scholarly journals On the variation of the ionospheric potential due to large‐scale radioactivity enhancement and solar activity

2015 ◽  
Vol 120 (8) ◽  
pp. 7060-7082 ◽  
Author(s):  
Nikolay N. Slyunyaev ◽  
Evgeny A. Mareev ◽  
Artem A. Zhidkov
Keyword(s):  
Solar Activity ◽  
Large Scale ◽  
Ionospheric Potential

scholarly journals Numerical Modeling of the Influence of Solar Activity on the Global Circulation in the Earth’s Mesosphere and Lower Thermosphere

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Igor Mingalev ◽  
Victor Mingalev
Keyword(s):  
Solar Activity ◽  
Large Scale ◽  
Input Parameter ◽  
Lower Thermosphere ◽  
Vertical Component ◽  
Neutral Wind ◽  
Wind System ◽  
Model Calculations ◽  
Global Circulation ◽  
Mesosphere And Lower Thermosphere

The nonhydrostatic model of the global neutral wind system of the earth’s atmosphere, developed earlier in the Polar Geophysical Institute, is utilized to investigate how solar activity affects the formation of the large-scale global circulation of the mesosphere and lower thermosphere. The peculiarity of the utilized model consists in that the internal energy equation for the neutral gas is not solved in the model calculations. Instead, the global temperature field is assumed to be a given distribution, that is, the input parameter of the model. Moreover, in the model calculations, not only the horizontal components but also the vertical component of the neutral wind velocity is obtained by means of a numerical solution of a generalized Navier-Stokes equation for compressible gas, so the hydrostatic equation is not applied. The simulation results indicate that solar activity ought to influence considerably on the formation of global neutral wind system in the mesosphere and lower thermosphere. The influence is conditioned by the vertical transport of air from the lower thermosphere to the mesosphere and stratosphere. This transport may be rather different under distinct solar activity conditions.

scholarly journals Construction of a century solar chromosphere data set for solar activity related research

2017 ◽  
Vol 3 (2) ◽  
pp. 5-8
Author(s):  
Линь Ганхуа ◽  
Lin Ganghua ◽  
Ван Сяо-Фань ◽  
Wang Xiao Fan ◽  
Ян Сяо ◽  
...  
Keyword(s):  
Data Mining ◽  
Solar Activity ◽  
Space Weather ◽  
Large Scale ◽  
Abnormal Behavior ◽  
Solar Chromosphere ◽  
Solar Cycles ◽  
Data Set ◽  
Related Research ◽  
Data Mining Algorithms

This article introduces our ongoing project “Construction of a Century Solar Chromosphere Data Set for Solar Activity Related Research”. Solar activities are the major sources of space weather that affects human lives. Some of the serious space weather consequences, for instance, include interruption of space communication and navigation, compromising the safety of astronauts and satellites, and damaging power grids. Therefore, the solar activity research has both scientific and social impacts. The major database is built up from digitized and standardized film data obtained by several observatories around the world and covers a timespan more than 100 years. After careful calibration, we will develop feature extraction and data mining tools and provide them together with the comprehensive database for the astronomical community. Our final goal is to address several physical issues: filament behavior in solar cycles, abnormal behavior of solar cycle 24, large-scale solar eruptions, and sympathetic remote brightenings. Significant progresses are expected in data mining algorithms and software development, which will benefit the scientific analysis and eventually advance our understanding of solar cycles.

About the Relation Between the Limb Effect of the Redshift on the Sun and the Large-Scale Distribution of Solar activity

1976 ◽  
Vol 71 ◽  
pp. 113-118
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Field ◽  
Large Scale ◽  
The Sun ◽  
Limb Effect

The measurement of the magnitude of the limb effect was homogenized in time and a recurrent period of maxima of 27.8 days was found. A relation was found between the maximum values of the limb effect of the redshift, the boundaries of polarities of the interplanetary magnetic field, the characteristic large-scale distribution of the background magnetic fields and the complex of solar activity.

Large Scale TIDs climatology over Europe using HF Interferometry method

2020 ◽  
Author(s):  
Estefania Blanch ◽  
Antoni Segarra ◽  
David Altadill ◽  
Vadym Paznukhov ◽  
Jose Miguel Juan
Keyword(s):  
Solar Activity ◽  
Propagation Velocity ◽  
Large Scale ◽  
Large Data ◽  
Density Fluctuations ◽  
Night Time ◽  
Wide Range ◽  
Propagation Parameters ◽  
The Difference ◽  
Sporadic E

<p>Travelling Ionospheric Disturbances (TIDs) are ionospheric irregularities that occur as plasma density fluctuations that propagate as waves through the ionosphere over a wide range of velocities and frequencies. It has been demonstrated that Large Scale TIDs (LSTID) can be detected with several ionospheric sensors such as ionosondes and their main characteristics such as velocity, direction of propagation and amplitude can be inferred.</p><p>We have applied the recent developed HF Interferometry (HF-Int) method to detect the occurrence and main characteristics of LSTIDs over Europe for different solar activities (2014 – 2019) in order to perform a climatological analysis. HF-Int determines the dominant period of oscillation and the amplitude of the LSTIDs using spectral analysis, and estimates the propagation parameters of the LSTIDs from the measured time delays of the disturbance detected at different sensor sites.</p><p>The results show that larger diurnal and seasonal occurrence of LSTID happens near sunrise hours and night-time, especially during equinox. In the morning sector, prevailing velocity propagation is westward influenced by the solar terminator effect and it also depends on the season: during winter the dominant propagation velocity is north-westward and during summer is south-westward. In the evening and night sector, the prevailing propagation velocity is southward suggesting auroral origin of the disturbance. The higher activity at night-time might be the result that neutral winds favour equatorward propagation at night whereas at day might prevent to propagate to low latitudes.</p><p>Similar behaviour has been found for high and low solar activity with the difference that during summer at low solar activity, large occurrence of sporadic E layer happens during day time. Then, ionospheric data experience large data gaps at the F region because of screening of the Es (Es Blanketing effect). This results in a poor statistic under such a conditions for daytime summer low solar activity and the number of detected LSTID is lower.</p>

Optical observations of large-scale undulations in the 23rd cycle of solar activity

2012 ◽  
Vol 52 (2) ◽  
pp. 197-203 ◽  
Author(s):  
D. G. Baishev ◽  
E. S. Barkova ◽  
K. Yumoto
Keyword(s):  
Solar Activity ◽  
Large Scale ◽  
Optical Observations ◽  
23Rd Cycle

scholarly journals Patterns of extreme weather associated with observed and proxy River Ammer flood records

2017 ◽  
Author(s):  
Norel Rimbu ◽  
Monica Ionita ◽  
Markus Czymzik ◽  
Achim Brauer ◽  
Gerrit Lohmann
Keyword(s):  
Solar Activity ◽  
Radiative Forcing ◽  
Large Scale ◽  
Western Europe ◽  
Extreme Temperature ◽  
Heavy Precipitation ◽  
Flood Frequency ◽  
Discharge Data ◽  
Blocking High ◽  
Northeastern Europe

Abstract. We investigate the relationship between the variability in the frequency of River Ammer floods (southern Germany) and temperature/precipitation extremes over Europe using observational River Ammer discharge data back to 1926 and the 5500-year-long flood layer record from varved Lake Ammersee sediments. We show that observed River Ammer flood frequency variability is not only related with local extreme precipitation, but also with large-scale temperature extreme anomalies. Less (more) extreme high temperatures over central and western (northeastern) Europe are recorded during periods of increased River Ammer flood frequency. We argue that changing radiative forcing due to cloudiness anomaly patterns associated with River Ammer floods induce these extreme temperature anomalies. Consistent patterns are obtained using observed discharge and proxy flood layer frequency data. Furthermore, a higher frequency of observed River Ammer floods and flood layers is associated with enhanced blocking activity over northeastern Europe. A blocking high over this region increases the probability of wave breaking and associated heavy precipitation over western Europe. A similar blocking pattern is associated with periods of reduced solar activity. Consequently, solar modulated changes in blocking frequency over northeastern Europe could explain the connection between River Ammer floods and solar activity, as also identified in previous studies. We argue that multi-decadal to millennial flood frequency variations in the Mid- to Late Holocene flood layer record from Lake Ammersee characterizes also the extreme temperatures in northeastern Europe.

scholarly journals Is Diminishing Solar Activity Detrimental to Canadian Prairie Agriculture?

2020 ◽  
Vol 3 (3) ◽  
Keyword(s):  
Solar Activity ◽  
Large Scale ◽  
Time Frame ◽  
Precipitation Pattern ◽  
Canadian Prairie ◽  
Canadian Prairies ◽  
Temperature And Precipitation ◽  
Mean Temperature ◽  
Grain Yield And Quality ◽  
The Impact

During the grain growing months of May-July, the mean temperature on the Canadian prairies has cooled down by 2ºC in the last 30 years. The cooling appears to be most certainly linked to diminishing solar activity as the Sun approaches a Grand Solar Minimum in the next decade or so. This cooling has led to a reduction in Growing Degree Days (GDDs) and has also impacted the precipitation pattern. The GDDs in conjunction with mean temperature and precipitation are important parameters for the growth of various grains (wheat, barley, canola etc.) on the prairies. In this study, we investigate the impact of declining GDDs and associated temperature and precipitation patterns on Prairie grain yields and quality. Our analysis shows that there has been a loss of about 100 GDDs over the time frame of 1985-2019. The loss in GDDs is also linked to some of the large-scale Atmosphere-Ocean parameters like the Pacific Decadal Oscillation (PDO), North Pacific Index (NPI) and Arctic Oscillation (AO). Our analysis suggests grain yield and quality could be significantly impacted in the coming years as solar activity continues to diminish.

Investigation of the coronal heating through phase relation of solar activity indexes

2020 ◽  
Vol 37 ◽  
Author(s):  
K. J. Li ◽  
J. C. Xu ◽  
Z. Q. Yin ◽  
J. L. Xie ◽  
W. Feng
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Phase Relation ◽  
Large Scale ◽  
Solar Rotation ◽  
Rotation Period ◽  
Magnetic Activity ◽  
Coronal Heating ◽  
Small Scale

Abstract The coronal heating problem is a long-standing perplexing issue. In this study, 13 solar activity indexes are used to investigate their phase relation with the sunspot number (SSN). Only three of them are found to statistically significantly lag the SSN (large-scale magnetic activity) by about one solar rotation period; the three indexes are total solar irradiance (TSI), the modified coronal index, and the solar wind velocity; the former two indexes may represent the long-term variation of energy quantity of the heated photosphere and corona, respectively. The Mount Wilson Sunspot Index (MWSI) and the Magnetic Plage Strength Index (MPSI), which reflect the large- and small-scale magnetic field activities, respectively, are also utilised to investigate their phase relations with the three indexes. The three indexes are found to be much more intimately related to MPSI than to MWSI, and MWSI statistically significantly leads TSI by about one rotation period. The heated corona is found to pulse perfectly in step with the small-scale magnetic activity rather than the large-scale magnetic activity; furthermore, combined with observations, our statistical evidence should thus attribute coronal heating firmly to small-scale magnetic activity phenomena, such as spicules, micro-flares, nano-flares, and others. The photosphere and the corona are synchronously heated, which should seemingly prefer magnetic reconnection heating to wave heating. In the long term, such a coronal heating way is inferred effective. Statistically, it is also small-scale magnetic activity phenomena that produce TSI enhancement. Coronal heating and solar wind acceleration are found to be synchronous, as standard models require.

scholarly journals Large-scale velocity fluctuations in polar solar wind

2005 ◽  
Vol 23 (3) ◽  
pp. 1025-1031 ◽  
Author(s):  
B. Bavassano ◽  
R. Bruno ◽  
R. D'Amicis
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
High Latitude ◽  
Large Scale ◽  
Activity Cycle ◽  
High Solar Activity ◽  
Time Lags ◽  
Polar Wind ◽  
Frequency Distributions ◽  
Long Range Correlations

Abstract. The 3-D structure of the solar wind varies dramatically along the Sun's activity cycle. In the present paper we focus on some properties of the polar solar wind. This is a fast, teneous, and steady flow (as compared to low-latitude conditions) that fills the high-latitude heliosphere at low solar activity. The polar wind has been extensively investigated by Ulysses, the first spacecraft to perform in-situ measurements in the high-latitude heliosphere. Though the polar wind is quite a uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize the solar wind structure is that of performing a multi-scale statistical analysis of the wind velocity differences. The occurrence frequency distributions of velocity differences at time lags from 1 to 1024h and the corresponding values of mean, standard deviation, skewness, and kurtosis have been obtained. A comparison with previous results in ecliptic wind at both low and high solar activity has been performed. It comes out that the kind of trend observed in the distributions for changing scale is the same for the different solar wind regimes. Differences between different flows just have an effect on the values of the distribution moments and the scales at which the transition from non-Gaussian to Gaussian-like behaviours occurs. This is typical of systems in which random fluctuations are mixed to coherent structures of some characteristic size, in other words, systems where long-range correlations cannot be neglected.

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