Upflows in the Upper Solar Atmosphere

Spectroscopic observations at extreme- and far-ultraviolet wavelengths have revealed systematic upflows in the solar transition region corona. These are best seen network structures of quiet Sun coronal holes, boundaries active regions, dimming regions associated with mass ejections. They been intensively studied past two decades because they likely to be closely related formation wind heating upper atmosphere. We present an overview characteristics these upflows, introduce their possible mechanisms, discuss potential roles energy transport Although investigations greatly improved our understanding left us several outstanding questions unresolved issues that should addressed future. New from Solar Orbiter mission, Daniel K. Inouye Telescope, Parker Probe will provide critical information advance generation, propagation, energization upflows.