Evidence of chromospheric evaporation in the 2004 december 1 solar flare

In this paper, we present the radio and hard X-ray evidence of chromospheric evaporation during an M1.0 flare which occurred on 2004 December 1. The radio emission was observed by the Solar Broadband Radio Dynamic Spectrometer in China, which yielded dynamic spectra of decimetric emission. The hard X-ray emission was observed by RHESSI. In the radio spectra, the burst is characterized by two groups of parallel-drifting structures, some of which change their drifting rates from positive to negative. Based on the standard flare model, we may explain these decimetric bursts in terms of chromospheric evaporation. On the other hand, RHESSI observations show that the hard X-ray emission in the energy range of 10-15 keV tends to rise from two footpoints to the looptop and eventually merges into a single looptop source, which is accepted as evidence of hard X-ray chromospheric evaporation. Such processes happened twice in this event. The drifting radio structures occurred between them, at the same time as the third hard X-ray peak was observed at 25-50 keV.