Coronal Holes and Open Magnetic Flux over Cycles 23 and 24

Abstract

As the observational signature of the footprints of solar magnetic field lines open into the heliosphere, coronal holes provide a critical measure of the structure and evolution of these lines. Using a combination of Solar and Heliospheric Observatory / Extreme ultraviolet Imaging Telescope (SOHO/EIT), Solar Dynamics Observatory / Atmospheric Imaging Assembly (SDO/AIA) and Solar Terrestrial Relations Observatory / Extreme Ultraviolet Imager (STEREO/EUVI A/B) extreme ultraviolet (EUV) observations spanning 1996-2015 (nearly two solar cycles), coronal holes are automatically detected and characterized. Coronal hole area distributions show distinct behavior in latitude, defining the domain of polar and low-latitude coronal holes. The northern and southern polar regions show a clear asymmetry, with a lag between hemispheres in the appearance and disappearance of polar coronal holes.

Accepted for publication in Solar Physics

References in corpus (2)

• Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features
• Measurements of EUV Coronal Holes and Open Magnetic Flux

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• Stirring the Base of the Solar Wind: On Heat Transfer and Vortex Formation
• Machine-learning approach to identification of coronal holes in solar disk images and synoptic maps
• How to Estimate the Far-Side Open Flux using STEREO Coronal Holes
• Rearrangements of Open Magnetic Flux and Formation of Polar Coronal Holes in Cycle 24
• The Merging of a Coronal Dimming and the Southern Polar Coronal Hole
• Straight outta photosphere: Open solar flux without coronal modeling
• Magnetic Field-Constrained Ensemble Image Segmentation of Coronal Holes in Chromospheric Observations
• Tracing Field Lines That Are Reconnecting or Expanding or Both
• Existence of The Closed Magnetic Field Lines Crossing The Coronal Hole Boundaries