Ravipati Raghavarao did his BSc and MSc, both from Andhra University, and DSc (1960) in Space Physics with Professor BR Rao. He was CSIR Pool Officer at Andhra University (1965-66) and then joined Physical Research Laboratory (PRL) in 1966. He also pursued research on radio astronomy while working with NW Broten of National Research Council (NRC) in Ottawa (1961-63), and then on space physics as a Research Associate in the University of Chicago for a year with CO Hines.

Academic and Research Achievements: Raghavarao’s pioneering findings involve measuring electron densities in the topside ionosphere over India, inaccessible to the ground-based ionosondes involving data acquisition from the International Satellites for Ionospheric Studies (ISIS) by establishing satellite command and telemetry reception facility, and measuring the in-situ electric fields and winds in the height region 100-350 km by the rocket-released Ba+Sr vapour clouds. He showed the occurrence characteristics of a layer of ionization above the F2 layer, named as Ionization Ledge (IL), formed in the height region 500-1200 km over the dip equator (dip eq.) and along the earth’s magnetic field-lines in the topside F layer with varying intensities during daytime. He also showed that the IL occurs only on the days when the Equatorial Electrojet (EJ) at 100 km height on the dip eq., reverses in direction (known as CEJ). He interpreted the IL as due to the inhibition of plasma flow down along the field lines, by hypothesizing the presence of an Equatorial Temperature Anomaly (ETA) in the neutral atmosphere similar to the Equatorial Ionization Anomaly (EIA). With Ba-Sr experiments, he discovered the presence of vertical winds at the onset time of Equatorial spread-F (ESF), and by numerical modeling, those vertical winds are shown to cause the ESF during post-sunset times and the CEJ in daytime. He was the first to show that the elusive occurrence of ESF, a night time phenomenon, is dependent on the intensification of EIA in the preceding afternoons. By analyzing the NASA satellite data, he discovered evidences not only for the ETA that he hypothesized for interpreting the IL, but also a similar anomaly in zonal winds and together he named them as the ETWA phenomenon at the F-region altitudes in the low-latitude region. Also, he showed evidences for the presence of vertical winds and their close association with the ETWA and the ESF, in support of his earlier discovery by the rocket experiments in India. He mentored five students for their PhD.

Other Contributions: Dr Raghavarao was Convener of International Symposia under IUGG.

Awards and Honours: Dr Raghavarao was awarded the Kalpathi Ramakrishna Ramanathan Medal of INSA (1996).