Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

• Main Authors: D. V. Phanikumar, A. K. Patra, C. V. Devasia, G. Yellaiah
• Format: Article
• Language: English
• Published: Copernicus Publications 2008-07-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/26/1865/2008/angeo-26-1865-2008.pdf
• ISSN: 0992-7689; 1432-0576

In this paper, we present seasonal variation of E region field-aligned irregularities (FAIs) observed using the Gadanki radar and compare them with the seasonal variation of <I>E_s</I> observed from a nearby location SHAR. During daytime, FAIs occur maximum in summer and throughout the day, as compared to other seasons. During nighttime, FAIs occur equally in both summer and winter, and relatively less in equinoxes. Seasonal variations of <I>E_s</I> (i.e. <I>f_tE_s</I> and <I>f_bE_s</I>) show that the daytime activity is maximum in summer and the nighttime activity is maximum in equinoxes. No relation is found between FAIs occurrence/SNR and <I>f_tE_s/f_bE_s</I>. FAIs occurrence, however, is found to be related well with (<I>f_tE_s&minus;f_bE_s</I>). This aspect is discussed in the light of the present understanding of the mid-latitude <I>E_s</I>-FAIs relationship. The seasonal variations of FAIs observed at Gadanki are compared in detail with those of Piura, which show a significant difference in the daytime observations. The observed difference has been discussed considering the factors governing the generation of FAIs.