Magnetic reconnection is one of the fundamental dynamical processes in the solar corona. The method of studying reconnection in active region-scale magnetic fields generally depends on non-local methods (i.e. requiring information across the magnetic field under study) of magnetic topology, such as separatrix skeletons and quasi-separatrix layers. The theory of General Magnetic Reconnection is also non-local, in that its measure of the reconnection rate depends on determining the maxima of integrals along field lines. In this work, we complement the above approaches by introducing a local description of magnetic reconnection, that is one in which information about reconnection at a particular location depends only on quantities at that location. This description connects the concept of the field line slippage rate, relative to ideal motion, to the underlying local geometry of the magnetic field characterized in terms of the Lorentz force and field-aligned current density. It is argued that the dominant non-ideal term for the solar corona, discussed in relation to this new description, is mathematically equivalent to the anomalous resistivity employed by many magnetohydrodynamic simulations. However, the general application of this new approach is adaptable to the inclusion of other non-ideal terms, which may arise from turbulence modelling or the inclusion of a generalized Ohm’s law. The approach is illustrated with two examples of coronal magnetic fields related to flux ropes: an analytical model and a nonlinear force-free extrapolation. In terms of the latter, the slippage rate corresponds to the reconnection that would happen if the given (static) force-free equilibrium were the instantaneous form of the magnetic field governed by an Ohm’s law with non-ideal terms.

The magnetic field of the low corona above quiet Sun regions is extremely challenging to observe directly, and the topology is difficult to discern from extreme ultraviolet (EUV) image data due to the lack of distinct loops that are present in, for example, active regions. We aim to show that the velocity field of faint propagating disturbances (PD) observed on-disk in the quiet corona can be interpreted in terms of the underlying magnetic topology. The PD are observed in Atmospheric Imaging Assembly/Solar Dynamics Observatory (AIA/SDO) time series in three channels: 304, 171, and 193 Å corresponding to the high chromosphere, transition region/low corona, and the corona, respectively. An established Time-Normalised Optical Flow method enhances the PD and applies a Lucas–Kanade algorithm to gain their velocity field. From the velocity field, we identify the source and sink locations of the PDs, and compare these locations between channels and with the underlying photospheric network. Source regions tend to be located above the photospheric network, and sink regions with the internetwork. Sink regions in the internetwork suggest either that closed field can be concentrated rather than evenly distributed in the internetwork, or that fieldlines opening into the corona can sometimes be concentrated above internetwork regions. We find regions of almost exact alignment between channels, and other regions where similar-shaped structures are offset by a few pixels between channels. These are readily interpreted as vertical or non-vertical alignment of the magnetic field relative to the observer viewing from above. Regions of isolated source regions in the cold (304 Å) or hotter (171 and 193 Å) channels can be interpreted in terms of the magnetic topology, but support for this is weaker. These results offer support for the future use of PD velocity fields as a coronal constraint on magnetic extrapolation models.

Continuous wavelet power spectrum approach has been utilized to examine the short- and long-term fluctuations of solar plage area (PA), solar flare index (SFI), and sunspot numbers (SSNs) from 1976 to 2022. Based on the distribution of monthly data from the hemisphere SSNs, the monthly average of the solar parameters under consideration has been divided into northern and southern groups. Besides, the N-S asymmetry, the periodicity, the interconnection, and phase synchronization between the northern and southern groups of the solar flare index and plage area have been presented using the wavelet technique. The findings show that the northern group of PAs has short and intermediate periods of 0.9, 1.5, 2.5, and 3.5 years, whereas the southern group shows the prevalence of periods of 0.7, 1.9, and 3.2 years. In contrast, the northern group of SFI displays periods of 0.6, 0.8, 1.5, and 3.5 years, whereas the southern group confirms the presence of discrete periods of 0.7 and 1.9 years. The PA and SFI data sets for the Solar Cycles (SCs) 21 – 24 show little correlation and fewer short periods in the cross-wavelet power spectra (XWT) and wavelet coherence (WTC) spectra between the northern and southern hemispheres.

In this paper, starting from solar storms, which are the main cause of geomagnetic storms, the effects of the speed (v) and density (Np) of solar plasma coming to the Earth on geomagnetic storms are investigated. During the ascending phase of the 25th solar cycle (2021 – 2022), various geomagnetic storms from G1 to G4 were examined. Multiple linear regression models are created to examine the effects of solar parameters that cause changes in geomagnetic storm processes. The effects of the speed and charge density of solar wind, coronal mass ejections (CMEs), corotating interaction regions (CIRs), and CME-CME interactions on the Dst index, which reflects disturbances in the Earth’s magnetic field and the scale of geomagnetic storms, are statistically analyzed. It is determined that a one-unit change in speed in 82 geomagnetic storms in the statistical models created a decrease in Dst of approximately −0.25 nT. In contrast, it is determined that a unit increase in particle density also reduces the effect and duration of a geomagnetic storm. However, if there is an increase in density during the main phase of the storm, then the storm level increases. We believe that our results will significantly contribute to predicting the formation of geomagnetic storms and their possible effects on space weather.

To model the structure and dynamics of the heliosphere well enough for high-quality forecasting, it is essential to accurately estimate the global solar magnetic field used as inner boundary condition in solar wind models. However, our understanding of the photospheric magnetic field topology is inherently constrained by the limitation of systematically observing the Sun from only one vantage point, Earth. To address this challenge, we introduce global magnetic field maps that assimilate far-side active regions derived from helioseismology into solar wind modeling. Through a comparative analysis between the combined surface flux transport and helioseismic Far-side Active Region Model (FARM) and the base Surface Flux Transport Model without far-side active regions (SFTM), we assess the feasibility and efficacy of incorporating helioseismic far-side information in space weather forecasting. We are employing the Wang-Sheeley-Arge solar wind (WSA) model for statistical evaluation and leveraging the EUropean Heliospheric FOrecasting Information Asset (EUHFORIA), a three-dimensional heliospheric MHD model, to analyze a case study. Using the WSA model, we show that including far-side magnetic data improves solar wind forecasts for 2013 – 2014 by up to 50% in correlation and 3% in root mean square error and mean absolute error, especially near the Earth and Solar TErrestrial RElations Observatory – Ahead (STEREO-A). Additionally, our 3D modeling shows significant localized differences in heliospheric structure that can be attributed to the presence or absence of active regions in the magnetic maps used as input boundaries. This highlights the importance of including far-side information to more accurately model and predict space weather effects caused by solar wind, solar transients, and geomagnetic disturbances.