Exploring the Properties of Transverse Waves at the Base of the Solar Wind

Transverse (or ‘Alfvénic’) waves are commonly invoked by theories and models to explain coronal heating and solar wind acceleration. However, direct measurements are sparse and most of what we know is derived from indirect proxies for wave activity. In this study, we present a large, statistical study of transverse waves directly observed in coronal plumes between May 2010 and May 2019 by SDO / AIA. The data was processed using an automated version of the Northumbria University Wave Tracking Code (NUWT) and presents a detailed picture of wave properties at the base of the solar wind. We find that the bulk wave parameters within the time periods analysed are largely consistent over most of a solar cycle. However, there is some evidence for smaller-scale variations with height, latitude, and over time periods of a few years. We will also explore the possibility of frequency-dependant processes which may give limits on the height at which wave dissipation, and thereby solar wind acceleration, begins. Lastly, we will give estimates for the total energy flux contained in the waves and discuss how it compares to the energy required to accelerate the solar wind.