REVIEW: Elemental abundances in the upper solar atmosphere

Elemental abundances in the solar wind (SW) and in solar energetic particles (SEP) are different from abundances in the photosphere. A reassessment of spectroscopic abundance measurements from high temperature solar plasmas [1] showed that, indeed, on the average, the solar upper atmosphere possesses a composition which is similar in nature to the composition of the SW and SEPs. In the last few years a detailed examination of spectra of the upper solar atmosphere has confirmed the above results and proceeded to show that elemental abundances change from region to region by as much as an order of magnitude. An account of these changes, a description of the regions in which the changes occur, and a possible elemental enrichment model is given.