WITHDRAWN: High-Resolution Radiometer for Remote Sensing of Solar Flare Activity from Low Earth Orbit Satellites

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The Dependence between Solar Flare Emergence and the Average Background Solar X-Ray Flux Emission

Solar flares, sudden bursts of intense electromagnetic radiation from the Sun, can significantly disrupt technological infrastructure, including communication and navigation satellites. To mitigate these risks, accurate forecasting of solar activity is crucial. This study investigates the potential of the Sun’s background X-ray flux as a tool for predicting solar flares. We analyzed data collected by solar telescopes and satellites between the years 2013 and 2023, focusing on the duration, frequency, and intensity of solar flares. We compared these characteristics with the background X-ray flux at the time of each flare event. Our analysis employed statistical methods to identify potential correlations between these solar phenomena. The key finding of this study reveals a significant positive correlation between solar flare activity and the Sun’s background X-ray flux. This suggests that these phenomena are interconnected within the framework of overall solar activity. We observed a clear trend: periods with increased occurrences of solar flares coincided with elevated background flux levels. This finding has the potential to improve solar activity forecasting. By monitoring background flux variations, we may be able to develop a more effective early warning system for potentially disruptive solar flares. This research contributes to a deeper understanding of the complex relationship between solar flares and the Sun’s overall radiative output. These findings indicate that lower-resolution X-ray sensors can be a valuable tool for identifying periods of increased solar activity by allowing us to monitor background flux variations. A more affordable approach to solar activity monitoring is advised.

Microwave Type U and RS Bursts in the X2.2 Solar Flare on 15 February 2011

Two groups of microwave type U and Reverse-Slope(RS)bursts after the Soft X-Ray(SXR)maximum were observed with the 2.6~3.8GHz spectrometer of Chinese Solar Broadband Radio Spectrometers(SBRS/Huairou)on 15 February 2011,when an X2.2 solar flare occurred in the Active Region(AR)NOAA 11158.A Shear-driven Quadrupolar Reconnection(SQR)model was utilized to analyze these bursts and the two loops involved were found to be basically in the same spatial scale and have a height difference of about 1300 km.These bursts were interpreted to be a result of a new reconnection process between the two similar-scaled loops.

Energy and spectral analysis of confined solar flares from radio and X-ray observations

The energy and spectral shape of radio bursts may help us understand the generation mechanism of solar eruptions,including solar flares,coronal mass ejections,eruptive filaments,and various scales of jets.The different kinds of flares may have different characteristics of energy and spectral distribution.In this work,we selected 10 mostly confined flare events during October 2014 to investigate their overall spectral behaviour and the energy emitted in microwaves by using radio observations from microwaves to interplanetary radio waves,and X-ray observations of GOES,RHESSI,and Fermi/GBM.We found that:all the confined flare events were associated with a microwave continuum burst extending to frequencies of9.4~15.4 GHz,and the peak frequencies of all confined flare events are higher than 4.995 GHz and lower than or equal to 17 GHz.The median value is around 9 GHz.The microwave burst energy(or nuence)and the peak frequency are found to provide useful criteria to estimate the power of solar flares.The observations imply that the magnetic field in confined flares tends to be stronger than that in 412 flares studied by Nita et al.(2004).All 10 events studied did not produce detectable hard X-rays with energies above~300 keV indicating the lack of efficient acceleration of electrons to high energies in the confined flares.

AR5629:A GREAT SOLAR RADIO OUTBURST ON AUGUST 15,1989

The great solar radio outburst without millisecond radio spikes on 15 August, 1989 was analysed and some significant results were given.

THE PROGRESS IN THE RESEARCH ON RADIO RAPID FLUCTUATION IN SOLAR FLARES FOR THE LAST YEAR

The research on‘Rapid Fluctuation in Solar Flares’is paid great attention becauseof its important position in the solar flare physics,and it is also one of the importantparts in the project“22 MAX GLOBAL CHARACTER RESEARCH OFSOLAR—TERRESTRIAL SYSTEM”.The Solar Radio High Time

Detection of solar radio burst intensity based on a mod ified multifactor SVM algorithm

To realize the automatic detection of solar radio burst(SRB)intensity,detection based on a modified multifactor support vector machine(SVM)algorithm is proposed.First,the influence of SRB on global navigation satellite system(GNSS)signals is analyzed.Feature vectors,which can reflect the SRB intensity of stations,are also extracted.SRB intensity is classified according to the solar radio flux,and different class labels correspond to different SRB intensity types.The training samples are composed of feature vectors and their corresponding class labels.Second,training samples are input into SVM classifiers to one-against-one training to obtain the optimal classification models.Finally,the optimal classification model is synthesized into a modified multifactor SVM classifier,which is used to automatically detect the SRB intensity of new data.Experimental results indicate that for historical SRB events,the average accuracy of SRB intensity detection is greater than 90%when the solar incident angle is higher than 20°.Compared with other methods,the proposed method considers many factors with higher accuracy and does not rely on radio telescopes,thereby saving cost.

Radio Fiber Fine Structure During the Solar Flare on July 14, 2000

On July 14, 2000, a type IV solar radio burst was observed at 10:43-11:00 UT with the 1-2 GHz digital spectrometer of National Astronomical Observatories of China (NAOC). Many fiber fine structures superposed on the type IV burst were detected in the same interval. A theoretical interpretation for the fibers is performed based upon a model of magnetic-mirror loop configuration in the solar corona. In this model, the source of the fiber emission is considered as the ducting of whistler solitons within the magnetic-mirror loop. A quantitative estimation using the observed data indicats that the magnetic field strength of the radio source is about 1.451×10 -2≤B 0≤2.734×10 -2 T, and that a fiber is composed of 4×10 15 solitons occupying a volume of about 1.2×108 km3. For the duct through which the whistler solitons passed within the magnetic-mirror loop, its diameter and the length are worked out, namely, d≈120 km and Δr≈104 km, respectively.

Evidence for a Strong Correlation of Solar Proton Events with Solar Radio Bursts

A statistical analysis is made on the correlation between solar proton events with energies >10Mev and solar radio bursts during the four-year period from 1997 November to 2000 November. We examine 28 solar proton events and their corresponding solar radio bursts at 15400, 8800, 4995, 2695, 1415, 606, 410 and 245 MHz. The statistical result shows that there is a close association between solar proton events and ≥3 solar radio bursts occurring at several frequencies, one or two days before. In particular, it is noteworthy that proton events occurring in pairs within the same month are preceded 1-2 days by individual radio bursts and most of the radio bursts of solar flares occur at all eight frequencies. Those 245 MHz radio bursts associated with proton events have intense peak fluxes (up to 67000 sfu). Solar proton events are preceded 1 or 2 days by≥ 3 radio bursts at several frequencies and proton events occurring in pairs within the same month are preceded 1 or 2 days by some individual radio bursts. These correlations may be used for providing short-term or medium-term prediction of solar proton events.

Solar Radio Burst Automatic Detection Method for Decimetric and Metric Data of YNAO

With the development of solar radio spectrometer, it is difficult to process a large number of observed data quickly by manual detection method. Yunnan astronomical observatories (YNAO) have two solar radio spectrometers with high time and frequency resolution. An automatic detection method of solar radio burst for decimetric and metric data of YNAO is proposed in this paper. The duration of solar radio burst was counted and analyzed. Channel normalization was used to denoise the original solar radio image. Through experimental comparison, Otsu method was selected as a binary method of solar radio spectrum, and open and close operations were used to smooth the binary image. Experiments show that the proposed method for automatic detection of solar radio bursts is effective.

LSTM neural network for solar radio spectrum classification

A solar radio spectrometer records solar radio radiation in the radio waveband. Such solar radio radiation spanning multiple frequency channels and over a short time period could provide a solar radio spectrum which is a two dimensional image. The vertical axis of a spectrum represents frequency channel and the horizontal axis signifies time. Intrinsically, time dependence exists between neighboring columns of a spectrum since solar radio radiation varies continuously over time. Thus, a spectrum can be treated as a time series consisting of all columns of a spectrum, while treating it as a general image would lose its time series property. A recurrent neural network(RNN) is designed for time series analysis. It can explore the correlation and interaction between neighboring inputs of a time series by augmenting a loop in a network.This paper makes the first attempt to utilize an RNN, specifically long short-term memory(LSTM), for solar radio spectrum classification. LSTM can mine well the context of a time series to acquire more information beyond a non-time series model. As such, as demonstrated by our experimental results, LSTM can learn a better representation of a spectrum, and thus contribute better classification.

OBSERVATION OF SOLAR RADIO EMISSION AT 3.2cm WAVELENGTH AT UAS

Ⅰ.INTRODUVTION This paper made preliminaily reduction of the data which we observed in March1989 at the active region AR5395. I list a part of microwave bursts and draw out a few oftime profiles at the end of the paper.

Multi-wavelength study of energetic processes during solar flare occurrence

This paper is an attempt to understand the physical processes occurring in different layers of the solar atmosphere during a solar flare.For a complete understanding of the flare,we must analyze multiwavelength datasets,as emission at different wavelengths originates from different layers in the solar atmosphere.Also,flares are transient and localized events observed to occur at all longitudes.With these considerations,we have carried out multi-wavelength analysis of two representative flare events.One event occurred close to the center of the solar disk and the other occurred close to the limb.In the former case,we examine emission from the lower layers of the solar atmosphere.Therefore the chromosphere,transition region and also photospheric magnetogram can be analyzed.On the other hand,in the near-limb event,coronal features can be clearly examined.In this paper,the first event studied is the M1.1 class flare from the active region NOAA 10649 located at S10 E14 and the second event is the M1.4 class flare from the active region 10713 located at S12 W90.In both cases,we have acquired excellent multi-wavelength data sets.The observations from multi-instrumental data clearly demonstrate that flares occur in the vicinity of sunspots.These are regions of strong magnetic field with mixed polarity.

Solar Activity during the Rising Phase of Solar Cycle 24

Solar activity refers to any natural phenomenon occurring on the sun such as sunspots, solar flare and coronal mass ejection etc. Such phenomena have their roots deep inside the sun, where the dynamo mechanism operates and fluid motions occur in a turbulent way. It is mainly driven by the variability of the sun’s magnetic field. The present paper studies the relation between various solar features during January 2009 to December 2011. A good correlation between various parameters indicates similar origin.

Total Solar Flux Intensity at 11.2 GHz as an Indicator of Solar Activity and Cyclicity

In this paper we present an overview of solar radio observations at 11.2 GHz on Mets?hovi Radio Observatory (MRO). The data were observed during the solar cycles 23 and 24 (2001-2013) both in solar maxima and minimum. In total, 180 solar radio bursts, with varying intensities and properties, were observed. We compare our data series with other similar data sets. A good correlation can be found between the data series. It is concluded that one can conduct scientifically significant solar radio observations with a low cost instrument as the one presented in this paper.

Cosmic Ray Associated with Coronal Index and Solar Flare Index during Solar Cycle 22 - 23

We study the relation between monthly average counting rates of the cosmic ray intensity (CRI) observed at Moscow Neutron Monitoring Station, solar flare index (SFI) and coronal index during the solar cycles 22 and 23, for the period 1986-2008. The long-term behaviour of various solar activity parameters: sunspot numbers (SSN), solar flare index (Hα flare index), coronal index (CI) in relation to the duration of solar cycles 22 and 23 is examined. We find that the correlation coefficient of CRI with the coronal index as well as Hα flare index is relatively large anti-correlation during solar cycle 22. However, the monthly mean values of sunspot number, Hα flare index, and coronal index are well positively correlated with each other. We have analyzed the statistical analysis of the above parameters using of linear model and second order polynomial fits model.

Calculation of ¹⁰Be &¹⁴C Production Rates in the Solar Atmosphere: Implications for Solar Flare Spectral Index

Production rates for the short-lived radionuclides 10Be (T1/2=1.36Myr) and14C(T1/2=5730 yr) in the solar atmosphere were calculated. As both radionuclides are produced through spallation reaction of solar energetic particles (SEP) with oxygen as the primary target, the prevalence of each radionuclide is linked. For the calculations, we assumed power law distribution for SEP with spectral index, r, ranging from 2.5 to 4. We find the 10Be and14Cflux rate at the surface of the Sun to range from 0.007 cm﹣2.s﹣1 to 2.55 cm﹣2.s﹣1 for 10Be, and from 0.13 cm﹣2.s﹣1 to 24.13 cm﹣2.s﹣1 for14C. These radio-nuclides are then entrained in the solar wind. From these flux rate calculations and comparison with experimentally measured flux rates ,we find the most likely time averaged solar flare spectral index to be r = ~3.3.

THE CHARACTERISTICS AND INTERPRETATION OF H_α LIMB FLARE AND RADIO BURST ON AUG. 16,1989 IN AR 5629

We observed completely a large burst event produced in AR 5629 at the west limb of the Sun using chromospheric and 3 cm radio telescopes. We used Kopp-Pneuman and Sturrock models to interpret the event.

Solar Influences on the North Atlantic Oscillation by Wavelet-Based Multifractal Analysis

There is increasing interest in the relation between the solar activity and climate change. Regarding the solar activity, the fractal property of the sunspot number (SSN) has been studied by many previous works. In general, fractal properties have been observed in the time series of the dynamics of complex systems. The purpose of this research is to investigate the relationship between the solar activity, total ozone, and the North Atlantic Oscillation (NAO) from a viewpoint of multi-fractality. To detect the changes of multifractality, we performed the wavelets analysis, and plotted the τ-function derived from the wavelets of these time series. We showed that the solar activity relate to the NAO, by observing the matching in monofractality or multifractality of these indices. When the SSN increased and the solar activity was stable, the NAO also became stable. When the SSN became maximum, the fractality of the SSN, F10.7 flux, geomagnetic aa, and NAO indices changed from multifractality to monofractality and those states became stable for most of the solar cycles. When the SSN became maximum, the fluctuations became large and multifractality became strong, and a change from multifractal to monofractal behavior was observed in the SSN, F10.7 flux, geomagnetic aa, and NAO indices. The strong interactions of the solar flux, geomagnetic activity, total ozone, and NAO occur in the SSN maximum. The strong interactions were inferred from the similarity of fractality changes and the wavelet coherence. The influence of the solar activity on the NAO was shown from a viewpoint of multi-fractality. These findings will contribute to the research on the effects of the solar activity on climate change.

太阳耀斑对无线电导航通信的影响

太阳耀斑是太阳最剧烈的活动,其喷射的X射线和高能粒子可对无线电导航和通信系统产生很大的影响.分析了太阳耀斑爆发后,影响无线电导航通信系统的机理和过程.耀斑可造成无线电导航定位系统的定位精度下降甚至失效、无线电通信噪声和误码率增大甚至通信中断.提出了降低太阳活动对导航和通信影响的一些应对措施.