An annular and partial solar eclipse was observed on 29 April 2014 over Australian and Antarctic regions. In this study we have analyzed the ionospheric response of this solar eclipse event. We have done a comprehensive study to find out the changes that occurred in various ionospheric parameters during the solar eclipse event over Australia and Antarctic region. We selected four Australian stations Brisbane (27.5° S, 152.9° E), Canberra (35.3° S, 149.1° E), Hobart (42.9° S, 147.3° E) and Perth (31.955° S, 115.859° E) as well as one Antarctic station Mawson (70.6455° S, 131.2573° E). We have studied the changes in the $E$ and $F$ ionospheric layers using the ground based observations at these stations. From our analysis we found that there occurred a decrease in the critical frequencies of sporadic $E$ $(f_oE_s)$ and $F$ $(f_oF2)$ layers during the time eclipse was in progress at all the four Australian stations while as at Antarctic the value of $f_oF2$ recorded an enhancement. At the same time an increase in the corresponding heights of these layers ($h'E_s$, $h'F2$) was also observed.
Annular solar eclipse, ionospheric parameters, sporadic $E$, critical frequency
1. Chandra, H., Sharma, S., Lele, P. D., Rajaram, G., Hanchinal, A. Ionospheric measurements during the total solar eclipse of 11 August 1999, // Earth Planets and Space, 2007. - v. 59 - p. 59.
2. Chavdarov, S. S., Chernysheva, S. P., Svechnikov, A. M. Influence of radio wave absorption in the ionosphere on the variation of sporadic $E$~layer parameters, // Geomagn. Aeron., 1968. - v. 8 - p. 294.
3. Chen, G., Zhao, Z., Zhou, C., Yang, G., Zhang, Y. Solar eclipse effects of 22 July 2009 on sporadic-$E$, // Journal of Annales Geophysicae, 2010. - v. 28 - p. 353.
4. Datta, R. N. Solar eclipse effect on sporadic-$E$ ionization, // Journal of Geophysical Research, 1972. - v. 77 - no. 1 - p. 260.
5. Datta, R. N. Solar eclipse effect on sporadic-$E$ ionization, 2, // Journal of Geophysical Research, 1973. - v. 78 - no. 1 - p. 320.
6. Jayachandran, P. T., Sriram, P., Rama Rao, P. V. S., et al. Sequential sporadic-E layers at low latitudes in the Indian sector, // Journal of Annales Geophysicae, 1999. - v. 17 - p. 519.
7. Nayak, C. K., Tiwari, D., Emperumal, K., Bhattacharyya, A. The equatorial ionospheric response over Tirunelveli to the 15 January 2010 annular solar eclipse: observations, // Ann. Geophys., 2012. - v. 30 - p. 1371.
8. Piggott, W. R., Rawer. K. Eds. URSI Handbook of Ionogram Interpretation and Reduction - Amsterdam: Elsevier., 1961. - 324 pp.
9. Rama Rao, P. V. S., Prasad, D. S. V. V. D., Sri Ram, P., et al. Ionospheric changes observed over Waltair (Dip 20° N) during the total solar eclipse of 24th October 1995, // TAO, 1997. - v. 8 - no. 2 - p. 203.
10. Reddy, C. A., Rao, M. M. On the physical significance of the $E_s$ parameters $f_bE_s$, $fE_s$ and $f_oE_s$, // Journal of Geophysical Research, 1968. - v. 73 - no. 1 - p. 215.
11. Rishbeth, H., Garriott, O. K. Introduction of Ionospheric Physics - New York: Academic Press., 1969. - 331 pp.
12. Sridharan, R., Raghavaro, R., Suhasini, R., et al. Winds, wind shears and plasma densities during the initial phase of a magnetic storm from equatorial latitudes, // Journal of Atmospheric and Terrestrial Physics, 1989. - v. 51 - p. 169.
13. Veenadhari, B., Dabas, R. S., Vohra, V. K., Lakshmi, D. R., Sethi, N. K., Garg, S. C. Study on Sporadic $E$ occurrences observed at New Delhi with Modern Digital Ionosonde, // Proc. GA, 2002. - v. 2 - p. 169.
