We report observations of the high frequency type II radio burst (≈430–30 MHz) that occurred in the solar corona on 2015 November 4. The drift rate of the burst, estimated close to the start frequency of its fundamental component (≈215 MHz), is unusually high (≈2 MHz s−1). Our analysis shows that the estimated speed of the magnetohydrodynamic shock driver of the burst varies with time. The peak speed and acceleration are very large, and , respectively. There is spatio-temporal correlation between the type II burst and the associated coronal mass ejection (CME) in the whitelight and extreme-ultraviolet images. The time profile of the shock speed and the light curve of the associated soft X-ray flare correlate well. These results indicate that in the present case, (i) the magnetohydrodynamic shock responsible for the high frequency coronal type II burst is driven by the CME and (ii) the time profile of the type II burst shock speed represents the near-Sun kinematics of the CME.

Forty-one solar type II radio bursts located close to the solar limb (projected radial distance r 0.8 R ) were observed at 109 MHz by the radioheliograph at the Gauribidanur observatory near Bangalore during the period 1997-2007. The positions of the bursts were compared with the estimated location of the leading edge (LE) of the associated coronal mass ejections (CMEs) close to the Sun. 38/41 of the type II bursts studied were located either at or above the LE of the associated CME. In the remaining 3/41 cases, the burst was located behind the LE of the associated CME at a distance of <0.5 R . Our results suggest that nearly all the metric type II bursts are driven by the CMEs.

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We report ground based, low frequency heliograph (80 MHz), spectral MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the 'halo' coronal mass ejection (CME) that occurred in the solar atmosphere on 2013 March 15. The magnetic field strengths (B) near the radio source were estimated to be B ≈ 2.2 ± 0.4 G at 80 MHz and B ≈ 1.4±0.2 G at 40 MHz. The corresponding radial distances (r) are r ≈ 1.9 R ⊙ (80 MHz) and r ≈ 2.2 R ⊙ (40 MHz). Subject headings: Sun -activity: Sun -flares: Sun -corona: Sun -radio radiation: Sun: coronal mass ejections (CMEs): Sun -magnetic topologythe referee for his/her comments that helped to bring out the results more clearly. The SOHO data are produced by a consortium of the Naval Research Laboratory (USA),

We report low-frequency (80 MHz) radio observations of circularly polarized non-thermal type I radio bursts ("noise storms") in the solar corona whose estimated energy is ∼10 21 erg. These are the weakest energy release events reported to date in the solar atmosphere. The plot of the distribution of the number of bursts (dN) versus their corresponding peak flux density in the range S to S + dS shows a power-law behavior, i.e., dN ∝ S γ dS. The power-law index γ is in the range −2.2 to −2.7 for the events reported in the present work. The present results provide independent observational evidence for the existence of picoflare category energy releases in the solar atmosphere which are yet to be explored.