Catalogue of Newly Emerging Coronal Holes during Solar Cycle 24, 2010-2019

Authors: Akash Vinod Shirke¹, Khagendra Katuwal² ¹ Department of Physics, UPES, Energy Acres, Dehradun, Uttarakhand, 248007, India ² Department of Astronomy, New Mexico State University, Las Cruces, NM 88003, USA Associated publication: Shirke & Katuwal, "Solar-Cycle Variation of Newly Emerging Coronal Holes during Solar Cycle 24" (link/DOI to be added upon publication) Description This dataset is a manually compiled, daily catalogue of newly emerging coronal holes (CHs) on the Sun, covering 2010 October 5 to 2019 December 31 (Solar Cycle 24). Each entry was produced by visual inspection of daily coronal-hole segmentation maps generated by the CHIMERA algorithm (Garton et al. 2018) and distributed through the SolarMonitor archive (https://www.solarmonitor.org), which combines SDO/AIA (171, 193, 211 Å) intensity ratios with co-temporal SDO/HMI magnetograms to identify coronal-hole boundaries. For each available daily map, the number of newly emerging coronal holes was counted and classified into three heliographic latitude zones: Northern zone: +20° < latitude ≤ +90° Southern zone: −90° ≤ latitude < −20° Equatorial zone: |latitude| ≤ 20° The Northern and Southern zones include both polar and non-polar coronal holes; they are not restricted to the polar caps. File contents Newly_emerging_CH_catalogue_SC24.xlsx Column Description Date (dd-mm-yyyy) Calendar date of the CHIMERA observation map Time (UTC) UTC timestamp of the specific map used for that entry Upper count Number of newly emerging CHs in the Northern zone (+20° to +90° lat) Lower Count Number of newly emerging CHs in the Southern zone (−90° to −20° lat) Equator Count Number of newly emerging CHs in the Equatorial zone (|lat| ≤ 20°) Total count Sum of Upper, Lower, and Equator counts for that entry Note on column naming: "Upper count" and "Lower Count" in this file correspond to "Northern zone" and "Southern zone" respectively in the associated paper. Missing data 383 calendar days (11.2% of the 3,407-day span) have no recorded count because no usable CHIMERA map was available for that day (data gaps or poor imaging conditions). These are recorded as blank/NaN in all count columns - they do not indicate a count of zero. Any analysis of this dataset should exclude these rows rather than treat them as zero-CH days. Multiple observations per day On 32 calendar dates, two separate CHIMERA maps were inspected and logged as two rows (e.g., one map near 00:xx UTC and a second near 20:xx–23:xx UTC on the same day). This occurs when SolarMonitor provided more than one usable map for that date. Users wishing to reduce the catalogue to strictly one row per calendar day should aggregate (e.g., sum or average) these paired entries according to their own analysis needs; the associated paper's monthly-summed figures use all logged entries as recorded. Temporal coverage Start: 2010-10-05 End: 2019-12-31 Total rows: 3,407 (including 383 missing-data rows and 32 same-day duplicate entries) Data sources Coronal hole segmentation maps: CHIMERA algorithm (Garton et al. 2018), distributed via SolarMonitor (https://www.solarmonitor.org), based on SDO/AIA and SDO/HMI observations. Solar Dynamics Observatory (SDO): Pesnell et al. 2012. Atmospheric Imaging Assembly (AIA): Lemen et al. 2012. License This dataset is released under a Creative Commons Attribution 4.0 International license (CC-BY 4.0). Please cite both this dataset and the associated publication when using this data. Contact Akash Vinod Shirke - [e-mail]