What is Ozone?
Ozone is a cousin of the oxygen molecule on which we depend for life. While the oxygen molecule consists of two oxygen atoms, the ozone molecule consists of three. That extra atom makes a big difference, in some ways that benefit us, and in other ways that are harmful. While ozone (O3) is an asset in the stratosphere, it has a mixed impact when it resides within the troposphere - the bottom layer of the atmosphere, which extends from the ground to where the stratosphere begins, at an altitude of about 16 km (10 miles). This is where we live. It is also where most weather takes place. (See animation of tropospheric ozone (QuickTime, 457 KB) depicting the relationship between altitude and ozone roles.)
Tropospheric O3 has distinct roles depending upon its altitude – in the upper troposphere it is a greenhouse gas, in the middle troposphere it acts as an atmospheric cleanser, and in the boundary layer it is a major component of photochemical smog. Tropospheric O3 is produced photochemically in situ and is also transported down from the stratosphere, but the proportion coming from each of these two sources to the global budget is poorly understood. TES measurements are improving our understanding of:
How Does TES Contribute to Our Understanding of Ozone?
In order to quantify the tropospheric budget of O3, and assess its participation in tropospheric chemistry and climate forcing, we need to know the origin, distribution, and fate of global tropospheric O3, and address key questions about how increasing ozone abundance in the troposphere is affecting:
- air quality on a global scale
- oxidizing reactions that “cleanse” the atmosphere
- climate change
TES data is used by scientists to determine the O3 production and chemistry produced from natural sources such as lightning and plant growth, human activities such as motor vehicles and industrial pollution, as well as wildfires. TES is engaged in a multi-year global survey of O3 and its precursors, the chemicals involved in its production. TES’s ability to generate vertical profiles of the atmosphere, distinguishing what is happening at different heights, is essential because different chemical reactions take place at different altitudes. In this way, TES is helping scientists to understand long-term variations in the quantity, distribution, and mixing of many tropospheric gases which, though they constitute a tiny portion of the atmosphere, have a large impact on climate and air quality.
Read more about how TES data are helping to reveal details of tropospheric O3 and O3 precursors:
Next: Detecting Altitudes
Back: Chemical Clues
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.