The Relationship of the Chromosphere to the Lower Solar Transition Region

Abstract

We examine the intensity correlations among lower transition region emission lines of N III, N IV, N V, O II, O III, O IV, O V, S IV, and S V. We find strong intensity correlations, with 1 σ deviations in line intensity ratios less than about 35% on spatial scales of 1''. For strong lines the percent deviations are significantly less than this. The line intensities were obtained from the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO). We find a dependence of the O II/O III and O V/N V ratios with intensity. The degree of correlation we obtain on arcsecond spatial scales is consistent with size scales for the basic transition region structures that are significantly less than 1'' (730 km).