arXiv subjects
Publications and source records attributed to Yu. I. Yermolaev.
In the present work, we study the possibility of assessing the inhomogeneities of the ionic composition along the axis of the magnetic cloud using the method that was recently used by Song et al. (2021). Possible violations of the used assumptions do not allow one to draw reliable conclusions.
A recent paper by Owens (2018) presents a statistical analysis of the properties of interplanetary coronal mass ejections (ICMEs) and variations in their compositions and ion charge-state signatures using data from the Advanced Composition Explorer (ACE) spacecraft. However, the article contains several serious flaws, which we will discuss here.
The ionospheric scattering of pulses emitted by PSR B0950+08 is measured using the 10-m RadioAstron Space Radio Telescope, the 300-m Arecibo Radio Telescope and the 14x25-m Westerbork Synthesis Radio Telescope (WSRT) at a frequency band between 316 and 332 MHz. We analyse this phenomenon based on a simulated model of the phase difference obtained between antennas that are widely separated by nearly 25 Earth diameters. We present a technique for processing and analysing the ionospheric total electron content (TEC) at the ground stations of the ground-space interferometer. This technique allows us to derive almost synchronous half-hour structures of the TEC in the ionosphere at an intercontinental distance between the Arecibo and WSRT stations. We find that the amplitude values of the detected structures are approximately twice as large as the values for the TEC derived in the International Reference Ionosphere (IRI) project. Furthermore, the values of the TEC outside these structures are almost the same as the corresponding values found by the IRI. According to a preliminary analysis, the detected structures were observed during a geomagnetic storm with a minimum Dst index of ~75 nT generated by interplanetary disturbances, and may be due to the influence of interplanetary and magnetospheric phenomena on ionospheric disturbances. We show that the Space Very Long Baseline Interferometry provides us with new opportunities to study the TEC, and we demonstrate the capabilities of this instrument to research the ionosphere.
This work is a continuation of our previous articles (Yermolaev et al. in J. Geophys. Res. 120, 7094, 2015; Yermolaev et al. in Solar Phys. 292, 193, 2017; Yermolaev et al. in Solar Phys. 293, 91, 2018), which describe the average temporal profiles of interplanetary plasma and field parameters in large-scale solar-wind (SW) streams: corotating interaction regions (CIRs), interplanetary coronal mass ejections (ICMEs including both magnetic clouds (MCs) and ejecta), and sheaths as well as interplanetary shocks (ISs). In this work we analyze the average profile of helium abundance Nα/Np for interval of 1976-2016. Our results confirm main early obtained results: Nα/Np is higher in quasi-stationary fast streams than in slow ones; it slowly changes in compression regions CIRs and Sheaths from values in undisturbed solar wind to values in corresponding type of piston (HSS or ICME); in Ejecta it is closed to abundance in undisturbed streams and it is maximal in MCs. We obtained for first time that Nα/Np correlates with plasma β-parameter in compression regions CIRs and Sheaths and anti-correlates in ICMEs. The Nα/Np vs. β dependence is stronger in MCs than in Ejecta and may be used as an indicator of conditions in CME formation place on the Sun.
This work is a continuation of our previous articles (Yermolaev et al. in J. Geophys.Res. 120, 7094, 2015, Yermolaev et al. in Solar Phys. 292, 193, 2017), which describe the average temporal profiles of interplanetary plasma and field parameters in large-scale solar-wind (SW) streams: corotating interaction regions (CIRs), interplanetary coronal mass ejections (ICMEs including both magnetic clouds (MCs) and ejecta), and sheaths as well as interplanetary shocks (ISs). Changes of longitude angle ϕ in CIRs from -2 to +2° agree with earlier observations. Besides we have for the first time analyzed the average temporal profiles of bulk velocity angles in Sheaths and ICMEs and found that the angle ϕ in ICME changes from 2 to -2° while in Sheath it changes from -2 to 2° (similar to change in CIR), i.e., the streams in CIR/Sheath and ICME deflects in the opposite side. When averaging the latitude angle θ on all intervals of the chosen SW type, the angle θ is almost constant ~1°. We made selection of SW events with increasing and decreasing angle θ for the first time and found that average temporal profiles for angle θ in selected events have the same < > shape as for angle ϕ. The difference in average profiles for angles ϕ and θ is explained by the fact that most events have increasing profiles for angle in ecliptic plane due to solar rotation while for angle in meridional plane numbers of increasing and decreasing profiles are equal.
In this paper we look for traces of interaction of CME/ICME with high-speed stream (HSS) of solar wind from coronal hole (CH) for two serial Carrington rotations (CRs) during December 2011 - January 2012. We analyze two cases. (1) In CR 2118 instead of predicted arrival of HSS the signatures of ICME with modified back side and compressed slow stream were observed. (2) In CR 2119 the predicted HSS was observed in time, and after arrival of preceding ICME. Our analysis shows that difference of these cases can be explained by different interactions between HSS and CME, which in the first case result in significant deflection of HSS of solar wind from the Sun-Earth line. Thus, the CH passage through the central meridian with simultaneous occurrence of CMEs in the nearby located sources can result in interaction between HSS and CME streams, deflection of the HSS stream aside of the ecliptic and changes in parameters of the solar wind.
This work is a continuation of our previous paper [Yermolaevetal2015] which describes the average temporal profiles of interplanetary plasma and field parameters in large-scale solar-wind (SW) streams: CIR, ICME (both MC and Ejecta) and Sheath as well as the interplanetary shock (IS). Like in the previous work we use data of OMNI database, our catalog of large-scale solar-wind phenomena during 1976--2000 [Yermolaevetal2009] and the double superposed epoch analysis (DSEA) method [Yermolaevetal2010]: re-scaling the duration of interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide. We present new detailed results of comparison of two pair phenomena: (1) both types of compression regions (CIR.vs.Sheath) and (2) both types of ICMEs (MC.vs.Ejecta). Obtained data allows us to suggest that the formation of all types of compression regions has the same physical mechanism irrespective of piston (High-Speed Stream (HSS) or ICME) type and differences are connected with geometry (angle between speed gradient in front of piston and satellite trajectory) and full jumps of speed in edges of compression regions. One of consequences of this hypothesis is the conclusion that one of the reasons of observed distinctions of parameters in MC and Ejecta can be fact that at measurements of Ejecta the satellite passes further from the nose area of ICME, than at measurements of MC. We also discuss the impact of Sheath in magnetospheric activity and its contribution in estimation of Sun's open magnetic flux.
The purpose of this work is to draw attention of readers to a problem of possible differences in generation of magnetic storms induced by various large scale solar wind (SW) streams: CIR, Sheath and ICME (including MC and Ejecta). Recently we showed that when using a modification of formula by Burton et al. [1975] for connection of interplanetary conditions with Dst and Dst* indices the efficiency of storm generation by Sheath and CIR is about 50 percent higher than generation by ICME [Nikolaeva et al., 2013, 2015]. In the literature there are many various functions coupling (FC) various interplanetary parameters with magnetospheric state. In this work we study the efficiency of main phase storm generation by different SW streams when using 12 another FCs on the basis of OMNI data during 1976 ... 2000. Obtained results show that for most part of FCs Sheaths have the highest efficiency and MCs have the lowest efficiency in accordance with our previous results. The reliability of the obtained data and possible reasons of divergences for various FCs and various SW types require further researches.
Using the OMNI data for period 1976-2000 we investigate the temporal profiles of 20 plasma and field parameters in the disturbed large-scale types of solar wind (SW): CIR, ICME (both MC and Ejecta) and Sheath as well as the interplanetary shock (IS). To take into account the different durations of SW types, we use the double superposed epoch analysis (DSEA) method: re-scaling the duration of the interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide. As the analyzed SW types can interact with each other and change parameters as a result of such interaction, we investigate separately 8 sequences of SW types: (1) CIR, (2) IS/CIR, (3) Ejecta, (4) Sheath/Ejecta, (5) IS/Sheath/Ejecta, (6) MC, (7) Sheath/MC, and (8) IS/Sheath/MC. The main conclusion is that the behavior of parameters in Sheath and in CIR are very similar both qualitatively and quantitatively. Both the high-speed stream (HSS) and the fast ICME play a role of pistons which push the plasma located ahead them. The increase of speed in HSS and ICME leads at first to formation of compression regions (CIR and Sheath, respectively), and then to IS. The occurrence of compression regions and IS increases the probability of growth of magnetospheric activity.
We study durations of main and recovery phases of magnetic storms induced by different types of large-scale solar-wind streams (Sheath, magnetic cloud (MC), Ejecta and CIR) on the basis of OMNI data base during 1976-2000. Durations of both main and recovery phases depend on types of interplanetary drivers. On the average, duration of main phase of storms induced by compressed regions (CIR and Sheath) is shorter than by MC and Ejecta while duration of recovery phase of CIR- and Sheath-induced storms is longer. Analysis of durations of individual storms shows that durations of main and recovery phases anti-correlate for CIR- and Sheath-induced storms and there is not dependence between them for (MC+Ejecta)-induced storms.
We compare of the cross polar cap potential (CPCP) saturation during magnetic storms induced by various types of the solar wind drivers. By using the model of Siscoe-Hill \citep{Hilletal1976,Siscoeetal2002a,Siscoeetal2002b,Siscoeetal2004,Siscoe2011} we evaluate criteria of the CPCP saturation during the main phases of 257 magnetic storms ($Dst_{min} \le -50$ nT) induced by the following types of the solar wind streams: magnetic clouds (MC), Ejecta, the compress region Sheath before MC ($Sh_{MC}$) and before Ejecta ($Sh_{E}$), corotating interaction regions (CIR) and indeterminate type (IND). Our analysis shows that occurrence rate of the CPCP saturation is higher for storms induced by ICME ($13.2%$) than for storms driven by CIR ($3.5%$) or by IND ($3.5%$).The CPCP saturation was obtained more often for storms initiated by MC ($25%$) than by Ejecta ($2.9%$); it was obtained for $8.6%$ of magnetic storms induced by sum of MC and Ejecta, and for $21.5%$ magnetic storms induced by Sheath before them (sum of $Sh_{MC}$ and $Sh_{E}$). These results allow us to conclude that occurrence rate of the CPCP saturation at the main phase of magnetic storms depends on the type of the solar wind stream.
Statistical analysis of occurrence rate of magnetic storms induced by different types of interplanetary drivers is made on the basis of OMNI data for period 1976-2000. Using our catalog of large scale types of solar wind streams we study storms induced by interplanetary coronal mass ejections (ICME) (separately magnetic clouds (MC) and Ejecta) and both types of compressed regions: corotating interaction regions (CIR) and Sheaths. For these types of drivers we calculate integral probabilities of storms with minimum Dst < -50, -70, -100, -150, and -200 nT. The highest probability in this interval of Dst is observed for MC, probabilities for other drivers are 3-10 times lower than for MC. Extrapolation of obtained results to extreme storms shows that such a magnetic storm as Carrington storm in 1859 with Dst = -1760 nT is observed on the Earth with frequency 1 event during ~500 year.
Statistical analysis of Dst behaviour during recovery phase of magnetic storms induced by different types of interplanetary drivers is made on the basis of OMNI data in period 1976-2000. We study storms induced by ICMEs (including magnetic clouds (MC) and Ejecta) and both types of compressed regions: corotating interaction regions (CIR) and Sheaths. The shortest, moderate and longest durations of recovery phase are observed in ICME-, CIR-, and Sheath-induced storms, respectively. Recovery phases of strong ($Dst_{min} < -100$ nT) magnetic storms are well approximated by hyperbolic functions $Dst(t)= a/(1+t/τ_h)$ with constant $τ_h$ times for all types of drivers while for moderate ($-100 < Dst_{min} < -50$ nT) storms $Dst$ profile can not be approximated by hyperbolic function with constant $τ_h$ because hyperbolic time $τ_h$ increases with increasing time of recovery phase. Relation between duration and value $Dst_{min}$ for storms induced by ICME and Sheath has 2 parts: $Dst_{min}$ and duration correlate at small durations while they anticorrelate at large durations.
We investigate relative role of various types of solar wind streams in generation of magnetic storms. On the basis of the OMNI data of interplanetary measurements for the period of 1976-2000 we analyze 798 geomagnetic storms with Dst < -50 nT and their interplanetary sources: corotating interaction regions (CIR), interplanetary CME (ICME) including magnetic clouds (MC) and Ejecta and compression regions Sheath before both types of ICME. For various types of solar wind we study following relative characteristics: occurrence rate; mass, momentum, energy and magnetic fluxes; probability of generation of magnetic storm (geoeffectiveness) and efficiency of process of this generation. Obtained results show that despite magnetic clouds have lower occurrence rate and lower efficiency than CIR and Sheath they play an essential role in generation of magnetic storms due to higher geoeffectiveness of storm generation (i.e higher probability to contain large and long-term southward IMF Bz component).
The comparison of specific interplanetary conditions for 798 magnetic storms with Dst < -50 nT for the period 1976-2000 was made on the basis of the OMNI archive data.We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and the minimum Dst index) and make a re-scaling of main phase of storm a such way that after this transformation all storms have equal durations of main phase in new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate high importance of Sheath in generation of magnetic storms as well as a significant differences in properties of MC and Ejecta and in their geoeffectiveness.
To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use global solar parameters: we identified different large-scale types of solar wind for 1976-2000 interval, obtained a fraction of interplanetary CMEs (ICMEs) and calculated magnitude of interplanetary magnetic field B averaged over 2 Carrington rotations. The floor of magnetic field is estimated as B value at solar cycle minimum when the ICMEs were not observed and it was calculated to be 4,65 \pm 6,0 nT. Obtained value is in a good agreement with previous results.
Recently Zhang et al. [2008] presented a statistical study of sizes and relative geoeffectiveness of ICMEs (bodies of magnetic clouds) and preceding sheaths for 46 events responsible for intense (Dst < -100 nT) geomagnetic storms in 1996-2005 in which only a single ICME was responsible for generating the storm. Here we would like to comment several results and conclusions of this paper.
Recently Tsurutani et al., (2008) (Paper 1) analyzed the complex interplanetary structures during 7 to 8 November, 2004 to identify their properties as well as resultant geomagnetic effects and the solar origins. Besides mentioned paper by Gopalswamy et al., (2006) the solar and interplanetary sources of geomagnetic storm on 7-10 November, 2004 have also been discussed in details in series of other papers. Some conclusions of these works essentially differ from conclusions of the Paper 1 but have not been discussed by authors of Paper 1. In this comment we would like to discuss some of these distinctions.