Studies on Longer Wavelength Type II Radio Bursts Associated with Flares and CMEs during the Rise and Decay Phase of 23rd Solar Cycle

A statistical study on the properties of CMEs and flares associated with DH-type II bursts in the 23rd solar cycle during the period 1997–2008 is carried out. A sample of 229 events from our recent work is used for the present study (Vasanth and Umapathy, 2013). The collected events are divided into two groups as (i) solar cycle rise phase events and (ii) solar cycle decay phase events. The properties of CMEs in the two groups were compared and the results are presented. It is noted that there is no difference in the properties of type II burst like start frequency and end frequency between the solar cycle rise phase events and decay phase events. The mean CME speed of solar cycle decay phase events (1373 km s−1) is slightly higher than the solar cycle rise phase events (1058 km s−1). The mean CME acceleration of solar cycle decay phase events (−15.18 m s−2) is found to be higher than that of the solar cycle rise phase events (−1.32 m s−2). There exists good correlation between (i) CME speed and width and (ii) CME speed and acceleration for solar cycle decay phase events (R=0.79, R=-0.80) compared to solar cycle rise phase events (R=0.60, R=-0.57). These results indicate that the type II bursts parameters do not depend upon the time of appearance in the solar cycle