Study of the evolution of Te and Ti at the low-latitude upper ionosphere using SROSS-C2 RPA observations

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:10.1016/j.jastp.2004.04.002

Cited by 8 publications

(3 citation statements)

References 19 publications

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“…In view of the satellite dynamics in the spin cycles, the spatial resolution of the measurements was about 95 km in space. The SROSS C2 RPA data has been validated using IRI and the data from other satellites like Hinatori in various studies on the equatorial and low‐latitude ionosphere in the Indian sector [e.g., Bhuyan and Chamua , 2002; Prabhakaran Nayar et al , 2004; Niranjan et al , 2003; Bhuyan et al , 2004].…”

Section: Satellite Instrumentationmentioning

confidence: 99%

Signatures of equatorial midnight temperature maximum as observed from in situ and ground‐based ionospheric measurements in the Indian sector

Niranjan¹,

Brahmanandam²,

Srivani³

2006

J. Geophys. Res.

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[1] Results of a preliminary study carried out on the features of midnight temperature maximum (MTM) over the Indian sector as observed from the first in situ electron temperature variations of Indian SROSS C2 RPA data, the thermospheric night airglow intensities at 630 nm recorded from a subtropical Indian station Waltair (17.7°N, 83.3°E) and a colocated Digital Ionosonde data are reported. The electron temperatures indicate that during the summer solstice months of low solar activity periods, there was a significant temperature gradient from the equator toward the latitudes of Waltair (14-18°N) from 2200 to 2400 hours IST even in the topside F region. In contrast, during the winter solstice months, temperature contours do not show significant gradient around midnight, though isolated peaks are seen between 0100 and 0300 hours IST, i.e., delayed in time by a couple of hours, suggesting that the MTM is weaker. The MTM induced F layer descent at subtropical latitudes due to a probable neutral wind modification and consequent increase in 630 nm night airglow zenith intensity are studied to characterize the MTM induced ionospheric changes in terms of the starting time, velocity of F layer descent indicative of the strength of MTM, and the time at minimum height indicative of the time of cessation of MTM induced perturbation. The results are discussed in the light of earlier work and the current understanding of the origin of equatorial MTM.Citation: Niranjan, K., P. S. Brahmanandam, and B. Srivani (2006), Signatures of equatorial midnight temperature maximum as observed from in situ and ground-based ionospheric measurements in the Indian sector,

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Section: Satellite Instrumentationmentioning

confidence: 99%

Signatures of equatorial midnight temperature maximum as observed from in situ and ground‐based ionospheric measurements in the Indian sector

Niranjan¹,

Brahmanandam²,

Srivani³

2006

J. Geophys. Res.

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“…The in-situ measurements of T e and T i were carried out using onboard RPA payload. The T e and T i at the upper ionosphere depends on the solar activity level and is found to exhibit diurnal, seasonal, altitudinal and latitudinal variations (Kohnlein, 1986;Bilitza, 1991;Oyama et al, 1996b;Prabhakaran Nayar et al, 2004). A study on the characteristics of the T e and T i helps in understanding the representative behaviour of the ionosphere both in the low and equatorial latitude regions at a height of $500 km.…”

Section: Introductionmentioning

confidence: 99%

Studies of electron and ion temperatures at 500km altitude during sunrise using Indian SROSS C2 satellite

Aggarwal¹,

Joshi²,

Iyer³

et al. 2009

Advances in Space Research

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“…Hence the ionospheric electron temperature also varies with local time, season, solar activity, magnetic activity, altitude, and location [see Schunk and Nagy , 1978; Bilitza , 1987]. The seasonal and solar activity variations of electron temperature are mostly obtained from satellite observations at fixed altitudes and modeling techniques are used to interpret these observations [e.g., Brace and Theis , 1978, 1981; Su et al , 1996; Watanabe and Oyama , 1996; Oyama et al , 1996, 1997; Venkatraman and Heelis , 1999; Prabhakaran Nayar et al , 2004; Sharma et al , 2005]. In addition to satellite observations, incoherent scatter radar (ISR) is a very powerful, ground‐based remote‐probing tool for the study of the ionospheric processes.…”

Section: Introductionmentioning

confidence: 99%

Electron temperature climatology at Millstone Hill and Arecibo

et al. 2007

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[1] In this paper, ionospheric electron temperature (Te) data for more than two solar cycles measured by the incoherent scatter radars (ISR) at Millstone Hill (42.6°N, 71.5°W) and Arecibo (18.3°N, 66.7°W) are compared with the theoretical Te calculated from the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (NCAR-TIEGCM) to investigate the temporal variations of Te. The comparisons are made for both low and high solar activity conditions and for three seasons: equinox, summer, and winter. The observations show that the diurnal variation of Te is characterized by morning and evening peaks at Arecibo and by a morning peak at Millstone Hill. The occurrence and strength of the peaks at Arecibo are significantly different from those at Millstone Hill. Daytime Te tends to increase with solar activity at both stations below $300 km. Te above 300 km generally decreases with solar activity; however, it increases with solar activity in equinox and summer at Arecibo, whereas it does so only in summer at Millstone Hill. The TIEGCM model can reproduce these variations. However, the modeled evening peak is weaker than that from observations at Arecibo. The simulations show that the daytime bulge of Te tends to occur at low latitudes and high solar activity, as seen in the observations, and the significant morning peak at low solar activity over Arecibo is associated with the equatorial anomaly. Moreover, an interesting feature predicted by the model is that the midday Te at the F 2 peak height increases with solar activity when F 10.7

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Study of the evolution of Te and Ti at the low-latitude upper ionosphere using SROSS-C2 RPA observations

Cited by 8 publications

References 19 publications

Signatures of equatorial midnight temperature maximum as observed from in situ and ground‐based ionospheric measurements in the Indian sector

Signatures of equatorial midnight temperature maximum as observed from in situ and ground‐based ionospheric measurements in the Indian sector

Studies of electron and ion temperatures at 500km altitude during sunrise using Indian SROSS C2 satellite

Electron temperature climatology at Millstone Hill and Arecibo

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