scholarly journals Solar activity effects in the ionospheric D region

1998 ◽  
Vol 16 (12) ◽  
pp. 1527-1533 ◽  
Author(s):  
A. D. Danilov
Keyword(s):  
Solar Activity ◽  
Middle Atmosphere ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Atmospheric Composition ◽  
Ion Chemistry ◽  
Theoretical Concepts ◽  
Rotation Method ◽  
Composition And Structure ◽  
D Region

Abstract. Variations in the D-region electron concentration within the solar activity cycle are considered. It is demonstrated that conclusions of various authors, who have analyzed various sets of experimental data on [e], differ significantly. The most reliable seem to be the conclusions based on analysis of the [e] measurements carried out by the Faraday rotation method and on the theoretical concepts on the D-region photochemistry. Possible QBO effects in the relation of [e] to solar activity are considered and an assumption is made that such effects may be the reason for the aforementioned disagreement in conclusions on the [e] relation to solar indices.Key words. Atmospheric composition and structure · Ion chemistry of the atmosphere · Middle atmosphere

scholarly journals Modelling the effects of the October 1989 solar proton event on mesospheric odd nitrogen using a detailed ion and neutral chemistry model

2002 ◽  
Vol 20 (12) ◽  
pp. 1967-1976 ◽  
Author(s):  
P. T. Verronen ◽  
E. Turunen ◽  
Th. Ulich ◽  
E. Kyrölä
Keyword(s):  
Chemical Reactions ◽  
Middle Atmosphere ◽  
Solar Proton ◽  
Solar Proton Event ◽  
Atmospheric Composition ◽  
Proton Event ◽  
Chemical Production ◽  
Ion Chemistry ◽  
Composition And Structure ◽  
Odd Nitrogen

Abstract. Solar proton events and electron precipitation affect the concentrations of middle atmospheric constituents. Ionization caused by precipitating particles enhances the production of important minor neutral constituents, such as nitric oxide, through reaction chains in which ionic reactions play an important role. The Sodankylä Ion Chemistry model (SIC) has been modified and extended into a detailed ion and neutral chemistry model of the mesosphere. Our steady-state model (containing 55 ion species, 8 neutral species, and several hundred chemical reactions) is used to investigate the effect of the October 1989 solar proton event on odd nitrogen at altitudes between 50–90 km. The modelling results show that the NO concentration is significantly enhanced due to the proton precipitation, reaching 107 –108 cm-3 throughout the mesosphere on the 20 October when the proton forcing was most severe. A comparison between the chemical production channels of odd nitrogen indicates that ion chemical reactions are an important factor in the total odd nitrogen production during intense ionization. The modelled electron concentration for the 23 October is compared with EISCAT incoherent scatter radar measurements and a reasonable agreement is found.Key words. Atmospheric composition and structure (Middle atmosphere – composition and chemistry); Ionosphere (Particle precipitation)

Trends in Parameters of the F2 Layer and the 24th Solar-Activity Cycle

2020 ◽  
Vol 60 (5) ◽  
pp. 586-596 ◽  
Author(s):  
A. D. Danilov ◽  
A. V. Konstantinova
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Activity Cycle

scholarly journals On the Prediction of Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
V. Courtillot ◽  
F. Lopes ◽  
J. L. Le Mouël
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Transfer Function ◽  
Singular Spectrum Analysis ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Planetary Motion ◽  
Data Sets ◽  
Solar Cycles ◽  
Jovian Planets

AbstractThis article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate, 193, 1979). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

scholarly journals Rarefied gas flows through meshes and implications for atmospheric measurements

2001 ◽  
Vol 19 (5) ◽  
pp. 563-569 ◽  
Author(s):  
J. Gumbel
Keyword(s):  
Middle Atmosphere ◽  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Atmospheric Composition ◽  
Gas Flows ◽  
Atmospheric Measurements ◽  
Rarefied Gas Flows ◽  
Flow Disturbances ◽  
Composition And Structure ◽  
Compression Effects

Abstract. Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flow, substantial compression effects are found both upstream and downstream of the mesh. Meshes attached to close instrument structures, on the other hand, cause only minor flow disturbances. In an accompanying paper, the approach developed here is applied to the quantitative analysis of rocket-borne density measurements in the middle atmosphere.Key words. Atmospheric composition and structure (instruments and techniques; middle atmosphere – composition and chemistry)

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