Analysis and parameterisation of ionic reactions affecting middle atmospheric HO&amp;lt;sub&amp;gt;x&amp;lt;/sub&amp;gt; and NO&amp;lt;sub&amp;gt;y&amp;lt;/sub&amp;gt; during solar proton events

Verronen, Pekka T.; Lehmann, Ralph

doi:10.5194/angeo-31-909-2013

Cited by 55 publications

(81 citation statements)

References 37 publications

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“…HO x response is seen at magnetic latitudes connected to the outer radiation belts, with, for example, the yearly amount of HO x varying with the observed magnitude of precipitation (Andersson et al, 2014b). The consideration of the effects of MEE on atmospheric species other than NO x , HO x , and ozone have not been investigated in detail to date, but they can be expected to be qualitatively similar to those caused by solar proton events (Verronen and Lehmann, 2013).…”

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

confidence: 99%

“…HO x production per ion pair as a function of altitude and ion pair production rate (IPR). Verronen and Lehmann, 2013;Nieder et al, 2014) is encouraged. Similarly, if atmospheric models include detailed cluster ion chemistry of the lower ionosphere (D region), then the ionization rates should be used to drive the production rates of the primary ions (N + 2 , N + , O + 2 , O + ) and neutrals (N, O) produced in particle impact ionization or dissociation (Sinnhuber et al, 2012).…”

Section: Appendix C: Recommendations For Geographic Projection Of Iprmentioning

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: Appendix C: Recommendations For Geographic Projection Of Iprmentioning

confidence: 99%

Solar forcing for CMIP6 (v3.2)

et al. 2017

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“…Energetic electron precipitation (EEP) from the radiation belts affects the neutral atmosphere at magnetic latitudes of about 55-72 • and results in the enhancement of HO x through water cluster ion chemistry. This process is only effective below about 80 km, where enough water vapour is available (Solomon et al, 1981;Sinnhuber et al, 2012;Verronen and Lehmann, 2013). The atmospheric penetration depth depends on the energy of the particles, e.g.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal hotspots in the mesospheric OH variations due to energetic electron precipitation

et al. 2014

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Abstract. Using Microwave Limb Sounder (MLS/Aura) and Medium Energy Proton and Electron Detector (MEPED/POES) observations between 2005-2009, we study the longitudinal response of nighttime mesospheric OH to radiation belt electron precipitation. Our analysis concentrates on geomagnetic latitudes from 55-72 • N/S and altitudes between 70 and 78 km. The aim of this study is to better assess the spatial distribution of electron forcing, which is important for more accurate modelling of its atmospheric and climate effects. In the Southern Hemisphere, OH data show a hotspot, i.e. area of higher values, at longitudes between 150 • W-30 • E, i.e. poleward of the Southern Atlantic Magnetic Anomaly (SAMA) region. In the Northern Hemisphere, energetic electron precipitation-induced OH variations are more equally distributed with longitude. This longitudinal behaviour of OH can also be identified using Empirical Orthogonal Function analysis, and is found to be similar to that of MEPED-measured electron fluxes. The main difference is in the SAMA region, where MEPED appears to measure very large electron fluxes while MLS observations show no enhancement of OH. This indicates that in the SAMA region the MEPED observations are not related to precipitating electrons, at least not at energies >100 keV, but rather to instrument contamination. Analysis of selected OH data sets for periods of different geomagnetic activity levels shows that the longitudinal OH hotspot south of the SAMA (the Antarctic Peninsula region) is partly caused by strong, regional electron forcing, although atmospheric conditions also seem to play a role. Also, a weak signature of this OH hotspot is seen during periods of generally low geomagnetic activity, which suggests that there is a steady drizzle of high-energy electrons affecting the atmosphere, due to the Earth's magnetic field being weaker in this region.

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“…Ionisation in the nighttime ionosphere is produced by scattered radiation at 304 nm, 584 nm, Ly-α and Ly-β lines (Brasseur and Salomon, 1986 (Brasseur and Salomon, 1986), initiate complex chains of ion-molecule reactions with chemically active minor neutral species (e.g. O, O 3 , NO, NO 2 , H 2 O, HO x , O 2 (1 g ), CO 2 , N 2 O 5 , HNO 3 and HCl) (Solomon et al, 1981;Verronen et al, 2008Verronen and Lehmann, 2013;Winkler et al, 2009) resulting in the formation and presence of various ion clusters and simple and complex negative ions in the D region, with number densities depending on altitude, season, local time and other factors.…”

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confidence: 99%

“…The authors thank the Education, Audiovisual and Culture Executive Agency (EACEA) for support of this work within the frame of the Erasmus Mundus Master Course in Space Science and Technology -SpaceMaster, 2009-2013 Topical Editor K. Hosokawa thanks two anonymous referees for their help in evaluating this paper.…”

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Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

2014

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Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lowerionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO + and O + 2 primary ions (i.e. NO + .H 2 O and O + 2 .H 2 O, respectively), and the channel forming H + (H 2 O) n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl + 2 proton hydrate layer upper border, comprising the NO + (H 2 O) n and O + 2 (H 2 O) n hydrated cluster ions, and the Cl + 1 hydrate cluster layer lower border, comprising the H + (H 2 O) n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, α eff , and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl + 2 and Cl + 1 , the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H 2 O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H 2 O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.

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Analysis and parameterisation of ionic reactions affecting middle atmospheric HO<sub>x</sub> and NO<sub>y</sub> during solar proton events

Cited by 55 publications

References 37 publications

Solar forcing for CMIP6 (v3.2)

Solar forcing for CMIP6 (v3.2)

Longitudinal hotspots in the mesospheric OH variations due to energetic electron precipitation

Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

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