FIG. 12.

Surface UV flux before, during a UV flare plus proton event, and after the flare (solid lines). The top of the atmosphere UV flux at quiescence (dashed black line) and at the peak of the flare (dashed blue line) are drawn for comparison. The dotted line is the surface UV radiation calculated for Earth. Vertical solid lines show the boundaries between the regions known as UVA (3150–4000 Å), UVB (2800–3150 Å), and UVC (<2800 Å). The first 800 s of the flare are omitted here because fluxes are identical to those shown in Fig. 11. Color images available online at www.liebertonline.com/ast.