Nighttime equatorial thermospheric meridional winds from ionospheric h'F data

Abstract

Nighttime equatorial thermospheric meridional winds have been derived using h′F data from two equatorial stations nearly on the same magnetic meridian. It is shown that the winds derived are quite consistent with earlier observations.

On the nature of low‐latitude Es influencing the genesis of equatorial plasma bubble

“…It may be mentioned that the postsunset height rise, observed using an equatorial ionosonde, does not involve the contribution due to meridional neutral winds [Krishna Murthy et al, 1990] and thus essentially represents the effect of the zonal electric field. To study the low-latitude E s parameters, we used ionosonde observations made from Sriharikota, a low-latitude station close to the Gadanki radar.…”

Thermospheric meridional winds as deduced from ionosonde chain at low and equatorial latitudes and their connection with midnight temperature maximum

“…Further, to calculate wind velocities, the zero‐wind height or the layer peak height in the absence of plasma drift and transport has to be evaluated [ de Medeiros et al , 1997]. Krishna Murthy et al [1990] also derive meridional wind velocities from the time derivative of h′F obtained at magnetic equatorial and low latitude stations using standard atmospheric models to calculate the plasma diffusion drift term.…”

Equatorial ionization anomaly and thermospheric meridional winds during two major storms over Brazilian low latitudes

“…The behavior of the nighttime meridional winds calculated by de Medeiros et al (1997) and that calculated by Krishnamurthy et al (1990) showed significant differences throughout the night, which may be attributed in part to the two widely different longitude sectors (Indian and Brazilian) and the epoch of study that their winds represented, among several other factors. Biondi et al (1999) have measured the thermospheric winds at Arequipa (Peru) and Arecibo (Puerto Rico) using Fabry-Perot interferometer technique applied to the 630 nm nightglow emission and they showed a large degree of night-to-night variation in the meridional wind that were attributed to the thermospheric circulation controlled by the solar EUV flux, latitude, longitude, subsolar point and local time variation.…”

“…Our analysis followed the methodology described by Krishnamurthy et al (1990) with some modifications introduced as will be explained eventually. The ionospheric data was obtained from the digisondes operated at São Luís and Fortaleza.…”

“…In Krishnamurthy et al (1990) the nighttime equatorial thermospheric meridional winds were calculated from the minimum F layer virtual height (h 0 F). In the present work the meridional winds were calculated from true height at the frequencies of 3.0 and 4.0 MHz.…”