34th Solar Physics Division Meeting, June 2003
Session 5 Coronal Mass Ejections I
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[5.06] Analysis of Onset Times between CMEs and Associated DH Type II Bursts

A.M. Rosas (CUA), N. Gopalswamy (NASA/GSFC), S. Yashiro (CUA), M.L. Kaiser (NASA/GSFC), R.L. Howard (NRL)

An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented.The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric,DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO).The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We find that 91% of CMEs have speeds greater than 450 km/s and 94% have angular widths greater than 60 degrees obtained from SOHO/LASCO C2 and C3 CME measurements.We made a linear and quadratic fit using CME height time measurements to extrapolate CME onset times to 2 and 1 solar radius. We find that the quadratic onset times (QOTs) illustrates less scatter in the difference times (CME onset time - DH onset time) than the linear onset times (LOTs). Both the QOT and LOT for 1 solar radius shows that ~ 80% DH type II bursts occurred within 1 hour of CME onset time and for 2 solar radius extrapolation shows ~ 87%. Correlation coefficients were found to be very weak between difference times and CME longitude, speed, angular width, and DH type II starting frequency. We are continuing to investigate the outlier (DH type II bursts occurring more than 2 hours after CMEs) events.(1) The onset times and starting frequency of DH type IIs with respect to CME onset times provides insight into the coronal density distribution.(2) The relationship between CME onset time and the occurrence of the DH type II will be discussed in terms of the radial distribution of the Alfven speed near the Sun.

This work is supported by NASA living with a Star and NSF/SHINE (ATM 0204588) and AFOSR Programs.

The author(s) of this abstract have provided an email address for comments about the abstract: arosas@cspsw1.gsfc.nasa.gov

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