Heating in the solar atmosphere
Global conditions in the solar corona from 2010-2016
Huw Morgan
Youra Taroyan (Aberystwyth University)
Aberystwyth University
Global conditions in the Sun's corona are dictated by the dominant plasma heating mechanisms and have a direct influence on the EUV irradiance of Earth. In the first study of its kind, this work applies recently developed analysis methods to a large dataset to determine mean global coronal conditions over the past 6 years. Processing of several hundred thousand AIA/SDO observations between 2010-2016 shows the mean temperature of the quiet corona rising from 1.17-1.37MK linked to a rise in the mean emission measure (~mass) and mean magnitude of the photospheric magnetic field from 1.9-2.35G. Quiet coronal conditions peak ~3 months following peaks in total active region magnetic field, showing the important influence of decaying active regions on the global corona. Power law relationships support a model of the quiet Sun as an ensemble of hydrostatic loops but cannot distinguish different heating mechanisms. An interesting relationship is shown between active region magnetic field and emission measure. Estimates of EUV irradiance at Earth show domination by the quiet Sun during solar minimum, and a substantial contribution even during maximum. During maximum, the active region contribution becomes dominant, driving a general irradiance increase and large variations. The EUV irradiance at Earth cannot be predicted by an estimate of active region area or sunspot index alone, highlighting the need for continued measurement.
13:30 - 15:00
EX - C3 (150)