METO 637

Lesson 19

NOx emission inventory

28%

13%

5%30%

19%

5%Fuel Combustion- Electric Utility

Fuel Combustion- Industrial

Fuel Combustion- Other

On-RoadVehicles

Non-RoadVehicles

All Other

VOC Emissions

33%

7%

29%

13%

18% SolventUtilization

Storage &Transport

On-RoadVehicles

Non-RoadVehicles

All Other

Sulfur Dioxide emissions

67%

17%

4%

3%2%

7%

Fuel Combustion- Electric Utility

Fuel Combustion- Industrial

Fuel Combustion- Other

MetalsProcessing

Non-RoadVehicles

All Other

A Typical Day in a Pollution Episode

•A common severe pollution weather pattern occurs when high pressure is centered just west of the Mid Atlantic region.

•Circulation around the high pressure center moves pollution from points west into the mid-Atlantic.

H

Fort Meade profile 6/19/2001

After Sunrise Ozone Levels Increase Sharply

• The ground heats up and the warm air above it erodes the inversion.

• Ozone and other compounds above the inversion layer mix with the pollution under the layer.

• This causes a dramatic increase in ground-level ozone, beginning around 10 AM.

Temperature

Alt

itu

de

Sub. inv.

Noct. inv.

Ozone Levels Reach a Maximum in the Afternoon

Temperature

Alt

itu

de

Sub. inv.

Temperature

Alt

itu

de

Sub. inv.

Noct. inv.

After Sunset• If the weather remains

the same, the temperature inversion forms again after dark.

• Ozone concentrations above the inversion remain at a constant, relatively, high level.

• Ozone trapped under the inversion reacts with other pollutants, and the surface; the ozone concentration diminishes. Ozone concentration

remaining constant

Ozone concentration diminishing

Temperature Inversion

Temperature

Alt

itu

de

Westerly transport is often present when the highest ozone is observed in the mid-Atlantic.

24 hr. Back-trajectories on days of 1-hr. ozone exceedances from 1997 through 2002, Baltimore area

Aircraft measurements of ozone

Aircraft measurements of Sulfur Dioxide

Upper level windsUpper level windsfrom the west…from the west…

……are turned by theare turned by thelee side troughlee side trough

Lee Side T

rough

daytimedaytime

Low Level Jet

nighttimenighttime

Air pollution from the southwest…Air pollution from the southwest…

……comes into Maryland overnightcomes into Maryland overnight

Plot of low-level winds from the Fort Meade, MD wind profiler during a high ozone episode

LLJLLJ LLJ

9:00 PM 11:00 PM 01:00 AM

03:00 AM 05:00 AM 07:00 AM

Rapid Update Cycle (RUC)

model depiction of

the LLJduring a high ozone period

(high wind speeds in red).

All three modes of transport are important when the highest pollution values are observed in the mid-Atlantic.

•Large scale ~ 800 km (~70-100 ppbv)(Much of the Eastern US)

•Medium scale ~ 200- 800 km(Carolinas to New England Region)

•Small scale ~ 100 km(N. Virginia to Baltimore,Research Triangle to NC/VA border)

Modes of Transport

Sources

• Different types of transport imply different types of sources– Local transport Cars, industry, and other

sources in the local area– Long distance transport Primarily power plants to

W, though plumes from cities certainly contribute.

– Low level jet Primarily cars and other

low level sources; moves from SW to NE

Effects of the August 15, 2003 Blackout on Air Quality

Compared with Aug 4, 2002

Coming soon to GRL

Selinsgrove, PA

Effects of the 2003 Blackout on Air Quality

CEM data indicatereductions of 60-80%

L. Marufu, B. Taubman, B. Doddridge et al.

Effects of the 2003 Blackout on Air Quality

In summary

• It isn’t all transport…• It isn’t all local…• It isn’t all power plants…• It isn’t all automobiles…• The problem will not be solved by addressing

any one of these problems individually. ALL of these will have to show significant reductions for us to breathe clean air.