On the Unresolved Fine Structures of the Solar Upper Atmosphere. IV. The Interface with the Chromosphere

Abstract

An important objective of the solar physics community is the unambiguous determination of the morphology of the fine structures of the solar upper atmosphere in quiet-Sun and coronal hole regions and the relationship of the cold chromosphere to the hot corona. Recently the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on board the Solar and Heliospheric Observatory succeeded in obtaining observations that can be used to achieve this goal. In this paper we study the spatial relationship between previously unresolved fine structures and the chromospheric emissions that underlie them. The main result is that looplike structures seen in transition region lines with length scales of 10''-20'' straddle the chromospheric network and have no chromospheric counterpart near their apparent footpoints.