Overview of IAP Node

Location (town, country): Prague, Czech Republic

Description of the infrastructure:

Pruhonice ionospheric observatory belongs to the oldest continuously working ionospheric observatories in the Europe (since 1958). The observatory is recently equipped with the latest model of the Digisonde DPS-4D, which enables VI and OI soundings used for detailed study of ionospheric climate, variability, irregularities, ionospheric forcing from above and below, for ionospheric modelling and forecasts. The routine outputs of the DPS-4D are main ionospheric parameters and vertical profiles of electron density and information on ionospheric drifts obtained in basic regime once per 15 min. The Pruhonice DPS4D also carries out oblique drift measurements in synchronous operation with other European DPS4Ds to detect a Doppler shift and an angle of perturbation arrival caused by TIDs. D2D soundings have 5-minute cadence. The Digisonde data are transferred in real time to GIRO DIDBase, GIRO mirror site at the IAP, WDC for Solar Terrestrial Physics, Chilton, UK, and to the public institutions and individual users (on request). All Pruhonice VI ionograms are manually checked and provides users with reliable high quality data.

A multipoint Continuous Doppler Sounding System (CDSS) is based on the measurements of the Doppler shift experienced by waves reflected from the ionosphere. The CDSSs are world-wide unique measuring networks, as they enable continuous monitoring of Acoustic Gravity Waves (AGW) gravity wave activity and provides long data series at different locations crucial for investigation of coupling processes in the Earth atmosphere. The CDSS including special software was developed at IAP and is in operation since 2004. There are three independent multipoint CDSS in the Czech Republic working at frequencies of 3.59, 4.65, and 7.04 MHz. Multipoint measurement makes it possible to investigate propagation of infrasonic waves, MSTIDs or ionospheric oscillations caused by fluctuations of geomagnetic field, severe tropospheric events, strong earthquakes, solar terminator, explosions etc. A precise frequency which is needed for Doppler shift measurements is generated by the direct digital synthesis derived from the high stability 10 MHz oscillators and controlled by the GPS clock. The overall stability of the order of 2x10-10 is achieved. The system is most suitable for studying of waves of periods from ~20 s to ~100 minutes. The height of reflections depends on the electron density in the ionosphere, and is determined from a nearby ionosonde. In 2010 the similar CDSS was installed with the same frequency of 3.59 MHz and three measuring paths in the vicinity of Hermanus and in 2012 in Louisville in the southern-most South Africa. The CDSS with working frequency of 4.63 MHz was also installed at the end of 2012 close to Tucuman in the northwest Argentina and in October 2013 in northern Taiwan with working frequency of 6.57 MHz. All data are collected in real time at the IAP data center and are available via the IAP website. The data are used in particular by scientific community, Masters and PhD students.

IAP installed electric field mills EFM-100 sensors produced by Boltek company to measure electric field at several places in the Czech Republic and Tatra Mountains in Slovakia to monitor electrostatic field. The electrostatic field is a consequence of a potential difference (around 250 kV) between the electrically conducting ionosphere and the Earth. The potential difference results from charge separation in clouds, usually in the thunderclouds. Interplanetary magnetic field in the solar wind might also contribute to the potential difference at high latitudes. A typical value of electric field intensity in a free flat terrain at the ground during fair weather is about 100 V/m. Local weather - charged thunderclouds cause distinct changes of the local electric field. Consequently, the local electric field can reach values of several kV/m, and even about 100 kV/m at distinct sharp high-mountain peaks. The response time of EFM-100 is about 0.1s. The raw data are stored with a 16 bit resolution and sampling frequency of 25 Hz to a dedicated data-logger with GPS time stamps (developed at IAP, Prague) and since 2018 are accessible via IAP website.

Services currently offered by the infrastructure:

The mirroring facility of the DIDBase is in operation at IAP since 2013. Currently the facility serves as real and near-real-time Digisonde database and historical (automatically scaled and manually checked) ionospheric data archive. The Digisonde, CDSS network data and microbarograph data are received, processed, stored and provided for national and international users via website. The mirroring facility enables faster connection and access to world-wide ionospheric data when comparing with the Lowell (USA) data storage. The mirror site has in average 220 national and international visitors/month.

New areas opening to users:

Analysis of wave coupling processes and consequences in the whole atmosphere and ionosphere using CDSSs and European Digisonde network measurements.
Validation of medium scale TIDs detection techniques.
Ionosphere/gravity wave climatology.
Troposphere - upper atmosphere - solar wind coupling studies exploiting atmospheric electricity, ionosphere and solar wind data.