How is ozone measured

Seen from space, the edge of the Earth is blurred by the pale blue atmosphere. Most dense at the surface, the atmosphere thins with altitude, until it gradually merges with vacuum. Total ozone is measured through the entire atmospheric column, from the surface to the edge of space.

It is simply a region where ozone is more common than it is at other altitudes. Satellite sensors and other ozone-measuring devices measure the total ozone concentration for an entire column of the atmosphere. One such instrument is an ozonesonde "sonde" comes from Old English, meaning messenger , which includes a balloon that carries the instrument up more than 21 miles In the stratosphere, it sucks in and holds air to test the amount of ozone gas using an electrochemical concentration cell ECC.

The ECC uses potassium iodide, which reacts with ozone to create an electrical current, to measure the amount of ozone present [source: NOAA ].

Although the balloon can burst when it reaches too high of an altitude, the device includes a parachute to reduce damage when it lands. In addition to these ozonesondes, aircraft that can fly especially high can also reach the lower stratosphere to measure the ozone in the air. Also, UV detectors on the ground measure how much UV light has penetrated the ozone layer to reach the surface of the earth , which gives us clues as to how much ozone is in the atmosphere. Both ground stations and planes can use lasers to detect ozone, as well.

Although the TOMS program closed in after the latest TOMS instrument started failing to transmit information, the program played an important role in revealing the state of the ozone for 30 years [source: Spector ]. In Payerne, the ozone profile is recorded directly in situ using ozone sondes attached to radio-sounding balloons. A microwave radiometer is also used in Payerne to determine the stratospheric and mesospheric ozone concentration between 20 and 70 kilometres altitude.

The spectrophotometers are based on the measurements of the absorption of the solar radiation in the UV light range nm which allow the total ozone quantity contained in the atmospheric column above the station to be calculated. Two types of instrument are used here, the Dobson and the Brewer. The Dobson spectrophotometer measures the differential intensity of wavelength pairs of the solar radiation, with one being weakly absorbed and the other being strongly absorbed as they cross through the atmosphere.

This allows the total ozone column to be derived. In order to mask disruptive effects, three different wavelength pairs are measured and combined. For the device depicted in the figure, a computer controls the sequence of operations necessary for measuring the ozone column.

The very-long series of ozone measurements taken in Arosa is based on this type of instrument. The Brewer spectrophotometer measures the absolute intensity of the solar radiation for four wavelengths in the range from to nm. The ozone column can be determined on the basis of the weighted sum of these measurements. This device works automatically and is very reliable; it has been used in Arosa for more than 30 years. Three times a week, MeteoSwiss measures the ozone profile using a radio-sounding balloon.

The ozone sonde is based on the chemical reaction between the ozone O 3 and potassium iodide KI molecules part of a chemical solution contained in the small white capsules see figure. The air is pumped into the inside of the Styrofoam sonde housing and then channelled into the capsule, which contains the low concentration potassium iodide solution.

According to the principle of an electrochemical cell, the ozone concentration in the air can be measured on the basis of the electrical current between two electrodes. This helps to improve our offer. This cookie is set by the website operator to store your cookie options. This cookie is used for an anonymous traffic analysis on our website. All topics Natural hazards. Pollutants Atmosphere Measuring the concentration of ozone The ozone layer is an important component of the atmosphere.

Measurements with an ozone sonde in the Antarctic. Photo: AWI.