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Hinode and IRIS Synoptic Observations of Solar Cycle Transition at Mid-Latitudes

Presentation #113.24 in the session “Solar Physics Division (SPD): Photosphere & Chromosphere, Solar Interior, and Solar Cycle”.

Published onJun 18, 2021
Hinode and IRIS Synoptic Observations of Solar Cycle Transition at Mid-Latitudes

Recent observations by McIntosh et al. using SDO/AIA coronal bright point density and the magnetogram-derived large scale open magnetic flux “g-nodes” have traced out extended solar cycle activity bands that originate at ~55 degrees latitude and propagate toward the equator. When the opposite hemisphere bands “terminate” at the equator, this event corresponds with the rapid rise of new cycle flux and active regions at mid-latitudes, ~35 degrees. We present weekly synoptic high-resolution observations of mid-latitude (35-40 degrees) magnetic flux and chromospheric emission from Hinode SOT/SP and IRIS starting from March 2017 until today, covering the end of cycle 24 and the beginnings of cycle 25. After carefully correcting for instrumental shifts, noise, and solar B-angle effects, we analyze time series of mean magnetic flux, chromospheric line intensity, and statistical properties of magnetic regions for signals of a developing cycle 25 and the passage of the activity bands in these typically quiet mid-latitude regions. Initial results show that the statistical properties of our activity metrics are roughly constant over the four year period, with a step function increase in activity that corresponds to a change to a lower observation latitude. Finally, we investigate the correspondence of SDO/AIA coronal bright points in our observational field of view to chromospheric emission and photospheric magnetic features.

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