Ionospheric Planetary Wave Activity and Its Role in Equatorial Spread F Day‐to‐Day Variability

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
G. Manju ◽  
R. P. Aswathy
Keyword(s):  
Planetary Wave ◽  
Wave Activity ◽  
Equatorial Spread F ◽  
Spread F

scholarly journals Features of 3–7-day planetary-wave-type oscillations in F-layer vertical drift and equatorial spread F observed over two low-latitude stations in China

2017 ◽  
Vol 35 (3) ◽  
pp. 763-776 ◽  
Author(s):  
Zhengping Zhu ◽  
Weihua Luo ◽  
Jiaping Lan ◽  
Shanshan Chang
Keyword(s):  
Planetary Wave ◽  
Rate Of Change ◽  
Lower Atmosphere ◽  
Main Role ◽  
Kelvin Wave ◽  
Low Latitude ◽  
Wave Type ◽  
Equatorial Spread F ◽  
Vertical Drift ◽  
Spread F

Abstract. Recent studies on the equatorial atmosphere–ionosphere coupling system have shown that planetary-wave-type oscillations, as an important seeding mechanism for equatorial spread F (ESF), play an important role in ESF irregularity development and its day-to-day variability in the equatorial latitudes. In this study, ionosonde virtual height and ESF measurements over Sanya (18.4° N, 109.6° E; 12.8° N dip latitude) and meteor radar neutral-wind measurements over Fuke (19.5° N, 109.1° E; 14° N dip latitude) during 2013 are used to investigate the features of planetary-wave-type oscillations in both the lower atmosphere and the ionosphere and their possible influences on ESF occurrence under the weak solar maximum year. The ∼ 3-day and ∼ 7-day planetary-wave-type oscillations have been observed in the neutral zonal winds and the time rate of change in F-layer virtual heights. According to the propagation characteristics, the 3-day and 7-day planetary-wave-type oscillations are basically recognized as ultrafast and fast Kelvin waves, respectively. With increasing heights, the 3-day wave oscillations are gradually amplified, while the 7-day wave oscillations are generally constant. By performing a cross-wavelet transform on the onsets of ESF and the vertical drifts of the F layer, we found that there are simultaneously occurring 7-day and 3-day common wave oscillations between them. The 7-day waves are mainly in the inversion phase, while the 3-day waves are mostly in an in-phase state, indicating that the 7-day waves may play a main role in ESF initiation. Approximate delays of 6 days for the 7-day waves and 5 days for the 3-day waves in their propagation upward from the lower atmosphere to the ionosphere are evaluated with wavelet power spectrum analysis. The estimated upward velocities from these time delays provide consistent evidence that the 7-day and 3-day waves propagate vertically upward with typical Kelvin wave characteristics. The results highlight the role of planetary-wave-type oscillations in the initiation and development of ESF in the Chinese low-latitude region.

Equatorial Spread-F and Magnetic Activity

Nature ◽  
1958 ◽  
Vol 181 (4625) ◽  
pp. 1724-1725 ◽  
Author(s):  
A. J. LYON ◽  
N. J. SKINNER ◽  
R. W. WRIGHT
Keyword(s):  
Magnetic Activity ◽  
Equatorial Spread F ◽  
Spread F

scholarly journals Seasonal dependence of the "forecast parameter" based on the EIA characteristics for the prediction of Equatorial Spread F (ESF)

2008 ◽  
Vol 26 (7) ◽  
pp. 1751-1757 ◽  
Author(s):  
S. V. Thampi ◽  
S. Ravindran ◽  
T. K. Pant ◽  
C. V. Devasia ◽  
R. Sridharan
Keyword(s):  
Seasonal Variability ◽  
Seasonal Pattern ◽  
Onset Time ◽  
Critical Value ◽  
Latitudinal Gradients ◽  
Electron Content ◽  
Total Electron ◽  
Equatorial Spread F ◽  
Spread F ◽  
Definite Role

Abstract. In an earlier study, Thampi et al. (2006) have shown that the strength and asymmetry of Equatorial Ionization Anomaly (EIA), obtained well ahead of the onset time of Equatorial Spread F (ESF) have a definite role on the subsequent ESF activity, and a new "forecast parameter" has been identified for the prediction of ESF. This paper presents the observations of EIA strength and asymmetry from the Indian longitudes during the period from August 2005–March 2007. These observations are made using the line of sight Total Electron Content (TEC) measured by a ground-based beacon receiver located at Trivandrum (8.5° N, 77° E, 0.5° N dip lat) in India. It is seen that the seasonal variability of EIA strength and asymmetry are manifested in the latitudinal gradients obtained using the relative TEC measurements. As a consequence, the "forecast parameter" also displays a definite seasonal pattern. The seasonal variability of the EIA strength and asymmetry, and the "forecast parameter" are discussed in the present paper and a critical value for has been identified for each month/season. The likely "skill factor" of the new parameter is assessed using the data for a total of 122 days, and it is seen that when the estimated value of the "forecast parameter" exceeds the critical value, the ESF is seen to occur on more than 95% of cases.

High frequency drift waves with wavelengths below the ion gyroradius in equatorial spread F

1978 ◽  
Vol 5 (8) ◽  
pp. 695-698 ◽  
Author(s):  
J. D. Huba ◽  
P. K. Chaturvedi ◽  
S. L. Ossakow ◽  
D. M. Towle
Keyword(s):  
High Frequency ◽  
Frequency Drift ◽  
Drift Waves ◽  
Equatorial Spread F ◽  
Spread F
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