Download or read book Peak flux density Spectra of Large Solar Radio Bursts and Proton Emission from Flares written by Edward W. Cliver and published by . This book was released on 1985 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have reexamined the relationship between U-shaped peak-flux-density microwave spectra and solar proton events for approx 200 large (Sp(> or = 2GHz) > or = 800 solar flux uits (sfu) microwave burst (1965 - 1979). The radio spectra fell into two basic classes: (a) U-shaped with two maxima ( > or = 800 sfu) in the range from 200 MHz to > or = 10 GHz (59 percent of all events), and (b) cutoff spectra with a maximum > or = 800 sfu at f > or = 2 GHz and Sp (200 MHz) 100 sfu (18 percent). Nine percent of the events had intermediate spectra with a maximum or = 800 sfu at f > or = 2 GHz and 100 sfu or = Sp (200 MHz) 800 sfu. We were unable to classify 15 percent of the events because of incomplete data. The associations of the three classes of spectra with Type II (and/or Type IV) meter wavelenght bursts and 10 MeV proton events of any size ( or = 0.01 pr per sq cm per sec per sr) are as follows: U-shaped Type II/IV (90 percent of large microwave bursts with U-shaped spectra are associated with Type II/IV events), protons (77 percent); intermediate Type II/IV (78 percent), protons (73 percent); and cutoff Type II/IV (22 percent), protons (33 percent). These statistics affirm various lines of evidence linking coronal shock waves and interplanetary proton events. They also suggest that the meter wavelength branch of the U-shaped spectrum may be attributable to second phase (vs flash phase) accelerated electrons.
Download or read book Peak flux density Spectra of Large Solar Radio Bursts and Proton Emission from Flares written by Edward W. Cliver and published by . This book was released on 1985 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Peak Flux Density Spectra of Large Solar Radio Bursts and Proton Emission from Flares written by and published by . This book was released on 1900 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Peak Flux Density Spectra of Large Radio Bursts and Proton Emission from Flares written by E. W. Cliver and published by . This book was released on 1985 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: From this study of the peak flux density spectra of nearly 200 large (sp> or = 2 GHz)> or = 800 solar flux units) microwave bursts and their associated proton and sweep frequency emissions, we have found the following: (1) There appear to be two basic peak-flux-density spectral types: (a) U-shaped, with two maxima> or = 800 sfu in the range of 200 MHz to> or = 19 GHz (59 percent of all events) and (b) cutoff, with a spectral maximum> or = 800 sfu at f> or = 2 GHz and Sp(200 MHz) 100 sfu (18 percent). (2) If the current NOAA proton prediction threshold of J ( 10 MeV)> or = 10 protons/sq cm/sec/sr had been in effect during the period covered by our data base (1965-1979), the U-burst ' yes or no' proton event forecast tool would have had a false alarm rate of approx. 50 percent and would have failed to provide a warning for approx. 50 percent of the significant prompt proton flares attributable to disk flares during this period. (3) The associations of flare-bursts of different peak flux density spectral type with Type II and/or Type IV bursts and with> 10-MeV proton events of any peak intensity are given. (4) In 74 percent of the microwave bursts with u-shaped spectra, the 200 MHz emission peak occurred during a Type III event. For 49 percent of the U-bursts, a Type II was in progress during, or began or = 0.5 min after, the peak 200-MHz emission. (5) Several (8 of 46) of the proton events with J ( 10 MeV)> or = 10 protons/sq cm/sec/sr (1965-1979) originated in visible hemisphere flares with relatively weak (Sp
Download or read book The Role of the Big Flare Syndrome in Correlations of Solar Energetic Proton Fluxes and Associated Microwave Burst Parameters written by S. W. Kahler and published by . This book was released on 1981 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: In previous studies correlating E> 10 MeV proton fluxes and spectra with various associated microwave burst parameters, the resulting high correlations were assumed to reflect a common acceleration process for the protons and the microwave-emitting electrons. We suggest and test an alternative explanation for these correlations, which we term the Big Flare Syndrome (BFS), that states that, statistically, energetic flare phenomena are more intense in larger flares, regardless of the detailed physics. Peak 1-8 A X-ray fluxes, characteristic of the thermal flare, are correlated with peak proton fluxes to derive correlation coefficients characteristics of the BFS. Of all microwave parameters tested for the 1973-1979 period, only the time-integrated flux densities at 8800 and 15400 MHz may be significantly larger than expected form the BFS. We fail to confirm previous results associating peak proton spectra with peak microwave spectral characteristics, thus finding no evidence that peak microwave fluxes are indicative of proton acceleration. We extend this conclusion to peak hard X-ray correlations. The strongly nonlinear relationship deduced between flare energy and proton production also appears invalid.
Download or read book The Great Burst of May 23 1967 written by John P. Castelli and published by . This book was released on 1967 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the largest radio bursts on record took place on May 23, 1967. Peak flux densities ranged between 23,000 flux units (10 to the minus 22nd power sq Wm/Hz) at 8800 MHz to about 370,000 units at 606 MHz. In addition to the high accuracy measurements of the peak flux densities at 606, 1415, 2695, 4995, and 8800 MHz, sweep frequency observations from 19 to 41 MHz show Type IV emission with Type II bursts occurring during the Type IV continuum. The associated flare was clearly visible in white light. In reviewing and compiling microwave radio data recorded during earlier white-light flares, it was found that all but one of eight events listed by Svestka (1966) had high microwave flux densities associated with them. In comparing radio burst intensity with optical flare importance for the series of three flares between 1809 and 2150 UT on May 23, 1967, there is only moderate agreement. The first radio burst was small; the second flare had the highest optical classification, while the third radio burst was by far the largest. The flux densities of the third radio burst may have been the highest ever recorded in the decimeter portion of the radio spectrum and among the largest four in the 8800 MHz region. It is suggested that the details of the development of the flare be followed on radio flux density plots to determine detailed correlation with particle events in space and with terrestrial effects. (Author).
Download or read book The Prediction of Solar Proton Events Based on Solar Radio Emissions written by William E. O'Brien and published by . This book was released on 1970 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The short-term prediction of solar proton events based on a distinct U-shaped radio burst signature is verified. The prediction techniques uses peak flux density values of discrete frequency solar radio burst observations in the 100 to 10,000 MHz region. The criteria are applied to all major proton events from 1952 to 1969 and afford almost total success in predicting near-earth particle events that eminated from visible hemisphere regions of the sun. A correlation between U-shaped radio burst signatures and solar proton events as detected by the ATS-1 satellite, during 1967 and 1968, is also shown to be highly successful. Finally, a 'modified' U-shaped criterion is set forth for the accurate short-terms prediction of polar cap absorption events that result in at least a 2.0 dB riometer measurement of absorption. This 'modified' spectral configuration is then correlated with the major absorption events of the current solar cycle and it is found that prediction occurred for all principal PCA events that originated from visible solar hemisphere flares. (Author).
Download or read book Observation and Forecasting of Solar Proton Events written by John P. Castelli and published by . This book was released on 1968 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar burst characteristics in the radio microwave region are used to differentiate between large flares that might produce proton events and those that might not. Proton events produce high-level absorption, disrupt polar communications, and can be dangerous to man and equipment in space. They may precede the auroral and magnetic storms that disturb many radiowave propagation systems. The probability of a proton event can now be predicted, an AFCRL study of the characteristics of flare-associated centimeter radar bursts having established that a signature of proton events is a high flux density in the 3-cm region and a particular burst peak flux spectral configuration. (Author).
Download or read book Solar Flares written by Zdenek Svestka and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first part of the originally planned publication by Z. Svestka and L. D. de Feiter 'Solar High Energy Photon and Particle Emission'. The second part, with the original title, was to be published by de Feiter in about one year from now. However, to the deep sorrow of all of us, Dr de Feiter died suddenly and unexpectedly when the present book was in print. Thus, unfortunately, de Feiter's second part may not appear. Due to the fact that the originally planned publication was divided into two parts, the present book is mainly descriptive and concerned with the flare morphology. It was expected that theoretical interpretations would be extensively developed in the second part, prepared by de Feiter. In particular, this refers to the theoretical back grounds of radio emissions, particle acceleration and particle propagation in space. Only in Chapter II, concerning the 'low-temperature' flare, do we go deeper into the theoretical interpretations, anticipating that de Feiter would have been concerned mainly with the 'high-energy' physics. Still, the book includes discussions on all important aspects of flares and thus can present the reader with a complete picture of the complex flare phenomenon. It is clear that many observed data on flares can be interpreted in different ways.
Download or read book Ionospheric Effects of Solar Flares written by Hermine Vloemans and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sudden Ionospheric Disturbances resulting from an interaction of the Solar Flare radiation with the constituents of the upper atmosphere constitute one of the three major aspects of ground level monitoring of solar flares -the other two being optical observations of flares, and the observations of solar bursts in radio wavelengths. SIDs, therefore, form a major part of flare monitoring programme in many observatories. Unlike the other two, however, the ionospheric effects of flares provide one major additional source of interest - the reaction of the ionospheric plasma to an impulsive ionization. The high atmosphere provides a low pressure laboratory without walls in which a host of reactions occur between electrons, ions and neutral particles. The resulting products and their distributions may bear no resemblance to those of the primary neutral constituents or their direct ionization products. The variations with the time of the day, with season and with solar activity that form the bulk of the ionospheric measurements are too slow to allow any insight into the nature of these ionospheric reactions whose lifetimes are often very short. The relaxation time of the ionospheric ionization is only a few minutes or fraction of a minute in the lower ionosphere and in the E-region and is about 30 min to an hour at 300 km. The flares provide a sudden short impulse comparable to these time scales.
Download or read book Using Solar Radio Burst Integrated Fluxes to Predict Energetic Proton Flux Increases written by William R. Barron and published by . This book was released on 1982 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-integrated solar ratio fluxes and their association with satellite observed solar energetic proton flux increases have been studied. The time-integration was only of the U-portion of the radio burst flux increase. The best correlations between the integrated radio fluxes and the proton peak fluxes were realized when the radio fluxes were multiplied by the factor exp (-3B), where B is the angular distance, in radians, between the site of the flare and the solar footpoint of the magnetic field connection between the sun and the earth. The solar footpoint positions were determined from the solar wind speed. Two-variate linear regressions were computed using the time-integrated radio fluxes at five discrete radio frequencies in the 606 to 8800 MHz frequency interval and peak proton fluxes at > 10 MeV and > 30 MeV. The higher frequencies of 2695, 4995 and 8800 MHz all correlated better with the > 10 -MeV protons than the lower frequencies. The > 30-MeV protons were even better correlated with the higher frequencies, but correlation with the lower frequencies were poorer. The Total Energy Density, E sub T, of the radio burst, an integration across the frequency interval of the time-integrated radio fluxes at each frequency, was found to be better correlated with the proton fluxes than any of the individual frequencies.
Download or read book On the Classification Distribution and Interpretion sic of Solar Microwave Burst Spectra and Related Topics written by John P. Castelli and published by . This book was released on 1972 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report discusses the classification, distribution, and interpretation of the peak flux-density spectra of solar radio bursts in decimenter-centimeter range (1m to 1cm). It is based on observations at discrete frequencies between 245 and 35000 MHz taken at the Sagamore Hill Radio Observatory, Hamilton, Mass., through the years 1966-1969. The peak flux-density spectra of over 2000 radio bursts were used in this investigation. (Author).
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Forecasting Peak Proton Flux and PCA Event Magnitudes Using flash phase Integrated Radio burst Flux Density written by David T. Newell and published by . This book was released on 1972 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new parameter is introduced for use in forecasting the magnitudes of solar proton and polar cap absorption events. Semi-integrated flux density is the integrated radio flux density under the start-to-maximum burst curve. An approximation to this function was correlated at five operational frequencies against both observed peak proton flux and observed riometer absorption, obtaining correlation coefficients > or = 0.88 at frequencies between 2695- and 8800-MHz. An operational real-time forecast scheme is detailed for the solar forecaster. Results from this study, which uses peak proton fluxes both corrected and uncorrected for solar disk positions, indicate that forecasts have a higher degree of correlation with observations if propagation corrections are not applied as present methods dictate. When used in conjunction with the Castelli 'U' burst spectrum criteria for forecasting the occurrence of proton events, radio data can be used exclusively for both a yes/no and an event magnitude forecast. A comparison with the method presently in use at the Air Weather Service's Aerospace Environmental Support Center, Solar Forecast Branch is made with very favorable results. (Author)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Literature 1979 Part 1 written by Siegfried Böhme and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics of Solar Flares written by Wilmot N. Hess and published by . This book was released on 1964 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
