Midlatitude nighttime enhancement in <i>F</i> region electron density from global COSMIC measurements under solar minimum winter condition

Luan, Xiaoli; Wang, Wenbin; Burns, A. G.; Solomon, Stanley C.; Lei, Jiuhou

doi:10.1029/2008ja013063

Cited by 68 publications

(87 citation statements)

References 32 publications

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“…The term Mid-latitude Summer Nighttime Anomaly (MSNA) is now being used to describe the anomalous electron density patterns in both Northern and Southern Hemispheres Lin et al, 2010). It must be mentioned here that the MSNA is different from winter nighttime enhancements (Evans, 1965;Titheridge, 1968;Davies et al, 1979;Balan and Rao, 1987;Luan et al, 2008), and northern hemispheric summer nighttime enhancements reported by Balan and Bailey (1992) and Balan et al (1994) since the latter ones appear as a secondary maximum in electron density, both in the premidnight and post-midnight hours.…”

Section: Introductionmentioning

confidence: 89%

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

et al. 2011

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Abstract. In this paper, we present model simulations of the Mid-latitude Summer Nighttime Anomaly (MSNA) in the Northern Hemisphere, which is characterized by noontime dip and evening maximum in the diurnal variation of the ionospheric density. The simulations are carried out using SUPIM (Sheffield University Plasmasphere Ionosphere Model) for solar minimum at 135 • E longitude where MSNA is most pronounced in the Northern Hemisphere. The simulations are used to understand the relative importance of electric fields, and zonal and meridional winds in the formation of MSNA. The wind velocities measured by the Middle and Upper atmosphere radar (MU radar) and those obtained from the horizontal wind model (HWM93) are used. The results show that the formation of MSNA is closely related to the diurnal variation of the neutral winds with little contribution from the changes in the electric fields. The observed features of MSNA are better reproduced when MU radar winds are used as model input rather than HWM winds.

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Section: Introductionmentioning

confidence: 89%

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

et al. 2011

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“…This enhancement is associated primarily with meridional winds and magnetic declination (e.g., [12][13][14]). Figure 3 is a summer case where we can see WSA-like variations for data from both sides.…”

Section: Weddell-sea Anomalymentioning

confidence: 99%

Ionospheric longitudinal variations at midlatitudes: Incoherent scatter radar observation at Millstone Hill

Zhang

Coster

Holt

et al. 2012

Sci. China Technol. Sci.

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Incoherent scatter radar (ISR) extra-wide coverage experiments during the period of 1978-2011 at Millstone Hill are used to investigate longitudinal differences in electron density. This work is motivated by a recent finding of the US east-west coast difference in TEC suggesting a combined effect of changing geomagnetic declination and zonal winds. The current study provides strong supporting evidence of the longitudinal change and the plausible mechanism by examining the climatology of electron density Ne on both east and west sides of the radar with a longitude separation of up to 40 o for different heights within 300-450 km. Main findings include: 1) The east-west difference can be up to 60% and varies over the course of the day, being positive (East side Ne > West side Ne) in the late evening, and negative (West side Ne > East side Ne) in the pre-noon. 2) The east-west difference exists throughout the year. The positive (relative) difference is most pronounced in winter; the negative (relative) difference is most pronounced in early spring and later summer.3) The east-west difference tends to enhance toward decreasing solar activity, however, with some seasonal dependence; the enhancements in the positive and negative differences do not take place simultaneously. 4) Both times of largest positive and largest negative east-west differences in Ne are earlier in summer and later in winter. The two times differ by 12-13 h, which remains constant throughout the year. 5) Variations at different heights from 300-450 km are similar. Zonal wind climatology above Millstone Hill is found to be perfectly consistent with what is expected based on the electron density difference between the east and west sides of the site. The magnetic declination-zonal wind mechanism is true for other longitude sectors as well, and may be used to understand longitudinal variations elsewhere. It may also be used to derive thermospheric zonal winds.

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“…The FORMOSAT-3 is a scientific satellite, developed by the US and Taiwan, that orbits at an altitude of approximately 500 km. Approximately 1000-2500 ionospheric RO events registered per day by the COSMIC mission have been used to study the various ionospheric phenomena (e.g., He et al, 2009;Liu et al, 2008, Luan et al, 2008Potula et al, 2011;Yue et al, 2010;Zeng et al, 2008). For ground-based observations, we used data from Ascension Island (345.6 • E, 8.0 • S) located in the low latitudes area in the Southern Hemisphere.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the characteristics of ionospheric parameters obtained from FORMOSAT-3 and digisonde over Ascension Island

et al. 2013

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Electron density profile data obtained from the FORMOSAT-3 radio occultation (RO) measurements over Ascension Island are used to study the bottomside thickness parameter B0 in the International Reference Ionosphere (IRI) model, scale height around the F region peak height, and other F2 region parameters. The RO data were collected when the radio occultation occurred at Ascension Island (345.6° E, 8.0° S) during the solar minimum activity period from May 2006 to April 2008. Results show that the B0 values are in moderate agreement with the ground-based observations in the equinox period (correlation coefficient r = 0.682) and winter (r = 0.570), with a strong correlation in summer (r = 0.750). The seasonal and diurnal variations in B0 over Ascension Island show peak values during the daytime and in winter. In addition, the B0 values were underestimated and overestimated in the RO measurements during the daytime and nighttime, respectively. Moreover, the comparison of scale heights shows that scale heights obtained from the retrieved data and digisonde observations are weakly correlation in all three seasons. Furthermore, although the effective scale height (H_T) values were reverse of those obtained from the RO measurements and are higher during the nighttime than in the daytime, they are in good agreement with those from ground-based observations. This paper also provides a comprehensive discussion of the effect of the asymmetric ionospheric electron density profiles on RO measurements

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Midlatitude nighttime enhancement in F region electron density from global COSMIC measurements under solar minimum winter condition

Cited by 68 publications

References 32 publications

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

Ionospheric longitudinal variations at midlatitudes: Incoherent scatter radar observation at Millstone Hill

Comparison of the characteristics of ionospheric parameters obtained from FORMOSAT-3 and digisonde over Ascension Island

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