Description of the Air Electricity Laboratory

The Air Electricity Laboratory is an informal structure unit of the Institute of Environmental Physics at the University of Tartu. The main research aspects of the Laboratory include

The basic equipment has mainly been built up of original instruments. The research potential of many of these original instruments excel the analogous commercial instruments, providing favourable conditions for research and graduate study. Using this equipment, continuous monitoring of the air ion mobility spectra has been performed since 1988, and a number of atmospheric aerosol size spectra measurement campaigns with the duration from 2 weeks to 6 months have been carried out in Estonia, Finland, Ireland, Germany, Netherlands, Lithuania and Russia. A database of regular atmospheric monitoring has been created during many years, rich in significant scientific information, inexhaustible for the professors and researchers as well as for graduate students.

The most essential parts of equipment for atmospheric research used at the Laboratory are (1) Air Ion Spectrometers (AIS), NO2 meter and other devices installed at Tahkuse Observatory; (2) two portable Electric Aerosol Spectrometers (EAS). EAS and AIS are original multichannel (parallel-principle) instruments designed at the Air Electricity Laboratory. Several parameters of EAS surpass those of other analogous instruments: measurement range of particle diameters of  3 nm - 10 µm, time resolution down to 4 s, ability to measure highly fluctuating particle concentrations. EAS is specially designed for measurements in free air. It is suitable for long-time monitoring of aerosol particle size distribution both in pure air in rural locations and in heavily polluted ambient air in the cities. The reliability of the instrument has been confirmed by measurements in many locations, especially by an extended period of six months of almost unattended (inspection period of two weeks) continuous monitoring of atmospheric aerosols in Helsinki during the winter of 1996/97.

Long-time series of aerosol measurements with EAS provide an opportunity to study the development of aerosol size spectra, check the spectral models, study the correlations with meteorological and radiation parameters, and the correlation with the distribution of pollution sources. The synchronous measurements made with two EAS at different places enable to study the regularities of air particulate pollution transport.

The equipment installed at Tahkuse Observatory:

The apparatus operates twenty four hours, the data are saved as 5 min averages; it is possible to monitor the mobility spectra of air ions (or charged aerosol particles) together with other atmospheric parameters during long periods. Such a combination of equipment is unique in the world.

A complete set of the generators of monodisperse aerosols, covering a particle diameter range from 3 nm to 4 µm has been installed in the Laboratory. Electrical separators are used as an aerosol standard. They cover the whole above range of diameters and produce aerosol particles with any prearranged average diameter, and with a narrow distribution (relative halfwidth below 5%). An original aerosol electrometer serves the measurements of the number concentration of aerosol particles. An optical aerosol spectrometer Lasair Model 1001 is available for the study of aerosols in a particle diameter range of 0.1–2 µm. Two high-resolution Air Ion Spectrometers serve the experiments on the effects of trace gases in the air.
The laboratory has two standard aerosol samplers and one high volume sampler.
The general purpose research instruments at the Laboratory include the devices for the measurement of air flow (rotameters, rheometers, drum-flowmeters, standard flowmeter Gilibrator-2), the sources and filters of compressed air, calibrated high voltage supplies, thermoanemometer etc.