Ramfjordheide research station

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View from the northwest of the site

The research station Ramfjordheide ( Norwegian Ramfjordmoen forskningsstasjon ) is operated by the University of Tromsø on Ramfjordheide (Ramfjordmoen). It is located about 20 kilometers outside of Tromsø in the Norwegian province of Troms on the Ramfjord near the village of the same name ( tettsted ) Ramfjord . There are a number of instruments on site for observing the upper layers of the atmosphere, including the Northern Lights. The instruments belong partly to the university and partly to other research institutions. The most conspicuous systems are two radar systems ( decimeter wave and ultra-short wave ) of the international research organization European Incoherent Scatter Scientific Association (EISCAT). She continues to operate an ionospheric heater and an ion probe here . There is also a LiDAR system, a meteor radar, a medium wave radar, the “MORRO” radar system, another ion probe (model “Digisonde DPS-4”) and optical measuring instruments (photometer, spectrometer, cameras).

EISCAT radars

The incoherent scatter radars send out strongly directed radar impulses to investigate the high atmosphere . An ultra-short wave system that went into operation in May 1985 transmits via four parabolic trough antennas, each with a side length of 30 by 40 meters, at frequencies around 224 MHz with a peak power of up to 3 megawatts.

A decimeter wave system has been transmitting since August 1981 via a parabolic dish 32 meters in diameter at frequencies around 930 MHz with a peak power of 2 megawatts. There are further receiving stations at Kiruna and Sodankylä (Finland), whereby information about electrical fields in the ionosphere can be derived from the observed ion flow.

Ionoprobe

The ion probe is mainly used as a diagnostic tool in conjunction with the heater. However, it is also used, among other things, to calibrate the scatter radars, can develop two-dimensional representations of totally reflected echoes via the distributed receiving antennas and also examine the mesosphere via partially reflected echoes.

The operated ion probe has a transmitter with a peak power of 10 kW. Opposite this are two receivers with six dipole antennas arranged in a square, two of which are installed within the square to enable the elimination of aliasing effects . There are signal-to-noise ratios achieved from 30 to 40 dB. The antenna fields of the heater can also be used for special applications. The instrument is a model built by the US National Oceanic and Atmospheric Administration (NOAA) called the Dynasonde. It was installed by the then Max Planck Institute for Aeronomy and put into operation in 1980. In July 1984 the receiving antennas were replaced by more powerful ones. The EISCAT Association took it over from the MPI in 1993. Since then, it has been operated by the British Antarctic Survey (BAS) with software called FAIS and the measurement data is made publicly available on the web in real time. In 2002 the real-time analysis system DSND was installed. With USAF SBIR , a prototype of a successor instrument ("Dynasonde-21") is being developed.

Ionospheric heater

The EISCAT ionospheric heater can transmit on frequencies between 3.85 and 8 MHz, of which 9 assigned bands may be used. It consists of 12 transmitters with 100 kilowatts each, which can generate a beam inclined by up to 30 ° by means of phase shifts with a scatter of about 14 ° (until the flux density is halved) via one of three static antenna fields. There are three antenna fields with crossed dipole antennas of different sizes available for two different frequency ranges: There are two fields with 6 to 6 antennas each and a total gain of 23 dBi each for the ranges from 3.8 to 5.7 and from 5.3 to 8 MHz. A similar third field was expanded and rebuilt in 1989 and 1990 so that with the quadrupled number of antennas (12 × 12) and a gain of 30 dBi instead of the previous range between 2.75 and 4, it is now also in the range between 5.3 and 8 MHz to send (the “super heater”, up to 1,300 megawatts ERP ). The system was designed by the Max Planck Institute for Aeronomy in collaboration with the University of Tromsoe and began regular operation in 1980. It was taken over by EISCAT at the beginning of 1993.

University instruments

The physics-technical faculty of the University of Tromsø operates another radar called "MORRO" for the investigation of the meso-, strato- and troposphere. It transmits over a 50 × 50 meter field of Yagi antennas with a peak power of 90 kilowatts at a frequency of 56 MHz.

In October 2011, a new LiDAR system for the investigation of sodium in the mesosphere and lower thermosphere went into operation, which, among other things, can carry out temperature measurements.

literature

  • MT Rietveld, JW Wright, N. Zabotin, MLV Pitteway: The Tromsø dynasonde . In: Polar Science . tape 2 , no. 1 , March 2008, p. 55–71 , doi : 10.1016 / j.polar.2008.02.001 (English).
  • MT Rietveld, H. Kohl, H. Kopka, P. Stubbe: Introduction to ionospheric heating at Tromsø - I. Experimental overview . In: Journal of Atmospheric and Terrestrial Physics . tape 55 , no. 4 -5 (March-April). Pergamon Press, 1993, pp. 577-599 , doi : 10.1016 / 0021-9169 (93) 90007-L (English, eiscat.no [PDF]).

Web links

Individual evidence

  1. ↑ ISR Factsheet (PDF; 921 kB) eiscat.com
  2. ↑ oulu.fi
  3. Jump up ↑ KJF Sedgemore, PJS Williams, GOL Jones, JW Wright: A comparison of EISCAT and Dynasonde measurements of the auroral ionosphere . In: European Geosciences Union (Ed.): Annales Geophysicae . tape 14 , no. 12 . Springer-Verlag, 1996, p. 1403-1412 , doi : 10.1007 / s00585-996-1403-x (English, ann-geophys.net [PDF]).
  4. ↑ MJ Kosch, Y. Ogawa, MT Rietveld, S. Nozawa, R. Fujii: An analysis of pump-induced artificial ionospheric ion upwelling at EISCAT
  5. ^ R. Barr, P. Stubbe: ELF radiation from the Tromsø “Super Heater” Facility . In: American Geophysical Union (Ed.): Geophysical Research Letters . tape 18 , no. 6 , June 1991, pp. 1035-1038 , doi : 10.1029 / 91GL01156 (English).
  6. ↑ eiscat.uit.no ( Memento of the original from February 26, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.eiscat.uit.no
  7. ↑ jpgu.org (PDF)