Statistical Links between Solar Cosmic Rays,Type-II Radio Emission,and Coronal Mass Ejections

Geomagnetism and Aeronomy - Type-II radio emission often accompanies events in solar cosmic rays and is an indicator of the propagation of a shock wave in the solar corona. Conversely, the shock...     

Forbush Effects Created by Coronal Mass Ejections with Magnetic Clouds

Geomagnetism and Aeronomy - In this paper, we study the effect of magnetic clouds on variations in the cosmic ray density recorded by neutron monitors. The statistical patterns and characteristic...     

Flares Unaccompanied by Interplanetary Coronal Mass Ejections and Solar Proton Events

Geomagnetism and Aeronomy - For a coronal mass ejection (CME) to occur, the magnetic pressure of the overlying layers must be lower than that of the underlying layers, and the corresponding...     

Similarities and Differences between Forbush Decreases Associated with Streams from Coronal Holes,Filament Ejections,and Ejections from Active Regions

Geomagnetism and Aeronomy - The Forbush decreases for the period from 1997 to 2020 were studied based on data from the database on Forbush effects and interplanetary disturbances created and...     

New Approaches to the Identification of Sources and the Onset of Stealth Coronal Mass Ejections

Geomagnetism and Aeronomy - New approaches to the identification of sources and the onset of stealth coronal mass ejections (CMEs) are discussed based on the stealth CME of July 7, 2012. It is...     

Dependence of the Occurrence of Coronal Mass Ejections on the Initial Length of the Eruptive Prominence

Geomagnetism and Aeronomy - A model of the eruption of a magnetic flux rope with ends rigidly fixed in the photosphere is analyzed. Long and short flux ropes exhibit different scenarios of...     

Regularities in the Formation of Coronal Mass Ejections Associated and not Associated with Type II Radio Bursts

Geomagnetism and Aeronomy - Regularities in the formation of coronal mass ejections (CMEs) associated (Radio Loud, RL CME) and not associated (Radio Quiet, RQ CME) with type II radio bursts (RBIIs)...     

Some Features of the Variation of the Magnetic Field Characteristics in the Umbra of Sunspots During Flares and Coronal Mass Ejections

The observed variations of the magnetic properties of sunspots during eruptive events (solar flares and coronal mass ejections (CMEs)) are discussed. Variations of the magnetic field characteristics in the umbra of the sunspots of active regions (ARs) recorded during eruptive events on August 2, 2011, March 9, 2012, April 11, 2013, January 7, 2014, and June 18, 2015, are studied. The behavior of the maximum of the total field strength B_max, the minimum inclination angle of the field lines to the radial direction from the center of the Sun α_min (i.e., the inclination angle of the axis of the magnetic tube from the sunspot umbra), and values of these parameters B_mean and α_mean mean within the umbra are analyzed. The main results of our investigation are discussed by the example of the event on August 2, 2011, but, in general, the observed features of the variation of magnetic field properties in AR sunspots are similar for all of the considered eruptive events. It is shown that, after the flare onset in six AR sunspots on August 2, 2011, the behavior of the specified magnetic field parameters changes in comparison with that observed before the flare onset.     

Comparison of Features of the Generation of Coronal Mass Ejections with Variable Velocity in the Field of View of LASCO Coronagraphs

Geomagnetism and Aeronomy - This paper compares features of the generation of coronal mass ejections (CMEs) with the lowest, intermediate, and highest velocities in the field of view of LASCO C2...     

Role of Chromospheric and Coronal Ejections in the Development of LDE Flares in the Sun

Geomagnetism and Aeronomy - Based on observations in the Hα and extreme ultraviolet lines, as well as in the radio and X-ray wavelengths, we study the eruptive events of September 22 and 24,...     

Study of Long-Duration Flares and Associated Chromospheric and Coronal Ejections in Solar Cycles 23 and 24

Geomagnetism and Aeronomy - A statistical study of long-duration (long-duration event, LDE) flares in the soft X-ray (SXR) range for solar cycles 23 and 24 is carried out. Graphs of the dependence...     

Sunspot Activity and Coronal Holes during the Declining Phase of Cycle 24

Geomagnetism and Aeronomy - The dynamics of coronal holes (CHs) during the declining phase of solar cycle 24 is studied based on observational data from the Atmospheric Imaging Assembly (AIA), the...     

Manifestation of the Identity of Brightness Temperatures of the Polar Coronal Hole and Low-Latitude Coronal Holes in the Centimeter Wave Range

This paper is devoted to an analysis of brightness temperatures of the polar and low-latitude coronal holes on the Sun in the cm-wave range during periods of minimum solar activity. Data from observations of the polar coronal hole received by the RATAN-600 radio telescope during the solar eclipse of March 29, 2006, and low-latitude observations of coronal holes and quiet Sun received earlier with the RATAN-600 and BPR radio telescopes in the period of minimum solar activity have been used in the paper. The obtained good agreement between the brightness temperatures of cm-wave emission of the polar coronal hole above the North Pole of the Sun and of the low-latitude coronal holes against the background of the quiet Sun reveals the identity of the temperature properties of large coronal holes, irrespective of the mode of their arrangement and location on the Sun during the periods of minimum solar activity.     

Coronal Holes of Cycle 24 in Observations at the Solar Dynamics Observatory

Geomagnetism and Aeronomy - The dynamics of the areas of coronal holes and their localization on the Sun in solar cycle 24 and the minimum of cycles 24–25 were analyzed. The study is based on...     

Main Properties of Forbush Effects Related to High-Speed Streams from Coronal Holes

The IZMIRAN database of Forbush effects and interplanetary disturbances was used to study features of the action of high-speed solar wind streams from coronal holes on cosmic rays. Three hundred and fifty Forbush effects created by coronal holes without other actions were distinguished. The mean values and distributions have been found for different characteristics of events from this group and compared with all Forbush effects and Forbush effects caused by coronal ejections. Despite the great differences in high-speed streams from coronal holes, this group turned out to be more compact and uniform as compared to events related to coronal ejections. Regression dependences and correlation relations between different parameters of events for the studied groups have been obtained. It has been shown that Forbush effects caused by coronal ejections depend considerably more strongly on the characteristics of interplanetary disturbances as compared to Forbush effects related to coronal holes. This suggests a significant difference between the modulation mechanisms of Forbush effects of different types and corroborates earlier conclusions based on indirect data.     

Observations and Interpretation of Rotational Properties of Polar Coronal Holes Based on SDO Data

Geomagnetism and Aeronomy - The rotational effect observed in variations of areas of polar coronal holes with a period of 14 days is analyzed with SDO data by using Coronal Hole Identification with...     

Formation and Evolutionary Changes of Coronal Holes in the Growth Phase of Cycle 23

Geomagnetism and Aeronomy - The regularities in the formation of coronal holes in the growth phase of cycle 23 are studied. The period from January 1, 1997, to March 1, 2000 (Carrington rotations...     

On the Dependence of the Solar Wind Velocity on the Fractional Area of Coronal Holes in Longitude

Geomagnetism and Aeronomy - The relationship between the fractional area of coronal holes and the maximum velocity of the fast solar wind at 1 AU based on AIA/SDO and ACE/SWEPAM observations is...     

Simulation of Coronal Mass Ejection Propagation Based on Data from Ground-Based Patrol Observations

Geomagnetism and Aeronomy - We present a model for the propagation of coronal mass ejections (CMEs) based on the interaction of CMEs with the solar wind through aerodynamic drag. The parameters of...     

Comparative Analysis of Terrestrial and Satellite Observations of Photospheric Magnetic Field in an Appendix to Simulation of Parameters of Coronal Holes and Solar Wind

Geomagnetism and Aeronomy - Data from observations of the photospheric magnetic field at a number of ground stations (STOP, WSO, GONG) and by the SDO/HMI satellite for 2014–2019 are examined...