The 27 day solar rotational effect on mesospheric nighttime OH and O<sub>3</sub> observations induced by geomagnetic activity

Fytterer, Tilo; Santee, M. L.; Sinnhuber, Miriam; Wang, S.

doi:10.1002/2015ja021183

Cited by 20 publications

(32 citation statements)

References 20 publications

(3 reference statements)

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“…In addition, mesospheric ozone effects have been observed (Andersson et al, 2014a;Fytterer et al, 2015b) which are caused by HO x increases during MEE precipitation (Verronen et al, 2011b). Although the HO x -driven response is short-lived, the frequency of MEE events is large enough to cause solar-cycle variability in ozone (Andersson et al, 2014a).…”

Section: Geomagnetic Forcing (Auroral and Radiation Belt Electrons)mentioning

confidence: 99%

“…The impact of magnetospheric particles on the atmosphere is strongly linked to the strength of geomagnetic activity; this has been shown both for the direct production of NO in the thermosphere (Marsh et al, 2004;Hendrickx et al, 2015) and mesosphere (Sinnhuber et al, 2016), for mesospheric OH production (Fytterer et al, 2015b), and for the EPP indirect effect Funke et al, 2014a). Geomagnetic activity can be constrained over centennial timescales by means of proxy data provided by geomagnetic indices.…”

Section: Geomagnetic Forcing (Auroral and Radiation Belt Electrons)mentioning

confidence: 99%

“…70-80 km in altitude). This altitude region was selected because of the clear and direct MEE impact seen in satellite observations (e.g., Andersson et al, 2014a, b;Fytterer et al, 2015b;Sinnhuber et al, 2016). WACCM version 4 (see above) was used with 1.9 • × 2.5 • horizontal resolution extending from the surface to 5.9 × 10 −6 hPa (≈ 140 km geometric height) in the specified dynamics mode, nudged to MERRA reanalysis at every dynamics time step below about 50 km.…”

Section: Mid-energy Electrons (Mees) From the Radiation Beltsmentioning

confidence: 99%

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Solar forcing for CMIP6 (v3.2)

et al. 2017

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Abstract. This paper describes the recommended solar forcing dataset for CMIP6 and highlights changes with respect to CMIP5. The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise. The solar forcing datasets are provided at daily and monthly resolution separately for the CMIP6 preindustrial control, historical (1850CMIP6 preindustrial control, historical ( -2014, and future (2015-2300) simulations. For the preindustrial control simulation, both constant and time-varying solar forcing components are provided, with the latter including variability on 11-year and shorter timescales but no long-term changes. For the future, we provide a realistic scenario of what solar behavior could be, as well as an additional extreme Maunderminimum-like sensitivity scenario. This paper describes the forcing datasets and also provides detailed recommendations as to their implementation in current climate models.For the historical simulations, the TSI and SSI time series are defined as the average of two solar irradiance models that are adapted to CMIP6 needs: an empirical onePublished by Copernicus Publications on behalf of the European Geosciences Union. A new and lower TSI value is recommended: the contemporary solar-cycle average is now 1361.0 W m −2 . The slight negative trend in TSI over the three most recent solar cycles in the CMIP6 dataset leads to only a small global radiative forcing of −0.04 W m −2 . In the 200-400 nm wavelength range, which is important for ozone photochemistry, the CMIP6 solar forcing dataset shows a larger solar-cycle variability contribution to TSI than in CMIP5 (50 % compared to 35 %).We compare the climatic effects of the CMIP6 solar forcing dataset to its CMIP5 predecessor by using timeslice experiments of two chemistry-climate models and a reference radiative transfer model. The differences in the long-term mean SSI in the CMIP6 dataset, compared to CMIP5, impact on climatological stratospheric conditions (lower shortwave heating rates of −0.35 K day −1 at the stratopause), cooler stratospheric temperatures (−1.5 K in the upper stratosphere), lower ozone abundances in the lower stratosphere (−3 %), and higher ozone abundances (+1.5 % in the upper stratosphere and lower mesosphere). Between the maximum and minimum phases of the 11-year solar cycle, there is an increase in shortwave heating rates (+0.2 K day −1 at the stratopause), temperatures (∼ 1 K at the stratopause), and ozone (+2.5 % in the upper stratosphere) in the tropical upper stratosphere using the CMIP6 forcing dataset. This solar-cycle response is slightly larger, but not statistically significantly different from that for the CMIP5 forcing dataset.CMIP6 models wi...

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Section: Geomagnetic Forcing (Auroral and Radiation Belt Electrons)mentioning

confidence: 99%

Section: Geomagnetic Forcing (Auroral and Radiation Belt Electrons)mentioning

confidence: 99%

Section: Mid-energy Electrons (Mees) From the Radiation Beltsmentioning

confidence: 99%

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Solar forcing for CMIP6 (v3.2)

et al. 2017

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“…A 27-day variation due to a recurrent geomagnetic activity has been observed in mesospheric nighttime O 3 and OH (Fytterer et al, 2015). These and other possible influences, such as the occurrence of stratospheric warmings, on our results have to be considered.…”

Section: Discussionmentioning

confidence: 69%

“…The origin of the non-zero phase lag between mesospheric water vapor and solar Lyman-α is uncertain. While Shapiro et al (2012) ascribes this feature to the long chemical lifetime of H O 2 at high altitudes, an influence of a recurrent geomagnetic activity (Fytterer et al, 2015) is likewise conceivable.…”

Section: Discussionmentioning

confidence: 94%

Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle

Lainer

Hocke

Kämpfer

2016

Journal of Atmospheric and Solar-Terrestrial Physics

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a b s t r a c tMany studies investigated solar-terrestrial responses (thermal state, O 3 , OH, H 2 O) with emphasis on the tropical upper atmosphere. In this paper the focus is switched to water vapor in the mesosphere at a mid-latitudinal location. Eight years of water vapor profile measurements above Bern (°°46.88 N/7.46 E) are investigated to study oscillations with the focus on periods between 10 and 50 days. Different spectral analyses revealed prominent features in the 27-day oscillation band, which are enhanced in the upper mesosphere (above 0.1 hPa, ∼64 km) during the rising sunspot activity of solar cycle 24. Local as well as zonal mean Aura MLS observations support these results by showing a similar behavior. The relationship between mesospheric water and the solar Lyman-α flux is studied by comparing the similarity of their temporal oscillations. The H 2 O oscillation is negatively correlated to solar Lyman-α oscillation with a correlation coefficient of up to −0.3 to −0.4, and the phase lag is 6-10 days at 0.04 hPa. The confidence level of the correlation is ≥99%. This finding supports the assumption that the 27-day oscillation in Lyman-α causes a periodical photodissociation loss in mesospheric water. Wavelet power spectra, cross-wavelet transform and wavelet coherence analysis (WTC) complete our study. More periods of high common wavelet power of H 2 O and solar Lyman-α are present when amplitudes of the Lyman-α flux increase. Since this is not a measure of physical correlation a more detailed view on WTC is necessary, where significant (two sigma level) correlations occur intermittently in the 27 and 13-day band with variable phase lock behavior. Large Lyman-α oscillations appeared after the solar superstorm in July 2012 and the H 2 O oscillations show a well pronounced anti-correlation. The competition between advective transport and photodissociation loss of mesospheric water vapor may explain the sometimes variable phase relationship of mesospheric H 2 O and solar Lyman-α oscillations. Generally, the WTC analysis indicates that solar variability causes observable photochemical and dynamical processes in the mid-latitude mesosphere.

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The response of mesospheric NO to geomagnetic forcing in 2002–2012 as seen by SCIAMACHY

et al. 2016

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Daily NO number density, retrieved from measurements of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) from 2002 to 2012 for polar summer in the mesosphere, is used to investigate the response of NO to geomagnetic activity, as expressed by the auroral electrojet (AE) index. Applying the superposed epoch analysis, we observe a clear response of NO to strong geomagnetic forcing at geomagnetic latitudes 55–75°N/S and altitudes above 66 km. The 27 day solar rotation cycle is observed, indicating that some of the observed geomagnetic events are related to solar coronal holes. We find a linear relationship between anomalies of AE and NO at geomagnetic latitudes 55–70°N/S and 70–74 km altitude. A clear auroral oval‐like structure is observed on days of strong geomagnetic forcing in both hemispheres, with small longitudinal inhomogeneities, which might be related to the South Atlantic Anomaly or the magnetic local time. The NO lifetime and production rate per AE anomaly has been derived from a least squares fit to the observations. Comparisons of results from a simple model using this empirical NO production and a lifetime varying from 1.2 days in summer to 10 days in winter to SCIAMACHY observations show good agreement. In particular, the strength and interannual variability of the wintertime maximum is well captured. This suggests that direct production of NO in the upper mesosphere above 72 km contributes substantially to the so‐called energetic particle precipitation indirect effect.

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The 27 day solar rotational effect on mesospheric nighttime OH and O₃ observations induced by geomagnetic activity

Cited by 20 publications

References 20 publications

Solar forcing for CMIP6 (v3.2)

Solar forcing for CMIP6 (v3.2)

Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle

The response of mesospheric NO to geomagnetic forcing in 2002–2012 as seen by SCIAMACHY

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The 27 day solar rotational effect on mesospheric nighttime OH and O3 observations induced by geomagnetic activity

Cited by 20 publications

References 20 publications

Solar forcing for CMIP6 (v3.2)

Solar forcing for CMIP6 (v3.2)

Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle

The response of mesospheric NO to geomagnetic forcing in 2002–2012 as seen by SCIAMACHY

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The 27 day solar rotational effect on mesospheric nighttime OH and O₃ observations induced by geomagnetic activity