Climatology and latitudinal gradients of quiet time thermospheric neutral winds over Millstone Hill from Fabry‐Perot interferometer measurements

Emmert, J. T.; Fejer, Bela G.; Sipler, D. P.

doi:10.1029/2002ja009765

Cited by 49 publications

(99 citation statements)

References 21 publications

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“…Therefore the stronger zonal wind can give rise to larger |R| for lower solar activity ( Figure 6). Zonal wind climatology over Millstone Hill has been published based on FPI measurements for a full solar cycle in 1989-2001 [15]. It was indicated that the eastward wind reach maximum before but close to midnight; the eastward wind in the evening is highest in winter; the eastward wind speed tends to be enhanced toward low solar activity, in particular, in winter.…”

Section: Zonal Wind Climatologymentioning

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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Section: Zonal Wind Climatologymentioning

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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“…The meridional winds at mid-latitude are consistent with the solar EUV forcing and the consequent latitudinal pressure gradients, namely poleward by day and equatorward at night (Hagan, 1993;Kawamura et al, 2000). At higher mid-latitudes, the meridional winds can be influenced by the aurorally driven high-latitude circulation cell even under quiet conditions (Hagan, 1993;Emmert et al, 2003).…”

Section: Introductionmentioning

confidence: 71%

“…Similarly, the strong meridional gradients have been reported by Salah et al (1987) very significant latitudinal gradients for meridional winds at all seasons, especially during equinox periods at solar minimum. The strong positive latitudinal gradients for VEWs and meridional winds at southern higher mid-latitudes suggest an influence by the high-latitude magnetospheric convection (Hagan, 1993; Emmert et al, 2003). Strong gradients also appear at higher mid-latitudes during summer solstice periods near noon.…”

Section: The Latitudinal Gradient Of Vewsmentioning

confidence: 98%

“…Detailed latitudinal trends of meridional winds are involved in the above climatological works (e.g. Biondi et al, 1999;Emmert et al, 2003;Foppiano et al, 2003) and other investigations (Salah et al, 1987;Oliver et al, 1988;Wickwar, 1989;Miller et al, 1993;Zhang et al, 1995). Miller et al (1997) have presented climatology of the F-layer meridional equivalent winds at various stations.…”

Section: Introductionmentioning

confidence: 99%

“…Buonsanto, 1990;Hagan, 1993;Biondi et al, 1999;Igi et al, 1999;Buonsanto and Witasse, 1999;Kawamura et al, 2000;Emmert et al, 2003;Foppiano et al, 2003). Up to now, some climatological models of the thermospheric horizontal winds (e.g.…”

Section: Introductionmentioning

confidence: 99%

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A climatology of the F-layer equivalent winds derived from ionosonde measurements over two decades along the 120°-150°E sector

et al. 2004

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Abstract. The vertical equivalent winds (VEWs) at the F-layer are analyzed along the 120 • -150 • E longitude sector with an emphasis on their latitudinal dependence. The VEWs are derived from the monthly median data of fourteen ionosonde stations over two decades. The results show that the VEWs have considerable dependences on the magnetic latitude with an approximate symmetry about the magnetic equator. They are mostly controlled by the electric field drifts in the magnetic equatorial region, and shift to be mostly contributed by neutral winds at mid-latitudes. The relative contribution of the two dynamic factors is regulated by the magnetic dip in addition to their own magnitudes. The VEWs generally have opposite directions and different magnitudes between lower and higher latitudes. At solar minimum, the magnitudes of VEWs are only between −20 and 20 m/s at lower latitudes, while at higher latitudes they tend to increase with latitudes, typically having magnitudes between 20-40 m/s. At solar maximum, the VEWs are reduced by about 10-20 m/s in magnitudes during some local times at higher latitudes. A tidal analysis reveals that the relative importance of major tidal components is also different between lower and higher latitudes.The VEWs also depend on local time, season and solar activity. At higher latitudes, the nighttime VEWs have larger magnitude during post-midnight hours and so do the daytime ones before midday. The VEWs tend to have an inverse relationship with solar activity not only at night, but also by day, which is different from the meridional winds predicted by the HWM93 model. The latitudinal dependence of VEWs has two prevailing trends: one is a maximum at the highest latitudes (as far as the latitudes concerned in the present work); the other is a mid-latitude maximum. These two latitudinal trends are mostly dependent on season, while they depend relatively weakly on local time and solar activity. The latitudinal gradients of VEWs also show a tendency of a midCorrespondence to: L. Liu (liul@mail.igcas.ac.cn) latitude maximum, except that there are much stronger latitudinal gradients at southern higher mid-latitudes in some seasons. The gradients during daytime are much smaller at solar maximum than minimum, whereas they are generally comparable at night under both solar activity levels.

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A preliminary study of thermosphere and mesosphere wind observed by Fabry‐Perot over Kelan, China

Huang

Zhao

et al. 2014

JGR Space Physics

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A Fabry-Perot interferometer (FPI) system was deployed in Kelan (38.7°N, 111.6°E), center China in November 2011, which observes the airglows at wavelengths of 892.0 nm, 557.7 nm, and 630.0 nm from OH and OI emissions in the upper atmosphere, to derive the wind and temperature at heights around 87 km, 97 km, and 250 km, respectively. From late 2011 through 2013 a series of more than 4500 measurements at each height are validated according to manufacture data quality criteria. By using these data, the morphology of wind in the mesosphere and thermosphere is investigated in this study. Preliminary results are as follows:(1) As for the diurnal variation, meridional and zonal winds at heights of 87 km and 97 km, which are derived through 892.0 nm and 557.7 nm airglows, usually range from À50 m/s to 30 m/s and À50 m/s to 50 m/s, respectively, with typical random errors of about 6-10 m/s at 87 km and 2-3 m/s at 97 km. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, westward at middle night, and back to eastward at dawn. The monthly mean winds are in good agreement with those of HWM93 results. Meridional and zonal winds at a height of 250 km, which are derived through 630.0 nm nightglow, range from À110 m/s to 80 m/s with typical random errors of about 8-10 m/s. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, zero at middle night, and westward at dawn; and they are also well consistent with HWM93 results. (2) As for the seasonal variation, meridional winds at the heights of 87 km and 97 km have a visible annual variation at 12-17 LT and with a little semiannual variation at all other hours, but the zonal winds at the heights of 87 km and 97 km have a semiannual variation all night. The seasonal dependence of the winds, both meridional and zonal winds, at the height of 250 km is generally annual, but isolated cases of semiannual variation are observed. (3) The horizontal winds at 250 km evidently respond to the two storms of July 2012, apparent enhancement of the velocity of the southwestward wind. But no other obvious storm effects can be found from the winds at 87 km and 97 km during the same period.

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Climatology and latitudinal gradients of quiet time thermospheric neutral winds over Millstone Hill from Fabry‐Perot interferometer measurements

Cited by 49 publications

References 21 publications

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

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

A climatology of the F-layer equivalent winds derived from ionosonde measurements over two decades along the 120°-150°E sector

A preliminary study of thermosphere and mesosphere wind observed by Fabry‐Perot over Kelan, China

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