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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20240517T103000
DTEND;TZID=Atlantic/Canary:20240517T113000
UID:iactalks-1771
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1771
CREATED:2024-05-17T10:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Seminario de Instrumentación: VLF For Ionospheric Studies: VLF4ION
 S
DESCRIPTION:Seminario de Instrumentación: VLF For Ionospheric Studies: VLF
 4IONS\nDr. Carine  BRIAND, Dr. Pauline  TEYSSEYRE\n\n \n\nThe ionosph
 eric D-layer (60 and 90km) is also called the         “ignorosphere&
 rdquo;, clearly indicating the level of knowledge on         this atmosphe
 ric layer. Its electron content follows a daily         cycle, but also th
 e seasonal cycle of the solar UV flux         radiation. In addition to th
 ese long-period variations, the         D-layer electron density is submit
 ted to much faster forcing,         like geomagnetic storms, solar eruptio
 ns (hours) or lightning         and Transient Luminous Events (seconds or 
 less). The electron         content of the D-layer controls the absorption
  of some radio         waves and links the neutral atmosphere to the magne
 tosphere and         radiation belts. The disturbances of the D-layer elec
 tron         density can lead to HF communications disruption, a threat no
 w         identified by the International Civil Aviation Organization. The
          project focuses on two natural hazards: solar flares because     
     they produce the strongest forcing of the D-layer, and the         lig
 htning strokes and Transient Luminous Events because their         links t
 o the D-layer are largely unclear. \nThe D-layer is too high for ball
 oons and too low for         satellites. Therefore, it is inaccessible to 
 continuous in situ         measurements. The most widely used technique to
  study the         D-layer consists of measuring the VLF emissions from ma
 n-made or         natural origin. VLF modes propagate in the waveguide for
 med by         the Earth and the ionosphere, with reduced loss (~2 dB/Mm),
  thus         propagating very long distances. An increase in electron den
 sity         alters the modes: the amplitude and phase are then affected, 
         which provides an efficient way to detect, in real time,         e
 lectron density variations. \nDuring this talk, we will detail the pr
 oject VLF4IONS, and in         particular, the network that is being built
  worldwide (including         Tenerife).\n
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