Intercontinental Transport of Pollutants

Most air pollutants have relatively short atmospheric lifetimes and inhomogeneous spatial distributions, usually most concentrated near their sources. More detailed information is needed on the global transport of pollutants and the nature and distribution of regional pollution effects.

Global Distribution of O3 and CO

In addition to providing information on ozone/carbon monoxide correlations, TES is providing the first global retrievals of vertically-resolved tropospheric ozone. TES measures three levels in the troposphere with 20% (or better) accuracy. For carbon monoxide, profile accuracies are 10% or better, except in the boundary layer, where lack of thermal contrast renders measurement difficult. For ozone, TES results generally agree with current understanding of the tropospheric ozone (O3) and carbon monoxide (CO) distributions:

• Ozone is higher in the Northern Hemisphere than in the Southern Hemisphere; the highest O3 is in the boreal spring and summer in the mid- to northern latitudes.
• Overall, CO is lower during the northern hemisphere summer because the abundance of OH radicals is higher. Conversely, increased O3 photolysis during the northern hemisphere summer causes the global abundance of O3 to increase.
• Atmospheric concentrations of CO vary widely around the world and throughout the year, and the lifetime of CO is relatively short (0.2 months). Tropospheric concentrations for CO are therefore quite variable (from 50 to 1000 ppbV).
• Other noticeable enhanced O3 areas in the Northern Hemisphere include the enhancement that occurs over India and the Arabian Sea during April-May, and the maximum that occurs in the Mediterranean Sea (covering 120W-120E) during spring and summer.
• In the tropics, enhanced O3 is correlated with enhanced CO in the biomass burning regions of Africa and South America and over the South Atlantic Ocean.

Back: Ozone

Ozone’s impact is all about location. High in the stratosphere, ozone shields us from the sun’s harmful UV rays. But beneath that, at the top of the troposphere, it acts as a greenhouse gas and contributes to global warming. In the middle of the troposphere, it plays a key role in a chemical process that cleans the air of certain pollutants. But at the bottom of the troposphere, where we live and breathe, it contributes to smog and is toxic to plants and animals. TES measurements allow scientists to track the abundance, creation, destruction, and movement of this critical chemical at various altitudes throughout the atmosphere.