Traveling planetary wave ionospheric disturbances and their role in the generation of equatorial spread-F and GPS phase fluctuations during the last extreme low solar activity and comparison with high solar activity

2014 ◽  
Vol 117 ◽  
pp. 7-19 ◽  
Author(s):  
A.J. de Abreu ◽  
P.R. Fagundes ◽  
M.J.A. Bolzan ◽  
M. Gende ◽  
C. Brunini ◽  
...  
Keyword(s):  
Solar Activity ◽  
Planetary Wave ◽  
High Solar Activity ◽  
Ionospheric Disturbances ◽  
Phase Fluctuations ◽  
Equatorial Spread F ◽  
Spread F

scholarly journals The statistical properties of spread F observed at Hainan station during the declining period of the 23rd solar cycle

2010 ◽  
Vol 28 (6) ◽  
pp. 1263-1271 ◽  
Author(s):  
G. J. Wang ◽  
J. K. Shi ◽  
X. Wang ◽  
S. P. Shang ◽  
G. Zherebtsov ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Temporal Variations ◽  
High Solar Activity ◽  
Positive Relation ◽  
Low Latitude ◽  
23Rd Solar Cycle ◽  
Reversal Time ◽  
Spread F ◽  
Maximum Occurrence

Abstract. The temporal variations of the low latitude nighttime spread F (SF) observed by DPS-4 digisonde at low latitude Hainan station (geog. 19.5° N, 109.1° E, dip lat. 9.5° N) during the declining solar cycle 23 from March 2002 to February 2008 are studied. The spread F measured by the digisonde were classified into four types, i.e., frequency SF (FSF), range SF (RSF), mixed SF (MSF), and strong range SF (SSF). The statistical results show that MSF and SSF are the outstanding irregularities in Hainan, MSF mainly occurs during summer and low solar activity years, whereas SSF mainly occurs during equinoxes and high solar activity years. The SSF has a diurnal peak before midnight and usually appears during 20:00–02:00 LT, whereas MSF peaks nearly or after midnight and occurs during 22:00–06:00 LT. The time of maximum occurrence of SSF is later in summer than in equinoxes and this time delay can be caused by the later reversal time of the E×B drift in summer. The SunSpot Number (SSN) dependence of each type SF is different during different season. The FSF is independent of SSN during each season; RSF with SSN is positive relation during equinoxes and summer and is no relationship during the winter; MSF is significant dependence on SSN during the summer and winter, and does not relate to SSN during the equinoxes; SSF is clearly increasing with SSN during equinoxes and summer, while it is independent of SSN during the winter. The occurrence numbers of each type SF and total SF have the same trend, i.e., increasing as Kp increases from 0 to 1, and then decreasing as increasing Kp. The correlation with Kp is negative for RSF, MSF, SSF and total SF, but is vague for the FSF.

scholarly journals Multi-station investigation of spread F over Europe during low to high solar activity

2018 ◽  
Vol 8 ◽  
pp. A27 ◽  
Author(s):  
Krishnendu Sekhar Paul ◽  
Haris Haralambous ◽  
Christina Oikonomou ◽  
Ashik Paul ◽  
Anna Belehaki ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Solar Cycle Variation ◽  
F Region ◽  
Perkins Instability ◽  
Spread F ◽  
Triggering Mechanisms

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions on the basis of the Rayleigh-Taylor (R-T) instability. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere with its generation attributed to the Perkins instability mechanism. Over midlatitudes it has also been correlated with geomagnetic storms through the excitation of travelling ionospheric disturbances (TIDs) and subsequent F region uplifts. The present study deals with the occurrence rate of nighttime spread F events and their diurnal, seasonal and solar cycle variation observed over three stations in the European longitude sector namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E geographic: geomagnetic Lat: 29.38 °N), Athens (geographic Lat: 37.98 °N, Long: 23.73 °E geographic: geomagnetic Lat: 34.61 °N) and Pruhonice (geographic Lat: 50.05 °N, Long: 14.41 °E geographic: geomagnetic Lat: 47.7 °N) during 2009, 2015 and 2016 encompassing periods of low, medium and high solar activity, respectively. The latitudinal and longitudinal variation of spread F occurrence was examined by considering different instability triggering mechanisms and precursors which past literature identified as critical to the generation of spread F events. The main findings of this investigation is an inverse solar cycle and annual temporal dependence of the spread F occurrence rate and a different dominant spread F type between low and high European midlatitudes.

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.

scholarly journals ANALISIS KORELASI KEMUNCULANSPREAD F DANSINTILASI IONOSFER DI WILAYAH BARATINDONESIA MENGGUNAKAN DATAIONOSFER AGAM KOTOTABANGSUMATERA BARAT

2020 ◽  
Vol 5 (2) ◽  
pp. 6-11
Author(s):  
Putri Andini ◽  
Usman Malik ◽  
Asnawi Husin
Keyword(s):  
Solar Activity ◽  
Data Interpretation ◽  
High Solar Activity ◽  
Minimum Phase ◽  
Matlab Software ◽  
It Value ◽  
West Region ◽  
Spread F ◽  
Correlation Level

This reseach has been done to know the correlation between spread F appearance and scintillation ionosphere on west region Indonesia. The method has been used is data interpretation using  computational way, then all of data is processed using matlab software. The occurance of spread F was minimum in 2008 with it value respectively around 45%. In 2011 the spread F was beginning to increase with it value respectively around 70%. The occurance of ionospheric scintilation was minimum in 2010 with it value respectively around 13%. These occurances were due to a minimum phase of solar activity. In 2013 the scintilation was beginning to increase with it value respectively around 75% in which the occurance was selected for S4  ≥ 0,6. The correlation level between spread F and scintilation is medium, because the value of R aquals 0,4 this case is be affected by solar activity. The value of R is 0 (no correlation) at weak solar activity and 0,6 at high solar activity.

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