Intermediate drift bursts and the coronal magnetic field

We have analyzed 12 decimetric continuum (type TV) events during solar flares showing intermediate drift (IMD) fine structures in the 1 - 3 GHz band. This is the first time IMD patterns have been reported above 1 GHz and that the full spectrum of both continuum and IMD bursts has been covered. The IMD pattern was usually shifted to higher frequency and tends to occur later than the continuum. Average drift rates of IMD bursts per event were found by cross-correlation yielding (v) overdot/v = -0.167 to -0.046 s(-1). The average second derivative of individual IMD bursts expressed as (v) double over dot(v) over dot(-2)v is 0.42 to 4.9. Normalized by the mean frequency, these high-frequency PMD bursts are found to be identical in their characteristics with this type of bursts below 1 GHz. The derived burst parameters require an important change in one of the two existing theories.