Sunspot Number Research Articles

Temporal and spatial variability of EUV flux at 094 Å and its relationship with sunspot activity

We study temporal and spatial variability of coronal EUV flux/emission/intensity at 094 Å and investigate latitudinal profiles of the EUV flux from centre to poles of solar disc based on daily image obtained from the SDO/AIA for the period from 10 February 2011 to 20 November 2021. Solar coronal activities (regions of high EUV flux) patterns of latitudinal EUV flux, latitudinal north-south asymmetry of EUV flux and relationship between EUV flux and sunspot numbers are discussed. The disc-integrated normalized EUV flux is found positive correlated with SDO/EVE normalised solar irradiance. It is shown that there are two kinds of migration of solar coronal activities in distribution of EUV flux at 094 Å during the rising phase of solar cycle 24: one towards the equator and another towards the poles in both hemispheres. The peaks of EUV flux occur in the region −25∘ to +25∘ solar latitudes in the years 2011 and 2014. The latitudinal EUV flux in northern and southern hemispheres have asymmetrical behaviour. The dominancy of EUV flux in northern hemisphere is found only at 5∘, 15∘, and 75∘ solar latitudes whereas the dominancy of EUV flux in southern hemisphere is found at the rest of the solar latitudes. We found that the dominancy of EUV flux in both the hemispheres is a function of time and solar latitude. The EUV flux is dominated in the southern hemisphere during the entire period. The EUV flux is positive correlated with sunspot numbers for full disc, northern and southern hemispheres and their relationship is found linear and significant.

Variability of River Runoff in Poland and Its Connection to Solar Variability

The aim of this research was to determine relationships between solar activity and variability of discharges of three Central European rivers: the Vistula, Odra and Warta in Poland in the multi-annual period of 1901–2020. Changes in precipitation and air temperature at Poznań meteorological station in the same period were also analyzed. The long-term variations in river runoff were investigated both from the point of view of temporal variability in relation to climate variations in the study area, and from the point of view of linear/non-linear links to solar activity, as described by the Wolf sunspot number. The wavelet transform analysis was used to highlight the frequency-time distribution of the coherences between solar and discharge variability. It was found that most of the links between solar activity and discharges were non-linear.

Ақсу-Жабағылы қорығындағы қасқырдың (Canis lupus Linnaeus, 1758) өсуі мен таралуы

The article is devoted to the reproduction and distribution of the wolf (Canis lupus Linnaeus, 1758) on the territory of the reserve since the establishment of the Aksu-Zhabagly State Nature Reserve until 2022. The article analyzes the data of the works and reports of scientists stored in the archive of the reserve, diaries of periodic observation of inspectors, and data from the book "Chronicles of Nature", for the last 2019-2022, control work was carried out on the number of wolves in the reserve and adjacent territories, as well as seasonal accounting and analysis of the dynamics of the number of wolves. Basically, this predator is found in the gorges of Large and Small Kayynda, with mountain valleys on the northern slope of Mount Zhabagly, in the valleys of the rivers Iirsu, Aksu, Balabaldyberek and Baldyberek. The wolf in most cases lives in groups, that is, in herds. Previously, wolves were found in 3-4 individuals, but in modern conditions they are found in about 10 individuals.

Іле өзенінің жайылмасында кездесетін жыртқыш аңдардың (Carnivora: Canidae, Mustelidae) сапалық құрамы мен орналасу ерекшеліктері

The article presents for the first time new data on habitats, shelters and the dynamics of the number of 6 species of predators found in the floodplain of the Ile River and adjacent territories in the spring and summer months (during the breeding season) in 2007-2019, 2022. The research was carried out using classical methods of theriological science. These predators can be divided into 2 groups: 1-sedentary and 2-nomads. The first group includes 3 species (jackal, fox, badger), and the second group includes 3 species (wolf, dressing, weasel). The share of predators in the use of biotopes is different: 3 species in floodplains of rivers (jackal, fox, badger), 1 species among reeds on islands (jackal), 3 species in fortified hilly sands (wolf, fox, bandaging), one species in open steppes of rare vegetation (weasel), 4 species in rocky-rocky places (wolf, fox, badger, weasel) and in localities there are 2 species (jackal, weasel). By the nature of the use of shelters, predators are divided into lairs, burrows and "freeloaders" (occupying other people's burrows). Lairs include one species (wolf), burrowers 3 species (jackal, fox, badger), 2 species (dressing, weasel) occupy other people's burrows. The number of predators fluctuated between 2017 and 2019 under the influence of various factors (food supply, excessive anxiety, poaching). During these years, on a 10-kilometer route (only 90 km), the average number of wolves was 0.33 individuals, jackals – 5.3, foxes-3.7, badgers-2, bandages -0.67 and weasels -1.0 individuals.

Study of long-term cosmic ray intensity variation with sunspot numbers, solar flare index, interplanetary magnetic fields and Alfven Mach number during solar cycle 24

Study of long-term cosmic ray intensity variation with sunspot numbers, solar flare index, interplanetary magnetic fields and Alfven Mach number during solar cycle 24

Automatic detection of sunspots on solar continuum HMI images blending local–global threshold

A huge collection of solar images to visualize sunspot are acquired by various solar observatories spread across the globe. This necessitates efficient tools for detecting and analyzing the sunspots encompassing diverse solar features. One such contribution is delivered in this work by exploiting the intrinsic intensity variations of solar images associated with sunspots and their attributes. The presented mechanism initially, pre-processes the acquired solar images by correcting the intensity variations introduced while profiling from the sun center to the limb followed by smoothening using a localized window. The resultant is then differenced from the global threshold that is obtained as a result of the statistical analysis computed over the probability distribution function of the input image. This arrangement offers higher discerning variations concerned with the local contextual structures related to sunspot, umbra, and penumbra. Also, it captures the major gradient variation between these regions that adds to the pixel heterogeneity surrounding them to finally render an automatic sunspot detection mechanism distinguishing the diverse solar regions. Receiver Operating Characteristics (ROC) investigation on annual solar images in Flexible Image Transport System (FITS) format reveals the presented method’s efficacy. Also, Pearson correlation analysis of the evaluated sunspot numbers from the detected sunspots with the solar catalog reveals the scheme’s detection closeness. Moreover, the model’s simplicity analyzed along the time and space dimensions affirms its extension to real-time analysis

Possible connection between solar activity and local seismicity

Recently, much attention has been paid to the relationship between solar and seismic activities toward earthquake (EQ) prediction. Some researchers believe in the existence of a connection between them; however, others completely refuse the existence of such a connection. In this study, the correlation between solar disturbances and occurrence of EQs during two consecutive solar cycles (SCs) 23 & 24 from 1996 to 2019 was investigated to explore such a relationship. The study was performed on both global and local scales. On a global scale, we studied the temporal variations of EQs number and the corresponding solar activity, represented by sunspot number. On the other hand, we selected several seismic zones characterized with high seismic activities and shallow depth EQs. For each zone we examined the day-to-day variations in the number of EQs and explored the space weather “chain of action” from the Sun to Earth in order to examine whether these events have an influence to increase the number of EQs or not. Results showed that, for the whole global seismicity, no clear correlation is found between EQs occurrence and solar activity, while for small active seismic zones, the connection between them is significant. An increase in the number of shallow EQs in the studied seismic zones is observed in association with the variations of examined space weather indices. Thus, the current study suggests a possible connection between solar activity and localized seismic activities. However, the solar-magnetosphere-lithosphere coupling and interaction during solar events need further study and investigation for a better understanding of their EQ triggering effects.

Correlative study of partial and halo CMEs with sunspots number during the solar cycle 24

Correlative study of partial and halo CMEs with sunspots number during the solar cycle 24

Предсказание временных рядов солнечной активности с помощью искусственной нейронной сети LSTM

A numerical model for predicting the parameters of solar activity — the number of sunspots R and the radioflux at a wave of 10.7 cm F10.7 ahead for 27 days — has been built. The numerical model uses an artificial neural network (NN) with LSTM (Long short-term memory) layers. For both the number of sunspots and the radioflux, the model predicts the levels and limits of variation of the values for 27 days. The average absolute prediction error of the model is less than 6 %. The real-time model is implemented on the site http://aurora.pgia.ru and can be an addition to long-term forecasts of other INTERNET resources.

Linking the solar cycle and Earth’s climate

In this paper, the authors have made an effort to investigate the impact of the solar cycle on Earth’s climate in the context of rainfall and temperature over a location, on El Nino/ La Nina, and world famines. The study shows that the peak sunspot number (SSN) often occurs in pairs. Multiple peaks are also seen frequently. The La Ninas follow multiple peaks, or sometimes associated with it. The El Ninos usually follow the solar minima, though not always. This study shows that the SSN trough will occur in 2020, thereby causing El Nino during 2019-2021. The multiple SSN peak is likely to occur during 2023-2028, predicting a La-Nina during this period. Multiple SSN peaks and very high SSN values bring about famines. The study shows that the total solar irradiance (TSI) bears a strong correlation with the SSN. Besides, the cosmic ray flux decreases as the SSN and the TSI increases. The monthly and yearly variations of SSN, TSI, and temperature show increasing trends over the years, indicating increased warming as the years advance. However, none of these parameters bears significant correlations with the temperature, either independently or together, implying that some other factors are also responsible for determining the temperature. The study shows no direct relationship between rainfall and the SSN. However, several years show a similar trend between the two. The investigation indicates a strong influence of the solar cycle on world climate.

What Do Halo CMEs Tell Us about Solar Cycle 25?

It is known that the weak state of the heliosphere due to diminished solar activity in cycle 24 backreacted on coronal mass ejections (CMEs) to make them appear wider for a given speed. One of the consequences of the weak state of the heliosphere is that more CMEs appear as halo CMEs (HCMEs), and halos are formed at shorter heliocentric distances. Current predictions for the strength of solar cycle (SC) 25 range from half to twice the strength of SC 24. We compare the HCME occurrence rate and other properties during the rise phase of cycles 23, 24, and 25 to weigh in on the strength of SC 25. We find that HCME and solar wind properties in SC 25 are intermediate between SCs 23 and 24, but closer to SC 24. The HCME occurrence rate, normalized to the sunspot number, is higher in SCs 24 and 25 than in SC 23. The solar wind total pressure in SC 25 is ∼35% smaller than that in SC 23. Furthermore, the occurrence rates of high-energy solar energetic particle events and intense geomagnetic storms are well below the corresponding values in SC 23, but similar to those in SC 24. We conclude that cycle 25 is likely to be similar to or slightly stronger than cycle 24, in agreement with polar-field precursor methods for cycle 25 prediction.

Geoefficiency of Sporadic Phenomena in Solar Cycle 24

The specific features of solar cycle 24 are discussed, including cosmic ray variations, characteristicsof solar flares, proton events, coronal mass ejections, and the level of geomagnetic activity. It is shownthat in terms of the sunspot number and other manifestations of solar activity, cycle 24 turned out to be themost modest one over the last 100 years of observations. A significant decrease in the geoefficiency of varioussolar events is described, which manifested itself in a smaller number and magnitude of Forbusheffects recorded on the Earth, the enhancements of the fluxes of protons and electrons of different energies,and geomagnetic storms.

Temperature of the Polar Inner Heliosheath: Connection to Solar Activity

We study the thermodynamics of the plasma protons in the polar regions of the inner heliosheath (IHS) and its connection with solar activity over solar cycle 24. First, we express the thermodynamic parameters of this plasma with respect to the year of energetic neutral atom (ENA) creation and perform a statistical analysis of temperatures, in order to provide a more precise characterization of the thermodynamics of IHS. Then, we perform an autocorrelation between the IHS temperature and the solar activity, using the proxies of sunspot number and fractional area of the polar coronal holes. We show that there is (i) high correlation between the time series of IHS proton temperatures and sunspot number, which is maximized for a time delay of τ ∼ 2.5 yr for both the north and south polar regions combined; (ii) high negative correlation between the temperature of the proton plasma in the north and south with the coronal hole fractional areas, where the time delay for the two poles combined is τ ∼ 2.71 ± 0.15 yr; and (iii) an asymmetry of a time-delay difference between the poles ∼0.22 yr, indicating that the southern polar ENA source region is ∼19 au closer than the northern one for a solar wind plasma protons of bulk speed of ∼400 km s−1. The findings demonstrate a connection between the IHS thermodynamics and solar activity through the solar wind, primarily manifested by the coronal holes expanding near solar minimum, which drives the expansion of fast solar wind over larger angles from high down to middle latitudes in the IHS.

A Prediction Method of Ionospheric hmF2 Based on Machine Learning

The ionospheric F2 layer is the essential layer in the propagation of high-frequency radio waves, and the peak electron density height of the ionospheric F2 layer (hmF2) is one of the important parameters. To improve the predicted accuracy of hmF2 for further improving the ability of HF skywave propagation prediction and communication frequency selection, we present an interpretable long-term prediction model of hmF2 using the statistical machine learning (SML) method. Taking Moscow station as an example, this method has been tested using the ionospheric observation data from August 2011 to October 2016. Only by inputting sunspot number, month, and universal time into the proposed model can the predicted value of hmF2 be obtained for the corresponding time. Finally, we compare the predicted results of the proposed model with those of the International Reference Ionospheric (IRI) model to verify its stability and reliability. The result shows that, compared with the IRI model, the predicted average statistical RMSE decreased by 5.20 km, and RRMSE decreased by 1.78%. This method is expected to provide ionospheric parameter prediction accuracy on a global scale.

Relationship between Solar Flux and Sunspot Activity Using Several Regression Models

This study examines the correlation and prediction between sunspots and solar flux, two closely related factors associated with solar activity, covering the period from 2005 to 2022. The study utilizes a combination of linear regression analysis and the ARIMA prediction method to analyze the relationship between these factors and forecast their values. The analysis results reveal a significant positive correlation between sunspots and solar flux. Additionally, the ARIMA prediction method suggests that the SARIMA model can effectively forecast the values of both sunspots and solar flux for a 12-period timeframe. However, it is essential to note that this study solely focuses on correlation analysis and does not establish a causal relationship. Nonetheless, the findings contribute valuable insights into future variations in solar flux and sunspot numbers, thereby aiding scientists in comprehending and predicting solar activity's potential impact on Earth. The study recommends further research to explore additional factors that may influence the relationship between sunspots and solar flux, extend the research period to enhance the accuracy of solar activity predictions and investigate alternative prediction methods to improve the precision of forecasts.

Spatiotemporal variation and multivariate controls of short‐cycle drought–flood abrupt alteration: A case in the Qinling‐Daba Mountains of China

AbstractA comprehensive understanding of the patterns of drought and flood alternation in adjacent months is essential for enabling climate adaptation and mitigation strategies. However, there is a paucity of knowledge regarding short‐cycle drought–flood abrupt alteration (s‐DFAA) and its responses to multiple environmental factors at various timescales. This is because of the inadequate formula construction of the existing short‐cycle drought–flood abrupt alteration index (SDFAI), such as the inability to introduce drought standards. To accurately capture the s‐DFAA's characteristics in the Qinling‐Daba Mountains (Qinba Mountains), we proposed a revised SDFAI (R‐SDFAI), which incorporates the standardized precipitation index (SPI) and allows for the customization of drought standards. Next, we used wavelet transform coherence and multiple wavelet coherence to investigate the timescale relationships between s‐DFAA events and their influence factors such as relative humidity, sunshine duration, temperature, evaporation, Arctic Oscillation (AO), Niño3.4 SSTA Index (Niño3.4), Total Sunspot Number Index (TSNI) and Pacific Decadal Oscillation Index (PDO). Our results showed that the R‐SDFAI outperformed traditional SDFAI in capturing s‐DFAA events and characterizing their severity. Furthermore, s‐DFAA events identified by R‐SDFAI at different levels (i.e., mild, moderate, severe, extreme and total) displayed insignificant downward trends. Spatially, there were more s‐DFAA events in the east than the west. Wavelet analysis indicated that meteorological factors and teleconnections significantly impact s‐DFAA events at large timescales, though their driving mechanisms differed substantially. Among meteorological factors, single relative humidity and its related combinations exhibited relatively high percent area of significant coherence (PASC, ranging from 17.47 to 29.46). Each teleconnection and its combinations are irreplaceable, with PASC values always increasing with the number of variables. The PASC ranges from 8.3 to 10.29 for one factor, 12.38 to 18.65 for two factors, 24.02 to 30.58 for three factors and 40.88 for four factors, respectively.

Hale cycle in solar hemispheric radio flux and sunspots: Evidence for a northward-shifted relic field

Context. Solar and heliospheric parameters occasionally depict notable differences between the northern and southern solar hemisphere. Although the hemispheric asymmetries of some heliospheric parameters vary systematically with the Hale cycle, this has not been found to be commonly valid for solar parameters. Also, no verified physical mechanism exists that can explain possible systematic hemispheric asymmetries. Aims. We use a novel method of high heliolatitudinal vantage points to increase the fraction of one hemisphere in solar 10.7 cm radio fluxes and sunspot numbers. We aim to explore the possibility that solar radio fluxes and sunspot numbers, the two most fundamental solar parameters, depict systematic, possibly mutually similar patterns in their hemispheric activities during the last 75 yr. Methods. We used three different sets of time intervals with increasing mean heliographic latitude and calculated corresponding hemispheric high-latitude radio fluxes and sunspot numbers. We also normalized these fluxes by yearly means in order to study the variation of fluxes in the two hemispheres over the whole 75 yr time interval. Results. We find that cycle-maximum radio fluxes and sunspot numbers in each odd solar cycle (19, 21, 23) are larger at northern high latitudes than at southern high latitudes, while maximum fluxes and numbers in all even cycles (18, 20, 22 24) are larger at southern high latitudes than at northern high latitudes. This alternation indicates a new form of systematic, Hale-cycle-related variation in solar activity. Hemispheric differences at cycle maxima are 15% for radio flux and 23% for sunspot numbers, on average. The difference is largest during cycle 19 and smallest in cycle 24. Normalized radio fluxes depict a dominant Hale-cycle variation in both hemispheres, with an opposite phase and overall amplitude of about 5% in the north and 4% in the south. Thus, there is systematic Hale-cycle alternation in magnetic flux emergence in both hemispheres. Conclusions. The hemispheric Hale cycle in flux emergence can be explained if there is a northward-directed relic magnetic field, which is slightly shifted northward. In that case, in odd cycles, the northern hemisphere is enhanced more than the southern hemisphere, and in even cycles, the northern hemisphere is reduced more than the southern hemisphere, establishing the observed hemispheric alternation. The temporal change of asymmetry during the seven cycles can be explained if the relic shift oscillates at the 210 yr Suess/deVries period, which also provides a physical cause to this periodicity. Gleissberg cycles are explained as off-equator excursions of the relic, each Gleissberg cycle forming one half of the full relic shift oscillation cycle. Having a relic field in the Sun also offers interesting possibilities for century-scale forecasting of solar activity.

Solar Flux Effects on the Variations of Equatorial Electrojet (EEJ) and Counter-Electrojet (CEJ) Current across the Different Longitudinal Sectors during Low and High Solar Activity

This study examined the effect of solar flux (F10.7) and sunspots number (R) on the daily variation of equatorial electrojet (EEJ) and morning/afternoon counter electrojet (MCEJ/ACEJ) in the ionospheric E region across the eight longitudinal sectors during quiet days from January 2008 to December 2013. In particular, we focus on both minimum and maximum solar cycle of 24. For this purpose, we have collected a 6-year ground-based magnetic data from multiple stations to investigate EEJ/CEJ climatology in the Peruvian, Brazilian, West & East African, Indian, Southeast Asian, Philippine, and Pacific sectors with the corresponding F10.7 and R data from satellites simultaneously. Our results reveal that the variations of monthly mean EEJ intensities were consistent with the variations of solar flux and sunspot number patterns of a cycle, further indicating that there is a significant seasonal and longitudinal dependence. During the high solar cycle period, F10.7 and R have shown a strong peak around equinoctial months, consequently, the strong daytime EEJs occurred in the Peruvian and Southeast Asian sectors followed by the Philippine regions throughout the years investigated. In those sectors, the correlation between the day Maxima EEJ and F10.7 strengths have a positive value during periods of high solar activity, and they have relatively higher values than the other sectors. A predominance of MCEJ occurrences is observed in the Brazilian (TTB), East African (AAE), and Peruvian (HUA) sectors. We have also observed the CEJ dependence on solar flux with an anti-correlation between ACEJ events and F10.7 are observed especially during a high solar cycle period.

Climatology of the Harmonic Frequency Separation of Ionospheric Alfvén Resonances at Eskdalemuir Observatory, UK

AbstractWe extracted the harmonic frequency separation (Δf) of Ionospheric Alfvén Resonances (IAR) observed in the Eskdalemuir induction coil magnetometer data for the 9 year data set of 2013–2021. To obtain Δf values, we used a machine learning technique that identifies the harmonics and from this we calculated the average separation. To investigate the climatology of the IAR, we have modeled the Δf of the IAR for the data set using a time of flight calculation with model Alfvén velocity profiles. When analyzing Δf from the model and data, we found that in general they follow the same trends. The modeled Δf and Δf from the data both show an inverse correlation with foF2, which confirms that the frequencies of the IAR are controlled by electron density. It follows that Δf is greater around midnight and during the winter months, due to the decrease in plasma mass density. Variability is also reflected when comparing yearly trends in Δf with the sunspot number; higher frequencies are observed and modeled at low sunspot number. It is difficult to examine trends with instantaneous geomagnetic activity as IAR are not visible in spectrograms when geomagnetic activity is high. We find cases where the difference in measured and modeled Δf is significant, suggesting that the model does not capture short term variations in plasma mass density that influence the IAR during these days. We plan to undertake further modeling of Δf on shorter timescales.

Factors affecting variations in the hydrological cycle at different temporal and spatial scales

The climate is changing intensively, causing major variations in the local, regional, and eventually global hydrological cycle. Furthermore, climate changes strongly affect individual components of the hydrological cycle. The prevailing present-day opinion is that climate change is primarily caused by anthropogenic production of CO2. This assumption is automatically accepted as the main reason or at least a contributory cause of changes in the hydrological cycle. However, changes in hydrological cycle appear to be a significantly more complex problem. At the same time, various other processes take place on different temporal and spatial scales. The article discusses numerous natural and human-caused factors that can affect changes in the hydrological cycle. When considering the factors that affect the planetary hydrological cycle on any temporal or spatial scale, it is necessary to consider many potential causes and understand their interactions. The natural factors discussed in this paper are Milanković cycles, Wolf number, Hurst phenomenon, earthquakes, volcanoes, and meteorite impacts. Among the anthropogenic influences, the role of dams and reservoirs is emphasized.