Abstract Details

Name: Binal Patel
Affiliation: Udaipur Solar Observatory, Physical Research Laboratory
Conference ID: ASI2021_456
Title : Investigation of DH type II solar radio bursts during solar cycle 23 and 24
Authors and Co-Authors : Binal Patel (Physical Research Laboratory), Bhuwan Joshi (Physical Research Laboratory)
Abstract Type : Poster
Abstract Category : Sun and the Solar System
Abstract : Type II solar radio bursts are caused by magneto-hydrodynamic shocks which propagate through the solar corona and interplanetary medium. The type II bursts in decameter-hectometer (DH: 30 MHz ≤ f ≤ 300 kHz) region are of particular interest due to its association with the energetic and wider Coronal Mass Ejections (CMEs) that frequently cause space-weather manifestations. We present the characteristics of DH type II bursts for the solar cycle 23 and 24. The bursts are classified according to their end frequencies into three categories, i.e. High Frequency Group (HFG; 1 MHz ≤ f ≤ 16 MHz), Medium Frequency Group (MFG; 200 kHz ≤ f < 1 MHz ), and Low frequency Group (LFG; 20 kHz ≤ f < 200 kHz). We find that the sources for LFG, MFG, and HFG events are homogeneously distributed over the active region belt. Our analysis shows a drastic reduction of the DH type II events during solar cycle 24 which includes only 35% of the total events (i.e. 179 out of 514). Despite having smaller number of DH type II events in the solar cycle 24, it contains a significantly higher fraction of LFG events (34% vs. 23%). This result suggests that cycle 24 is rich in terms of producing CMEs that are able to drive shocks up to larger heliocentric distances in comparison to cycle 23. The profiles relating CME heights with respect to the end frequencies of type II bursts suggest that for HFG and MFG categories, the location for majority of CMEs (≈ 65%-70%) is in well compliance with ten-fold Leblanc coronal density model, while for LFG events a lower value of density multiplier (≈ 3) seems to be compatible. The properties of the type II associated CMEs and flares are explored for each group in detail for both the solar cycle.