Characteristics of flares with H alpha emission protruding over major sunspot umbrae

A sample of 47 importance greater than or equal to 1 flares whose H alpha e mission occurred or protruded over umbrae of major sunspots (so called Z-fl ares) was studied to investigate characteristics of the associated dm - m r adio, microwave and soft X-ray emission as the energy release site permeats into regions of strong magnetic fields. A close time association was found between the microwave burst peak and the 'contact' of the H alpha emission with the sunspot umbra. The H alpha emission attained maximum close to or a few minutes after the contact. The soft X-ray bursts were delayed more, a ttaining maximum 0-10 min after the contact. The onset of bursts in the dm- m wavelength range was associated with the period of growth or the peak of the microwave burst. Two categories of type III and TV bursts could be reco gnized: the ones starting some ten minutes before the microwave peak, and t hose that begin close to the microwave burst peak. Type III bursts occur pr eferably when the microwave burst peaks simultaneously with or after the co ntact. The results are explained presuming that the contact reveals a perme ation of the energy release process into a region of strong magnetic fields , where the process intensifies, and where the accelerated particles have a ccess to magnetic field lines extending to large coronal heights. Different manifestations of the energy release process in various magnetic field top ologies are considered to account for the various time sequences observed.