The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 1. Driving Mechanism

Wang, Jack C.; Yue, Jia; Wang, Wenbin; Qian, Liying; Wu, Qian; Wang, Ningchao

doi:10.1029/2022ja030948

Cited by 10 publications

(19 citation statements)

References 78 publications

(151 reference statements)

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“…As previously noted, the atomic oxygen concentration at altitudes above 95 km is mainly under dynamical control (Brasseur & Solomon, 2005; Garcia & Solomon, 1985; Jones et al., 2018). Therefore, the seasonal variation of O at altitudes between 95 and 114 km in Figure 1 is most likely explained by dynamics, and seasonal changes in advection via the lower‐thermospheric circulation might be one potential candidate among others (J. C. Wang et al., 2022). To understand the impact of the lower‐thermospheric circulation on the O budget, the contribution of each dynamical forcing to the O seasonal variation is investigated throughout this paper.…”

Section: Vertical Distribution Of O and Comparisons With Nrlmsis 20 A...mentioning

confidence: 99%

“…It also plays an essential role in dynamical-chemical coupling processes across multiple atmospheric layers on various spatial and temporal scales (e.g., Holton & Alexander, 2000;Jones et al, 2018;H.-L. Liu & Roble, 2004;Orsolini et al, 2022;Yue et al, 2013;. In the mesosphere and lower thermosphere (MLT), the mean meridional circulation is mainly caused by the momentum deposition via wave breaking or dissipation (Sato et al, 2018;J. C. Wang et al, 2022).…”

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confidence: 99%

“…The well-known summer-to-winter meridional circulation in the mesosphere is referred to as the mesospheric circulation (Holton & Alexander, 2000). It was later found that there exists another meridional circulation from the winter to the summer hemisphere above this mesospheric circulation, located between about ∼95 to ∼130 km J. C. Wang et al, 2022;.…”

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confidence: 99%

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The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 2. Impact on Atomic Oxygen

Wang,

Yue,

Wang

et al. 2023

JGR Space Physics

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As a companion study of the Part 1 (J. C. Wang et al., 2022, https://doi.org/10.1029/2022JA030948), the impact of the lower‐thermospheric circulation on atomic oxygen (O) in the mesosphere and lower thermosphere (MLT) region is investigated in this Part 2 using Specified Dynamics Configuration Runs of the Whole Atmosphere Community Climate Model eXtended (SD‐WACCMX) output. The asymmetry of the O profile in the summer and winter MLT region is mainly driven by local vertical advection, which is associated with the lower‐thermospheric winter‐to‐summer circulation and middle‐to‐upper thermospheric summer‐to‐winter circulation. It is found that meridional transport and eddy diffusion only weakly modulate the O budget within this altitude range. The globally and annually averaged transport effect due to the vertical advection is quantitatively estimated. It is shown that the vertical advection is the dominant mechanism in redistributing O at altitudes between 84 and 103 km, suggesting the vertical wind can efficiently transport O between its source and sink region within the vertical column. This study demonstrates that whole atmosphere coupling on seasonal time scales is a complex interaction involving multiple underlying mechanisms within the space‐atmosphere interaction region.

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Section: Vertical Distribution Of O and Comparisons With Nrlmsis 20 A...mentioning

confidence: 99%

mentioning

confidence: 99%

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The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 2. Impact on Atomic Oxygen

Wang,

Yue,

Wang

et al. 2023

JGR Space Physics

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“…The gravity wave with the opposite phase speed can propagate into lower thermosphere and dissipate there (H.-L. Liu, 2007). Additionally, the tidal waves also play a significant role in acceleration the winter-to-summer flow in the lower thermosphere (Wang et al, 2022). The reversal of zonal gravity wave drag can enhance the winter-to-summer return flow therein, which is referred to as the lower thermospheric residual circulation (H.-L. Liu, 2007).…”

Section: Figures 6a and 6b Display The Meridional Pressure Gradient F...mentioning

confidence: 99%

Influence of Mesospheric Gravity Wave Drag on the Formation of Winter Helium Bulge in the Thermosphere

et al. 2023

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The understanding of the temporal and spatial evolution of thermospheric neutral species, which act to determine the drag force on space vehicles and debris, is of central importance for geospace environment research (Emmert, 2015; Qian & Solomon, 2012, and references therein). The atomic oxygen (O), molecular oxygen (O 2 ), and molecular nitrogen (N 2 ) are regarded as the thermospheric major species, which control the behavior of the thermosphere. There are, thus, a lot of investigations focused on their characteristics and responses to external forces for several decades (e.g., Meier, 2021;Ren et al., 2020). Recently, observational and simulation studies pointed out that the light species helium (He) can also significantly modulate the variation of thermosphere and its response to geomagnetic storms (Bernstein & Pilinski, 2022;Thayer et al., 2012). The accuracy of thermospheric density predictions was improved via the incorporation of helium in the forecasting model (Kim et al., 2012). In this basis, helium should also be considered as a major part of the thermosphere (Sutton et al., 2015). However, the physical mechanisms that are responsible for the variation of helium in the thermosphere are still primitive owing to the lack of effective measurements and numerical models.Helium is an ideal inert tracer in the thermosphere, because the chemical production and loss of the component are negligible (Kockarts, 1973). As a result, helium behaves differently from other major species in the thermosphere. One of the most significant structures is that helium concentration in winter is higher than that in summer by 1-2 orders of magnitude, termed the winter helium bulge, which was first observed by G. Keating and Prior (1968). Since then, a series of studies devoted on exploring the formation of the anomalous structure and its responses to external forces (e.g.

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“…Previous modeling studies (e.g., Miyoshi et al, 2015;Zhang J. et al, 2021Zhang J. et al, , 2022Orsolini et al, 2022;Wang et al, 2022) suggest that the climatological direction of the mesosphere-lower thermosphere (MLT) mean meridional circulation (MMC), characterized by upwelling in the middle winter latitudes, equatorward flow near ∼100-120 km, and poleward flow near ∼80-100 km, reverses following the onset of SSWs. Ground-totopside model of Atmosphere and Ionosphere for Aeronomy (GAIA) model simulations from Miyoshi et al (2015) revealed that MMC reversed in the lower thermosphere.…”

Section: Introductionmentioning

confidence: 99%

Direct Observational Evidence of Altered Mesosphere Lower Thermosphere Mean Circulation from a Major Sudden Stratospheric Warming

Gasperini

Jones

Harding

et al. 2022

Preprint

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Sudden stratospheric warmings (SSWs) are large-scale phenomena characterized by dramatic dynamic disruptions in the stratospheric winter polar regions. Previous studies, especially those employing whole atmosphere models, indicate that SSWs have strong impacts on the circulation of the mesosphere lower thermosphere (MLT) and drive a reversal in the mean meridional circulation (MMC) near 90-125 km altitude. However, the robustness of these effects and the roles of SSW-induced changes in global-scale wave activity to drive the reversal have been difficult to observe simultaneously. This work employs horizontal lower thermospheric (~93-106 km altitude) winds near 10S-40N latitude from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument onboard the Ionospheric Connection Explorer (ICON) to present observational evidence of a prominent MLT MMC reversal associated with the January 2021 major SSW event and to demonstrate connections to semidiurnal tidal activity and possible associations with a ~3-day ultra-fast Kevin wave (UFKW).

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The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 1. Driving Mechanism

Cited by 10 publications

References 78 publications

The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 2. Impact on Atomic Oxygen

The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 2. Impact on Atomic Oxygen

Influence of Mesospheric Gravity Wave Drag on the Formation of Winter Helium Bulge in the Thermosphere

Direct Observational Evidence of Altered Mesosphere Lower Thermosphere Mean Circulation from a Major Sudden Stratospheric Warming

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