Dynamical influence of the Madden-Julian oscillation on the Northern Hemisphere mesosphere during the boreal winter

Sun, Cong; Yang, Chengyun; Li, Tao

doi:10.1007/s11430-020-9779-2

Cited by 5 publications

(8 citation statements)

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“…A study broadly comparable to Sun et al (2021), but focused on the stratosphere and based on reanalysis data is presented by Yang et al (2019). They analyze the northern hemisphere stratospheric temperature response to partly all MJO phases, but highlight a stratospheric warming after MJO phase 4 with a time lag of 30 d. This can be regarded as consistent with our results in the same sense as discussed before in the context of Sun et al (2021) for the mesosphere. Furthermore, the order of magnitude of the temperature response is in their analyses comparable to our results of the boreal winter situation without QBO filtering (Fig.…”

Section: Relation To Previous Studiessupporting

confidence: 88%

“…The influence of the MJO on mesospheric temperatures during boreal winter has recently been analyzed by Sun et al (2021).…”

Section: Relation To Previous Studiesmentioning

confidence: 99%

“…A period of 100 days around SSWs is excluded, which further limits the comparability to our results. Sun et al (2021) concentrate mainly on the temporal evolution after MJO phase 4 and on the northern hemisphere. As one main result they report a cooling of the northern hemisphere mesosphere 35 days after MJO phase 4.…”

Section: Relation To Previous Studiesmentioning

confidence: 99%

“…However, converted to time lags this appears to be earlier than the time lag of 35 days. Sun et al (2021) also show the meridional plane temperature response of the MA for different https://doi.org/10.5194/egusphere-2022-998 Preprint. Discussion started: 13 October 2022 c Author(s) 2022.…”

Section: Relation To Previous Studiesmentioning

confidence: 99%

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Signatures of the Madden-Julian Oscillation in Middle Atmosphere zonal mean Temperature: Triggering the Interhemispheric Coupling pattern

Hoffmann

Buth

Savigny

2022

Preprint

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Abstract. The Madden–Julian oscillation (MJO) is the dominant mode of intraseasonal variability in the troposphere. The influence of the MJO on the middle atmosphere (MA) and particularly on its temperature is of interest for both the understanding of MJO-induced teleconnections and research on the variability of the middle atmosphere. However, only few studies dealing with the influence of the MJO on MA temperature are available. We analyze statistically the connection of the MJO and the MA zonal mean temperature based on observations by the MLS satellite instrument. We consider all eight MJO phases, different seasons and the state of the quasi-biennial oscillation (QBO). We show that the MA temperature is influenced by the state of MJO in large areas of the MA and under roughly all considered atmospheric conditions. The zonal mean temperature response is characterized by a particular spatial pattern, which we link to the interhemispheric coupling (IHC) mechanism, a known dynamical feature of the MA. The strongest temperature deviations are on the order of ± 10 K and are found in the polar winter MA during boreal winter when the QBO is in the easterly phase. Other atmospheric conditions also show temperature responses with the characteristic spatial pattern, but weaker and more noisy. The QBO turns out to have a relatively big influence during boreal winter but only a small influence during austral winter. We also discuss the role of sudden stratospheric warmings (SSWs), which have an ambivalent influence on our interpretation, because they introduce strong temperature variability in the polar winter MA themselves. In addition, SSWs are one possibility to explain the QBO influence during boreal winter. Furthermore, we also analyze the change of the temperature response pattern while the MJO progresses from one phase to the next. We find a largely systematic reaction of the MA to the phase changes, particularly a gradual altitude shift of the MA temperature response pattern, which can be seen more or less clearly depending on the atmospheric conditions. Overall, a major outcome of the present study is the finding that the tropospheric MJO can trigger the IHC mechanism, which affects many areas of the MA. It is therefore a noteworthy example for the complex couplings across different atmospheric layers and geographical regions in the atmosphere. Additionally, it highlights close linkages of known dynamical features of the atmosphere, particularly the MJO, the IHC, the QBO, and SSWs. Because of the wide coverage of atmospheric regions and included dynamical features, the results might help to further constrain the underlying dynamical mechanisms and could be used as a benchmark for the representation of atmospheric couplings on the intraseasonal timescale in atmospheric models.

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Section: Relation To Previous Studiessupporting

confidence: 88%

“…The influence of the MJO on mesospheric temperatures during boreal winter has recently been analyzed by Sun et al (2021).…”

Section: Relation To Previous Studiesmentioning

confidence: 99%

Section: Relation To Previous Studiesmentioning

confidence: 99%

Section: Relation To Previous Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Signatures of the Madden-Julian Oscillation in Middle Atmosphere zonal mean Temperature: Triggering the Interhemispheric Coupling pattern

Hoffmann

Buth

Savigny

2022

Preprint

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“…There is also increasing evidence that the variability of the MJO itself is partly controlled by the stratosphere. A prominent example of this is the influence of the quasi-biennial oscillation (QBO) during boreal winter: Yoo and Son (2016) found that the MJO amplitude tends to be larger during the QBO easterly phase and smaller during the QBO westerly phase, and several studies followed up on this (e.g., Son et al, 2017;Marshall et al, 2017;Zhang and Zhang, 2018;Densmore et al, 2019;Wang and Wang, 2021). The influence on the MJO from above is also covered by a more general recent review by Haynes et al (2021).…”

Section: Introductionmentioning

confidence: 99%

Signatures of the Madden–Julian oscillation in middle-atmosphere zonal mean temperature: triggering the interhemispheric coupling pattern

Hoffmann,

Buth,

von Savigny

2023

Atmos. Chem. Phys.

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Abstract. The influence of the Madden–Julian oscillation (MJO) on the middle atmosphere (MA) and particularly on MA temperature is of interest for both the understanding of MJO-induced teleconnections and research on the variability of the MA. We analyze statistically the connection of the MJO and the MA zonal mean temperature based on observations by the Microwave Limb Sounder (MLS) satellite instrument. We consider all eight MJO phases, different seasons and the state of the quasi-biennial oscillation (QBO). We show that MA temperature anomalies are significantly related to the MJO and its temporal development. The MJO signal in the zonal mean MA temperature is characterized by a particular spatial pattern in the MA, which we link to the interhemispheric coupling (IHC) mechanism, as a major outcome of this study. The signal with the largest magnitude is found in the polar MA during boreal winter with temperature deviations on the order of ±10 K when the QBO at 50 hPa is in its easterly phase. Other atmospheric conditions and locations also exhibit temperature signals, which are, however, weaker or noisier. We also analyze the change in the temperature signal while the MJO progresses from one phase to the next. We find a gradual altitude shift in parts of the IHC pattern, which can be seen more or less clearly depending on the atmospheric conditions. The statistical link between the MJO and the MA temperature highlights illustratively the far-reaching connections across different atmospheric layers and geographical regions in the atmosphere. Additionally, it highlights close linkages of known dynamical features of the atmosphere, particularly the MJO, the IHC, the QBO and sudden stratospheric warmings (SSWs). Because of the wide coverage of atmospheric regions and included dynamical features, the results might help to further constrain the underlying dynamical mechanisms and could be used as a benchmark for the representation of atmospheric couplings on the intraseasonal timescale in atmospheric models.

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Solar-wind-dependent streamline model for Mercury’s magnetosheath

Schmid

Narita

Plaschke

et al. 2022

A&A

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Context. Mercury's magnetosphere and magnetosheath are unique in the Solar System plasmas as they are highly time dependent, since the planet has only a small-scale magnetosphere originating from the weak intrinsic planetary magnetic field. Yet, it is believed that the plasma therein reaches a quasi-stationary state, that is, the ground state of magnetospheric dynamics, when the solar wind smoothly passes by the magnetosphere without energy or momentum exchange in quiet conditions. Aims. Here, we aim to we construct a semi-analytical streamline model for Mercury's magnetosheath to extend the modeling effort from the magnetospheric plasma to the magnetosheath plasma. The magnetosheath model should have the capability of determining the plasma density and the bulk velocity as a function of the radial distance from the planet, the zenith angle to the Sun, and the solar wind condition. Methods. Our magnetosheath model was constructed with (1) the steady-state continuity equation around a magnetospheric obstacle where the bow shock and magnetopause location may depend on the solar wind condition, (2) the jump conditions at the bow shock, and (3) the adiabatic behavior in the magneotsheath. Results. Our magnetosheath model reasonably explains and reproduces the in-situ measurements around Mercury by the MErcury Surface, Space Environment, GEochemistry and Ranging (MESSENGER) spacecraft as well as numerical simulations.Conclusions. The presented streamline model of Mercury's magnetosheath serves as a useful tool for the on-going two spacecraft BepiColombo mission when analyzing the plasma data by tracing the plasma parcel along the streamline both forward from one spacecraft to another and backward, locating the shock crossing coordinate, or when estimating the elapsed time of plasma parcel after the shock crossing.

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Dynamical influence of the Madden-Julian oscillation on the Northern Hemisphere mesosphere during the boreal winter

Cited by 5 publications

References 47 publications

Signatures of the Madden-Julian Oscillation in Middle Atmosphere zonal mean Temperature: Triggering the Interhemispheric Coupling pattern

Signatures of the Madden-Julian Oscillation in Middle Atmosphere zonal mean Temperature: Triggering the Interhemispheric Coupling pattern

Signatures of the Madden–Julian oscillation in middle-atmosphere zonal mean temperature: triggering the interhemispheric coupling pattern

Solar-wind-dependent streamline model for Mercury’s magnetosheath

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