Measurements of the topside ionosphere over Arecibo during the total solar eclipse of February 26, 1998

Abstract

Abstract. The Arecibo incoherent scatter radar facility was operated on February 26, 1998, and was used to observe the total solar eclipse that occurred over the Caribbean. A maximum of 87% obscuration was observed over Arecibo at 1430 LT (1830 UT). The radar was operated using an experimental technique, which uses a 300/•s single/multi-frequency pulse, to gather data from the altitude range 146-2412 km. The Sheffield University plasmasphere ionosphere model was used to interpret the measurements. The electron temperature was found to have decreased by 600 K at 400 km altitude, but the magnitude of the decrease becomes smaller with increasing altitude. This is shown to be the result of the lesser degree of obscuration of the solar disk at latitudes north of Arecibo. Conjugate point photoelectron heating effects are also shown to play a significant role in the electron energy balance during the eclipse. The H + ion temperature exhibited a response to the eclipse, with

Ionospheric behavior over Europe during the solar eclipse of 3 October 2005

“…The ionospheric response to solar eclipses has been the purpose of many works, both theoretical and experimental. Changes in the ionospheric plasma density and temperature, diffusion processes, etc., have already been studied and time constants estimated (Baron and Hunsuker, 1973;Jakowski et al, 1983;Cohen, 1984;MuellerWodarg et al, 1998;Huang et al, 1999;McPherson et al, 2000; and the references therein). Thus, it is now proven that the plasma redistribution during eclipses may lead to modifications of the electron density profile shape, measurable by the equivalent slab thickness.…”

Effects of the 16 February 1980 solar eclipse on the composition of the low‐latitude ionosphere as seen by Atmosphere Explorer E

“…They used a technique which allowed them to make separate measurements of the H + and O + temperatures; no such ability exists for the AE data. MacPherson et al [2000] found a drop of around 200 K for the H + temperature and none for the O + temperature. In other words, the temperatures of the heavier ions behave the same as the neutral gas, while the ionized hydrogen temperature responds similarly to electron temperature.…”

“…Both experimental [ Salah et al , 1986] and theoretical [ Roble et al , 1986] examinations of the annular eclipse of 30 May 1984 at Millstone Hill found no change in ion or neutral temperatures at this altitude. MacPherson et al [2000] examined the solar eclipse of 26 February 1998 using incoherent scatter radar at Arecibo. They used a technique which allowed them to make separate measurements of the H + and O + temperatures; no such ability exists for the AE data.…”

“…Much work has been done in the past decade using radars to study the effects of eclipses on the atmosphere, usually at lower altitudes [ Jones et al , 2004; Farges et al , 2003; Altadill et al , 2001]. With the exception of that by MacPherson et al [2000], these investigations have examined the production of gravity waves by eclipses. Using the incoherent radar installation at Arecibo, Puerto Rico, MacPherson et al [2000] examined the effects of the 26 February 1998 eclipse on the temperature of the ionosphere and the effect on the O + ‐ H + transition height.…”

“…With the exception of that by MacPherson et al [2000], these investigations have examined the production of gravity waves by eclipses. Using the incoherent radar installation at Arecibo, Puerto Rico, MacPherson et al [2000] examined the effects of the 26 February 1998 eclipse on the temperature of the ionosphere and the effect on the O + ‐ H + transition height. They found that temperature variations were ion species dependent, with H + temperatures dropping by about 200 K, but the O + temperature was unchanged.…”