Meto 621 chem
Download
1 / 26

METO 621 CHEM - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

METO 621 CHEM. Lesson 6. 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.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' METO 621 CHEM' - qiana


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Meto 621 chem

METO 621 CHEM

Lesson 6


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



After sunrise ozone levels increase sharply
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.

Sub. inv.

Altitude

 Noct. inv.

Temperature


Ozone levels reach a maximum in the afternoon
Ozone Levels Reach a Maximum in the Afternoon

Sub. inv.

Sub. inv.

Altitude

Altitude

 Noct. inv.

Temperature

Temperature


After sunset
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.

Altitude

Ozone concentration remaining constant

Temperature Inversion

Ozone concentration diminishing

Temperature


Daily ozone cycle
Daily Ozone Cycle

Ozone production

follows a daily

cycle with maximum

concentrations

typically observed

in the late afternoon.

This cycle is a signature of the dynamic processes of atmospheric air pollution

Ozone Concentration

Sunrise

Sunset

Time of day





Comparison of aug 2 and 8 2002
Comparison of Aug 2 and 8, 2002 two days

  • Ozone data for August 8 is typical for local pollution on a clear warm day.

  • The NOx and VOC are emitted early in the morning and the ozone amount slowly increases as the temperature increases. The peak production is at about 3-4 in the afternoon when the temperature at the ground is a maximum.

  • The back trajectory shows fast upper level winds, which start at a high altitude and then subside to boundary levels at Baltimore.

  • Small probability of upper air being polluted.


Comparison of aug 2 and 8 20021
Comparison of Aug 2 and 8, 2002 two days

  • On the 2nd of August the back trajectories show that the air is moving slowly at the boundary layer, and the probability of this air being polluted is high.

  • The nocturnal inversion typically breaks down at about 10-11 in the morning.

  • Hence the peak in ozone at this time must come from downward transport.

  • The overall shape of the ozone data on Aug 2 is a combination of locally produced ozone peaking at about 3 pm and a downward movement of ozone from above at about 10.00 am.

  • This ozone above the boundary layer is yesterday’s ozone

  • The winds above the boundary layer are usually high. Hence the ozone has been transported some distance


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


Aircraft measurements of sulfur dioxide
Aircraft measurements of Sulfur Dioxide is observed in the mid-Atlantic.


Lee side trough
Lee Side Trough is observed in the mid-Atlantic.

Upper level winds

from the west…

…are turned by the

lee side trough

daytime


Low level jet
Low Level Jet is observed in the mid-Atlantic.

Air pollution from the southwest…

…comes into Maryland overnight

nighttime


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

LLJ

LLJ

LLJ


Rapid Update Cycle (RUC) model depiction of the LLJ profiler during a high ozone episodeduring a high ozone period (high wind speeds in red).

9:00 PM

11:00 PM

01:00 AM

03:00 AM

05:00 AM

07:00 AM


Modes of Transport profiler during a high ozone episode

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)


Sources
Sources profiler during a high ozone episode

  • 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


How Significant? profiler during a high ozone episode

  • On the mid-Atlantic’s worst ozone days, a significant amount of pollution comes from long distance transport originating in upwind states.

  • UMD Aircraft measure levels as high as 110 ppbv floating in from the west


Effects of the august 15 2003 blackout on air quality
Effects of the August 15, 2003 Blackout on Air Quality profiler during a high ozone episode

Selinsgrove, PA

Compared with

Aug 4, 2002

Coming soon to GRL


Effects of the 2003 blackout on air quality
Effects of the 2003 Blackout on Air Quality profiler during a high ozone episode

CEM data indicate

reductions of 60-80%

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


Effects of the 2003 blackout on air quality1
Effects of the 2003 Blackout on Air Quality profiler during a high ozone episode


In summary
In summary profiler during a high ozone episode

  • 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.


ad