Investigation of the nighttime D-region ionosphere characteristics at Palmer Station antartica by using tweek atmospherics

摘要

The D-region is the lowest layer of the ionosphere. During nighttime, the lack of ionization source from the Sun makes this region difficult to measure. This region has no measurable effects on Ionosonde frequencies. Rocket measurements are accurate but limited to the location, time and high in cost. Very Low Frequency (VLF) signal from the communication and navigation instruments can effectively be used to study the region but it is limited to the location of the transmitter. In this study, tweek atmospherics is used to analyze the D-region Ionosphere. Tweek Atmospherics is a lightning generated signal that propagates in the earth-ionosphere waveguide by multiple reflections. The ionospherics height and the estimated electron density for D-region ionosphere are easily determined using the first order mode cut-off frequency of the tweeks. This study presents the results of the D-region ionosphere in Antarctica by examining the tweek atmospherics signal observed at Palmer Station, (64.76°S, 64.07°W) during the winter season on the 15^th June 2010 for 24 hours. The results from 1248 tweeks show that the D-region reflection heights were found to vary according to the sunset and sunrise at the Palmer Station, between 64 and 83 km and the equivalent electron density were found to vary between 24.64 and 32.60 el/cm³ respectively. Tweeks also were found to travel as far from 12,197 km from the lightning source.