happened to polar ozone?

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Feb. 2, 2005

Antarctic MeasurementsAntarctic Measurements

Aurora over Halley Bay Station, Antarctica, 75.6ºS 26.5ºE Brunt Ice Shelf, Coats Land

105 days of continuous darkness, twice per year re-supply Population: 65 in summer, 15 in winter

Aurora over Halley Bay Station, Antarctica, 75.6ºS 26.5ºE Brunt Ice Shelf, Coats Land

105 days of continuous darkness, twice per year re-supply Population: 65 in summer, 15 in winter

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Feb. 2, 2005

Digression: Dobson UnitsDigression: Dobson Units

3 mm = 300 Dobson Units3 mm = 300 Dobson Units

• Total Ozone is a measure of the total column amount above us. Measured in Dobson Units

• If we bring all of the ozone above us down to the Earth’s surface

• The thickness would be about 3 millimeters (~0.1 inches) = 300 Dobson Units (approximately the global average)

• 100 Dobson Units = 1 millimeter in thickness

• Total Ozone is a measure of the total column amount above us. Measured in Dobson Units

• If we bring all of the ozone above us down to the Earth’s surface

• The thickness would be about 3 millimeters (~0.1 inches) = 300 Dobson Units (approximately the global average)

• 100 Dobson Units = 1 millimeter in thickness

The Dobson Unit is a convenient unit of measurement for total column ozone

The Dobson Unit is a convenient unit of measurement for total column ozone

2¢2¢10¢10¢

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Feb. 2, 2005

October Antarctic OzoneOctober Antarctic Ozone

Halley Bay October Averages Minimum value of October TOMS average

1960 1970 1980 1990 2000100

150

200

250

300

350

Min. of Oct. TOMSHalley Bay (J. Shanklin, BAS)BUV

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Feb. 2, 2005

TOMS - August 31, 2003

Orange/Yellow indicates higher ozone levels.

Blue colors indicate low ozone values

Dark color over pole shows the extent of polar night, no

ozone observations

Antarctic ozone hole is defined as the

region covered by low ozone values

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Feb. 2, 2005

The 2003 MovieThe 2003 Movie

Greg Shirah, NASA/GSFC SVS

QuickTime™ and aYUV420 codec decompressorare needed to see this picture.

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Feb. 2, 2005

October Average Ozone HoleOctober Average Ozone Hole

lowozone

highozone

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Feb. 2, 2005

Arctic & Antarctic Trends

1970 1980 1990 2000

200

250

300

350

400

450

500

BUVNimbus-7Meteor-3EP-TOMSNOAA-14NOAA-9Aura-OMI (prelim.)

SH October

NH March

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Feb. 2, 2005

Polar Stratospheric CloudsPolar Stratospheric Clouds

Central, Sweden January 14, 2003 - P. Newman

HCl and ClONO2 react on the surface of cloud particles, releasing Cl2. As the sun rises in the spring, the Cl2 is photolyzed by visible light, starting a catalytic

reaction that depletes ozone 1-2% per day!

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Feb. 2, 2005

Global Total OzoneGlobal Total Ozone

1980 1985 1990 1995 2000 2005-20

-15

-10

-5

0

5

60˚S-60˚N60˚S-60˚N

Solar maximaSolar maximaVolcanoesVolcanoes

El C

hic

ho

nE

l Ch

ich

on

Pin

atu

bo

Pin

atu

bo

Quasi-biennial OscillationQuasi-biennial Oscillation

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Feb. 2, 2005

What’s being done?What’s being done?

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Feb. 2, 2005



Figure from Trends of the Commonly Used Halons Below Published by Butler et al. [1998]

CFC-12

50 years

102 years

5 years

42 years

85 years

U. S. CFC production stopped by President George Bush in 1992

Montreal Protocol Signed (1987)

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Feb. 2, 2005



NASA continues to measure ozone and gases that destroy ozone

NASA continues to measure ozone and gases that destroy ozone










are needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

50

Feb. 2, 2005

Future Antarctic Ozone Levels

WMO Assessment [2003]

1.Will CFCs and halons decrease as expected?2. Greenhouse gas warming of the lower atmosphere has a cooling affect in the stratosphere, increasing polar O3 loss

3. Stratospheric water vapor increases (of unknown origin) will increase polar O3 loss

Minimum Antarctic Ozone September-November

1960197019801990200020102020203020402050206050

100

150

200

250

300

TOMSCMAMUMETRAC

MAECHAM/CHEME39/CCCSR/NIESUIUC ULAQ

GISS 98 Assessment

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Feb. 2, 2005

What Can You Do?What Can You Do?

• Avoid excessive solar exposure (limit sun between 11AM and 2PM).

• Wear and encourage others to wear sunscreen (SPF rating of 15). Even with sunscreen, prolonged exposure is not smart.

• Check your skin regularly.• Wear sunglasses that screen UV. • Hats and other coverings• Make note of the UV index on the news or web:

http://www.epa.gov/sunwise/uvindex.html

• Avoid excessive solar exposure (limit sun between 11AM and 2PM).

• Wear and encourage others to wear sunscreen (SPF rating of 15). Even with sunscreen, prolonged exposure is not smart.

• Check your skin regularly.• Wear sunglasses that screen UV. • Hats and other coverings• Make note of the UV index on the news or web:

http://www.epa.gov/sunwise/uvindex.html

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Feb. 2, 2005

Summary• Stratospheric ozone is a critical gas for

screening solar UV radiation.• Human produced ozone destroying

substances (ODS) have caused large losses of ozone over both poles and small global losses.

• ODSs have been regulated under international agreements and are slowly decreasing. Ozone levels should recover within the next 50-70 years.

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Feb. 2, 2005

Educational Activities and Resources

Educational Activities and Resources

• Jeannie Allen (Sr. Science Education Specialist) [email protected] 301-614-6627

• See handout prepared by Jeannie• Chem Matters http://chemistry.

org/education/chemmatters.html

• Jeannie Allen (Sr. Science Education Specialist) [email protected] 301-614-6627

• See handout prepared by Jeannie• Chem Matters http://chemistry.

org/education/chemmatters.html

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Feb. 2, 2005

ENDEND

Jan. 10, 2003 - local noon, Kiruna, SwedenJan. 10, 2003 - local noon, Kiruna, Sweden

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Feb. 2, 2005

What About Global Warming?

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Feb. 2, 2005

Greenhouse Effect

Without the greenhouse effect, the average surface temperature would be ~0º F!

UV-Vis radiation from the sun is absorbed by Earth’s surface.

Earth’s surface reemits heat as longwave radiation.

CO2

H2O

Atmospheric gases like CO2 and H2O trap outgoing radiation

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Feb. 2, 2005

Historical Record of CO2

250

275

300

325

350

375

1000 1200 1400 1600 1800 2000

South Pole Flask Data NOAA/CMDL (2001)

Law Dome ice core Etheridge et al. (1999)

Atm

osp

her

ic C

O2 (

ppm

v)

Year

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Feb. 2, 2005

Variations of the Earth’s surface temperature for the past 1,000 years

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Feb. 2, 2005

The last 160,000 years (from ice cores) and the next 100 years:

Time (thousands of years)

160 120 80 40 Now

–10

0

10

100

200

300

400

500

600

700

CO2 now

Temperature

difference from today °C

CO

2 c

once

ntra

tion

(ppm

v)

Lowest possible CO2

stabilisation level by 2100

Double pre-industrial CO2

CO2 in 2100(with business as usual)

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Feb. 2, 2005

OCEANS LAND

ATMOSPHERE

Only about ½ of the CO2 emitted each year shows up in the atmosphere. The rest is absorbed by the ocean or by plants on land.

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Feb. 2, 2005

Feedbacks make predicting future climate challenging!

Positive Feedback:

More CO2Oceans WarmMore H2OMore Warming

Negative Feedback:

More CO2Oceans Warm More H2OMore High Clouds

More Reflected Sunlight

Cooling

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Feb. 2, 2005

Ozone Hole Theory

Ozone Hole Theory

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Feb. 2, 2005

Polar Ozone DestructionPolar Ozone Destruction

1. O3 + Cl ClO + O21. O3 + Cl ClO + O2

Only visible light (blue/green) needed for photolyzing ClOOClNo oxygen atoms required

Net: 2O3 + h 3O2

2 O32 O3 3 O23 O2

3. ClOOCl+h2 Cl+O23. ClOOCl+h2 Cl+O2

2. 2 ClO + M ClOOCl + M2. 2 ClO + M ClOOCl + M

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Feb. 2, 2005

Polar ProcessesPolar ProcessesPolar ozone losses differ from the standard

photochemical balance:

1. Ozone usually has a very long lifetime: months to years

2. Ozone production is zero, losses are not compensated by production

3. Very cold conditions, cold enough to form clouds in the dry stratosphere.

Polar ozone losses differ from the standard photochemical balance:

1. Ozone usually has a very long lifetime: months to years

2. Ozone production is zero, losses are not compensated by production

3. Very cold conditions, cold enough to form clouds in the dry stratosphere.

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Feb. 2, 2005

Polar Stratospheric CloudsPolar Stratospheric Clouds

Central, Sweden January 14, 2003 - P. Newman

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Feb. 2, 2005

Antarctic ozone lossAntarctic ozone loss

Cold T PSCs + high Cly het reactions Large catalytic loss

Cold T PSCs + high Cly het reactions Large catalytic loss

JanJan FebFeb MarMar AprApr MayMay JunJun JulJul AugAug SepSep OctOct NovNov DecDec180180

190190

200200

210210

220220

230230

Tem

per

atur

e (K

)T

emp

erat

ure

(K)

-136-136

-118-118

-100-100

-82-82

-64-64

-46-46

Tem

perature (˚F

)T

emp

erature (˚F)

Minimum temperature over Antarctica at ~ 20 km (66 kft)Minimum temperature over Antarctica at ~ 20 km (66 kft)

Polar night begins to fall and temperatures start to coolPolar night begins to fall and temperatures start to cool

Type I - PSC (nitric acid hydrate)Type I - PSC (nitric acid hydrate)

Type II - PSC (water ice particles)Type II - PSC (water ice particles)

Polar stratospheric clouds begin to formPolar stratospheric clouds begin to formChlorine is freed from reservoir species into radical forms

HCl + ClONO2 Cl2 + HNO3

Chlorine is freed from reservoir species into radical formsHCl + ClONO2 Cl2 + HNO3

Sunrise (visible radiation) breaks apart Cl2

Rapid catalytic ozone loss

Sunrise (visible radiation) breaks apart Cl2

Rapid catalytic ozone lossTemperatures warm above PSC temperatures

Ozone loss stopsTemperatures warm above PSC temperatures

Ozone loss stopsOzone hole breaks-up, mixes low ozone across SHOzone hole breaks-up, mixes low ozone across SH

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Feb. 2, 2005

Solomon et al. (1986), Wofsy and McElroy (1986), and Crutzen and Arnold (1986) suggest reactions

on cloud particle surfaces as mechanism for activating Chlorine

Solomon et al. (1986), Wofsy and McElroy (1986), and Crutzen and Arnold (1986) suggest reactions

on cloud particle surfaces as mechanism for activating Chlorine

HCl

ClONO2 HNO3

Cl2

Cl2 is easily photolyzed by UV & blue/green lightHNO3 is sequestered on PSC

Antarctic ozone hole theoryAntarctic ozone hole theory

feb. 2, 2005 1 the atmosphere and atmospheric ozone dr. paul a. newman nasa’s goddard space...

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