Air Pollution Meteorology

Community Air Pollution

EHS 582

Dvonch

Air Quality in the News

Research on Global 'Sun Block' Needed Now, Experts ArgueScienceDaily (Jan. 28, 2010)

Internationally coordinated research and field-testing on 'geoengineering' the planet's atmosphere to

limit risk of climate change should begin soon along with building international governance of the

technology, say scientists from the University of Calgary and the United States. Solar-radiation

management (SRM) would involve releasing megatonnes of light-scattering aerosol particles in the

upper atmosphere to reduce Earth's absorption of solar energy, thereby cooling the planet. Another

technique would be to release particles of sea salt to make low-altitude clouds reflect more solar energy technique would be to release particles of sea salt to make low-altitude clouds reflect more solar energy

back into space…. Long-established estimates show that SRM could offset this century's predicted

global average temperature rise more than 100 times more cheaply than achieving the same cooling by

cutting emissions…

SRM would also cool the planet quickly, whereas even a massive program of carbon dioxide emission

cuts will take many decades to slow global warming because the CO2 already accumulated in the

atmosphere will take many years to naturally break down. The 1991 eruption of Mount Pinatubo, for

example, cooled the planet by about 0.5 degrees Celsius in less than a year by injecting sulphur into the

stratosphere. But a world cooled by managing sunlight will present risks, the scientists note. The planet

would have less precipitation and less evaporation, and monsoon rains and winds might be weakened.

Some areas would be more protected from temperature changes than others, creating local 'winners' and

losers.‘ "If the world relies solely on SRM to limit (global) warming, these problems will eventually

pose risks as large as those from uncontrolled emissions,“…

Differential Heatingof Earth

Incident Solar Radiation

January

July

(Courtesy of NASA)

Earth Albedo

Albedo =Reflected Solar Radiation

Incoming Solar Radiation

Annual Global Average Albedo = 30 %

Fresh Snow = 90 % Plowed Field = 15 % Water = 10 % (Small )zenithθ

Energy Balance

Energy Balance as Function of Time of Day

Global Surface Temperatures

Air Pollution Meteorology

Important Terms

• Inversion

• Wind speed & • Wind speed &

direction

– stagnation

• Stability

• Vertical motion

Convection

Planetary Boundary Layer

…is that part of the atmosphere that is directly impacted by

the Earth’s surface

– 300 to 3000 meters in depth

Planetary Boundary Layer

Atmospheric Stability (Dry Processes)

Z

Environmental Lapse Rate

• If the atmosphere cools at a

rate less than the DALR, the

atmosphere is STABLE andZ

T

Dry Adiabatic LR

atmosphere is STABLE and

will suppress the parcel motion.

Atmospheric Stability (Dry Processes)

Z

Environmental Lapse Rate

• If the atmosphere cools at the same

rate as the DALR, the atmosphere

is NEUTRAL and will have noZ

T

Dry Adiabatic LR

is NEUTRAL and will have no

impact on the parcel motion.

Atmospheric Stability (Dry Processes)

Z

• If the atmosphere cools at a

rate greater than the DALR, the

atmosphere is UNSTABLE and

parcel will continue to move until

it reaches a level where the atmosphereZ

T

Dry Adiabatic LR

Environmental Lapse Rate

it reaches a level where the atmosphere

is warmer than the parcel itself.

EHS 582 Community Air Pollution

Stability in Saturated Air

1.6

1.8

2

2.2

ΓΓ

Absolutely

stable

Absolutely

unstable

Conditionally

unstabled w

Alt

itude

(km

)

0.8

1

1.2

1.4

1.6

-2 0 2 4 6 8 10 12 14Temperature (

oC)

stableunstable

1 4

32

Alt

itude

(km

)

Stability in Multiple Layers

2

2.5

3A

ltit

ude

(km

)

Conditionally unstable

Saturated neutral

Saturated neutral

0

0.5

1

1.5

0 5 10 15 20 25

Alt

itude

(km

)

Temperature (oC)

Γe

Γd

Γw

Absolutely unstable

Absolutely stable

Unsaturated neutral

Conditionally unstable

Environmental Lapse Ratechange air temperature with altitude

Γe = −∆T

∆z= −

T zhi( )− T zlo( )zhi − zlo

Γe = −20o C −15oC

2 km − 1 km= −

5o C

km

Γe = −15o C − 21oC

1 km − 0 km= +

6o C

km

Temperature Inversion

1.5

2A

ltit

ude

Alt

itude

(km

)

Top temp.

0

0.5

1

10 12 14 16 18 20 22

Alt

itude

Temperature (oC)

Alt

itude

(km

)

Strength

Top h

eight

Thick

ness

Bas

e hei

ght

Top temp.

Base temp.

Types of Inversions

Large-Scale Subsidence Inversion Radiation Inversion

H

warm radiated air

cool marine air

warm air from subsidence

land

sea

land

surface air cooled

Rising smoke forms a ceiling over the valley due to an inversion

Trapping Pollutants Under an Inversion

1.5

2

2.5

3

Alt

itude

(km

)

0

0.5

1

1.5

0 5 10 15 20 25 30Temperature (

oC)

Γe

Alt

itude

(km

)

Figure 6.11

AM and PMTemperature Profiles

500

600

700

260270280290300310320

Morgan Hill

8/06/90

15:30 PST

Pre

ssure

(m

b)

260 270 280 290 300 310 320

700

800

900

1000

Temperature (K)

15:30 PST

03:30 PST

Pre

ssure

(m

b)

Impact of Changing Mixing DepthLos Angeles, Dec. 19, 2000

Mark Z. Jacobson

Noon Late afternoon

The Beach!

H

H

Basic sea-breeze cell

Large-scale sea-breeze cell

LMountain chimney effect: injection of pollutants to free troposphere

Elevated pollution layers

Sea Breeze Circulation

Desert Coast Ocean

(hot) (warm) (cold)

HLL

Basic sea-breeze cell

Elevated Pollution From Sea Breeze

(Los Angeles, July 22, 2000)

M. Z. Jacobson

Sea-Breeze Impact on Pollution

Eagle Harbor

Pellston

Eagle Harbor

Pellston

Grand Rapids

Flint

Dexter

Detroit Detroit

Dexter

Flint

Grand Rapids

Smoke Stack Plumes

• What type of plume behavior did you

observe in the UM Power Plant this AM?

• What factors affect the behavior of this

plume? Other plumes?

-Occurs overnight/early morning

-Result: Long-range transport

-Occurs during the morning as the lower portion

of the boundary layer warms.

-Result: Enhanced deposition close to the source.

-Occurs during the late morning and early

Atmospheric Stability

-Occurs during the late morning and early

afternoon. Pollutants caught in up/downdrafts.

-Result: Deposition close to the surface.

-Occurs during the mid-afternoon or under

cloudy conditions.

-Result: Pollutants spread out fairly evenly.

-Occurs during the early evening as surface

cools and becomes more stable.

-Result: Long range transport with some

vertical dispersion.

Air Pollution Modeling

where:

The "standard" algorithm used in plume studies is the Gaussian Plume Model

of O.G. Sutton(1932) is as follows:

http://www.shodor.org/os411/courses/_master/tools/calculators/gplume/gplumeinfo.html

1. C(x,y,z) is the concentration of the emission (in micrograms per

cubic meter) at any point x meters downwind of the source, y meters

laterally from the centerline of the plume, and z meters above ground

level.

2. Q is the quantity or mass of the emission (in grams) per unit of

time (seconds)

3. u is the wind speed (in meters per second)

4. h is the height of the source above ground level (in meters)

5. σy and σz are the standard deviations of a statistically normal

plume in the lateral and vertical dimensions, respectively

Differential Heatingof Earth

Convection

Current Weather

Coriolis Effect

At the surface air will flow away from an area

of high pressure and move in a clockwise direction.

1012 mb

1016 mb

Similarly, at the surface air will flow toward the center

of lower pressure and move in a counter clockwise manner.

Weather

Cold Frontal Boundary

Colder Air Warmer Air

If the rising air has enough moisture, water vapor will condense

to form clouds and precipitation. This type of precipitation is

generally short-lived, but relative heavy in nature.

Warm Frontal Boundary

Colder AirWarmer Air

If the rising air has enough moisture, the water vapor will

condense to form clouds and precipitation. This precipitation

is typically light and of long duration.

Weather

Weather