Efficiency of the Russian Efficiency of the Russian Ground – Based VLFGround – Based VLF

Navigational System Under Navigational System Under Impact of the Space Weather Impact of the Space Weather

DisturbancesDisturbances A.V. Shirochkov andA.V. Shirochkov and L.N. Makarova L.N. Makarova

Arctic and Antarctic Research Arctic and Antarctic Research Institute, Saint- Petersburg, RussiaInstitute, Saint- Petersburg, Russia

The Russian ground-based VLF The Russian ground-based VLF navigational system was designed to navigational system was designed to

cover the whole huge territory of the cover the whole huge territory of the country, which extends for ten hour country, which extends for ten hour

belts in longitudebelts in longitude..  

It consists of several transmitting It consists of several transmitting

and receiving stationsand receiving stations located at located at the polar and middle latitudes. The the polar and middle latitudes. The system is used for communication system is used for communication

purposes as well.purposes as well. The working frequencies are 11,9 The working frequencies are 11,9

kHz and 14,9 kHz. Efficiency of the kHz and 14,9 kHz. Efficiency of the system under impact of specific system under impact of specific Space Weather disturbances is Space Weather disturbances is

consideredconsidered..   

VLF radio links of the Russian navigation VLF radio links of the Russian navigation systemsystem

FIG. 1. Solar proton event of FIG. 1. Solar proton event of September 29-30,1989.September 29-30,1989.

• Curve 1- riometer (30 Curve 1- riometer (30 MHz) absorption at MHz) absorption at Dixon Island;Dixon Island;

• Curve 2- VLF phase Curve 2- VLF phase variations at variations at Novosibirsk-Anadyr Novosibirsk-Anadyr radiopath;radiopath;

• Curve 3- VLF phase Curve 3- VLF phase variations at variations at Krasnodar-Anadyr Krasnodar-Anadyr radiopath;radiopath;

• Curve 4- averaged Curve 4- averaged undisturbed VLF phase undisturbed VLF phase variations at variations at Novosibirsk-Anadyr Novosibirsk-Anadyr path;path;

• Curve 4*-averaged Curve 4*-averaged undisturbed VLF phase undisturbed VLF phase variations at variations at Krasnodar-Anadyr pathKrasnodar-Anadyr path

FIG.2. Solar proton event of FIG.2. Solar proton event of October 19-21,1989October 19-21,1989

Curve 1- riometer Curve 1- riometer (30 MHz) (30 MHz) absorption at absorption at Dixon Island;Dixon Island;

Curve 2- VLF Curve 2- VLF (11,9 kHz) phase (11,9 kHz) phase variations at variations at Krasnodar-St. Krasnodar-St. Petersburg Petersburg radiopath;radiopath;Curve 3- VLF Curve 3- VLF (11,9 kHz) phase (11,9 kHz) phase variations at variations at Novosibirsk-St. Novosibirsk-St. Petersburg Petersburg radiopath. radiopath. 

Fig.3 Solar proton event of October 19-21,1989Fig.3 Solar proton event of October 19-21,1989..Curve 1- riometer (30 MHz) absorption at Dixon Island;Curve 1- riometer (30 MHz) absorption at Dixon Island;

Curve 2- VLF (11,9 kHz) phase variations at Komsomolsk/Amur-St.Petersburg Curve 2- VLF (11,9 kHz) phase variations at Komsomolsk/Amur-St.Petersburg pathpath

Figure 4. Diurnal variations of the VLF signals Figure 4. Diurnal variations of the VLF signals (phase and amplitude) on October 28, 2003(phase and amplitude) on October 28, 2003

The panels indicate the following data (from top to bottom):

phase at the link Novosibirsk - Krasnodar (11,9 kHz); phase at the link Novosibirsk - Khabarovsk (11,9 kHz);

phase at the link Novosibirsk - St. Petersburg (ll,9;12,65;14,90 kHz);

amplitude at link Novosibirsk - St. Petersburg (the same frequencies);

phase at the link Krasnodar - St. Petersburg (ll,9;12,65;14,90 kHz);amplitude at the link "e“ AE-index variations (UT).

Figure 5Figure 5

Figure 5a. Fluxes of energetic electrons above the Northern Figure 5a. Fluxes of energetic electrons above the Northern polar cap recorded by the Russian satellite CORONAS polar cap recorded by the Russian satellite CORONAS - - F F during the superstorm of October during the superstorm of October 28 -28 -November November 6,2003 6,2003

Figure 6. Diurnal variations of the VLF phase at the link Figure 6. Diurnal variations of the VLF phase at the link Krasnodar - St. Petersburg (11,9 kHz) during Chernobyl Krasnodar - St. Petersburg (11,9 kHz) during Chernobyl

catastrophe catastrophe (at 04 UT on April 26,1986) -thick curve. Thin curve represents usual undisturbed (at 04 UT on April 26,1986) -thick curve. Thin curve represents usual undisturbed

VLF phase variations.VLF phase variations.

SUMMARYSUMMARYThe Russian system of the VLF navigation radio links cover a The Russian system of the VLF navigation radio links cover a great part of a vast territory of the country and plays great part of a vast territory of the country and plays important role in the whole navigation service of Russia.important role in the whole navigation service of Russia.Efficiency of the system is seriously deteriorated during Efficiency of the system is seriously deteriorated during severe Space Weather disturbances such as the powerful severe Space Weather disturbances such as the powerful solar proton events and intense geomagnetic superstorms.solar proton events and intense geomagnetic superstorms.Analysis of the VLF phase variations during the recent Analysis of the VLF phase variations during the recent superstorms allowed one to determine a real source of the superstorms allowed one to determine a real source of the middle latitude ionospheric disturbances. The precipitating middle latitude ionospheric disturbances. The precipitating electrons of relativistic and subrelativistic energies are electrons of relativistic and subrelativistic energies are capable to produce the observed ionospheric effects.capable to produce the observed ionospheric effects.The data of the Russian and foreign VLF radio links were The data of the Russian and foreign VLF radio links were used to determine both polar and equatorial boundaries of used to determine both polar and equatorial boundaries of energetic electrons zones of precipitation during the Space energetic electrons zones of precipitation during the Space Weather disturbances. Weather disturbances. Numerical estimations of the ionospheric effects could be Numerical estimations of the ionospheric effects could be made by evaluation of electron density variations. Such made by evaluation of electron density variations. Such procedure could be done by using data of simultaneous procedure could be done by using data of simultaneous satellite, VLF phase and riometer observations.satellite, VLF phase and riometer observations.The Russian VLF navigation system could be used also for The Russian VLF navigation system could be used also for monitoring the technological catastrophes such as the monitoring the technological catastrophes such as the nuclear power stations malfunctions.nuclear power stations malfunctions.