We have statistically analyzed a set of 115 low frequency ( Deca-Hectometer wavelengths range ) type II and type III bursts associated with major Solar Energetic Particle ( SEP : E _ { p } > 10 MeV ) events and their solar causes such as solar flares and coronal mass ejections ( CMEs ) observed from 1997 to 2014 .
We classified them into two sets of events based on the duration of the associated solar flares:75 impulsive flares ( duration < 60 min ) and 40 gradual flares ( duration > 60 min ) .On an average , the peak flux ( integrated flux ) of impulsive flares X2.9 ( 0.32 J m ^ { -2 } ) is stronger than that of gradual flares M6.8 ( 0.24 J m ^ { -2 } ) .
We found that impulsive flare-associated CMEs are highly decelerated with larger initial acceleration and they achieved their peak speed at lower heights ( –27.66 m s ^ { -2 } and 14.23 R _ { o } ) than the gradual flare-associated CMEs ( 6.26 m s ^ { -2 } and 15.30 R _ { o } ) , even though both sets of events have similar sky-plane speed ( space speed ) within LASCO field of view .
The impulsive flare-associated SEP events ( Rt = 989.23 min : 2.86 days ) are short lived and they quickly reach their peak intensity ( shorter rise time ) when compared with gradual flares associated events ( R _ { t } =1275.45 min : 3.34 days ) .
We found a good correlation between the logarithmic peak intensity of all SEPs and properties of CMEs ( space speed : cc = 0.52 , SE _ { c } c = 0.083 ) , and solar flares ( log integrated flux : cc = 0.44 , SE _ { c } c = 0.083 ) .
This particular result gives no clear cut distinction between flare-related and CME-related SEP events for this set of major SEP events .
We derived the peak intensity , integrated intensity , duration and slope of these bursts from the radio dynamic spectra observed by Wind/WAVES .
Most of the properties ( peak intensity , integrated intensity and starting frequency ) of DH type II bursts associated with impulsive and gradual flare events are found to be similar in magnitudes .
Interestingly , we found that impulsive flare-associated DH type III bursts are longer , stronger and faster ( 31.30 min , 6.43 sfu and 22.49 MHz h ^ { -1 } ) than the gradual flare- associated DH type III bursts ( 25.08 min , 5.85 sfu and 17.84 MHz h ^ { -1 } ) .
In addition , we also found a significant correlation between the properties of SEPs and key parameters of DH type III bursts .
This result shows a closer association of peak intensity of the SEPs with the properties of DH type III radio bursts than with the properties DH type II radio bursts , at least for this set of 115 major SEP events .