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Perturbations of the terrestrial low ionosphere caused by solar flares

Perturbations of the terrestrial low ionosphere caused by solar flares. Aleksandra Nina Institute of Physics, Belgrade, Serbia. Contents. Ionosphere Significance of its study VLF signals – “ionospheric probes” Belgrade VLF station Analyze of low ionosphere response to the solar X-flares.

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Perturbations of the terrestrial low ionosphere caused by solar flares

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  1. Perturbations of the terrestrial low ionosphere caused by solar flares Aleksandra Nina Institute of Physics, Belgrade, Serbia

  2. Contents • Ionosphere • Significance of its study • VLF signals – “ionospheric probes” • Belgrade VLF station • Analyze of low ionosphere response to the solar X-flares

  3. Introduction • Terrestrial ionosphere • Methods • This talk: experimental and theoretical research of the perturbations of low ionosphere (D region)

  4. Solar flares and CME GRB Earthquakes Vulcan eruptions Nuclear tests Lightning Terrestrial Gamma-Ray Flashes Significance • Science - ionospheric diagnostics - study of physical and chemical processes - detection of different pure natural and man-induced events: 1. processes in the Sun 2. processes in the outer spaces 3. processes in the Earth • Telecommunications • - radio communications, • - planned networks of mobile communications satellites, • - high precision applications of global navigation satellite systems, etc.

  5. VLF signals – “ionospheric probes” • Numerical programs: LWPC, ModeFinder • Advantage: - continual emission - large space that can be analyzed • VLF networks -transmitters -receivers: AWESOME, AbsPAL, SAVNET, AARDDVARK

  6. Belgrade VLF station on Institute of Physics • AbsPal - electrical antenna - works as of 2004 - simultaneously records 6 signals • AWESOME (Atmospheric Weather Electromagnetic System for Observation Modeling and Education) - two magnetic loop antennas - works as of 2008 • simultaneously records 15 signals AbsPAL AWESOME VLF receiver systems at Belgrade station

  7. Solar X-flare perturbations • Theoretical model: Wait’s model of ionosphere: reflection height H’ and sharpness β • Numerical program for simulation VLF signal propagation: LWPC (Long-Wave Propagation Capability): - Input parameters:βandH’ • Output: ALWPC and PLWPC • Unperturbed ionosphere: β = 0.3 km-1H’=74 km • Perturbed ionosphere: determination ofβand H’ • Case: • February 18th, 2011 • - Recording: • - GOES-15 satellite • - Belgrade AWESOMEreceiver • - DHO (Germany) transmitter (23.4 kHz)

  8. Ionospheric response (preliminary results) G(t) – electron gain rate L(t) – electron loss rate Upper half of D region: I - Quasi equilibrium regime II - Photo-ionization regime III - Recombination regime P(t) – photo-ionization rate R(t) – recombination rate I(t) – radiation flux by satellite αeff – effective recombination coefficient Ks– coefficient (dependent on energy interval of data registered by satellite)

  9. Conclusions • The applications of the low ionospheric investigations in science and information technologies • Research of low ionosphere by VLF waves • Presentation of Belgrade VLF station • Experimental and theoretical analyzes of the low ionospheric response to particular solar X-flares - electron concentration - electron gain and electron loss rates (preliminary results)

  10. SGR 1806-20 HESSI Perturbers • Solar radiation - regular variation - transient variations • Outer space • Terrestrial

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