Response of middle atmospheric temperature to the 27 d solar cycle: an analysis of 13 years of microwave limb sounder data

Rong, Piao; Savigny, Christian von; Zhang, Chunmin; Hoffmann, Christoph G.; Schwartz, M.

doi:10.5194/acp-20-1737-2020

Cited by 4 publications

(7 citation statements)

References 30 publications

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“…The composite Mg II index provided by the university of Bremen (see Section 2.2) is used as the solar proxy for the SEA. The SEA has been described in detail in many other publications (e.g., Rong et al., 2020; von Savigny et al., 2019) and only a very brief summary is given here. In a first step anomaly time series of Mg II, foF2 and hmF2 are determined by subtracting a 35‐day running mean from the original time series (see Figure 14).…”

Section: Discussionmentioning

confidence: 99%

“…Rong et al. (2020) and von Savigny et al. (2019) discussed these effects on quasi‐27‐day signatures in the stratosphere and mesosphere.…”

Section: Discussionmentioning

confidence: 99%

“…However, also during periods without pronounced 27-day cycles in the Mg II index similar variations are present, which may potentially be caused by planetary wave signatures from the lower atmosphere. Rong et al (2020) andvon Savigny et al (2019) discussed these effects on quasi-27-day signatures in the stratosphere and mesosphere.…”

Section: Sea Of the F2 Layermentioning

confidence: 99%

“…Solar 27-day signatures have also been reported in several parameters or constituents in the middle atmosphere (i.e., stratosphere and mesosphere) including temperature (e.g., Dyrland & Sigernes, 2007;Hood, 1986;Rong et al, 2020;Thomas et al, 2015;von Savigny et al, 2012), ozone (e.g., Fioletov, 2009;Hood, 1986), odd hydrogen (Wang et al, 2015), mesospheric water vapor (Thomas et al, 2015), atomic oxygen in the MLT region (Lednyts'kyy et al, 2017), radio reflection heights (von Savigny et al, 2019), and even in noctilucent clouds (Robert et al, 2010)-also known as polar mesospheric clouds. In many cases, the identification of solar 27-day signatures in middle atmospheric parameters is relatively straightforward and typically based on correlation analyses or SEA.…”

Section: Solar 27-day Signatures In the Middle Atmospherementioning

confidence: 99%

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The Height‐Dependent Delayed Ionospheric Response to Solar EUV

et al. 2022

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Based on the analysis of electron density Ne profiles (Grahamstown ionosonde), a case study of the height‐dependent ionospheric response to two 27‐day solar rotation periods in 2019 is performed. A well‐defined sinusoidal response is observed for the period from 27 April 2019 to 24 May 2019 and reproduced with a Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulation. The occurring differences between model and observations as well as the driving physical and chemical processes are discussed based on the height‐dependent variations of Ne and major species. Further simulations with an artificial noise free sinusoidal solar flux input show that the Ne delay is defined by contributions due to accumulation of O+ at the Ne peak (positive delay) and continuous loss of O2+ ${\mathrm{O}}_{2}^{+}$ in the lower ionosphere (negative delay). The neutral parts' 27‐day signatures show stronger phase shifts. The time‐dependent and height‐dependent impact of the processes responsible for the delayed ionospheric response can therefore be described by a joint analysis of the neutral and ionized parts. The return to the initial ionospheric state (and thus the loss of the accumulated O+) is driven by an increase of downward transport in the second half of the 27‐day solar rotation period. For this reason, the neutral vertical winds (upwards and downwards) and their different height‐dependent 27‐day signatures are discussed. Finally, the importance of a wavelength‐dependent analysis, statistical methods (superposed epoch analysis), and coupling with the middle atmosphere is discussed to outline steps for future analysis.

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Section: Discussionmentioning

confidence: 99%

“…Rong et al. (2020) and von Savigny et al. (2019) discussed these effects on quasi‐27‐day signatures in the stratosphere and mesosphere.…”

Section: Discussionmentioning

confidence: 99%

Section: Sea Of the F2 Layermentioning

confidence: 99%

Section: Solar 27-day Signatures In the Middle Atmospherementioning

confidence: 99%

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The Height‐Dependent Delayed Ionospheric Response to Solar EUV

et al. 2022

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“…It has long been known that not only the ionized upper atmosphere, but also the neutral middle atmosphere, is influenced by external drivers. The possibly most well known one is solar variability (e.g., Keuer et al, 2007;Beig, 2011;Stober et al, 2014;Qian et al, 2019), which influences the middle atmosphere on the 11-year cycle time scale, but also on shorter time scales like the 27 d solar rotation (e.g., Rong et al, 2020). Another factors are particle precipitation, which may influence the atmosphere from the lower thermosphere down to the surface (Mironova et al, 2015) in a more irregular manner and which is also related to geomagnetic variability.…”

Section: Introductionmentioning

confidence: 99%

Influence of geomagnetic disturbances on mean winds and tides in the mesosphere/lower thermosphere at midlatitudes

et al. 2021

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Abstract. Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51.3∘ N, 13.0∘ E) and Kazan (56∘ N, 49∘ E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyse the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end, we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies for geomagnetic effects on mean winds over Collm and Kazan qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere and greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.

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Solar Activity Driven 27‐Day Signatures in Ionospheric Electron and Molecular Oxygen Densities

Schmölter

Savigny

2022

JGR Space Physics

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Solar extreme ultraviolet (EUV) radiation is absorbed in different ionization and dissociation processes in the upper atmosphere driving the creation of the ionospheric plasma. The composition of this plasma is significantly affected by variations of the solar activity but geomagnetic (driven by the solar wind) and meteorological variability contribute to ionospheric variability as well (Rishbeth & Mendillo, 2001). Thus, changes of the plasma occur on different spatial and temporal scales, which may further depend on additional parameters (e.g., solar zenith angle). Nevertheless, significant signatures in the ionospheric plasma are related to corresponding changes in the solar EUV radiation. The 27-day solar rotation period (appearance and disappearance of active regions on the solar disc) causes continuous variations of the solar EUV spectrum which in turn cause observable 27-day signatures for different ionospheric parameters (Ma et al., 2012).Photoionization of O to O + at heights from 150 to 500 km defines the so-called F region with the maximum of the plasma density profile. The amount of O + dominates the ionospheric plasma in this region. Photoionization of O 2 to 𝐴𝐴 O + 2 and photodissociation of O 2 to O at heights from 90 to 150 km (as well as further absorption processes or charge exchange) cause a different plasma composition in the lower ionosphere. Additionally, recombination processes occur depending on the existing plasma composition at different heights (Kelley, 2009). The 27-day signatures, which are driven by the solar EUV radiation, thus also show height-dependent variations based on the contribution of the different processes (Schmölter et al., 2022).In the upper ionosphere the 27-day signatures of the plasma density are controlled by production and loss of O + (Ren et al., 2018;Schmölter et al., 2022). The production due to photoionization of O is almost immediate and increased due to the photodissociation of O 2 and upward transport processes during the time of increasing solar activity (first phase of 27-day solar rotation period). The recombination is not immediate and therefore an accumulation of O + may occur resulting in an observable time difference between the solar and ionospheric 27-day signatures (Schmölter et al., 2022). This delayed ionospheric response and its variability has been characterized

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Response of middle atmospheric temperature to the 27 d solar cycle: an analysis of 13 years of microwave limb sounder data

Cited by 4 publications

References 30 publications

The Height‐Dependent Delayed Ionospheric Response to Solar EUV

The Height‐Dependent Delayed Ionospheric Response to Solar EUV

Influence of geomagnetic disturbances on mean winds and tides in the mesosphere/lower thermosphere at midlatitudes

Solar Activity Driven 27‐Day Signatures in Ionospheric Electron and Molecular Oxygen Densities

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