The correlation of VLF propagation variations with atmospheric planetary-scale waves

Abstract

Variations in the received daytime phase of long distance, cesium-controlled, VLF transmissions are compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-'region from Brown and Williams (1971) and to variations of f-min from Deland and Friedman (1972) which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The VLF variations appear to lag the stratospheric variations by about 4 days during the 1965 period, but lead the latter by about 4 days during the 1969 period.The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. The above correlations are interpreted a s due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed.These correlations provide further evidence for the coupling between the lower ionosphere a t about 70 km altitude (the daytime VLF reflection height) and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation. INTRODUC TlONNumerous observations support the view that ionization variations in the D and E-regions a r e coupled to metoerological variations in the stratosphere. Evidence for this coupling is the connection of ionospheric variations, which have been determined almost exclusively from ground-based MF or HF (> 1 MHz) radio 397IREX=EDlNG PAGE BLANK NOT FILMED I https://ntrs.nasa.gov/search.jsp?R=19750003225 2018-05-10T18:26:41+00:00Z transmieeions, to preeeure or temperature variation8 in the stratosphere (Bowhiil, 1969;Gregory and Manson, 1969;Schwentek, 1969; Thomae, 1971; Lauter and Taubenhiem, 1971). Brown and Williams (1951) have correlated variations in the height of a constant electron density surface in the E-region, estimated from ionosonde observations, with height variations of the 10-mb isobaric surface in the stratosphere. Deland and Cavalieri (1973) have further shown the electron density heights determined by Brown and Williams to be well correlated with planetary-ecale fluctuations of f-min (the minimum frequency a t which reflection from the ionosphere is recorded by an ionoeonde). Deland and Friedman (1972) have shown these same f-min variations to be correlated directly with atmospheric pressure fields for the stratosphere.Long distance VLF (3-30kHz) tranemissions have been used for many years to study a variety of ionospheric disturbances related to solar x-rays, solar energetic particles, trapped energetic particles, aurora, and magnetic storms (e. g. Bracewell et a:., 1951; Crombie, 1965; Belrose and Thomae, 1968;Westerlund et al. , 1969;Zmuda and Potemra, 1972;Potemra and Rosenb...

Dynamics of the large-scale ULF electromagnetic wave structures in the ionosphere

“…But the theoretical investigation of the wave processes, as well as the basics of energy transfer from the lower atmosphere to the upper one, shows that the system of the stable zonal winds screen the upper atmosphere effectively (especially in summer) from the influence of the large-scale planetary waves, generated in the tropo-stratosphere (Charney and Drazin, 1961;Dickinson, 1968 planetary waves (with wave numbers 1 and 2), are created during equinoxes, when zonal winds change their direction (Dickinson, 1969). Nevertheless, some experimental data indicate permanent existence of ULF electromagnetic planetary-scale perturbations in E-and F-regions of the ionosphere (Cavalieri et al, 1974;Manson et al, 1981;Sharadze et al, 1988Sharadze et al, , 1989Zhou et al, 1997;Fagundes et al, 2005). Among them, special attention must be paid to the large-scale zonal fastand slow-wave perturbations, propagating on a fixed latitude along the parallels around the Earth.…”

Zonal flows and magnetic fields driven by large‐amplitude Rossby‐Alfvén‐Khantadze waves in the E‐layer ionosphere

“…However, the presence of charged particles in this weakly ionized gas substantially enriches the class of ultralow-frequency planetary waves from that in the troposphere. There are numerous ground-based and satellite observations of planetaryscale structures in the ionosphere with periods of days: Cavalieri et al [1974], Cavalieri [1976], Manson et al [1981], Hirooka and Hirota [1985], Randel [1987], Sorokin [1988], Sharadze et al [1988Sharadze et al [ , 1989, Williams and Avery [1992], Forbes and Leveroni [1992], Bauer et al [1995], Zhou et al [1997], Lastovicka [1997], Smith [1997], Lawrence and Jarvis [2003], Burmaka et al [2006], and Alperovich and Fedorov [2007]. Fagundes et al [2005Fagundes et al [ , 2009aFagundes et al [ , 2009b report correlations of the planetary-scale structures with periods of days with enhanced levels of ionospheric disturbances between 18:00 and 21:00 UT.…”

Electromagnetic oscillations of the Earth's upper atmosphere (review)

“…In these waves, ions and neutrals are oscillating while electrons are immovable. These slow, weather-forming waves were discovered by ionospheric observations (Cavalieri et al, 1974;Sharadze and Khantadze, 1979;Sharadze et al, 1989;Sharadze, 1991).…”

“…Large-scale wave structures play an important role in the processes of general energy balance and circulation of the atmosphere and ocean. The large amount of observational data (Cavalieri et al, 1974;Cavalieri, 1976;Manson et al, 1981;Sorokin, 1988;Sharadze et al, 1988Sharadze et al, , 1989Bauer et al, 1995;Zhou et al, 1997;Alperovich and Fedorov, 2007) verify the permanent existence of ULF electromagnetic planetary scale perturbations in Eand F-regions of the ionosphere. Among them, the ionospheric ultra-low-frequency (ULF) perturbations of planetary scale (10 3 − 10 4 km), propagating at fixed latitude along the Earth's parallel, are of special interest to the experimental observations (Burmaka et al, 2006).…”