Effects of the equatorial ionosphere anomaly on the interhemispheric circulation in the thermosphere

Qian, Liying; Burns, A. G.; Wang, Wenbin; Solomon, Stanley C.; Zhang, Yongliang; Hsu, V.

doi:10.1002/2015ja022169

Cited by 29 publications

(47 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 1a and 1b Figure 1a) and the run with the residual circulation ( Figure 1b). The upwelling reduces O/N 2 in the winter hemisphere, and the downwelling increases O/N 2 in the summer hemisphere [Burns et al, 1989;Qian et al, 2016a]. It is evident that in most part of the thermosphere (vertically, from about z = À5 and upward), there is a summer-to-winter interhemispheric circulation, with upwelling in the summer hemisphere and downwelling at low to mid-high latitudes in the winter hemisphere, driven by summer-to-winter difference in solar radiation.…”

Section: Resultsmentioning

confidence: 99%

Impact of the lower thermospheric winter‐to‐summer residual circulation on thermospheric composition

Qian

Yue

2017

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Gravity wave forcing near the mesopause drives a summer‐to‐winter residual circulation in the mesosphere and a reversed, lower thermospheric winter‐to‐summer residual circulation. We conducted modeling studies to investigate how this lower thermospheric residual circulation impacts thermospheric composition (O/N2). We found that the upwelling associated with the residual circulation significantly decreases O/N2 in winter and the downwelling in summer slightly increases O/N2. Consequently, the residual circulation reduces the summer‐to‐winter latitudinal gradient of O/N2, which causes the simulated latitudinal gradient of O/N2 to be more consistent with observations. The smaller summer‐to‐winter latitudinal gradient of O/N2 would decrease the ionosphere winter anomaly in model simulations, which would bring the simulated winter anomaly into better agreement with ionospheric observations. The lower thermospheric residual circulation may be a process that has been largely ignored but is very important to the summer‐to‐winter latitudinal gradients, as well as annual/semiannual variations in the thermosphere and ionosphere.

show abstract

Section: Resultsmentioning

confidence: 99%

Impact of the lower thermospheric winter‐to‐summer residual circulation on thermospheric composition

Qian

Yue

2017

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…The local solar EUV heating shows a summer to winter gradient, since the southern polar region is sunlit all of the time. The plasma‐neutral collisional heating maximizes in the regions above the polarward edges of the EIA crests where the temperature difference between the plasma and neutral, as well as the plasma density, is large [ Qian et al , ]. These maxima are more toward the summer hemisphere in the west sector than they are in the east sector due to the location of the magnetic equators in these two sectors.…”

Section: Resultsmentioning

confidence: 99%

“…In the southern hemisphere winter, the winter enhancement of O/N 2 is weaker than it is in the northern winter primarily as a result of the annual asymmetry in electron density [ Qian et al , ]. Figure shows the counterparts of Figures g and h for July 2003 (southern winter).…”

Section: Resultsmentioning

confidence: 99%

“…However, since the displacement between the south geomagnetic pole and south geographic pole is larger than that for the north poles, this convergence zone is located at lower latitudes compared to its January counterpart (i.e., the convergence zone in the northern winter (January) in the west sector). Note that due to the ionospheric annual anomaly [ Qian et al , ], the July downwelling in both sectors is weaker than their January counterparts; consequently, the July O/N 2 enhancement in the convergence zones is weaker than it is in January.…”

Section: Resultsmentioning

confidence: 99%

“…As we did in our companion studies [ Qian et al , , ], we utilize recent global O/N 2 data measured by the Global Ultraviolet Imager on board the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite (TIMED/GUVI, version 08), combined with modeling studies using the National Center for Atmospheric Research Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model (NCAR/TIE‐GCM) to describe these longitudinal changes in O/N 2 and to determine their causes. Descriptions of the TIMED/GUVI and NCAR/TIE‐GCM are given in Qian et al [] and Qian et al [].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Longitudinal variations of thermospheric composition at the solstices

et al. 2016

Self Cite

View full text Add to dashboard Cite

O/N2, measured by the Global Ultraviolet Imager on board the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, has large longitudinal variations at the solstices, which are simulated well in upper atmosphere general circulation models. These longitudinal variations are caused by the displacement of the Earth's magnetic poles from the geographic ones. The location of a magnetic pole affects the latitude at which the winds, driven by heating in summer, converge in the subauroral region of the winter hemisphere. In the magnetic pole's longitude sector, this convergence occurs at relatively low latitudes, which results in the maximum values of O/N2 also occurring at relatively low latitudes. These latitudes have a relatively small solar zenith angle, contributing to a strong winter anomaly. In the zonally opposite longitude sector, maximum values of O/N2 occur at relatively high latitudes because the summer‐to‐winter wind convergence also occurs at relatively high latitudes. These high latitudes have a relatively large solar zenith angle, so ionization is weak, contributing to a weak winter anomaly. Therefore, the displacement between the magnetic and geographic poles not only results in a strong longitudinal variation of O/N2 but also results in a strong longitudinal variation of the ionosphere winter anomaly.

show abstract

Solar cycle variations of thermospheric composition at the solstices

et al. 2016

Self Cite

View full text Add to dashboard Cite

We examine the solar cycle variability of thermospheric composition (O/N2) at the solstices. Our observational and modeling studies show that the summer‐to‐winter latitudinal gradient of O/N2 is small at solar minimum but large at solar maximum; O/N2 is larger at solar maximum than at solar minimum on a global‐mean basis; there is a seasonal asymmetry in the solar cycle variability of O/N2, with large solar cycle variations in the winter hemisphere and small solar cycle variations in the summer hemisphere. Model analysis reveals that vertical winds decrease the temperature‐driven solar cycle variability in the vertical gradient of O/N2 in the summer hemisphere but increase it in the winter hemisphere; consequently, the vertical gradient of O/N2 does not change much in the summer hemisphere over a solar cycle, but it increases greatly from solar minimum to solar maximum in the winter hemisphere; this seasonal asymmetry in the solar cycle variability in the vertical gradient of O/N2 causes a seasonal asymmetry in the vertical advection of O/N2, with small solar cycle variability in the summer hemisphere and large variability in the winter hemisphere, which in turn drives the observed seasonal asymmetry in the solar cycle variability of O/N2. Since the equatorial ionization anomaly suppresses upwelling in the summer hemisphere and strengthens downwelling in the winter hemisphere through plasma‐neutral collisional heating and ion drag, locations and relative magnitudes of the equatorial ionization anomaly crests and their solar cycle variabilities can significantly impact the summer‐to‐winter gradients of O/N2 and their solar cycle variability.

show abstract

Effects of the equatorial ionosphere anomaly on the interhemispheric circulation in the thermosphere

Cited by 29 publications

References 33 publications

Impact of the lower thermospheric winter‐to‐summer residual circulation on thermospheric composition

Impact of the lower thermospheric winter‐to‐summer residual circulation on thermospheric composition

Longitudinal variations of thermospheric composition at the solstices

Solar cycle variations of thermospheric composition at the solstices

Contact Info

Product

Resources

About