Accession Number : ADA614949


Title :   Correlation of Solar X-ray Flux and SID Modified VLF Signal Strength


Descriptive Note : Master's thesis


Corporate Author : AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT


Personal Author(s) : Kranich, Shannon N


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a614949.pdf


Report Date : 26 Mar 2015


Pagination or Media Count : 102


Abstract : This paper presents a quantitative comparison of the X-ray flux during solar flares, as measured by the GOES-15 satellite, and the associated effects on the ionization levels in the lower ionosphere as measured by Sudden Ionospheric Disturbance (SID) monitors around the globe. These monitors detect signals from a variety of different transmitting stations, each sending a unique Very Low Frequency (VLF) or Low Frequency (LF) radio wave signal ranging from 16.4 to 77.5 kHz. Global signal propagation distances are achieved via the Earth-ionosphere waveguide propagation mode. During a solar flare, the increased X-ray flux enhances the ionization response in the sunlit ionosphere. The resulting SID in the lower ionosphere alters LF and VLF signal propagation. The monitored signal strength increases as a result of increased conductivity of the layer and a decrease in height of the ionosphere boundary. X-ray flux and SID modified signal strength were analyzed from March 2010 to June 2014. Ionospheric incubation times, and duration and strength of signal enhancement are related to flare strength via the X-ray flux enhancement.


Descriptors :   *FLUX(RATE) , *IONOSPHERIC DISTURBANCES , *SOLAR FLARES , *X RAYS , CONDUCTIVITY , GLOBAL , IONIZATION , LOW FREQUENCY , RADIO SIGNALS , RADIO WAVES , THESES , VERY LOW FREQUENCY , WAVEGUIDES


Subject Categories : Astrophysics
      Atmospheric Physics


Distribution Statement : APPROVED FOR PUBLIC RELEASE