Abstract
We present the observing program proposed by Paris and Côte d’Azur Observatories for monitoring solar activity during the upcoming cycle 25 and providing near real time images and movies of the chromosphere for space-weather research and applications. Two optical instruments are fully dedicated to this task and we summarize their capabilities. Short-term and fast-cadence observations of the chromosphere will be performed automatically at Calern observatory (Côte d’Azur), where dynamic events, as flare development, Moreton waves, filament instabilities and Coronal Mass Ejections onset, will be tracked. This new set of telescopes will operate in 2021 with narrow bandpass filters selecting Hα and CaII K lines. We present the instrumental design and a simulation of future images. At Meudon, the Spectroheliograph is well adapted to the long-term and low-cadence survey of chromospheric activity by recently improved and optimized spectroscopic means. Surface scans deliver daily (x, y, λ) datacubes of Hα, CaII K and CaII H line profiles. We describe the nature of available data and emphasize the new calibration method of spectra.
Highlights
Solar activity is the primary driver of space weather and space climate (e.g., Schrijver et al, 2012; Pomoell & Poedts, 2018)
Ground-based observations of the chromosphere are of particular interest, because this layer is the source of solar activity
New solar cycle 25 will be intensively observed at Paris and Côte d’Azur observatories with new and fast automatic instruments (MeteoSpace at Calern in 2021) or with improved capabilities existing ones (Meudon Spectroheliograph)
Summary
Solar activity is the primary driver of space weather and space climate (e.g., Schrijver et al, 2012; Pomoell & Poedts, 2018). It varies over a wide range of time scales from several minutes with solar flares and Coronal Mass Ejections (CMEs; e.g., Shibata & Magara, 2011) to hundreds of years with the %100-year modulation (Gleissberg cycle) of the 11-year solar cycle (e.g., Hathaway, 2015) Both short-term and long-term full-disk observations of the Sun are critical for improving our understanding of solar activity at all time scales, and for monitoring and predicting it in space weather forecast applications (e.g., Ueno et al, 2010; Malherbe et al, 2019). Using empirical laws derived from observations and MHD models, one can further quantify the flare-energy release from Ha bright ribbons (e.g., Toriumi et al, 2017), and/or the maximum energy available for a solar flare from the CaII K size and area of an active region (e.g., Aulanier et al, 2013)
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