Response of the mid-latitude D-region ionosphere to the total solar eclipse of 22 July 2009 studied using VLF signals in South Korean peninsula

In this paper, we analyze VLF signals received at Busan to study the the D-region changes linked with the solar eclipse event of 22 July 2009 for very short (similar to 390 km) transmitter receiver great circle path (TRGCP) during local noon time 00:36-03:13 UT (09:36-12:13 KST). The eclipse crossed south of Busan with a maximum obscuration of similar to 84%. Observations clearly show a reduction of similar to 6.2 dB in the VLF signal strength at the time of maximum solar obscuration (84% at 01:53 UT) as compared to those observed on the control days. Estimated values of change in Wait ionospheric parameters: reflection height (h') in km and inverse scale height parameter (beta) in km(-1) from Long Wave Propagation Capability (LWPC) model during the maximum eclipse phase as compared to unperturbed ionosphere are 7 km and 0.055 km(-1), respectively. Moreover, the D-region electron density estimated from model computation shows 95% depletion in electron density at the height of similar to 71 km. The reflection height is found to increase by similar to 7 km in the D-region during the eclipse as compared to those on the control days, implying a depletion in the Lyman-alpha flux by a factor of similar to 7. The present observations are discussed in the light of current understanding on the solar eclipse induced D-region dynamics. (C) 2014 COSPAR. Published by Elsevier Ltd. All rights reserved.