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Space weather profoundly impacts Earth and its surrounding space environment, necessitating improved prediction to safeguard critical infrastructure such as communication and satellites. Solar flares can disrupt communications and pose radiation risks to airline passengers. While traditional methods offer rough estimates of solar activity trends, the potential of artificial intelligence in this domain warrants exploration. This study addresses this research gap by evaluating the performance of recurrent neural networks (RNNs) for sunspot forecasting and assessing the suitability of extreme gradient boosting (XGBoost) for solar event classification. Two publicly available datasets serve as the foundation for this research. To enhance algorithm performance through optimal hyperparameter selection, metaheuristic optimizers are employed. A unique contribution is the introduction of a modified particle swarm optimization algorithm, specifically tailored to the study's needs. Two experiments were conducted: In the first, RNNs predicted sunspot occurrence up to three steps ahead. The best-performing model, optimized using the introduced modified metaheuristic, achieved an impressive R 2 value of 0.840448, surpassing competing algorithms. In the second experiment, XGBoost models assessed solar flare severity, with the top model again optimized by the modified metaheuristic, achieving an accuracy of 0.981565. This novel approach highlights the potential for enhancing solar activity forecasting techniques and offers valuable insights into feature impacts on model decisions, thereby advancing our understanding of space weather. [ABSTRACT FROM AUTHOR]

Solar radio bursts are intense radio radiation sources that occur during the energy-release process and represent a hot topic in solar-physics and space-weather research. In this paper, we present a multimode prediction model for daily solar radio bursts. The model uses deep learning and machine learning to obtain data information from different dimensions and to establish the relationship between the characteristics of the solar active region on the solar surface and solar radio bursts. For this model, we use data from the Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) total solar magnetic map, the Royal Observatory of Belgium World Data Centre in Brussels, and NOAA sunspot parameters (including number, area, and type of sunspots) as inputs. The output results are then compared with the list of solar radio bursts recorded by the Radio Solar Telescope Network (RSTN) to determine whether solar radio bursts are present and to determine the key parameters for determining radio bursts. Based on 5449 days of observational data, we find that the prediction accuracy of the model is 0.898 ± 0.011, and that the number of sunspots is a key parameter in determining the occurrence of solar radio bursts. Specifically, when the number of sunspots is greater than 15, the probability of occurrence of solar radio bursts is greater than 90%. We have identified the key parameters and thresholds for determining solar radio bursts and highlighted the key parameters for space-weather prediction. In addition, the prediction model can also be used for predicting in other fields. [ABSTRACT FROM AUTHOR]

The emergence of active regions on the Sun is an integral feature of the solar dynamo mechanism. However, details about the generation of active-region-scale magnetism and the journey of this magnetic flux from the interior to the photosphere are still in question. Shifting paradigms are now developing for the source depth of the Sun's large-scale magnetism, the organization of this magnetism into fibril flux tubes, and the role of convection in shaping active-region observables. Here we review the landscape of flux emergence theories and simulations, highlight the role flux emergence plays in the global dynamo process, and make connections between flux emergence on the Sun and other cool stars. As longer-term and higher fidelity observations of both solar active regions and their associated flows are amassed, it is now possible to place new constraints on models of emerging flux. We discuss the outcomes of statistical studies which provide observational evidence that flux emergence may be a more passive process (at least in the upper convection zone); dominated to a greater extent by the influence of convection and to a lesser extent by buoyancy and the Coriolis force acting on rising magnetic flux tubes than previously thought. We also discuss how the relationship between stellar rotation, fractional convection zone depth, and magnetic activity on other stars can help us better understand the flux emergence processes. Looking forward, we identify open questions regarding magnetic flux emergence that we anticipate can be addressed in the next decade with further observations and simulations. [ABSTRACT FROM AUTHOR]

Introduction: The external use treatment in the handling of psoriasis is first option in the light and light moderated psoriasis and as complementary therapy in severe or intense psoriasis. Calendula officinalis L. has anti-inflammatory, healing and antibacterial properties. Objective: To determine the Efficacy of marigold pomade to 20 % in the treatment of psoriasis. Methodology: A quasi experimental study was carried out in 40 patients from the dermatology service at Juan Bruno Zayas Hospital in the period corresponding to January - May of 2019; divided in a control group (pomade without Marigold) and a study group (Marigold pomade to 20 %). Injuries in the first week were classified and evolution was assessed when concluding fifth and tenth weeks. Finally, response to treatment was also assessed. Results: In the fifth week the 55 % of patients from study group showed light flakes while in the control group predominated intense erythema (75 %) and in the study group with equal frequency (35 %) to light and moderated, while the control group predominated intense (75 %). In the tenth week in the study group, flakes between absentee and light represented 80 % and 75 % of erythema; while in the control group the light and missing 15 %, as for flakes as for erythema. The treatment proved to be effective in 80 % of the patients from the study group, in contrast to the control group where the excellence response was in 15 %. Conclusion: Marigold pomade to 20 % is effective for the treatment of psoriasis and succeeds in attaining the maximum efficiency among the fifth and tenth weeks of treatment. [ABSTRACT FROM AUTHOR]

Recent interest of solar physicists in the analysis of the coronal mass ejections and circular solar flares in fan-spine magnetic configurations (FSCs) necessitates measurements of the corresponding coronal magnetic fields. A dominant sunspot with the circumjacent magnetic flux of opposite polarity produces a specific coronal region of the quasi-transverse (QT-) propagation of microwaves. We make use of the theory of QT-propagation to evaluate the strengths of coronal magnetic fields in the active regions NOAA 11579, 12242, and 12488 while they are non-flaring. Microwave polarization changes were observed with the RATAN-600 radio telescope, the Siberian Solar Radio Telescope, and the Nobeyama Radioheliograph. Changes in the sign of circular radio polarization provide the strengths of coronal fields in a QT-region if the coronal plasma density Ne and the length scale of magnetic field divergence Ld are known. We evaluate the length scale by means of the potential-field source-surface (PFSS) model and the coronal density from the Gaussian inversion of the differential emission measure (from the Solar Dynamics Observatory observational data), obtaining NeLd = (0.46–0.64)×1010 m−2. The resulting coronal fields of 1.4×10−3 T and 2.34×10−3 T are attributed to the heights of 100 Mm and 50.2 Mm. We discuss the validity and consistency of the involved values to draw conclusions on the feasibility of coronal radio magnetography of FSCs. [ABSTRACT FROM AUTHOR]

Active regions on the surface of the Sun are potential sources of solar flares. These include active regions that are not directly facing Earth, such as those on the Sun's far-side. However, unlike Earth-facing active regions, far-side active regions including the east limb are difficult to observe. Therefore, east limb active region observation and analysis capability are necessary to predict the occurrences of east limb flares. The purpose of this study is to develop an automatic detection system of active regions occurring in the solar east limb using EUV intensity data from the EUVI instrument onboard the STEREO-A and STEREO-B spacecraft. Random forest and support vector machine algorithms were used in the system development. Active regions will be detected as bright regions in these EUV data. This detection system supports routine space weather forecasting activities at the Research Center for Space, part of the Space Weather Information and Forecast Services (SWIFtS). The system combines STEREO/EUVI with SDO/AIA data into a single composite map in the heliographic coordinate system, and then automatically detects the presence of east limb bright regions based on their intensities in near real-time. It also provides the estimated time of arrival (ETA) of the east limb bright regions on the east limb of the solar disk. The system also calculates the bright regions' mean intensity, total intensity, area and angular width. A machine-learning model has also been developed based on eight years of data to classify bright regions as different types of photospheric entities according to the calculated parameters. A validation test using an operational dataset produced accuracy scores of 79% and 64% for the random forest and support vector machine algorithms, respectively. [ABSTRACT FROM AUTHOR]

Halo coronal mass ejections (CMEs) from the Sun are the subset of CMEs, which are more energetic than the normal CMEs. Only the more energetic CMEs are observable in white-light coronagraphs when they are traveling along the line of sight (LOS) and a CME is better observed when it is traveling perpendicularly to the LOS. We investigated the flare associated front side halo CMEs, their active regions (ARs) and flare ribbon properties observed during the period of 2010 – 2016 in Solar Cycle 24. The aim of this study is to investigate the statistical relationship between the kinematic properties of CMEs and their source active region and flare ribbon properties. The properties of the solar source region (sunspot classification according to Hale and McIntosh, sunspot area, and the number of spots) and flare ribbons (total unsigned magnetic flux, total unsigned reconnection flux, active region area, and ribbon area) are obtained for the selected events and analyzed to find the dependence of the halo CME properties (linear speed, kinetic energy, space speed, and mass) on the source region characteristics. From the preliminary analysis, 13% of halo CMEs are found to be associated with X-class flares, 52% with M-class flares, and 35% with C-class flares. It is found that many events (45/60) were produced by β γ δ and β γ Hale-type sunspot groups and Ekc/Dkc/Fkc McIntosh sunspot classes, which implies a degree of complexity of the involved sunspots. We found moderate correlations between the active region properties and CME properties, but strong correlation between the flare ribbons and CME properties. This result indicates that the kinematics of CMEs are determined by the role of magnetic reconnection and the flux related to it. We estimated the synthetic CME mass (using a synthetic CME generated based on a full ice-cream cone structure proposed recently by Na et al., Astrophys. J.906, 46, 2021). It is demonstrated that the estimated mass of halo CMEs is 1.44 times (without occulted area) and 2 times (with occulted area) that of the observed CME mass. Further, the relations between the halo CME synthetic mass with the active region and flare ribbon properties have been obtained. [ABSTRACT FROM AUTHOR]

Individual sunspot observations have formed a ground basis of international sunspot number, a unique reference for long-term solar variability in the centennial timescale. The original datasets were subjected to exploitations and analyses upon the recalibrations of the sunspot number series. In this context, this study reviewed and analysed original sunspot records and their databases in the Kawaguchi Science Museum (KSM) in Japan. KSM hosts sunspot drawings and logbooks from 1972 to 2013. This dataset has a longer chronological coverage than what was known to the scientific community (1981-2010). These records have been digitized and publicized in a museum database, which allows users to access individual sunspot drawings and numerical data in KSM logbooks. These records are highly homogeneous as a single observer's dataset (Hitoshi Takuma), who used a 15-cm refractor at the Kawaguchi Juvenile Museum in 1972-2003 and a 20-cm refractor at KSM in 2003-2013. We also reviewed the Takuma data series, his monthly observation days (21.3 days/month), sunspot number in the whole disk and each hemisphere, and sunspot positions in a butterfly diagram. We also assessed Takuma's data stability in comparison with the international sunspot number and reference datasets of the SILSO. Takuma's data appear stable until 2003, when he changed the observation site and instrument. His data stability was quantitatively compared with the SILSO reference datasets, confirming the substantial long-term stability of the data and establishing its reliability as an alternative reference for sunspot number recalibration. [ABSTRACT FROM AUTHOR]

• TRNSYS-FLUENT coupling method for sunspot simulation. • Sunspot impact on cooling floor conditions for different localization and solar heat flux. • Dynamic thermal behavior of indoor air regarding to the sunspot displacement. The dynamic thermal simulation of buildings is a real challenge, in terms of regulations and labelling but also of decisions (implementation, materials choice, architectural design, rehabilitation ...). Today, we lack reference models of the dynamic thermal behaviour of the cooling floor under solar radiation effect. In fact, the simulation models developed in literature are represented in a very simplified method and cannot be used for a detailed analysis of thermal comfort. The present study aims to reduce the knowledge gap and resolve the limitations such as (i) studying the effect of sunspot for a real weather conditions, (ii) visualize the dynamic thermal behaviour of indoor air and surface cooling floor relative to the sunspot shifting and (iii) predict different sunspot shape as a function of geographic location. A 3D model is presented in this paper to evaluate the sunspot impact on cooling floor coupled to underground tank under climatic conditions in Algeria. The sunspot is calculated using a coupled TRNSYS-FLUENT dynamic simulation. Simulations are run for different periods and weather conditions. The results have shown that the developed model can provide a real simulation of thermal performance of the cooling floor taking into account the sunspot shifting. The incident solar heat flux on cooling floor reaches a maximum of 300 W/m2 for Bechar city and 120 W/m2 for Oran city. A wide surface temperature ranges of 13 °C between the umbrageous and illuminated areas. For Oran weather conditions, the indoor air temperature in the umbrageous area is around 24 °C, while that of the illuminated area is 28 °C which can cause a temperature heterogeneity in the room. [ABSTRACT FROM AUTHOR]

We present a study of wave processes occurring in solar active region NOAA 11131 on 10 December 2010, captured by the Solar Dynamics Observatory in the 1600 Å, 304Å and 171Å channels. For spectral analysis, we employed pixelized wavelet filtering together with a developed digital technique based on empirical mode decomposition. We studied the ~3-minute wave dynamics to obtain relationships with the magnetic structuring of the underlying sunspot. We found that during development of wave trains the motion path occurred along a preferential direction, and that the broadband wavefronts can be represented as a set of separate narrowband oscillation sources. These sources become visible as the waves pass through the umbral inhomogeneities caused by the differing magnetic field inclination angles. We found the spatial and frequency fragmentation of wavefronts, and deduced that the combination of narrowband spherical and linear parts of the wavefronts provide the observed spirality. Maps of the magnetic field inclination angles confirm this assumption. We detect the activation of umbral structures as the increasing of oscillations in the sources along the front ridge. Their temporal dynamics are associated with the occurrence of umbral flashes. Spatial localization of the sources is stable over time and depends on the oscillation period. We propose that these sources are the result of wave paths along the loops extending outwards from the magnetic bundles of the umbra. [ABSTRACT FROM AUTHOR]

The prediction of a time series such as climate indices and the sunspot number (SSN) with long-term oscillatory behaviors has been a challenging task due to the complex combination of oscillations. Frequency extraction algorithms have been developed to separate a time series into different oscillation components according to frequency, such as empirical model decomposition (EMD) and wavelet analysis. In the current study, the deep learning long short-term memory (LSTM) model was employed to predict the oscillation components extracted using EMD. The SSN series was modeled with the hybrid EMD-LSTM model. The simulation study results indicate that the LSTM model reproduces the smooth cyclic pattern of the sine function, and only a few hidden units are needed to model it. The EMD-LSTM model achieves better performance than does the LSTM model for mid-range SSN predictions while the LSTM achieves better performance within the first few time lags. However, the cyclic prediction of the SSN requires mid-range lags; thus, the superior performance of the EMD-LSTM model for these lags cannot be ignored. Furthermore, the remaining components from the significant EMD signals can be modeled to reveal the variability (or uncertainty) in the prediction. The summed residual is fitted by k-nearest neighbor resampling. The final SSN prediction results show that the EMD-LSTM model predicts a later and larger SSN for Solar Cycle 25 than does the LSTM model. Overall, the results lead to the conclusion that the EMD-LSTM model might be a suitable alternative for modeling complex sunspot time series with cyclic patterns. [ABSTRACT FROM AUTHOR]

Sunspot prediction is an important task for space weather and solar physics. Traditional point forecast may not be sufficiently satisfactory and reliable. To quantify the uncertainty of point prediction, a hybrid interval prediction model has been proposed for sunspot forecasting. Three major steps are taken: (1) the complementary ensemble empirical mode decomposition (CEEMD), to decompose the sunspot sequence into a series of modal components, (2) the fuzzy information granulation (FIG), to extract the minimum, average and maximum value of each window, and (3) the extreme learning machine (ELM), to conduct point prediction and interval prediction, superimposing the prediction values of all components as the final forecast results. The empirical study focus on the 13-month smoothed monthly sunspot number recorded by Solar Influences Data Analysis Center (SIDC) and show that the mixed model with the filtered CEEMD is more effective than the unfiltered one. It also enables us to track changes of the sunspot number with fast calculating speed and high accuracy both in point prediction and interval prediction. [ABSTRACT FROM AUTHOR]

The Total Solar Irradiance (TSI) primarily varies on an 11-year time scale and is governed by features such as sunspots and associated decay products such as plage and faculae. These short-lived physical features can also modulate the solar irradiance at intermediate and short temporal scales. Here we investigate the periodic variations, at solar-surface-rotation time scales, of photometric indices derived from images obtained at the San Fernando Observatory (SFO), and we compare them to the properties of the contemporaneous TSI as measured by the Total Irradiance Monitor (TIM) onboard the SOlar Radiation and Climate Experiment (SORCE) spacecraft. Both the daily ground- and space-based data, which span from early 2003 to late 2018, present missing pixels. We use an autoregressive gap-filling method to construct continuous time series to be analyzed via Fourier and wavelet spectral techniques. Lomb–Scargle periodograms, which can handle time series with missing data, are used for comparison. Both the Fourier spectral power and the periodograms yield compatible results with statistically significant periodicities in the range 25 – 35 days. All of the time series have maximum power at 27 days. Significant secondary periods are found at 29 – 30 days and 34 – 35 days. Wavelet analyses of the full time series show that the photometric index resulting from the red-continuum photometric sum [ Σ r ] and the TSI exhibit common high power at surface-solar-rotation scales during the active part of the solar cycle. The phase relation at the surface-solar-rotation scales is not definite. During the solar minimum interval between Solar Cycles (SCs) 23 and 24, variations in the TSI are found to be related to variations both in the photometric index Σ K , calculated from Ca ii K-line photometric sums and in the magnetic flux in the solar activity latitudinal band (as found in previous work). This suggests that the TSI changes during the minimum are caused by the reduced line-blanketing effect of diffused magnetic field. [ABSTRACT FROM AUTHOR]

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 • Fully automated adaptive thresholding sunspot detection framework delineating umbra & penumbra. • Local-Global thresholding method exploiting intensity variations across multiple levels. • ROC analysis in both manual and automatic modes affirms scheme's performance. • Higher correlation values attained for sunspot numbers with the HFC and SILSO catalogs. • Complexity analysis reveals the involved minimal operations without compromising performance. [ABSTRACT FROM AUTHOR]

This paper explores the role of bubbles in an overlapping-generations economy where some agents are more productive than the others. Due to missing credit markets, productive and unproductive agents cannot trade their financial assets to achieve mutual benefit, making the economy to perform below its potential. Introducing bubbles on the one hand crowds out some productive resources as it does in the current literature. It on the other hand may divert resources away from unproductive agents to productive ones. We find that bubbles are growth enhancing when the unproductive agents' productivity level lies within an interval. Furthermore, in sharp contrast to the existing literature, the equilibrium bubble size is stable. This finding enables us to construct a two-state stationary sunspot equilibrium in which one state is associated with small bubbles and low growth whereas the other one has large bubbles and high growth. • Bubbles crowd out productive resources in an OLG model with financial frictions. • Bubbles re-allocate resources as productivity level of agents lies in an interval. • When the re-allocative effect dominates, bubbles are growth enhancing. • The equilibrium bubble size is unique and stable. • A two-state stationary sunspot equilibrium is found. [ABSTRACT FROM AUTHOR]

Abstract Korean chronicles have a large amount of observational records of natural phenomena, including astronomical and meteorological events over two thousand years. Here we examine the correlation of solar activity and climate change from historical sunspot and frost records in the Korean chronicles. There are 42 sunspot records in Goryeo Dynasty (918–1392 CE) and 13 records in Joseon Dynasty (1392–1910 CE). The sunspot records in Goryeo Dynasty show a periodicity in good agreement with the well-known solar activity of 11 years. Korean sunspot records suggest that the solar activity in Joseon Dynasty decreased compared with that in the previous ∼500 years. In order to examine the long-period variation of solar activity, we include Chinese historical sunspot records in our analysis to supplement the lack of Korean records, and find a new ∼240-yr long-period solar activity from the power spectral analysis. Korean chronicles also have about 700 frost records during the last millennium. We investigate these frost records and find a sign of cooling down that can be interpreted as climate change during the last millennium. We also find ∼240-yr cooling period from the historical frost records, which is well in accord with that of solar activity. Therefore, we conclude that the solar activity has decreased during the last one thousand years and also has a long-term variation of ∼240 years. Highlights: • The correlation of solar activity and climate change has been examined from Korean historical sunspot and frost records. • Korean sunspot records suggest that the solar activity has decreased during the last one thousand years. A new ∼240 yr long-period solar activity was found from the combined Korean and Chinese records. • Korean frost records also show a sign of cooling down and ∼240-yr cooling period. [ABSTRACT FROM AUTHOR]

In this study, we modified the previously introduced X-ray flare production potential (FPP) of each modified Zurich sunspot group based on its X-ray flare peak flux. Then, using these FPPs, the daily total sunspot number (Zurich number) calculation equation was modified; thus, new sunspot number data (CRz) were produced. We also compared ISSN and CRz with some geomagnetic indices (Dst, the maximum CME speed, and Ap indices). We found that the CRz data describe the geomagnetic indices quite well compared to ISSN. By using the regression equation between CRz and the sunspot area, the CRz dataset was recalculated back to 1874. Those reconstructed datasets were compared to observational data, and it was found that reconstructed and observed monthly datasets show very good agreement. The only small differences exist in maxima and minima of cycles. [ABSTRACT FROM AUTHOR]

Abstract Cosmogenic radionuclides provide information about air masses exchanges between stratosphere and troposphere. The 7Be concentration in aerosols usually shows a seasonal variability, depending also of the climatic conditions. There are, however, fewer data available of the behavior of other cosmogenic radionuclides, such as 10Be and 22Na. In this work about 7 years of aerosols collected in Cáceres (Spain) were analyzed. The 7Be concentration was higher than 22Na and 10Be, being the 22Na/7Be and 10Be/7Be ratios (1.16 ± 0.02)·10−4 and (1.5 ± 0.3)·10−4 respectively. For the 22Na/7Be, a seasonal variation was observed, being higher in spring/summer. Seasonal variation of 7Be and 22Na were explained using a model taking into account local values of the solar radiation, rainfall and dry deposition. The effective residence time for 7Be and 22Na were (9.9 ± 1.0) and (11.3 ± 1.4) d respectively. Both 7Be and 22Na seemed to decrease with increasing number of sunspots, although it was not statistically significant probably due to the low solar activity reported in the analyzed period. Highlights • Activity values of 10Be, only reported once in the literature. • Seasonal variability of 7Be and 22Na was related to local meteorological variables. • 7Be and 10Be concentrations are correlated. • Similar effective residence time for 7Be and 22Na. [ABSTRACT FROM AUTHOR]

In ground-based large aperture solar telescopes, the speckle image reconstruction technique combined with adaptive optics (AO) correction is generally used to get near diffraction-limited solar images. In order to select the high quality images from the AO-corrected high resolution solar image sequence, an automated noreference image quality assessment (IQA) is needed. According to the noise characteristics of solar AO images, an IQA metric based on an image power spectrum and human visual system is developed. By the incorporation of noise masking and shifting the spatial frequency range of summation, our IQA metric could select sharper images with less noise than previous works based on the image power spectrum, even if there is image scaling. Compared with existing general-purpose IQA metrics and previous metrics specifically designed for solar IQA, experimental results verify that the proposed metric gains better performance whether on robustness to blur and noise, or on selecting high quality frames containing solar granulations, sunspots, or both of them. [ABSTRACT FROM AUTHOR]

It is widely known that molecular signatures in celestial object play a vital role in deriving the physical conditions of the object using spectroscopic technique. The present study therefore focuses on the evaluation of Franck-Condon factors (FCFs) and r-centroids for the A-X band system of Boron mono-sulphide (BS) molecule by a numerical integration method using the suitable potential. With the help of FCFs and r-centroids, the vibrational temperature of the source is estimated and is found to be about 6893 K. The vibrational temperature estimated in the present study reveals that the rotational temperature of the molecule has to be considered for the identification of the chosen band system in the astrophysical spectra. The vibration rotation interaction (VRI) effect for the chosen band system is discussed. It is found that the VRI effect may influence the effective temperature of the source and hence the effect of VRI has to be considered at the time of identifying the BS molecular lines in the spectra of sunspot or any celestial object. [ABSTRACT FROM AUTHOR]

Incursions of high-energy particles from space, specifically solar energetic particles and galactic cosmic rays, have significant effects on the Earth, including disruption of the Earth’s magnetic field, generation of electric fields strong enough to damage electronic devices as well as the production of auroras at low-latitudes, within 45° of the magnetic equator. We examine the relationships among 14 C production, auroral abundance, auroral color and sunspot abundance using existing data supplemented by a new dataset. The new dataset, based on Chinese and Korean records from A.D. 1100–1700, includes 46 new or revised records of sunspots and 279 records of low-latitude auroras. Low-latitude auroras are predominantly red (66%, 835 events) with lesser proportions of white (20%, 253 events) and black auroras (6%, 67 events). All other auroral colors (green, yellow, multicolored, blue and purple) aggregate to a total of 100 events (8%). Overall, white auroras are more frequent during times of higher 14 C production. We use two empirical methods of evaluating the flux of high-energy particles: modeled peaks and lows in 14 C production and peaks and lows in the 14 C calibration curve. We find that comparison to modeled 14 C production gives significant results. White auroras are significantly more abundant (98% probability) at times of high production of 14 C. Red auroras are somewhat more abundant (88% probability) at times of low production of 14 C. The abundances of black, multicolored, green, yellow, and blue auroras between times of low and high 14 C production are not significantly different. Violet/purple auroras are significantly more abundant (98% probability) at times of low 14 C production. The positive correlation of violet/purple auroras with times of low 14 C production rate and the lack of correlation of blue auroras with times of high 14 C production is surprising, for this portion of the visible spectrum contains strong emission lines and some lines with high energies of excitation. Observations of emissions in the blue to violet part of the spectrum may be biased towards time periods when the atmosphere is exceptionally clear, as these colors are more difficult for the human eye to perceive. [ABSTRACT FROM AUTHOR]

The variability of the solar activity dominates the variability of the earth's atmosphere, which affects human life and technology on earth. To understand the effects of solar activity on earth's atmosphere different efforts are underway to model the variations of total solar irradiance (TSI) associated to the variations of photometric sunspot index (PSI) and core to wing ratio of Mg II index, for example, linear regression approach. In this study, feed-forward neural networks (NNs) algorithm, which takes the non-linear relationship between the dependent and independent variables, has been implemented to model daily TSI using PSI and Mg II index. First, data between 1978 and 2008 have been used to train and validate NNs, through which the parameters such as weights and biases are estimated. Therefore, NNs has been used to predict TSI between the years 2008 and 2013 from test data. The output of NNs have been compared with PMOD composite TSI and result has shown good agreement. Linear correlation between NNs predicted TSI and PMOD composite is found to be about 0.9307 for the years between 1978 and 2013. This means that NNs predicted TSI from solar proxies explains about 86.6% of the variance of TSI for solar cycles 21–24, and over 90% during solar cycle 23. Predicting TSI using NNs further strengthens the view that surface magnetism indeed plays a dominant role in modulating solar irradiance. [ABSTRACT FROM AUTHOR]

This paper revisits evidence of solar activity influence on the economy. We examine whether economic recessions occur more often in the years around and after solar maximums. This research strand dates back to late 19th century writings of the British economist William Stanley Jevons, who claimed that "commercial crises" occur with periodicity matching solar cycle length. Quite surprisingly, our results suggest that the hypothesis linking solar maximums and recessions is well anchored in data and cannot be easily rejected. [ABSTRACT FROM AUTHOR]

Light bridge (LB) is bright structure crossing the umbra of sunspots and associated to the breakup or assembly of sunspots. In this paper, a LB is presented and studied using the observatory data obtained by Hinode satellites. Force-free factor ( α ) and the z -component of current ( J z ) and tension force ( T z ) are calculated basing on the vector magnetograms observed by Spectro-Polarimeter (SP) of the Solar Optical Telescope (SOT) on board Hinode . It is found that the amplitudes of α and J z of LB are generally larger than those of umbra. It is found that there are two signs of J z along LB, which are divided at near the middle position of LB. It is found that the amplitudes of T z of LB are smaller than those of umbra and there are changes of sign of T z between the boundary of LB and umbra. Through comparisons and investigations, it suggest that LB and umbra maybe two different magnetic systems, which is a necessary condition for interaction magnetic reconnection. [ABSTRACT FROM AUTHOR]

The southern interior ecoprovince ( SIE) of British Columbia, Canada represents the northernmost extent of the great western North American deserts, it is experiencing some of the nation's fastest economic and population growth making it one of Canada's most water-stressed regions, and it includes two headwater basins of the transboundary (Canada- US) Columbia River. Statistical trend analyses were performed on 90-year regional indicator time series for annual conditions in observed temperature, precipitation, and streamflow reflecting the three major SIE river basins: the Thompson, and transboundary Okanagan and Similkameen. Results suggest that regional climate has grown warmer and wetter, but with little net impact on total water supply availability. The outcome might reflect mutual cancellation of increases in precipitation inputs vs. evapotranspiration losses. Conclusions appeared largely insensitive to low-pass data filtering, Pacific Decadal Oscillation effects, or solar output variability. Ensemble historical global climate model runs over the same time interval support this absence of appreciable trend in regionally integrated annual runoff volume, but a possible mismatch in precipitation results suggests a direction for further study. Overall, while important changes in hydrologic timing and extremes are likely occurring here, there is limited evidence for a net change in overall water supply availability over the last century. [ABSTRACT FROM AUTHOR]

A method based on set and graph operations was developed to find and track related entities of sunspot groups on a series of consecutive solar images. Of course, if we can track entities of a sunspot group, we can also track various properties ( e.g., position, area, magnetic field, and intensity) associated with them. A new higher-level sunspot-group entity belonging to the whole image series, a family, was introduced to cope with the mergings and separations of various sunspot group entities. To demonstrate the usefulness of the method, it was applied to NOAA AR 11429 using Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) images. This large sunspot group produced several X, M, and C class flares, among others, an X5.4 class flare on 2012 March 7. Abrupt transient and permanent variations in the mean line-of-sight (LOS) magnetic field of the large umbra families were found during the X5.4 flare. Two small umbra families immediately next to the polarity inversion line (PIL) and facing each other at opposite sides of the PIL exhibited abrupt stepwise changes in their mean LOS magnetic field during the X5.4 flare. The family with positive polarity decreased and the family with negative polarity increased. Some of the large umbra families also showed abrupt decrease in their darkness during the flare. We conjecture that an umbra family being a part of a long, narrow magnetic field strip pushing in an opposite magnetic polarity penumbral domain might be one of the triggering causes of several flares. Flare-related changes were observed at every spatial scale of the studied sunspot group. Two of the large opposite-polarity umbra families underwent shearing and converging motions. The break and the turning points of the motion curves of these families were related to flares. Some of the flares coincided with abrupt changes in the motion curves. [ABSTRACT FROM AUTHOR]

Using the software developed by us, we produced a digitized (tabulated) database of sunspot umbrae and pores observed at Mount Wilson Observatory (MWO) in 1917–2013. The database includes the heliographic coordinates, areas and the polarity and strength of magnetic fields of umbrae and pores in the MWO sunspot drawings. Using this database we study here the properties and long-term variation of sunspot umbrae and pores, separately for leading and trailing polarity spots. We find that the leading sunspots have tendency for larger umbrae and stronger magnetic field strength than the trailing spots. The average field strength and area of sunspot umbrae vary with sunspot cycle. Furthermore, the mean magnetic field strength in sunspot umbrae exhibits a gradual increase from early 1960s to 1990s. The nature of this increase is discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new model to calculate the sunspot position and area is presented. [•] Obtained results are in good agreement with published data. [•] The developed model is coupled with the building simulation software ZAER. [•] The coupled tool permits the precise calculation of the radiation exchanges. [•] A simulation case study demonstrates the applicability of the proposed tool. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this study is to evaluate a practical laboratory task where final year undergraduate students design, implement and validate an inferred security wireless sensor access system. Design/methodology/approach – The quality of the learning and technical environment was evaluated from a number of perspectives using a mixed methods approach where both quantitative and qualitative data was collected and analysed. Two-tailed paired t-tests were used to analyse data on student performance, while a targeted survey was used to assess the achievement of the learning outcomes. The students' experience of working with the Sun Microsystems SunSPOTs was evaluated and the evolution of their perception of both ubiquity and security from inception to completion of the activity was explored. Findings – The results of this study indicate that the students' level of engagement with the assigned laboratory task was higher than with the two other forms of continuous assessment used on the module. Quantitative feedback gathered indicated that the learning outcomes were achieved, while the qualitative data indicated a high level of student satisfaction with the laboratory assignment. Originality/value – A novel wireless sensor network laboratory that encourages students to engage with the concepts of ubiquity and security is presented and evaluated. [ABSTRACT FROM AUTHOR]

Previous studies have identified possible linkages between solar activity and tropical cyclone activity in the United States and Caribbean. This study used historical typhoon records dating back to the early 1700s, the Central Weather Bureau records (since 1897), and the JTWC (Joint Typhoon Warning Center) (since 1945) to investigate the relationship between solar activity and the number of typhoons in Taiwan. The results show that a negative relationship exists between solar activity and typhoon frequency in Taiwan at decadal time scales. Fewer typhoons occurred during the periods 1770 to 1790 and 1930 to 1960, with a higher number of typhoons occurring during 1810 to 1830 and 1870 to 1930. A likely mechanism for the relationship is that more intense solar activity can warm the lower stratosphere and the upper troposphere through absorption of solar radiation by atmospheric ozone. This would decrease the convective available potential energy and reduce the frequency of typhoon occurrence. As a consequence, fewer typhoons form over the western North Pacific with fewer affecting Taiwan. The negative correlation between solar activity and the number of typhoons affecting Taiwan is important to understand changes in the frequency and behavior of typhoons resulting from climate change. [ABSTRACT FROM AUTHOR]

The Lower Yellow River (LYR) has been characterized as a frequently breaching, overflowing and shifting river in historical periods. Understanding the factors that influence the LYR variations is critical for river management and disaster prevention. This study constructed a spatio-temporal data base of the LYR’s breaching and overflowing events (BOEs) and course-shifting events (CSEs) occurring in the late Holocene. The data base and corresponding solar activity data were analyzed to determine the overall influence, temporal influence and spatial influence of solar activity on the LYR. Results showed that 75.5% of the LYR CSEs and 61.7% of the LYR BOEs occurred in sunspot number decline phases of 11 yr solar cycles, suggesting that the LYR changed more frequently during the sunspot number decline phases. The underlying mechanism of this phenomenon was further interpreted as the high correlation between sunspot decline phases and heavy rainfall in the middle reaches of Yellow River (MYR). Five of the six heavy rainfall years over the last 60 years and 14 of the 16 well-known heavy rainfall records from 132 BC to AD 1933 in the MYR occurred in sunspot decline phases. Heavy rainfall in the MYR promoted the increase of the LYR runoff and the sediment rate and then raised the possibility of the occurrence of BOEs and CSEs. The study also found that the frequency of BOEs was positively related to the fluctuation amplitude of the sunspot maximum intensity in long time series. The flow directions of the LYR courses were found to affect the influence of solar activity on BOEs. The highest correlation between sunspot decline phases and BOEs was presented during the lifetime of eastward flows while the lowest during the lifetime of northward flows. In addition, human activities may undermine the impact of solar activities on the LYR changes. [ABSTRACT FROM PUBLISHER]

The linear relationship between the maximum amplitudes ( R) of sunspot cycles and preceding minima ( R) is one of the precursor methods used to predict the amplitude of the upcoming solar cycle. In the recent past this method has been subjected to severe criticism. In this communication we show that this simple method is reliable and can profitably be used for prediction purposes. With the 13-month smoothed R of 1.8 at the beginning, it is predicted that the R of the ongoing cycle will be around 85±17, suggesting that Cycle 24 may be of moderate strength. Based on a second-order polynomial dependence between the rise time ( T) and R, it is predicted that Cycle 24 will reach its smoothed maximum amplitude during the third quarter of the year 2013. An important finding of this paper is that the rise time cycle amplitude relation reaches a minimum at about 3 to 3.5 years, corresponding to a cycle amplitude of about 160. The Waldmeier effect breaks down at this point and T increases further with increasing R. This feature, we believe, may put a constraint on the flux transport dynamo models and lead to more accurate physical principles-based predictions. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a prominent 11-year cycle, supported by the pattern of the autocorrelation function and measures of Euclidean distances, in the mean annual sunspot number time series has been observed by considering the sunspot series for the duration of 1749 to 2007. The trend in the yearly sunspot series, which is found to be non-normally distributed, is examined through the Mann-Kendall non-parametric test. A statistically significant increasing trend is observed in the sunspot series in annual duration. The results indicate that the performance of the autoregressive neural network-based model is much better than the autoregressive moving average and autoregressive integrated moving average-based models for the univariate forecast of the yearly mean sunspot numbers. [Copyright &y& Elsevier]

The aim of this work was to identify the sunspot performance in tomato fruits (Solanum lycopersicum). A scale and an index that permits described the intensity and severity of sunspot damage. Additionally, we realized a histological, quality and nutritional study. The 80 percent of evaluated fruit was affected by sunspot, with law intensity but a maxim severity in the scale. The histological in healthy and damaged fruits show different between pericarp cell sizes and morphologic. The quality values not show affectations, but the lycopene concentration decreased in fruits with sunspot (92 to 74 µg/g). Results allow confirm the present of sunspot disorder, characterized by aberrant ripening and low lycopene concentration in the tomato shoulder fruits. These observations provide a basis for comparing sunspot in uniformly ripening tomatoes with other blotchy ripening disorders. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: This epidemiologic study tested an hypothesized association between the year of birth of persons with major mental illnesses and solar activity over the past century. Methods: We collected data on diagnoses and birthdates of psychiatric patients born between 1926 and 1975 (N =1954) in south Italy for comparison to yearly solar activity as registered by the International Observatories. Results: We found a strong inverse correlation between high solar activity (HSA) and incidence of schizophrenia and bipolar disorder in a 20-year period whereas the incidence of non-affective/non-psychotic disorders was moderately associated with HSA in the same period. Conclusions: Interpretation of the observed correlations between HSA during years of birth and the incidence of mental illnesses remains unclear, but the findings encourage further study. [Copyright &y& Elsevier]

Abstract: We use the Detrended Cross-Correlation Analysis (DCCA) to investigate the influence of sun activity represented by sunspot numbers on one of the climate indicators, specifically rivers, represented by river flow fluctuation for Daugava, Holston, Nolichucky and French Broad rivers. The Multifractal Detrended Cross-Correlation Analysis (MF-DXA) shows that there exist some crossovers in the cross-correlation fluctuation function versus time scale of the river flow and sunspot series. One of these crossovers corresponds to the well-known cycle of solar activity demonstrating a universal property of the mentioned rivers. The scaling exponent given by DCCA for original series at intermediate time scale, , is which is almost similar for all underlying rivers at confidence interval showing the second universal behavior of river runoffs. To remove the sinusoidal trends embedded in data sets, we apply the Singular Value Decomposition (SVD) method. Our results show that there exists a long-range cross-correlation between the sunspot numbers and the underlying streamflow records. The magnitude of the scaling exponent and the corresponding cross-correlation exponent are and , respectively. Different values for scaling and cross-correlation exponents may be related to local and external factors such as topography, drainage network morphology, human activity and so on. Multifractal cross-correlation analysis demonstrates that all underlying fluctuations have almost weak multifractal nature which is also a universal property for data series. In addition the empirical relation between scaling exponent derived by DCCA and Detrended Fluctuation Analysis (DFA), is confirmed. [ABSTRACT FROM AUTHOR]

The continuous wavelet transform is adapted to account for signal truncation through renormalization and by modifying the shape of the analyzing window. Comparison is made of the instant, integrated, and mean wavelet power with previous algorithms. The edge adapted and renormalized admissible wavelet transforms are used to estimate the level of solar magnetic activity from the sunspot record. The solar activity is compared to Oerlemans’ temperature reconstruction and to the Central England Temperature record. A correlation is seen for years between 1610 and 1990, followed by a strong deviation as the recently observed temperature increases. [ABSTRACT FROM AUTHOR]

Abstract: By using the monochromatic images and magnetograms obtained with the satellite Hinode, 35 pairs of bipolar moving magnetic features (MMFs) in sunspot penumbrae are studied in the following three aspects: the morphological characteristics, velocities of motion and responses in low atmospheric layers. Then the following conclusions are drawn. (1) The bipolar MMFs appear in pairs of positive and negative polarities, are located in the midst of the approximately vertical magnetic fields in spot penumbrae, and move toward the outer boundaries of penumbrae. This indirectly justifies that the bipolar MMFs originate in the horizontal magnetic fields of penumbrae. In the time intervals of 2-8 hours and at the same positions, there appear the bipolar MMFs with similar morphologial characteristics and velocities of motion. This povides an evidence which supports the model of magnetic lines in the shape of sea serpent. (2) In the process of motion of bipolar MMFs there may appear brightenings in the photospere and chromosphere, and this implies that the middle and low layers of solar atmosphere are heated by the bipolar MMFs. (3) The sites of occurrence of bipolar MMFs and the distribution of penumbral magnetic field agree with the structural characteristics of uncombed sunspot penumbrae. [Copyright &y& Elsevier]

The parameter G, which is determined from the general number of sunspots groups N g according to the daily observations G=∑(1/ N g)2, is offered. This parameter is calculated for the days when there is at least one sunspots group. It characterizes the minimum epoch solar activity. Parameter G mounts to the maximum during the epoch close to the minimal activity of sunspots. According to the data of the sequence of sunspots group in Greenwich–USAF/NOAA observatory format, observation data of Kislovodsk solar station and also daily Wolf number, the changes of parameter G during 100 years were reconstructed. It is demonstrated in the paper that parameter G’s amplitude in minimal solar activity n is linked with the sunspot cycle’s amplitude W n+1 or one and half cycles. The 24th activity cycle prediction is calculated, which makes W24=135(±12). [ABSTRACT FROM AUTHOR]

We study the periodicity of twisting motions in sunspot penumbral filaments, which were recently discovered from space ( Hinode) and ground-based (SST) observations. A sunspot was well observed for 97 minutes by Hinode/SOT in the G-band (4305 Å) on 12 November 2006. By the use of the time – space gradient applied to intensity space – time plots, twisting structures can be identified in the penumbral filaments. Consistent with previous findings, we find that the twisting is oriented from the solar limb to disk center. Some of them show a periodicity. The typical period is about ≈ four minutes, and the twisting velocity is roughly 6 km s−1. However, the penumbral filaments do not always show periodic twisting motions during the time interval of the observations. Such behavior seems to start and stop randomly with various penumbral filaments displaying periodic twisting during different intervals. The maximum number of periodic twists is 20 in our observations. Studying this periodicity can help us to understand the physical nature of the twisting motions. The present results enable us to determine observational constraints on the twisting mechanism. [ABSTRACT FROM AUTHOR]

The record of the sunspot number visible on the sun is regularly collected over the centuries by various observatories for studying the different factors influencing the sunspot cycle and solar activity. Sunspots appear in cycles, and last several years. These cycles follow a certain pattern which is well known. We analyzed monthly and yearly averages of sunspot data observed from year 1818 to 2002 using rescaled range analysis. The Hurst exponent calculated for monthly data sets are 0.8899, 0.8800 and 0.8597 and for yearly data set is 0.7187. Fractal dimensions1 calculated are 1.1100, 1.1200, 1.1403 and 1.2813. From the study of Hurst exponent and fractal dimension, we conclude that time series of sunspots show persistent behavior. The fundamental tool of signal processing is the fast Fourier transform technique (FFT). The sunspot data is also analyzed using FFT. The power spectrum of monthly and yearly averages of sunspot shows distinct peaks at 11 years confirming the well known 11-year cycle. The monthly sunspot data is also analyzed using FFT to filter the noise in the data. [ABSTRACT FROM AUTHOR]

We investigate p-mode absorption in a sunspot using SOHO/MDI high-resolution Doppler images. The Doppler power computed from a 3.5-hour data set is used for studying the absorption in a sunspot. The result shows an enhancement in absorption near the umbral – penumbral boundary of the sunspot. We attempt to relate the observed absorption with the magnetic-field structure of the sunspot. The transverse component of the potential field is computed by using the observed SOHO/MDI line-of-sight magnetograms. A comparison of the power map and the computed potential field shows enhanced absorption near the umbral – penumbral boundary where the computed transverse field strength is higher. [ABSTRACT FROM AUTHOR]

Using the Lomb-Scargie periodogram we analyzed two sunspot series: the one over the past 11000 years at the 10-year interval based upon the survey data of 14C concentration in tree-rings, reconstructed by Solanki et al.; and the sunspot number over the past 7000 years, derived from geomagnetic variations by Usoskin et al. We found the periods and quasi-periods in solar activity, such as about 225, 352, 441, 522 and 561 a, and near 1000 and 2000 a. An approach of wavelet transform was applied to check the two sunspot time series, with emphasis on investigating time-varying characteristics in the long-term fluctuations of solar activity. The results show that the lengths and amplitudes of the periods have changed with time, and large variations have taken place during some periods. [ABSTRACT FROM AUTHOR]

We present a study of magnetic fields in umbral dots (UDs) and its consequences on the Joule heating of the UDs. Hamedivafa ( Astron. Astrophys. 407, 761, ) studied the Joule heating using the vertical component of the magnetic field. In this paper the magnetic field profile in the UDs is investigated by including a new azimuthal component of the magnetic field that might explain a relatively large enhancement of Joule heating causing higher brightness near the circumference of the UDs. [ABSTRACT FROM AUTHOR]

Abstract: The distributing profile of electric current in solar plasma loop is a key factor for the MHD instabilities of the loops. However, it is very difficult to measure such profile in single loop. In this paper, we assume that, in spite of the complexity of the structure in most of the sunspots, the distribution of the electric current in some small simple sunspots may reflect the main feature of the distribution in solar plasma loops. We utilize the high-cadence, high-resolution vector magnetograms observed by Big Bear Solar Observatory (BBSO) to derive the longitudinal electric current and analyze the distribution of the longitudinal electric current in the region of sunspots, and simulate the distributing features of the solar plasma loops. From these analysis, we find that the electric current in some small simple sunspots, or to say in plasma loops, are concentrated to their center. Such distribution feature is consistent with the theory of pinch effect in current-carrying plasma loops. [Copyright &y& Elsevier]

This paper builds a banking environment where both fundamental runs (that stress macroeconomic variables, such as negative technology shocks, as the cause of bank runs) and sunspot runs (where self-fulfilling expectations generate equilibria where agents panic and run on banks) coexist. A policy of narrow banking will prevent runs, but holding excessively high levels of liquidity will prevent socially productive investment opportunities, and thus will not be optimal. In addition, banks lose their role as intermediaries under this policy. A policy of suspension of convertibility may reduce welfare relative to the case where bank runs are allowed to take place, if the probability of sunspot runs is sufficiently low. [ABSTRACT FROM AUTHOR]