5 papers
Quantifying the effect of passband on observations in the Ca II K line
Ajay Kumar Yadav, Theodosios Chatzistergos, Natalie Krivova +33
Full-disk observations of the Sun in the Ca II K line have been carried out since the late 19th century at various observatories worldwide. These long-term records of solar activit…
Observations of the formation of a proto-spot in a pre-existing field environment
Mariarita Murabito, Ilaria Ermolli, Salvo L. Guglielmino +2
Bipolar emerging flux regions (EFRs) form active regions (ARs) that generally evolve in a pre-existing magnetic environment in the solar atmosphere. Reconfiguration of the small- a…
Estimation of Polar Magnetic Fields using Ca II K Polar Network as a Proxy
Dibya Kirti Mishra, Bibhuti Kumar Jha, Theodosios Chatzistergos +3
The polar magnetic field plays a crucial role in the solar dynamo model and contributes to predicting future solar cycles. However, continuous and direct measurements of this polar…
Ca II K Polar Network Index of the Sun: A Proxy for Historical Polar Magnetic Field
Dibya Kirti Mishra, Bibhuti Kumar Jha, Theodosios Chatzistergos +4
The Sun's polar magnetic field is pivotal in understanding solar dynamo processes and forecasting future solar cycles. However, direct measurements of the polar field is only avail…
The Extreme Space Weather Event of 1872 February: Sunspots, Magnetic Disturbance, and Auroral Displays
Hisashi Hayakawa, Edward W. Cliver, Frédéric Clette +19
We review observations of solar activity, geomagnetic variation, and auroral visibility for the extreme geomagnetic storm on 1872 February 4. The extreme storm (referred to here as…