Both remote sensing and in situ measurements are used to make these observations. Remote sensing can be used to determine water vapor, ozone, and chlorine monoxide concentrations and the temperature and density in the middle atmosphere. From the surface of the Earth , an upward-looking microwave radiometer, operating at 22 GHz can observe water vapor in the upper regions of the atmosphere. Microwave receiver used to sense water vapor in the upper regions of the atmosphere.
Spectral analysis is used to determine altitude profile of the water vapor concentration.
The receiver was taken on the RV Polarstern to Antarctica. From space , a millimeter wave radiometer can look into the limb of the Earth s atmosphere. In Situ measurements of the middle atmosphere are most conveniently made from sounding rockets. Various electrode arrangements can be used to observe the electrodynamics of the region. A swept voltage is applied to the collector disk and surrounding guard ring and the resulting current is measured by an electrometer.