How is ozone measured in the atmosphere

But how is the ozone concentration actually measured? Above all balloons are used to measure the ozone concentration from the ground to an altitude of 30 km.

A roughly 60 m long cord is attached to the rubber balloons. During its ascent the sonde transmits the measured values by radio to the receiving station on the ground, where they are collected, analysed and input into global scientific networks. Measurement of the ozone concentration is performed electrochemically. The ambient air is pumped into a sensor chamber filled with a potassium iodide solution.

The reaction of the ozone in the air with the iodide generates an electrical signal proportional to the volume of ozone. There are about 50 locations worldwide at which ozone-altitude profile measurements are regularly conducted with ozone sondes.

To this day, the meteorologists and atmospheric chemists release a helium balloon with an ozone measuring sonde once a week from the roof of the station and let it rise to an altitude of about 35 kilometres. For an internationally comparable dataset it is important to ensure that all ozone sonde stations conduct comparable measurements. Compressed to sea-level pressure, the ozone in the atmosphere would form a layer about the height of two pennies stacked together. Levels in the ozone hole are much less—only the height of a single dime.

How much is this, compared to the rest of the atmosphere? If all of the air in a vertical column that extends from the ground up to space were collected and squeezed together at a temperature of 0 degrees Celsius and a pressure of 1 atmosphere, that column would be 8 kilometers thick or about 5 miles.

National Aeronautics and Space Administration. Goddard Space Flight Center. Topics What is Ozone? 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 device is light enough to be elevated using a radio-sounding balloon, allowing for a precise in-situ measurement of the ozone profile from ground level up to an altitude of km. Radiosounding in Payerne. MeteoSwiss has two other methods for indirectly measuring ozone profiles via so-called remote sensing technic.

These measurements necessitate relatively complex information processing and provide a profile with a spatial resolution between 7 and 15 kilometres and at altitude levels between 20 and 70 kilometres. Microwave radiometry. The international Global Atmosphere Watch programme GAW makes a major contribution to the monitoring of atmospheric composition. To the top of the page Last modified Menu Close. Search Schliessen. News MeteoSwiss press releases and information. Forecasts This content is currently available only in German, French and Italian.