Observation of periodic fluctuations in electron and ion temperatures at the low-latitude upper ionosphere by SROSS-C2 satellite

Nayar, S. R. Prabhakaran; Alexander, Lalitha T.; Radhika, V. N.; John, Thomas; Subrahmanyam, P.; Chopra, P.; Bahl, M. K.; Maini, H. K.; Singh, V.R.; Singh, Davinder; Garg, S. C.

doi:10.5194/angeo-22-1665-2004

Cited by 9 publications

(8 citation statements)

References 31 publications

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“…The paper reported that morning overshoot is stronger at higher altitudes. But, the SROSS‐C2 conducted most of its ionospheric measurements near India, in the geographic longitude (GLON) range of 50°E–100°E (Prabhakaran Nayar et al, , section 2). Furthermore, in every season the statistics were based only on several tens of days in total (and only during two passes per day; see Alexander, , Figure 3).…”

Section: Introductionmentioning

confidence: 99%

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

et al. 2020

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The rapid increase of electron temperature in the early morning hours at low latitudes is a well‐known ionospheric phenomenon called morning overshoot. In this study, we extensively investigate the dependence of morning overshoot on local time, season, latitude/longitude/altitude, and magnetic activity. The electron temperature and density data set used in this study are obtained from (1) the Swarm constellation at two different altitudes of 470 and 520 km with identical payloads and (2) the Floating Potential Measurement Unit onboard International Space Station at an altitude of 400 km. Based on the data between 2014 and 2019, the main findings of this study are as follows: (1) on a global average, morning overshoot generally weakens with decreasing altitudes. (2) Morning overshoot is stronger around the dip equator than at midlatitude regions. As latitude increases, the overshoot decreases gradually and shifts to later local times. (3) In off‐equatorial regions the overshoot is stronger in the winter than in the summer hemisphere, especially at higher altitudes. (4) Lastly, the morning overshoot shows multiday oscillations, which are negatively correlated with plasma density and affected by geomagnetic activity.

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Section: Introductionmentioning

confidence: 99%

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

et al. 2020

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“…Bhuyan et al (2004) further examined the diurnal, seasonal and latitudinal variation of ion temperature at 500 km and reported latitudinal gradients in T i during the period of morning and afternoon enhancement. Prabhakaran Nayar et al (2004) using SROSS C2 data for the period 1995-2000 examined the periodicities in electron and ion temperature and found periodicities ranging from 14 days (short) to 1.3 years (long) in both T e and T i . Zhang and Holt (2004) have studied the climatology of plasma temperature and the relationship between T e and N e from the long term data base of the Millstone Hill radar.…”

Section: Introductionmentioning

confidence: 99%

“…Schunk and Nagy (1978) had reviewed the local time, altitude and latitudinal variation of the electron and ion temperature in the F-region. Some interesting features of the low latitude ionosphere such as the morning and afternoon enhancement, the temperature and wind anomaly, latitudinal asymmetry, and short and long term periodicities have been observed and extensively studied (Brace and Theis, 1981;Oyama et al, 1996;Watanabe et al, 1995;Balan et al, 1997;Bhuyan et al, 2002aBhuyan et al, , b, 2004Prabhakaran Nayar et al, 2004). Brace and Theis (1981) used Atmospheric Explorer C satellite data to derive a model of electron temperature and found low nighttime temperature followed by a morning peak, a daytime plateau and a secondary evening enhancement.…”

Section: Introductionmentioning

confidence: 99%

Effect of solar cycle on topside ion temperature measured by SROSS C2 and ROCSAT 1 over the Indian equatorial and low latitudes

Borgohain

Bhuyan

2012

Ann. Geophys.

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Abstract. The effect of solar activity on the diurnal, seasonal and latitudinal variations of ion temperature T i and its relationship with corresponding ion density N i over the Indian low and equatorial topside ionosphere within 17.5 • S to 22.5 • N magnetic latitudes are being investigated, combining the data from SROSS C2 and ROCSAT 1 for the 9-year period from 1995 to 2003 during solar cycle 23. T i varies between 800 K and 1100 K during nighttime and rises to peak values of ∼1800 K in the post sunrise hours. Daytime T i varies from 1000 K to 1500 K. The time of occurrence, magnitude and duration of the morning enhancement show distinct seasonal bias. For example, in the June solstice, T i increases to ∼1650 K at ∼06:00 h and exhibits a daytime plateau till 17:00 LT. In the equinoxes, enhanced ion temperature is observed for a longer duration in the morning. There is also a latitudinal asymmetry in the ion temperature distribution. In the equinoxes, the daytime T i is higher at off equatorial latitudes and lower over the Equator, while in the solstices, T i exhibits a north-south gradient during daytime. Nighttime T i is found to be higher over the Equator. Daytime ion temperature exhibits insignificant positive correlation with F 10.7 cm solar flux, while nighttime ion temperature decreases with increase in solar flux. Daytime ion temperature and ion density are negatively correlated during solar minimum, while nighttime T i does not exhibit any correlation. However, during high solar activity, significant positive correlation of T i with N i has been observed over the Equator, while at 10 • S and 10 • N temperature and density exhibit significant negative correlation. The neutral temperature T n derived from the MSISE 90 model is found to be higher than measured T i during nighttime, while daytime T i is higher than model T n .

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“…In this paper, we focus on the morphology and mechanisms of the ∼27 day variation of N m F 2 . There have been many studies of N m F 2 variations with this periodicity [e.g., Bartels , 1950; Titheridge , 1973; Kane et al , 1995; Forbes et al , 2000; Rishbeth and Mendillo , 2001; Pancheva et al , 2002; Rich et al , 2003; Prabhakaran Nayar et al , 2004; Wang et al , 2007; Oinats et al , 2008; Astafyeva et al , 2008; Afraimovich et al , 2008; Liang et al , 2008; Hocke , 2008; Min et al , 2009; Borries and Hoffmann , 2010]. However, the latitudinal, seasonal, local time, and solar cycle changes of this variation are not fully understood.…”

Section: Introductionmentioning

confidence: 99%

The effect of ∼27 day solar rotation on ionospheric F₂ region peak densities (N_mF₂)

Ma¹,

Xu²,

Wang³

et al. 2012

J. Geophys. Res.

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[1] Ionospheric F 2 region peak electron densities (N m F 2 ) observed from 11 ionosonde stations in the East Asian-Australian sector from 1969 to 1986 have been used to investigate the effect of $27 day solar rotation on the ionosphere. These stations were located from the magnetically equatorial regions to the middle latitudes in both hemispheres. We found that, averaged over all stations and for 18 years, the normalized standard deviation of the midday $27 day variations of N m F 2 was 8% and that of the midnight variations was 10%. We applied different data analysis methods, including Fourier transform, band-pass filter, and multiple linear regression analysis, to determine quantitatively the sources of the observed $27 day variations of N m F 2 and their relative contributions to these variations. Our results show that the $27 day variations in solar radiation and geomagnetic activity, caused by solar rotation, are the main drivers of the ionospheric $27 day variations. They accounted for more than 85% of the variations seen in the N m F 2 $27 day variation, and their contributions became about 95% at higher latitudes. At geomagnetically low latitudes, the contribution of the $27 day variation in solar EUV radiation was greater than that of the $27 day variation in geomagnetic activity. However, the contribution from geomagnetic activity became more significant and was even larger than the contribution of solar radiation at higher latitudes, especially at midnight. At all latitudes the correlation between the $27 day variations of N m F 2 and solar radiation was evidently positive, whereas that between N m F 2 and geomagnetic activity was positive at geomagnetically low latitudes and became negative at higher middle latitudes. We did not found large seasonal or solar cycle changes in the $27 day variations of N m F 2 . These variations, however, did show significant differences between the two hemispheres.

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Observation of periodic fluctuations in electron and ion temperatures at the low-latitude upper ionosphere by SROSS-C2 satellite

Cited by 9 publications

References 31 publications

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

Effect of solar cycle on topside ion temperature measured by SROSS C2 and ROCSAT 1 over the Indian equatorial and low latitudes

The effect of ∼27 day solar rotation on ionospheric F₂ region peak densities (N_mF₂)

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Observation of periodic fluctuations in electron and ion temperatures at the low-latitude upper ionosphere by SROSS-C2 satellite

Cited by 9 publications

References 31 publications

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

Effect of solar cycle on topside ion temperature measured by SROSS C2 and ROCSAT 1 over the Indian equatorial and low latitudes

The effect of ∼27 day solar rotation on ionospheric F2 region peak densities (NmF2)

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The effect of ∼27 day solar rotation on ionospheric F₂ region peak densities (N_mF₂)