Peak-flux-density spectra of large radio bursts and proton emission from flares. Environmental research papers, July 1981-July 1985

Technical Report · Mon Aug 19 04:00:00 EDT 1985

OSTI ID:5147350

Cliver, E W; McNamara, L F; Gentile, L C

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, the authors 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% 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%). (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 the data base (1965-1979), the U-burst yes or no proton event forecast tool would have had a false alarm rate of approx. 50% and would have failed to provide a warning for approx. 50% 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% of the microwave bursts with u-shaped spectra, the 200 MHz emission peak occurred during a Type III event. For 49% 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 < or = 300 sfu) and associated 200-MHz emission.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5147350
• Report Number(s): AD-A-169134/4/XAB; AFGL-TR-85-0180
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics &amp; Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
FLUX DENSITY
FORECASTING
HADRONS
NUCLEONS
PROTONS
RADIATIONS
RADIOWAVE RADIATION
SOLAR ACTIVITY
SOLAR FLARES
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR RADIO BURSTS
SPECTRA
STELLAR RADIATION
VISIBLE SPECTRA