Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

A. K. Patra (1) , S. Sripathi (1) , P. B. Rao (2) , K. S. V. Subbarao (3)

1 National MST Radar Facility
2 NRSC - National Remote Sensing Centre [Hyderabad]
3 Space Physics Laboratory

The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the E_s parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of E_s (h'E_s) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (f_tE_s) and the blanketing frequency (f_bE_s) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (f_tE_s-f_bE_s) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the E_s parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

Domaines: Océan, Atmosphère; Sciences de la Terre

A. K. Patra, S. Sripathi, P. B. Rao, K. S. V. Subbarao. Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region. Annales Geophysicae, 2005, 23 (3), pp.773-779. ⟨hal-00317611⟩