A statistical study of satellite traces and evolution of equatorial spread F

Narayanan, Viswanathan Lakshmi; Sau, Sukanta; Gurubaran, S.; Shiokawa, K.; Balan, N.; Emperumal, K.; Sripathi, S.

doi:10.1186/s40623-014-0160-4

Cited by 33 publications

(33 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even though plasma bubble generation may need a seed perturbation to trigger the instability (Tsunoda 2010;Narayanan et al 2014), one of the most important factor for the plasma bubble growth is zonal electric field. At the sunset terminator, the eastward electric field is enhanced before the electric field become westward during nighttime.…”

Section: Introductionmentioning

confidence: 99%

Effects of pre-reversal enhancement of E × B drift on the latitudinal extension of plasma bubble in Southeast Asia

2015

View full text Add to dashboard Cite

We investigated the effects of the F region bottomside altitude (h'F), maximum upward E × B drift velocity, duration of pre-reversal enhancement and the integral of upward E × B drift on the latitudinal extension of equatorial plasma bubbles in the Southeast Asian sector using the observations recorded by three GPS receivers and two ionosondes. The GPS receivers are installed at Kototabang (0.2°S, 100.3°E; 9.9°S magnetic latitude), Pontianak (0.02°S, 109.3°E; 9.8°S magnetic latitude) and Bandung (6.9°S, 107.6°E; 16.7°S magnetic latitude) in Indonesia. The ionosondes are installed at magnetically equatorial stations, Chumphon (10.7°N, 99.4°E; 0.86°N magnetic latitude) in Thailand and Bac Lieu (9.3°N, 105.7°E; 0.62°N magnetic latitude) in Vietnam. We analysed those observations acquired in the equinoctial months (March, April, September and October) in 2010-2012, when the solar activity index F 10.7 was in the range from 75 to 150. Assuming that plasma bubbles are the major source of scintillations, the latitudinal extension of the bubbles was determined according to the S4 index. We have found that the peak of h'F, maximum upward E × B drift and the integral of upward E × B drift during the pre-reversal enhancement period are positively correlated with the maximum latitude extension of plasma bubbles, but that duration of pre-reversal enhancement does not show correlation. The plasma bubbles reached magnetic latitudes of 10°-20°in the following conditions: (1) the peak value of h'F is greater than 250-450 km, (2) the maximum upward E × B drift is greater than 10-70 m/s and (3) the integral of upward E × B drift is greater than 50-250 m/s. These results suggest that the latitudinal extension of plasma bubbles is controlled mainly by the magnitude of pre-reversal enhancement and the peak value of h'F at the initial phase of development of plasma bubbles (or equatorial spread F) rather than by the duration of pre-reversal enhancement.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of pre-reversal enhancement of E × B drift on the latitudinal extension of plasma bubble in Southeast Asia

2015

View full text Add to dashboard Cite

show abstract

“…This finding is consistent with the diurnal occurrence of scintillation observed in all seasons, which suggests that is associated with the presence of E sb . Furthermore, it is possible that the scintillation events observed in the late afternoon sector could be due to plasma irregularities in the F-region (e.g., Chatterjee et al 2014); however, post sunset F-region scintillations are normally observed after~19:00 LT (Somayajulu et al 1984;Gwal et al 2004;Carter et al 2013;Narayanan et al 2014). Therefore, it is unlikely that the late-afternoon GPS scintillation events analyzed here (~17:00 LT) are due to F-region plasma irregularities.…”

Section: Characteristics Of Daytime Ghz Scintillation In the Vicinitymentioning

confidence: 99%

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

et al. 2015

View full text Add to dashboard Cite

Observations made in non-equatorial regions appear to support the hypothesis that the daytime scintillation of radio signals at gigahertz (GHz) frequencies is produced by the gradient-drift instability (GDI) in the presence of a blanketing sporadic E (E sb ) layer. However, the only evidence offered, thus far, to validate this notion, has been some observations of E sb in the vicinity of GHz scintillations. A more comprehensive evaluation requires information about electric field, together with the presence of a steep gradient, which is presumed to be that of E sb . In this regard, the region in the vicinity of the equatorial electrojet (EEJ) appears to be an ideal "laboratory" to conduct such experiments. The dominant driver of electron drift there is the same as that of the EEJ, the vertical polarization electric field, and indications are that the presence of E sb in that vicinity is controlled by a balance in horizontal transport of E sb , between the EEJ electric field and the neutral wind, as described in a model by Tsunoda (On blanketing sporadic E and polarization effects near the equatorial electrojet, 2008). In this paper, we present, for the first time, results from a comprehensive study of daytime GHz scintillations near the magnetic equator. The properties, derived from measurements, are shown, for the first time, to be consistent with a scenario in which E sb presence is dictated by the Tsunoda model, and the plasma-density irregularities responsible for GHz scintillations appear to be produced by the GDI.

show abstract

“…Relationships between spread-Fs and other ionospheric parameters, particularly the F2-layer (foF2) and h′F variations with the occurrence of spread-Fs, have also been statistically examined (Rungraengwajiake et al 2013;Joshi et al 2013;Madhav Haridas et al 2013;de Abreu et al 2014ade Abreu et al , b, c, 2017Abadi et al 2015;Manju and Madhav Haridas 2015;Smith et al 2015;Liu and Shen 2017). In addition, the effects of seasonal, solar, and magnetic activity variabilities on the h′F threshold have also been investigated (Manju et al 2007;Manju and Madhav Haridas 2015;Madhav Haridas et al 2013;Stoneback et al 2011;Narayanan et al 2014Narayanan et al , 2017. Devasia et al (2002) first introduced the concept of threshold height (h′Fc) as a critical parameter controlling the day-to-day equatorial spread-F (ESF) variability.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the downward drifts across sunset and the upward drifts across midnight were also consistent with the delay in the appearance of ionospheric irregularities after midnight. Narayanan et al (2014) studied the relationship between the occurrence of satellite traces (STs) in ionograms and the formation of ESFs using observations from an Indian dip equatorial station during solar minimum conditions. They found that the ST occurred later in the night as well implying that the PRE was not the cause of the ST during these times.…”

Section: Introductionmentioning

confidence: 99%

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

Wang

Guo

Zhao

et al. 2018

Earth Planets Space

View full text Add to dashboard Cite

Ionospheric irregularities are an important phenomenon in scientific studies and applications of radio-wave propagation. Spread-F echoes in ionograms are a type of high-frequency band irregularities that include frequency spread-F (FSF), range spread-F (RSF), and mixed spread-F (MSF) events. In this study, we obtained spread-F data from four ionosondes at low-and mid-latitudes near the 120°E chain in China during the 23rd solar cycle. We used these data to investigate spread-F occurrence percentages and variations with local time, season, latitude, and solar activity. The four ionosondes were located at Haikou (HK) (20°N, 110.34°E), Guangzhou (GZ) (23.14°N, 113.36°E), Beijing (BJ) (40.11°N, 116.28°E), and Changchun (CC) (43.84°N, 125.28°E). We also present possible correlations between spread-Fs and other ionospheric parameters, such as the critical frequency of the F2-layer (foF2) and the virtual height of the bottom-side F-layer (h′F). In particular, we investigated the possible threshold of the foF2 affecting the FSF and the relationship between the h′F and the RSF. The main conclusions are as follows: (a) the FSF occurrence percentages were anti-correlated with solar activity at all four sites; meanwhile, RSF occurrence rates increased with the increase in solar activity at HK, but not at the other three sites; (b) FSF occurrence rates were larger at the mid-latitudes than expected, while FSFs occurred more often after midnight; (c) the highest FSF occurrence rates mostly appeared during the summer months, while RSFs occurred mostly in the equinoctial months of 2000-2002 at HK and GZ; (d) a lower foF2 was suitable for FSF events; nevertheless, h′F and RSF occurrences satisfied the parabolic relationship; (e) the foF2 thresholds for FSFs were 15, 14, 7.6, and 7.8 MHz at HK, GZ, BJ, and CC, respectively. The h′Fs occurring between 240 and 290 km were more favorable for RSF occurrences. These results are important for understanding ionospheric irregularity variations in eastern Asia and for improving space weather modeling and forecasting capabilities .

show abstract

A statistical study of satellite traces and evolution of equatorial spread F

Cited by 33 publications

References 41 publications

Effects of pre-reversal enhancement of E × B drift on the latitudinal extension of plasma bubble in Southeast Asia

Effects of pre-reversal enhancement of E × B drift on the latitudinal extension of plasma bubble in Southeast Asia

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

Contact Info

Product

Resources

About