scholarly journals Interplanetary magnetic field and its possible effects on the mid-latitude ionosphere II

1994 ◽  
Vol 37 (2) ◽  
Author(s):  
Y. Tulunay
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Sector Structure ◽  
Quiet Time ◽  
Time Value ◽  
The Mean ◽  
The Imf

Using criticaI frequencies, f0F2 from the Uppsala, Lannion and Dourbes ionosonde stations, the possible effects of the orientation of the IMF on mid-latitude ionosphere are further investigated. For this purpose, the regular diurnal, seasonal and solar cycle variations in the f0F2 data were removed by subtracting the mean of f0F2 for the same UT on all the magnetically quiet days (Ap< 6) within 15 days around the IMF Bz turnings. This yields the deviation from the average quiet-time value ?f0F2. The data are sorted according to the polarity of the IMF Bz and the effects of the southward turnings are discussed. Hapgood et al. (1991), Tulunay et al. (1991), Tulunay and Rahman (1992) investigated the possible effects of the IMF on mid-latitude ionosphere by employing the Slough and Argentine Islands f0F2 data. In order to facilitate a comparison the same method of analysis is being adopted again. However, in the present work the southward polarity changes in IMF Bz with no consideration of the IMF sector structure were considered only.

scholarly journals Interplanetary magnetic field and its possible effects on the mid-latitude ionosphere III

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
Y. Tulunay
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Seasonal Effects ◽  
Ionospheric Variability ◽  
Winter Anomaly ◽  
The Mean ◽  
The Imf

Using critical frequencies, f0F2 from the Lannion, Slough, Poitiers, Garchy, Dourbes, Rome, Juliusrud, Gibilmanna, Pruhonice, Uppsala, Kaliningrad, Miedzeszyn, Sofia, Athens and Kiev ionosonde stations, the possible effects of the orientation of the Interplanetary Magnetic Field (IMF) on mid-latitude ionosphere are further investigated. This time, only the southward polarity changes in IMF Bz with seasonal effects were considered. The same method of analysis was employed to facilitate a comparison between the recent results presented here with those which appeared in the preceding papers in the series. That is, the regular diurnal, seasonal and solar cycle variations in the f0F2 data were removed by subtracting the mean of the f0F2 for the same UT on all magnetically quite days (Ap < 6) within 15 days around the IMF Bz turnings (Tulunay, 1994). This last paper also includes the seasonal effects on the ionospheric data. The results confirm that much of the day-to-day variability of the mid-latitude ionosphere may be related to the orientation of the southward IMF Bz , characterized by the ionospheric winter anomaly. Day-to-day ionospheric variability becomes more significant towards higher latitudes.

scholarly journals Study of Geomagnetic Storms, Interplanetary Magnetic Field and Solar Wind

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Chandrasekhar Bhoj ◽  
Lalan Prasad
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Correlation Coefficient ◽  
Geomagnetic Storms ◽  
Solar Cycle 24 ◽  
Time Periods ◽  
Cycle 24 ◽  
The Imf

The aim of this paper is to investigate the association of the geomagnetic storms with the IMF for solar cycle 24. Result of the present analysis shows that IMF is geoeffective parameter but its impact varies in accordance with different time periods. The correlation coefficient between Dst and IMF found to be -0.6 for solar cycle 24.

scholarly journals Study of Geomagnetic Storms, Interplanetary Magnetic Field and Solar Wind

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Chandrasekhar Bhoj ◽  
Lalan Prasad
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Correlation Coefficient ◽  
Geomagnetic Storms ◽  
Solar Cycle 24 ◽  
Time Periods ◽  
Cycle 24 ◽  
The Imf

The aim of this paper is to investigate the association of the geomagnetic storms with the IMF for solar cycle 24. Result of the present analysis shows that IMF is geoeffective parameter but its impact varies in accordance with different time periods. The correlation coefficient between Dst and IMF found to be -0.6 for solar cycle 24

scholarly journals The mean solar magnetic field as an indicator of the interplanetary magnetic field

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
J. Bremer
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Structure Data ◽  
Solar Magnetic Field ◽  
Private Communication ◽  
Sector Structure ◽  
Ionospheric Effect ◽  
Ionospheric Response ◽  
The Earth ◽  
The Mean

The Mean Solar Magnetic Field (MSMF) measured daily by ground based observations at the Standford Observatory shows similar structures like the Interplanetary Magnetic Field (IMF) near the Earth about 5 to 7 days later. The ionospheric effect in the mid-latitude F2-region due to such MSMF changes is most marked for strong MSMF changes from anti to pro sectors. The mean ionospheric response is very similar to the results obtained earlier with IMF sector structure data derived from Svalgaard (1976) and Wilcox (1982, private communication). Therefore, the MSMF data can successfully be used to predict the mean IMF sector structure and the mean ionospheric response 5 to 7 days in advance.

scholarly journals Model of the comet outbursts based on a fragmentation of ice grains in its atmosphere

1996 ◽  
Vol 172 ◽  
pp. 221-222
Author(s):  
D.A. Andrienko ◽  
I.I. Mischishina
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
High Velocity ◽  
Physical Nature ◽  
Cycle Phase ◽  
Sector Structure ◽  
Two Peaks ◽  
Geomagnetic Perturbations

Outbursts of the comet's brightness play a significant role in the study of the physical nature and evolution of comets. The causes of cometary outbursts are still not properly understood. It is known, however, that there is correlation between the outbursts and the high-velocity flux of solar wind. The evidences of such causal relationship are the following: the existence of the correlation between the geomagnetic perturbations and the outburst activity of the comets [1]; two-peaks distribution of the comet's outbursts, which depends on the 11-year solar cycle phase with maxima at phases 0.2–0.3 and 0.7–0.8, in coincidence with the distribution of physical characteristics of high-velocity fluxes [2]; the repeated character of the outbursts with main intervals of 7–8, 14–15, 22–24 and 30 days, this corresponds to the four-sector structure of the interplanetary magnetic field [3].

scholarly journals Magnetopause energy transfer dependence on the interplanetary magnetic field and the Earth's magnetic dipole axis orientation

2012 ◽  
Vol 30 (3) ◽  
pp. 515-526 ◽  
Author(s):  
M. Palmroth ◽  
R. C. Fear ◽  
I. Honkonen
Keyword(s):  
Magnetic Field ◽  
Energy Transfer ◽  
Interplanetary Magnetic Field ◽  
Large Data ◽  
Seasonal Effect ◽  
Dipole Orientation ◽  
Data Set ◽  
Axis Orientation ◽  
Simulation Results ◽  
The Imf

Abstract. We examine the spatial variation of magnetospheric energy transfer using a global magnetohydrodynamic (MHD) simulation (GUMICS-4) and a large data set of flux transfer events (FTEs) observed by the Cluster spacecraft. Our main purpose is to investigate whether it is possible to validate previous results on the spatial energy transfer variation from the GUMICS-4 simulation using the statistical occurrence of FTEs, which are manifestations of magnetospheric energy transfer. Previous simulation results have suggested that the energy transfer pattern at the magnetopause rotates according to the interplanetary magnetic field (IMF) orientation, and here we investigate whether a similar rotation is seen in the locations at which FTE signatures are observed. We find that there is qualitative agreement between the simulation and observed statistics, as the peaks in both distributions rotate as a function of the IMF clock angle. However, it is necessary to take into account the modulation of the statistical distribution that is caused by a bias towards in situ FTE signatures being observed in the winter hemisphere (an effect that has previously been predicted and observed in this data set). Taking this seasonal effect into account, the FTE locations support the previous simulation results and confirm the earlier prediction that the energy transfers in the plane of the IMF. In addition, we investigate the effect of the dipole orientation (both the dipole tilt angle and its orientation in the plane perpendicular to the solar wind flow) on the energy transfer spatial distribution. We find that the energy transfer occurs mainly in the summer hemisphere, and that the dayside reconnection region is located asymmetrically about the subsolar position. Finally, we find that the energy transfer is 10% larger at equinox conditions than at solstice, contributing to the discussion concerning the semiannual variation of magnetospheric dynamics (known as "the Russell-McPherron effect").

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