TROPOSPHERIC OZONE

The characters of the tropospheric ozone

• About 8 % of the total column ozone is in the troposphere. The tropospheric ozone also plays an important role in the atmosphere.
• Ozone is a green house gas and possibly contributes to the global warming.



• Ozone is harmful for human being and crops in the troposphere.



• Ozone oxidizes many chemical substances in the troposphere, and controls tropospheric chemistry.

• The source of the tropospheric ozone
• Intrusion from the stratosphere.
• Most of ozone in the atmosphere is in the stratosphere and created from solar UV radiation. The stratospheric ozone sometimes flows into the troposphere by the upper layer trough and cut-off low activities. Some part of ozone may subside in the troposphere directly by the Hadley circulation



• Photochemical reactions.
• Ozone is produced from relatively longer-wavelength solar radiation under nitrogen oxides (NOx) and organic compounds that are volitile (VOC's), like methane.



• Since ozone is strongly linked to sunlight, ozone tends to accumulate in the atmosphere during the day (summer)

• Weather conditions, concentration of VOC's and Nox control the amount of tropospheric ozone created



• Sources of VOC's and Nox
• Natural NOx
• Forest fires



• Decaying organic matter



• Lightning



• Natural VOC's
• Forest fires



• Growing terrestrial vegetation
• Blue Ridge Mountains



• Ocean



• Human sourced Nox and VOC's
• Transportation

• The City Link and Photochemical Smog
• Meteorological connection



• Reddish, yellow-brown, and gray hazes



• Health Effects
• Emphysema, asthma



• Reduced plant growth



• Decrease in agricultural crop yield



• Weaken defense mechanisms of plants



• The trend of the tropospheric ozone
• Some global monitoring stations show the increase of ozone in the troposphere. It may be a big problem, because if tropospheric ozone increases, it might damage to human beings and many crops, and fairly contribute to the global warming and change the tropospheric chemistry. If the tropospheric chemistry changes, the nature of pollution and acid rain might change.



• Not all monitoring stations show the increasing trend. We have to monitor the tropospheric ozone at many suitable observation points. This also has the mean to study influence of human activities on Nature.



• Ozone in the upper troposphere and lower stratosphere functions as a greenhouse gas. Just how strong its greenhouse effect is, compared to carbon dioxide, is something scientists have yet to quantify, but it could be much weaker.