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•The Atmosphere is a very thin shield that protects us.

•Earth’s equatorial radius is 6378 km and the atmosphere is 500 km.

Structure and circulation

Importance for climate

Composition and significance

Atmospheric deposition

2

– “Wind, rain and radioactivity do not stop at the border for passport control, but go where they will. Pollution? Coming soon to a place near you. We’re all down winders now.” David Nyhan Boston Globe

– Prinn 4.01 Chemically complex dynamic system interacting in significant ways with the oceans, land, and living organisms.

3

Effect of atmospheric constituents on biogeochemical cycles influenced by

• Residence time

• Reactivity

• Water solubility

Important terms• Pollutant “any substance, as certain chemicals or

waste products, that renders the air, soil, water, or other natural resource harmful or unsuitable for a specific purpose”.

• Contaminant-added and changes from original concentration Is CO2 a pollutant or contaminant?

• Nutrient-A substance that provides nourishment essential for growth and the maintenance of life, i.e. trace metals Se, Zn

• Source-Receptor

• Primary versus Secondary PollutantCO2, CO, VOCs, N2O,NO, NH3, SO2, H2S

NO2, HNO3, O3, aerosols

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Fig. 10–2

troposphere

• where weather occurs

• contains 95% of Earth's mass

• Heated from beneath; decreasing temperature with altitude; unstable, causes mixing

• Consists of 20% O2, 79% N2, 0.03% CO2, 1% Ar, H2O © Brooks/Cole Publishing Company / ITP

Ozone layer 10-30 km thick5mm if compressed

Atmospheric O2 is 21%209,460 ppmOzone 12 ppm

Ozone in troposphere 40 ppb

Stull 1998

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Stull 1998

Electromagnetic Radiation

Fig. 3–8© Brooks/Cole Publishing Company / ITP

6

Figure 3.2 Schlesinger (1997) and S and B

Factors driving atmospheric circulation

• Incoming solar radiation

• Rotation of the earth

• High and low pressure systems

• Need to fill in air once air has moved from one place to another

• Intersection with land masses

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Initial pattern of air circulation

Deflections in the paths of air flownear the earth’s surface

30°S

Easterlies

Westerlies

Southeasttradewinds

(Doldrums)

Northeasttradewinds

Westerlies(from the west)

Easterlies(from the east)

60°S

equator

30°N

60°N

Atmosphere transports heat, water and atmospheric constituents

Stull 1998

8

Wind horizontal movement of air

• Wind moves from and around high pressure to low pressure areas

• At a high air subsides

• Due to the Earth’s rotation air is deflected to the right in the N hemisphere as it moves clockwise and out from high pressure

• Then counterclockwise and into low

Fig 2.6 Ruddiman

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Figure B4. “the simplified global pattern becomes more complicated when continents added into the picture.” NRC

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Jet streams..

Subtropical and polar jet streams-

ITCZ confluence of NE (N Hemisphere) and SE trade winds

Important areas of transport

Atmospheric Rivers

• “Imagine a stream of water thousands of km long and as wide as the distance between NY and DC flowing towards you at 30 mph..7-15 Mississippi Rivers..a river of water vapor in the atmosphere” EOS 92 #32

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Schematic of some major atmospheric transport pathways(focusing on those affecting North America).

Micrometeorological scale 0 to10 km

Mesometeorological scale 10 to 100s km

Synoptic scale- 100 to 1000s km General Circulation

Global scale->5 x 10^3

1-4 wks

1-2 m

3-13 d

1-2 wk

1-2 wk

4-17 d

1y

Primary versus secondary

S and B Table 3.1 and Table 3.2

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From Seinfeld and Pandis

Concentrations stable for those that are inert with increasing variability for those of low concentration and chemically reactive

Table 3.4 biogenic gases

Schlesinger (1997) S and B Table 3.5

Source strength – source variability-sink strength and variability

C- soot/CO2 inert-sink photosynthesis/ocean

Denitrification

Fossil fuels

Agriculture

Plankton

Decaying proteins

Biological activity

Fossil fuels

Anaerobic decayFires, decay of chlorophyllVegetation emissions

Sinks are oxidation, gas exchange, washout

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Oxidative capacity of the atmosphere

• Cleanses the atmosphere

• Did not start until oxygenated atmosphere

• O3 attack water and makes OH

• NO important also

• Not constant- light, water vapor, atm chemistry

• Impacts– Removes CH4 and CO

– Starting point for aerosols

What is Ozone?

• Gaseous ozone (O3) is an allotrope of oxygen. It is a natural component of Earth’s atmosphere, existing mainly in the upper atmosphere (stratosphere). It is formed from O2 via a variety of photochemical reactions.

• Ozone is unstable and will react with (oxidize) surfaces, vegetation and many other materials, including our lungs.

• Interesting note- Some early work on ozone focused on damage to aircraft seals and rubber at high elevation. The reaction with rubber bands was also used as a means to quantify the amount of ozone in the atmosphere.

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Formation in the Troposphere

http://www.bbc.com/news/science-environment-20563591

http://elte.prompt.hu/sites/default/files/tananyagok/atmospheric/ch08s02.html

Volatile organic compounds, nitrogen oxides, and sunlight

• Troposphere-– Natural and anthropogenic

• Preindustrial 10- 20 ppb stratosphere intrusions, lightning, natural surface emissions of CO, CH4 and VOCs, wildfire

• Current baseline 50-60 ppb

• Forms OH influences oxidizing capacity of the atmosphere

• Stratosphere– Natural processes and anthropogenic impacts

Ozone Table 3.6 S and B

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Reactions some are in S and B starting pg 66

From the stratosphere and natural source of VOC and NO

• O3

• O3 + H2O—2OH

• OH + CO CO2 + H (H+O2 HO2)

• OH + CH4 CH3 + H2O

CO2 is not reactive with other gases in the atmosphere

• Concentration is affected by interaction with Earth’s surface– Carbonate-silicate cycle=chemical weathering

– Gas exchange with sea water following Henry’s Law

– Photosynthesis and respiration

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Nitrogen

• NO and NO2=NOx

• Combustion

• Natural sources-wildfires, lightning, microbial processes

• NO in combustion converted to NO2

• NO2 + light– NO + O

• O + O2– O3

Importance as a sink

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www.epa.gov/airnow

Air pollution

Hydrocarbons + nitrogen oxides + light– > ozone and other oxidants

winds

Pressure

Figure 7: Average ozone (O3, ppbv), carbon monoxide (CO, ppbv), oxides of nitrogen (NOx, ppbv), nitrogen monoxide (NO, ppbv), sulfur dioxide (SO2, ppbv), and particulate matter (PM2.5, µg m-3) for each hour of the day (PST) of the days classified in Q1 at UNRG and WCAQ.

June to Nov 2012

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NOx emissions in Southern California now less than half of what they were 20 years ago! (Lurmann et al 2015)

NO2 Concentrations and NOx emissions in Southern California

Changing O3 at Europe mountain sites

Volz et al 1988; Marenco et al 1994

Pre-industrial background O3

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Changing background and AQ standards

Time

Ozo

ne

For trends in background O3 see: Gratz et al 2014; Jaffe et al 2003; Parrish et al 2004; Oltmans et al 2006; Jaffe and Ray 2007;

Cooper et al 2010; 2014; NAS 2010; Papers in Special Section of STOTEN on NVROI

O3 distributions across the Western US and gaps in data3-year Average 4th Highest 8-Hour Ozone value by County 2011-2013

AQS Federal Reference Method data from the monitoring site in each County with the highest Ozone values

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Fine et al., 2015

Given…

• Limited Sources

• Complex Terrain

• Location

• Climate

Hypothesis

Entrainment of air aloft will influence measured O3 and thus, regional and global sources with contribute to O3

measured in rural Nevada.

Nevada Rural Ozone Initiative

Funded by the Nevada Division of Environmental Protection

Great Basin National Park

Fine et al., 2015

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• Correlation between sites in NV and high elevation in California

• Monthly means above those considered chronic threshold levels for trees (Gustin et al., 2015; Fine et al., 2015)

• Change higher in the Valleys

• Rapid increase in ozone ~8-10:00– Convective growth of the boundary layer

– Mixing of air aloft : bottom up entrainment of pollution in the residual layer/free troposphere

• Secondary peak in rate of increase ~13:00– Photochemical production from local sources or in put from regional transport

• Rapid decrease in ozone at dusk due to reaction with surfaces.

Gustin et al., 2015

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Seasonal patterns Gustin et al., 2015

-MDA 8 higher in the spring (LRT) Summer(Wildfires)-Need to consider climate change and O3 importance as a greenhouse gas -Public lands and National Parks in Western United States impacted (also wildlife and humans)

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Ultraviolet radiation

UVA-0.315 to 0.4 um longest wavelength, least energetic, can cause some damage to living cells

UVB-0. 28 to 0.315 um damaging to living cells, under normal conditions most absorbed by ozone

UVC-< 0.28 highest energy shortest wavelength

•O2 = O + O•O3 = O2 + O

•O2 + O =O3

•O2•O2

•O2

•O2

•O2

•O2

UV-A

UV-B UV-C

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How Does Depletion Occur?

CFCl3 + light ClCl + O3-ClO + O2ClO + O Cl + O2Net O + O3 2O2

Ozone Thinning

•Antarctic depletion in their spring which is our fall; Arctic depletion in the spring

Dobson unit data

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Ozone depleting chemicals

• Hydroxyl radical

• Nitric acid

• CFCs-Halogen containing compounds-nontoxic and non flammable

• Bromine containing fire retardants

• Methyl Bromide

• Carbon tetrachloride/Methyl chloroform

HCFCs

• 2016 Agreement to phase out due to GHG

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Elements August 2010Particulates- solid particles and liquid droplets

Aerosol- PM and the gas within which it is suspended

Table 3.3 S and B

Figure 3.7

Primary PM direct

Secondary formed through gas to particle conversion

May be altered in the atmosphere-aged

http://earthobservatory.nasa.gov/GlobalMaps/

Natural versus anthropogenic sources

• Natural-volcanoes, ocean spray, dust storms, fires, biogenic particles

• Human- industrial, agriculture, traffic, mining, incineration, combustion

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• Large-scale haze phenomena exist around the world

United States’ East Coast

Light ScatteringLight Absorption

reduction in solar radiation at surface

Direct Effects of Aerosol

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Direct Effects of Aerosol

H2O

H2O H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

If too small requires too much energy required for water molecules to condense on each other

Other Effects of Aerosol

Normal Atmosphere Atmosphere with Inversion

Temperature

Hei

gh

t

Temperature

Hei

gh

t

Hot Air Hot Air

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“Global Dimming”

http://z.about.com/d/weather/1/0/k/2/-/-/77509771.jpg

• 10-25% dimming in Beijing, Karachi, New Delhi• 20% sunlight reduction since 1970 in Guangzhou• 2% per decade dimming on Indian subcontinent• >4% per decade dimming in Chinahttp://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=550&ArticleID=5978&l=en

Beijing, China

PM and oceans

• Deposition of dust can have negative or positive effects– Copper inhibit phytoplankton

– the decline of coral reefs in the Caribbean region has been linked to Saharan dust deposition-not well understood

– Important source of nutrients

– Elements Gasso, Santiago, Grassian, Vicki H., Miller, Ron L.Interactions between Mineral Dust, Climate, and Ocean EcosystemsELEMENTS 2010 6: 247-252

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Atmospheric Deposition

http://nadp.sws.uiuc.edu/ntn/

Dry and wet are important --- DRY not well quantified

https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter08_FINAL.pdf

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Climate Systemhumans

Fourth assignment

• I have picked papers for you all to read. See paper picks.

• Read the The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System Science 290, 291 (2000) P. Falkowski, et al.

• Place your assigned paper into the context of the Falkowski paper

• Same format for paper.. read summarize critique for presentation do the same but include how it fits into the older literature.

• Assigned people will give presentation. Keep at 7 minutes.