Chromospheric Evaporation in Solar Flares

Abstract

Chromospheric evaporation suggests the mass upflows from chromosphere to corona after the electron heating at the chromosphere during the solar flares. It takes place at the rising phase, and has a typical timescale about 100 s and a typical speed about 300–400 km s^-1. Such characteristics are well observed as the blueshift at the spectral lines. By the way, the facts of the high-frequency cutoff negatively drifting on the radio dynamic spectra and the hard X-ray footpoint source motions along the loop legs are also thought to be the signatures of the chromosphere evaporation. In this paper, we show the observational evidences of the chromospheric evaporation at radio, EUV and X-ray emissions.