On the inclusion of data from solar cycle 19 to estimate F2 layer characteristic long term trends

<p>The effect of including solar cycle 19 (1954-1964) in ionospheric trend estimation is assessed using experimental foF2 values. The dominant influence on the F2 layer is solar EUV radiation. In fact, around 90% of inter-annual variance of ionospheric parameters, such as foF2, is explained by solar EUV proxies such as the sunspot number, Rz, and solar radio flux at 10.7 cm, F10.7. This makes necessary to filter out solar activity effects prior to long term trends estimation, which is reduced at most to the remaining 10% variance. In general solar activity is filtered assessing the residuals of a linear regression between foF2 and Rz, or between foF2 and F10.7. Solar cycle 19 is a strong cycle during which Rz and F10.7 exceeded the values beyond which the ionosphere does not respond linearly to a further increase in EUV radiation. This effect, called saturation, implies a break down of the linearity between foF2 and EUV, and results in persistent negative residuals during this period. Since solar cycle 19 is at the beginning of the time series, trends result to be positive, or less negative, than trends without considering this period. In this case the filtering process is generating a “spurious” trend in the filtered data series which may lead to erroneous conclusions. hmF2 that do not present a saturation effect is also analyzed.</p><div> </div>

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Long-term dynamics of OH * temperatures over central Europe: trends and solar correlations

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-15033-2016 ◽

2016 ◽

Vol 16 (23) ◽

pp. 15033-15047 ◽

Cited By ~ 16

Author(s):

Christoph Kalicinsky ◽

Peter Knieling ◽

Ralf Koppmann ◽

Dirk Offermann ◽

Wolfgang Steinbrecht ◽

...

Keyword(s):

Time Series ◽

Solar Activity ◽

Solar Radio ◽

Linear Trend ◽

Temperature Time Series ◽

Time Interval ◽

Radio Flux ◽

Solar Radio Flux ◽

Temperature Time

Abstract. We present the analysis of annual average OH* temperatures in the mesopause region derived from measurements of the Ground-based Infrared P-branch Spectrometer (GRIPS) at Wuppertal (51° N, 7° E) in the time interval 1988 to 2015. The new study uses a temperature time series which is 7 years longer than that used for the latest analysis regarding the long-term dynamics. This additional observation time leads to a change in characterisation of the observed long-term dynamics. We perform a multiple linear regression using the solar radio flux F10.7 cm (11-year cycle of solar activity) and time to describe the temperature evolution. The analysis leads to a linear trend of (−0.089 ± 0.055) K year−1 and a sensitivity to the solar activity of (4.2 ± 0.9) K (100 SFU)−1 (r2 of fit 0.6). However, one linear trend in combination with the 11-year solar cycle is not sufficient to explain all observed long-term dynamics. In fact, we find a clear trend break in the temperature time series in the middle of 2008. Before this break point there is an explicit negative linear trend of (−0.24 ± 0.07) K year−1, and after 2008 the linear trend turns positive with a value of (0.64 ± 0.33) K year−1. This apparent trend break can also be described using a long periodic oscillation. One possibility is to use the 22-year solar cycle that describes the reversal of the solar magnetic field (Hale cycle). A multiple linear regression using the solar radio flux and the solar polar magnetic field as parameters leads to the regression coefficients Csolar = (5.0 ± 0.7) K (100 SFU)−1 and Chale = (1.8 ±  0.5) K (100 µT)−1 (r2 = 0.71). The second way of describing the OH* temperature time series is to use the solar radio flux and an oscillation. A least-square fit leads to a sensitivity to the solar activity of (4.1 ± 0.8) K (100 SFU)−1, a period P  =  (24.8 ± 3.3) years, and an amplitude Csin  =  (1.95 ± 0.44) K of the oscillation (r2 = 0.78). The most important finding here is that using this description an additional linear trend is no longer needed. Moreover, with the knowledge of this 25-year oscillation the linear trends derived in this and in a former study of the Wuppertal data series can be reproduced by just fitting a line to the corresponding part (time interval) of the oscillation. This actually means that, depending on the analysed time interval, completely different linear trends with respect to magnitude and sign can be observed. This fact is of essential importance for any comparison between different observations and model simulations.

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Long-term trends in the ionospheric F2 region with different solar activity indices

Annales Geophysicae ◽

10.5194/angeo-31-291-2013 ◽

2013 ◽

Vol 31 (2) ◽

pp. 291-303 ◽

Cited By ~ 38

Author(s):

J. Mielich ◽

J. Bremer

Keyword(s):

Solar Activity ◽

Geomagnetic Activity ◽

Data Series ◽

Radio Flux ◽

Model Calculations ◽

Long Term Trends ◽

Global Mean ◽

Good Agreement ◽

Activity Indices

Abstract. A new comprehensive data collection by Damboldt and Suessmann (2012a) with monthly foF2 and M(3000)F2 median values is an excellent basis for the derivation of long-term trends in the ionospheric F2 region. Ionospheric trends have been derived only for stations with data series of at least 22 years (124 stations with foF2 data and 113 stations with M(3000)F2 data) using a twofold regression analysis depending on solar and geomagnetic activity. Three main results have been derived: Firstly, it could be shown that the solar 10.7 cm radio flux F10.7 is a better index for the description of the solar activity than the relative solar sunspot number R as well as the solar EUV proxy E10.7. Secondly, the global mean foF2 and hmF2 trends derived for the interval between 1948 and 2006 are in surprisingly good agreement with model calculations of an increasing atmospheric greenhouse effect (Rishbeth and Roble, 1992). Thirdly, during the years 2007 until 2009, the hmF2 values and to a smaller amount the foF2 values strongly decrease. The reason for this effect is a reduction of the thermospheric density and ionization due to a markedly reduced solar EUV irradiation and extremely small geomagnetic activity during the solar cycle 23/24 minimum.

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Galactic Cosmic Ray Modulation Up to Recent Solar Cycles

Latvian Journal of Physics and Technical Sciences ◽

10.2478/v10047-011-0029-2 ◽

2011 ◽

Vol 48 (4) ◽

pp. 66-70

Author(s):

R. Agarwal ◽

R. Mishra

Keyword(s):

Solar Cycle ◽

Solar Radio ◽

Cosmic Ray ◽

Radio Flux ◽

Solar Cycles ◽

Cosmic Ray Intensity ◽

Cosmic Ray Modulation ◽

Solar Radio Flux ◽

Yearly Average ◽

Galactic Cosmic Ray

Galactic Cosmic Ray Modulation Up to Recent Solar Cycles Cosmic ray neutron monitor counts obtained by different ground-based detectors have been used to study the galactic cosmic ray modulation during the last four solar activity cycles. Since long, systematic correlative studies have been per-formed to establish a significant relationship between the cosmic ray intensity and different helio-spheric activity parameters, and the study is extended to a recent solar cycle (23). In the present work, the yearly average of 10.7 cm solar radio flux and the interplanetary magnetic field strength (IMF, B) have been used to find correlation of the yearly average cosmic ray intensity derived from different neutron monitors. It is found that for four solar cycles (20-23) the cosmic ray intensity is anti-correlated with the 10.7 cm solar radio flux and the IMF, B value with some discrepancy. However, this is in a good positive correlation with the flux of mentioned wavelength for four different solar cycles. The IMF, B shows a weak correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23.

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Stability of solar correction for calculating ionospheric trends

Annales Geophysicae ◽

10.5194/angeo-34-1191-2016 ◽

2016 ◽

Vol 34 (12) ◽

pp. 1191-1196 ◽

Cited By ~ 11

Author(s):

Jan Laštovička ◽

Dalia Burešová ◽

Daniel Kouba ◽

Peter Križan

Keyword(s):

Solar Activity ◽

Solar Cycle ◽

Global Climate ◽

Standard Technique ◽

Model Data ◽

Data Set ◽

Long Term Trends ◽

Cycle 24 ◽

Activity Dependence

Abstract. Global climate change affects the whole atmosphere, including the thermosphere and ionosphere. Calculations of long-term trends in the ionosphere are critically dependent on solar activity (solar cycle) correction of ionospheric input data. The standard technique is to establish an experimental model via calculating the dependence of ionospheric parameter on solar activity from the whole analysed data set, subtract these model data from observed data and analyse the trend of residuals. However, if the solar activity dependence changes with time, the solar correction calculated from the whole data set may result in miscalculating the ionospheric trends. To test this, data from two European ionospheric stations – Juliusruh and Slough/Chilton – which provide long-term reliable data, have been used for the period 1975–2014. The main result of this study is the finding that the solar activity correction used in calculating ionospheric long-term trends need not be stable, as was assumed in all previous investigations of ionospheric trends. During the previous solar cycle 23 and the current solar cycle 24, the solar activity correction appears to be different from that for the previous period and the Sun seems to behave in a different way than throughout the whole previous era of ionospheric measurements. In future ionospheric trend investigations the non-stability of solar activity correction has to be very seriously taken into account, because it can substantially affect calculated long-term trends of ionospheric parameters.

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PROBLEMS OF ANALYSIS AND FORECAST OF CHARACTERISTICS OF THE FIRST PHASE 25 CYCLE OF SOLAR ACTIVITY, DETERMINING STATES OF BIOSPHERE SYSTEMS

News of the Tula state university. Sciences of Earth ◽

10.46689/2218-5194-2021-4-1-45-58 ◽

2021 ◽

Vol 4 (1) ◽

pp. 45-58

Author(s):

A.V. Volkov ◽

◽

A.A. Khadartsev ◽

Keyword(s):

Economic Development ◽

Solar Activity ◽

Flux Density ◽

Solar Radio ◽

Radio Flux ◽

Solar Radio Flux ◽

Socio Economic Development

The paper considers the results of the analysis and prediction of the dynamics of so-lar activity from the series of the solar radio flux density at a frequency of 2.8 GHz and the relative Wolf numbers, proposed by the leading analytical groups, as well as by the authors of this publication. The typological characteristics of the upcoming situations of socio-economic development of Russia are indicated.

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Response of the mesopause airglow to solar activity inferred from measurements at Zvenigorod, Russia

Annales Geophysicae ◽

10.5194/angeo-26-1049-2008 ◽

2008 ◽

Vol 26 (5) ◽

pp. 1049-1056 ◽

Cited By ~ 30

Author(s):

N. Pertsev ◽

V. Perminov

Keyword(s):

Solar Activity ◽

Solar Radio ◽

Measured Data ◽

Atmospheric Dynamics ◽

Radio Flux ◽

Mesopause Region ◽

Radiative Processes ◽

Solar Radio Flux ◽

Flux Change ◽

Solar Influence

Abstract. Ground-based spectrographical observations of infrared emissions of the mesopause region have been made at Zvenigorod Observatory (56 N, 37 E), located near Moscow, Russia, for 670 nights of 2000–2006. The characteristics of the hydroxyl and molecular oxygen (865 nm) airglow, heights of which correspond to 87 and 94 km, are analyzed for finding their response to solar activity. The measured data exhibit a response to the F10.7 solar radio flux change, which is 30%–40%/100 sfu in intensities of the emissions and about 4.5 K/100 sfu in hydroxyl temperature. Seasonal variations of the airglow response to solar activity are observed. In winter it is more significant than in summer. Mechanisms that may provide an explanation of the solar influence on intensities of the emissions and temperature are considered. Radiative processes not involving atmospheric dynamics appear insufficient to explain the observed effect.

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Solar activity forcing of the middle atmosphere

Annales Geophysicae ◽

10.1007/s00585-995-0879-0 ◽

1995 ◽

Vol 13 (8) ◽

pp. 879-885 ◽

Cited By ~ 11

Author(s):

K. Mohanakumar

Keyword(s):

Solar Activity ◽

Solar Radio ◽

Middle Atmosphere ◽

Strong Association ◽

Positive Association ◽

High Solar Activity ◽

Radio Flux ◽

Activity Increase ◽

Mean Values ◽

Solar Radio Flux

Abstract. Studies on the influence of solar activity in 11-year cycle on middle atmospheric thermodynamic parameters, such as temperature, pressure and density, and zonal and meridional wind components over three meteorological rocket launching stations, located in the tropics (Thumba), mid-latitude (Volgograd) and high-latitude (Heiss Island) regions of the northern hemisphere have been carried out. The temperature in all the three regions showed a negative response in the stratosphere and positive association in the mesosphere with the changes in solar activity. The temperature decreases by 2–3% from its mean value in the stratosphere and increases by 4–6% in the mesosphere for an increase in 100 units of solar radio flux. Atmospheric pressure is found to be more sensitive to solar changes. An average solar maximum condition enhances the pressure in the stratosphere by 5% and in the upper mesosphere by 16–18% compared to the respective mean values. Density also showed strong association with the changes in solar activity. Increase in the solar radio flux tends to strengthen winter westerlies in the upper stratosphere over the mid-latitude and summer easterlies in the middle stratosphere over tropics. Larger variability in the zonal wind is noted near stratopause height. Results obtained from the study indicate that there is an external force exerted on the Earth's atmosphere during the period of high solar activity. These results can be incorporated for further studies on the dynamics of the middle atmosphere in association with the changes in solar activity.

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A Study of Long-Term Solar Activity at 37 GHz

Open Astronomy ◽

10.1515/astro-2017-0384 ◽

2012 ◽

Vol 21 (3) ◽

Cited By ~ 3

Author(s):

J. Kallunki ◽

N. Lavonen ◽

E. Järvelä ◽

M. Uunila

Keyword(s):

Solar Activity ◽

Solar Radio ◽

Data Series ◽

Public Knowledge ◽

Solar Cycles ◽

Data Set ◽

Radio Observatory ◽

The Public ◽

Radio Map

AbstractIn this paper we investigate the solar activity at the radio frequency (37 GHz) using an extensive data series (solar radio maps) from the Metsähovi Radio Observatory. This paper aims to present this unique solar radio map collection to the public knowledge. The data set covers the years from 1978 to 2011 (solar cycles 21–24). We investigate the long-term solar activity on the ground of the distribution of solar radio brightenings and the differential rotation of the Sun.

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Notes on the correlation between sudden stratospheric warmings and solar activity

Annales Geophysicae ◽

10.5194/angeo-37-375-2019 ◽

2019 ◽

Vol 37 (3) ◽

pp. 375-380

Author(s):

Ekaterina Vorobeva

Keyword(s):

Solar Activity ◽

Correlation Coefficient ◽

Solar Radio ◽

Correlation Coefficients ◽

Occurrence Rate ◽

Radio Flux ◽

Lyman Alpha ◽

Sunspot Numbers ◽

Solar Radio Flux ◽

Analogous Method

Abstract. A correlation between solar activity and normalized occurrence rate of sudden stratospheric warmings (SSWs) has been found. As a proxy for solar activity, the 10.7 cm solar radio flux has been used. In order to find the correlation, we derived a normalized occurrence rate of major sudden stratospheric warmings (MSSWs) based on both the ERA-40/ERA-Interim dataset and NCEP data. Based on this distribution, we calculated the correlation coefficient, which amounts to 0.63, with a significance of 90.68 %, for ERA-40/ERA-Interim, and 0.55 for the NCEP–NCAR-I reanalysis, with a significance of 83.80 %. Additionally, we calculate correlation coefficients for Lyman-alpha flux and sunspot numbers with the analogous method for the same period.

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