A statistical study of long-term evolution of coronal hole properties as observed by SDO

Abstract

The study of the evolution of coronal holes (CHs) is especially important in the context of high-speed solar wind streams (HSS) emanating from them. Stream interaction regions may deliver large amount of energy into the Earths system, cause geomagnetic storms, and shape interplanetary space. By statistically analysing 16 long-living CHs observed by the SDO, we focus on coronal, morphological and underlying photospheric magnetic field characteristics as well as investigate the evolution of the associated HSSs. We use CATCH to extract and analyse CHs using observations taken by AIA and HMI. We derive changes in the CH properties and correlate them to the CH evolution. Further we analyse the properties of the HSS signatures near 1au from OMNI data by manually extracting the peak bulk velocity of the solar wind plasma. We find that the area evolution of CHs mostly shows a rough trend of growing to a maximum followed by a decay. No correlation of the area evolution to the evolution of the signed magnetic flux and signed magnetic flux density enclosed in the projected CH area was found. From this we conclude that the magnetic flux within the extracted CH boundaries is not the main cause for its area evolution. We derive CH area change rates (growth and decay) of 14.2 +/- 15.0 * 10^8 km^2/day showing a reasonable anti-correlation (cc =-0.48) to the solar activity, approximated by the sunspot number. The change rates of the signed mean magnetic flux density (27.3 +/- 32.2 mG/day) and the signed magnetic flux (30.3 +/- 31.5 * 10^18 Mx/day) were also found to be dependent on solar activity (cc =0.50 and cc =0.69 respectively) rather than on the individual CH evolutions. Further we find that the CH area-to-HSS peak velocity relation is valid for each CH over its evolution but revealing significant variations in the slopes of the regression lines.

arXiv commentAccepted at A&A

References in corpus (20)

• Observables Processing for the Helioseismic and Magnetic Imager Instrument on the Solar Dynamics Observatory
• Coronal Holes and Open Magnetic Flux over Cycles 23 and 24
• Statistical Analysis and Catalog of Non-polar Coronal Holes Covering the SDO-era using CATCH
• Preconditioning of interplanetary space due to transient CME disturbances
• Automated Coronal Hole Identification via Multi-Thermal Intensity Segmentation
• Characteristics of Low-Latitude Coronal Holes near the Maximum of Solar cycle 24
• SDO Observations of Magnetic Reconnection at Coronal Hole Boundaries
• The Solar Internetwork. II. Magnetic Flux Appearance and Disappearance Rates
• 3-Phase Evolution of a Coronal Hole, Part I: 360° remote sensing and in-situ observations
• Parameters of the Magnetic Flux inside Coronal Holes
• Photospheric magnetic structure of coronal holes
• Coronal hole boundaries evolution at small scales: I. EIT 195 A and TRACE 171 A view
• The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-Latitude of their Solar Source Coronal Holes
• Estimation of the magnetic flux emergence rate in the quiet Sun from Sunrise data
• Low-latitude coronal holes, decaying active regions and global coronal magnetic structure
• Short-term evolution of coronal hole boundaries
• Dipolar Evolution in a Coronal Hole Region
• 3-Phase Evolution of a Coronal Hole, Part II: The Magnetic Field
• Magnetic Evolution and Temperature Variation in a Coronal Hole
• Interchange reconnection between an active region and a corona hole

Cited by in corpus (15)

• The Sun and Space Weather
• Multi-channel coronal hole detection with convolutional neural networks
• Generic profile of a long-lived corotating interaction region and associated recurrent Forbush decrease
• How the area of solar coronal holes affects the properties of high-speed solar wind streams near Earth -- An analytical model
• Statistical Approach on Differential EmissionMeasure of Coronal Holes using the CATCH Catalog
• Coronal heating and solar wind formation in quiet Sun and coronal holes: a unified scenario
• On the Dependency between the Peak Velocity of High-speed Solar Wind Streams near Earth and the Area of Their Solar Source Coronal Holes
• Influence of coronal hole morphology on the solar wind speed at Earth
• How to Estimate the Far-Side Open Flux using STEREO Coronal Holes
• On the short term stability and tilting motion of a well-observed low-latitude solar coronal hole
• Space weather: the solar perspective -- an update to Schwenn (2006)
• Investigating Ionospheric TEC Variations in Solar and Geomagnetic Influences Across Solar Activity Phases
• Comparative analysis of two episodes of strongly geoeffective CME events in November and December 2023
• Investigating the Relationship Between Physical Properties and Spatial Irregularities at Coronal Hole Boundaries
• Cycle Variation in the Occurrence of Great Soft X-ray Solar Flares