Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Xiong, Chao; Zhou, Yunliang; Lühr, Hermann; Ma, Shijing

doi:10.5194/angeo-33-185-2015

Cited by 18 publications

(29 citation statements)

References 47 publications

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“…This corresponds to a wave speed of about 590 m/s. The propagation speed is consistent with previous model and observational work reporting a phase speed of the equatorward wind surge of about 600 m/s [e.g., Fuller‐Rowell et al , ; Fujiwara et al , ; Ritter et al , ; Xiong et al , ]. The peak vertical disturbed wind is about 40–50 m/s around −0:20, which is weaker in comparison to those in the horizontal directions.…”

Section: Resultssupporting

confidence: 90%

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

et al. 2017

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The temporal and spatial variation in thermospheric winds are studied at 400 km altitude in response to substorms that start at different universal time (UT), using a global ionosphere and thermosphere model. The substorm‐induced disturbance winds at high latitudes are mainly in the poleward, westward, and upward directions in the dusk sector and in the equatorward, westward, and upward directions in the nighttime. The daytime perturbation is due to ion drag, driven by variations in interplanetary magnetic field Bz, whereas the nighttime perturbation is due to both the Bz and hemispheric power input. The nightside disturbed winds respond somewhat later than the dayside owing to low background ion density. Ion drag is the dominant driving force in the daytime for both meridional and zonal disturbed winds, whereas Joule heating is the dominant factor for the vertical winds. The nighttime meridional and zonal winds are driven by a combination of ion drag, Joule heating, and heating of the auroral belt, whereas the vertical winds are mainly caused by auroral belt heating. The viscous force acts to resist the ion drag, whereas the Coriolis force is negligible. The disturbed winds exhibit large variations with UT during equinox and local winter conditions. With more solar illumination, stronger disturbed winds can be generated. Weak or even opposite variations with UT in the disturbed winds are found in local summer, which is due to a smaller UT variation of the daytime ion density and a larger contribution from auroral heating than from ion drag.

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Section: Resultssupporting

confidence: 90%

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

et al. 2017

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“…Similar WN1 patterns in thermospheric mass density and zonal wind are also found at the southern middle latitudes, and the most prominent tidal components are D0 and DW2 (e.g. Xiong et al, 2015b). One interesting feature of D0 is that it shows an anti-phase diurnal variation between hemispheres both in the F region electron density as well as in the thermospheric mass density and zonal wind (Xiong et al, 2015b).…”

Section: Nonmigrating Tides At Middle Latitudessupporting

confidence: 55%

“…Xiong et al, 2015b). One interesting feature of D0 is that it shows an anti-phase diurnal variation between hemispheres both in the F region electron density as well as in the thermospheric mass density and zonal wind (Xiong et al, 2015b). By employing the global ionosphere-thermosphere model (GITM) simulation, H. found that the thermospheric zonal wind plays an important role in causing the WN1/WN2 patterns of the F region electron density at middle latitudes, but additional contributions are needed to explain the full extension of observed tides.…”

Section: Nonmigrating Tides At Middle Latitudesmentioning

confidence: 99%

The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

et al. 2016

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Abstract. In this paper we use more than a decade of in situ electron density observations from CHAMP and GRACE satellites to investigate the solar activity dependence of nonmigrating tides at both low and middle latitudes. The results indicate that the longitudinal patterns of F region electron density vary with season and latitude, which are exhibiting a wavenumber 4 (WN4) pattern around September equinox at low latitudes and WN1/WN2 patterns during local summer at the southern/northern middle latitudes. These wave patterns in the F region ionosphere can clearly be seen during both solar maximum and minimum years. At low latitudes the absolute amplitudes of DE3 (contributing to the WN4 pattern) are found to be highly related to the solar activity, showing larger amplitudes during solar maximum years. Similarly a solar activity dependence can also be found for the absolute amplitudes of D0, DW2 and DE1 (contributing to the WN1 and WN2 pattern) at middle latitudes. The relative amplitudes (normalized by the zonal mean) of these nonmigrating tides at both low and middle altitudes show little dependence on solar activity. We further found a clear modulation by the quasi-biennial oscillation (QBO) of the relative DE3 amplitudes in both satellite observations, which is consistent with the QBO dependence as reported for the E region temperatures and zonal wind. It also supports the strong coupling of the low-latitude nonmigrating tidal activity between the E and F regions. However, the QBO dependence cannot be found for the relative amplitudes of the nonmigrating tides at middle latitudes, which implies that these tides are generated in situ at F region altitudes.

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“…Xiong et al . [] show CHAMP and Gravity Recovery and Climate Experiment (GRACE) observations of mass density that present a wave 1 pattern in longitude (more clearly in the southern hemisphere than the northern hemisphere) that resembles the WINDII O( 1 D) VER and temperature variations with longitude.…”

Section: Discussionmentioning

confidence: 99%

WINDII observations of thermospheric O(¹D) nightglow emission rates, temperature, and wind: 1. The northern hemisphere midnight temperature maximum and the wave 4

Shepherd

2016

JGR Space Physics

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The midnight temperature maximum (MTM) is a large‐scale neutral temperature anomaly with a wide‐ranging effect on the nighttime thermospheric dynamics at low latitudes. The focus of the current study is an investigation of the extent of the MTM to northern midlatitudes (20°N–40°N), employing multiyear observations of O(1D) airglow volume emission rates (VERs), Doppler temperatures (DoT), and neutral winds over the altitude range of 190–300 km by the Wind Imaging Interferometer (WINDII) experiment on board the Upper Atmosphere Research Satellite. The MTM dependence on longitude, season, local time, and altitude was examined. Midnight maxima were observed both in the O(1D) VER and DoT with peaks at ~24 local time (LT) during winter solstice, 22 LT for fall equinox, and 2 LT for spring equinox. The peak in the DoTs was marked with strong southward meridional winds (e.g., ~100–150 m s−1). Latitude/longitude maps of the VER and DoT revealed wave 4 signatures most persistently seen around local midnight, with very little variation in phase, while the amplitude of the individual peaks varied with time. The observed perturbations in the O(1D) VER and temperature were out of phase with respect to longitude. Two of the peaks at ~100°E and 260°E–300°E were almost stationary, while the other two peaks varied in strength over the period of observation. A common feature was that one of the wave 4 peaks was always over the American sector; it was constant with local time, and the meridional wind was southward only over the same region.

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Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Cited by 18 publications

References 47 publications

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

WINDII observations of thermospheric O(¹D) nightglow emission rates, temperature, and wind: 1. The northern hemisphere midnight temperature maximum and the wave 4

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Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Cited by 18 publications

References 47 publications

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

Universal time variation of high‐latitude thermospheric disturbance wind in response to a substorm

The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

WINDII observations of thermospheric O(1D) nightglow emission rates, temperature, and wind: 1. The northern hemisphere midnight temperature maximum and the wave 4

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WINDII observations of thermospheric O(¹D) nightglow emission rates, temperature, and wind: 1. The northern hemisphere midnight temperature maximum and the wave 4