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Ann. Geophysicae manuscript No. (will be inserted by the editor)

Magnetospheric response to magnetic clouds: multi-satellite observations during 1995-1998
Yu. I. Yermolaev , G. N. Zastenker , N. S. Nikolaeva , J.-A. Sauvaud
Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117810 Moscow, Russia CESR/CNES, Toulouse, France

Received: 31 December 2000 / Revised: 1 August 2001 / Accepted: 6 June 1997

Abstract. On the basis of ISTP spacecraft and ground observations during first 40 months of INTERBALL operation in 1995-1998 we study magnetosphere response to magnetic cloud passages including geomagnetic storms and polar activations. During this time 35 magnetic clouds were measured in the solar wind which resulted in 14 from 19 strong (peak -100 nT) magnetic storms observed at the ground stations. The low and moderately high changes in magnetic cloud IMF and solar wind parameter variations result in the usual magnetosphere response to the similar changes without magnetic cloud passages. Extremely high jumps of parameters in the magnetic clouds generate unusual response: (1) strong and complicated magnetospheric compression and deformation relative to average locations; (2) large-amplitude oscillations of geomagnetic tail structures past satellites, and (3) acceleration of ions and electrons in the plasma sheet and their injections in the polar regions. During magnetic clouds correlates with number of polar actithe value of peak vations, and the same dependence is observed for strong magnetic storms. Key words. Magnetic cloud, magnetosphere, magnetic storms and substorms

1 Introduction One of the main problems of solar-terrestrial physics concerns which magnetospheric responses are caused by different variations in the solar/interplanetary medium. This problem plays a key role in our understanding of geophysics. Also, this knowledge has a practical application in many areas of mankind's activity. Many papers describe the processes of solar wind energy input into the magnetosphere and the development of magnetospheric disturbances in response (see, e.g. (Gonzales et al. (1994, 1999); Kamide et al. (1998); Petrukovich and Klimov
Correspondence to: Yu. I. Yermolaev e-mail: yermol@afed.iki.rssi.ru

(2000); Wilson (2000) and references therein). It was shown that the existence of southward component of the interplanetary magnetic field (IMF) results in the input of solar wind energy to the magnetosphere and its accumulation in the magnetic tail. When this energy reaches a sufficient level it can be released by the reconfiguration of current systems and as plasma acceleration or heating, which results in the magnetospheric disturbances, such as magnetic storms and substorms. Another group of investigators has studied selected events in the solar atmosphere, in the interplanetary space and in the magnetosphere and correlations between these events (see, e.g. Gosling et al. (1991); Webb (1995); Tsurutani et al. (1995); Crooker (2000) and references therein). They found that geoeffective events (in the sense that they can cause geomagnetic storms) in the interplanetary space include magnetic clouds (MC), which are interplanetary manifestation of the coronal mass ejections, and corotating interaction regions (CIR) derived from the interaction of fast and slow streams in the solar wind. MCs and CIRs are often geoeffective because they are faster than the ambient plasma and compress any southward IMF in the vicinity of their edges or inside the event. However, the measurements both during maximum (Gosling et al., 1991) and minimum (Yermolaev et al., 2000a,b) of the solar cycle showed that not all MCs are geoeffective. Thus, influence of MCs on the magnetosphere calls for further investigations. Correlation of MC passages with polar magnetospheric disturbances is not sufficiently studied yet because these disturbances have characteristic time of several tens minutes and they should be compared not with the magnetic cloud as a whole, but with its separate structures and disturbances. These include the interplanetary shock (IS) before MC, the leading and trailing edges (LE and TE) of MC, the IS before TE, the jump of plasma pressure, the changes in IMF magnitude and orientation. It is also important to study the displacement of magnetospheric boundaries (including the bow shock and magnetopause) under these unusual interplanetary conditions. Such an analysis of several strong magnetic clouds has already been done on the basis of multi-satellite INTERBALL project (Yermolaev et al., 1997a, 1998, 2000a,b), and here we summarize the results of our analysis on the basis of full statistics of magnetic clouds during the first 40 months of INTERBALL observations (August, 1995 - De-

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

cember, 1998). We limited our study to the time interval of relatively low solar activity before the maximum of the solar cycle.
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2 General view of interval It is known that substantial variations occur over the 11-year solar cycle in disturbances of solar wind and Earth's magnetosphere. We study the time interval in the vicinity of minimum (1996) and the growth phase of the cycle. To evaluate magnetospheric disturbances the geomagnetic indices measured at the ground stations are usually used. The index, which connects with the geomagnetic field near the equator and the disturbance of the ring current, adequately describes the development of the global large-scale disturbances - magnetic storms. index Figures 1 - 3 show hour-averaged values of (http:// spidr.ngdc.noaa.gov) during 47 solar rotations (40 months from August, 1995 to December, 1998). Large mag-100 nT) are indicated by red triannetic storms (peak gles. There were 19 large storms, and their number slightly increased in the end of interval, closer to the maximum of index data solar cycle. This tendency is confirmed by for 1999-2000 period when there were 17 strong magnetic storms during 24 months (Yermolaev , 2001). To analyze interplanetary conditions for magnetic storms we use the key parameters of plasma and magnetic field measured by WIND (Ogilvie et al., 1995; Lepping et al., 1995) and, in some cases, by the other spacecraft (SOHO and IMP8) (http://cdaweb.gsfc.nasa.gov). Green and brown horizontal lines in top of panels present time intervals of MC and CIR observations, respectively, and red vertical lines IS preceding them. Characteristic behavior of plasma and magnetic field in MC and CIR has been previously discussed in the literature and may be found in papers by Gosling and Pizzo (1999) and Crooker (2000). MCs are characterized, among other features, by high and rotating magnetic field, and low density and temperature. We will not present the total SW and IMF data sets and show only results of our analysis. Figures 1 - 3 show that the 19 large storms were connected with 14 magnetic clouds and 5 corotating interaction regions. At the same time the analysis of data indicated at least 35 MCs during August, 1995 - December, 1998. A part of them was studied earlier (Yermolaev et al., 1998, 2000a,b), another part was added from the list of coronal mass ejections (Gopalswamy et al., 2000), and a part was selected recently. Thus we compare MCs connected with magnetic storms in wide range of . The list of events considered is presented in Table 1, which includes the date and duration of MC observations (the interval between MC IS and LE is indicated additionally in brackets). Also indicated here are the regions of space in which the INTERBALL/Tail Probe (INTERBALL-1 hereafter) satellite was situated: SW is the solar wind, MSH - the magnetosheath, MS - magnetosphere (the tail lobes, plasma and neutral sheets, mantle, LLBL and PSBL). As seen from Table 1, INTERBALL-1 was in different regions of the magnetosphere and measured the parameters of plasma, magnetic field and energetic particles there. The INTERBALL/Auroral Probe (INTERBALL-2) satellite with a low-apogee 6-hour

orbit measured various parameters in the polar magnetosphere. Owing to a variety of satellite locations at the time MC passages, we have a possibility of investigating the different magnetospheric regions under different solar wind conditions. 3 Geoeffectiveness of magnetic clouds As indicated in Figures 1 - 3, the magnetic storm durations are close to those of the magnetic cloud. For instance for January 10-11, 1997 magnetic cloud (Burlaga et al., 1998), duration of magnetic storm and magnetic cloud were 18 h and



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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

1 9 9 7 - 1 9 9 8 : D s t , nT
0 -2 0 0 1 2 / 14 / 9 6 0 -2 0 0 1 /1 0 /9 7 0 -2 0 0 2 /6 /9 7 0 -2 0 0 3 /5 /9 7 0 -2 0 0 4 /1 /9 7 0 -2 0 0 4 /2 8 /9 7 0 -2 0 0 5 /2 5 /9 7 0 -2 0 0 6 /2 1 /9 7 0 -2 0 0 7 /1 8 /9 7 0 -2 0 0 8 /1 4 /9 7 8 /2 4 /9 7 9 /3 /9 7 5 /1 1 /9 8 D a te 5 /2 1 /9 8 5 /3 1 /9 8 7 /2 8 /9 7 8 /7 /9 7 4 /1 4 /9 8 4 /2 4 /9 8 5 /4 /9 8 7 /1 /9 7 7 /1 1 /9 7 3 /1 8 /9 8 3 /2 8 /9 8 4 /7 /9 8 6 /4 /9 7 6 /1 4 /9 7 2 /1 9 /9 8 3 /1 /9 8 3 /1 1 /9 8 5 /8 /9 7 5 /1 8 /9 7 1 /2 3 /9 8 2 /2 /9 8 2 /1 2 /9 8 4 /1 1 /9 7 4 /2 1 /9 7 1 2 / 27 / 9 7 1 /6 /9 8 1 /1 6 /9 8 3 /1 5 /9 7 3 /2 5 /9 7 1 1 / 30 / 9 7 1 2 / 10 / 9 7 1 2 / 20 / 9 7 2 /1 6 /9 7 2 /2 6 /9 7 1 1 /3 /9 7 1 1 / 13 / 9 7 1 1 / 23 / 9 7 1 /2 0 /9 7 1 /3 0 /9 7 1 0 /7 /9 7 1 0 / 17 / 9 7 1 0 / 27 / 9 7 1 2 / 24 / 9 6 1 /3 /9 7 9 /1 0 /9 7 9 /2 0 /9 7 9 /3 0 /9 7

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variations for January, 1997 - May, 1998


Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds Table 1. Magnetic clouds observed on INTERBALL-1 as well as on WIND (*) and SOHO+IMP-8 (**). N Date 1995 Aug.22-23 * Oct.18-19 * 1996 Dec.24-25 * 1997 Jan.10-11 * Feb. 9-11 * Apr.10-11 * Apr. 21-23 * May 15-16 * June 8-9 * June 19 * July 15-16 * Aug. 3-4 * Sept. 3 * Sept.18-20 * Sept. 21 * Sept.21-22 * Oct. 1-2 ** Oct. 10-12 * Nov. 7-8 * Nov. 22-23 * Dec. 10-11 * Dec. 30-31 * 1998 Jan. 7-8 * Feb. 4-5 * Feb. 17-18 * Mar 4-5 * May 2-3 *,** May 4-5 * June 2 *,** June 24-25 * Sept. 25-26 * Oct. 18-20 * Nov. 7-8 *,** Nov. 8-10 * Nov. 13-14 * Average Durations, h MC (+ Shock) 19 28 33 23 41 22 43 46 24 10 45 13 12 56 5 19 42 45 24 18 15 25 29 41 14 30 ? 15 8 35 29 22 ? 34 32 27 (+7) (+8) (+10) (+4) (+14) (+9) (+1) (+4) (+3) (+6) (+6) (+4) (+10) (+4) (+5) (+3) (+4) (+5) (+7) (+10) (+16) (+7) (+14) (+17) (+16) (+4) (+14) (+9) ? (+4) (+7) (+9) (+4) (+13) (+4) (+8) Space regions by INTERBALL-1 MS/MSH/SW MS/MSH/MS Conditions in SW

5

Sharp changes jumps changes Multiple P jumps Quiet SW Quiet SW jumps jumps jumps jumps jumps and variations jumps and jumps

jumps Quiet SW jumps jumps jumps and variations jumps and jumps

23 h, respectively. Therefore, we can compare the instant of magnetic storm beginning with MC structure. Our analysis of SW and IMF data for all events shows that, on the whole, the large drop of index is observed after southward IMF turning with 0-2 h delay (We used 1-hour averaged index data). Usually these IMF turnings occurred in the compressed region between IS and MC LE or inside of MC body due to slow IMF rotation, and our observations agree with previous results (Burlaga et al., 1998; Crooker , 2000). To describe the polar disturbances we used either the magnetic field data of several polar ground stations, near

which the events took place, or the integral polar indices. In particular, we analyzed Contracted Oval, Standard Oval, and Expanded Oval calculated for 3 systems of stations located on 3 concentrical circles near the northern magnetic pole (For more details see the Auroral Oval Indices on the Cluster/Ground-Based Data Center web site http://www.wdc.rl.ac.uk/gbdc/ovals/plots). The analysis of additional data indicates that these indices are sensitive to substorms and allow us to select them. However, in a small number of cases they demonstrate polar activations which are not substorms. In our analysis the activations were deter-

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

al. (1998) and Wilson (2000)). However, the observed difdependences for strong storms ference between and magnetic clouds can be explained by fact that duration of magnetic storm, as a rule, is shorter than duration of MC. The details of such a relation during MC passage periods requires further investigations.

4 Magnetospheric boundaries Since the location of the magnetopause (MP) is determined by the balance of plasma and magnetic field pressures in the solar wind, decelerated and heated at the bow shock (BS), and inside the magnetosphere, any change of conditions in the interplanetary medium results in a displacement of the MP and hence in the displacement of the BS, for which MP is an obstacle when the solar wind flows around it. The INTERBALL-1 satellite locations at BS and MP crossings allow the BS and MP locations to be compared with the solar wind conditions determined by other spacecraft and with model predictions. We considered 44 MP crossings by the INTERBALL-1 satellite at MC passage time. Figure 7 presents the locations , where of these crossings in the meridional plane ( ) and at the cross-section of the tail (YZ), as well as the average locations of MP (at SW pressure of 2 nPa (Sibeck et al., 1991)) and BS (Fairfield , 1971). It is seen from the figure the deviation of a real MP location from average one varies from 1-2 on the MS dayside up to 5-7 in the tail. In this case the real MP more often occurs to be closer to the Earth than average location predicted by the model. SW parameters (the plasma pressure and the IMF component) were determined for each MP crossing taking into account the time delay of plasma propagation between two spacecraft. The range of variation of these parameters for MCs under consideration was found to be rather wide: 0.3 42 nPa and -21 21 nT. The existing

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mined as follows. If even one of three indices on the interval of 15 minutes decreased more than 200 nT from the previous level, and duration of this reduction was more than 10 minutes we call all these phenomena "activations". It is necessary to have in mind that about 2/3 of the cases relate to substorms. Figures 4 - 5 show these indices for magnetic cloud of January 10-12,1997. The comparison of Fig.3 in paper by Burlaga et al. (1998) and Figs. 4,5 shows that the drop in indices are observed soon after the passage of MC LE. However, the changes in the IMF orientation and jumps in the field magnitude and SW pressure for this event can be found not for all activations. The SW and IMF data and Auroral Oval Indices were analyzed in detail and the similar comparison of polar indices variations with MC structures was made for all MCs shown in Figs. 1 - 3 and Table 1. Table 2 presents the minimum of hour-averaged values index and number of activations of polar indices reof lated to the set of MC structures. For event of January 10-11, 1997, MC LE (at 04:30 UT) corresponds to activation (this is designated as 1 activation per 1 structure, i.e. 1/1), while no activation corresponds to IS before MC LE (at 01:00 UT) and MC TE (at 01:00 UT on January 11) (this is desigindex were observed nated as 0/1). The decreases of the usually for all MCs. However, in some cases (for example, on September 21, 1997 and on June 24-25, 1998) the index pointed to very weak magnetic storms or even their absence component was (on June 2, 1998). In last cases the IMF less than -5 nT only during short time intervals (less 1.5 h). The comparison of activations with the MC structure has shown that only 185 of 237 activations (78% of their total number) can be associated with IS before MC LE (IS1), LE, ( 0), and the TE, IS before TE (IS2), the sign of IMF jumps of field ( ) and dynamical pressure of SW plasma ( ). In this case, the highest relative frequency of activations (the ratio of the number of activations to the number of events of selected type) is observed after IS1 and LE. However, some strong jumps of and IMF (as, for example, a very high pressure at MC TE on January 11, 1997 when SW could push the magnetosphere at geosynchronous orbit) have not resulted in activations. It should be noted that this large jump was observed after 8 h of positive IMF . and number of activations presented The data about in Table 2 were shown by black diamonds in Figure 6 and approximated by solid line. The activations can be connected not only with MCs, but also with magnetospheric disturbances caused by other reasons. The dependence of the number of activations on index for large magnetic storms ( nT), which is presented by open circles and dashed line, is very closed to dependence for all magnetic clouds, but the number of activations for strong storms is slightly less than for magnetic clouds. These data allow us to suggest that there is a relation between number of activations and index. Despite a high scatter of the data, we note that the passage of MC causing strong decrease of index is accompanied by a higher number of polar activations (the linear approximation gives the dependence for number of activations ). The problem of establishing a relation between slowly varying global geomagnetic indices and rapidly varying polar indices has been already discussed in the literature (see, e.g. Kamide et

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

7

Fig. 4. Time dependences of the auroral indices Contracted Oval, Standard Oval, and Expanded Oval on January 10, 1997.

MP models (Sibeck et al., 1991; Roelof and Sibeck, 1993; Petrinec and Russell, 1996; Kuznetsov and Suvorova, 1997; Shue et al., 1997) have narrower range of variation. The last version of the MP model (Shue et al., 1998) was obtained using higher SW parameters. We compared the real MP crossings with two models, and figure 8 presents the distance between the measured location and those predicted in the models by Shue et al. (1997) (circles) and Shue et al. (1998) (diamonds). In this case, positive distances correspond to the event when the measured boundary lies inside model predictions (i.e., closer to the Earth). The distance was measured along the normal to the model boundary. Figure 8 clearly demonstrates that both models well predict the MP position in the subsolar region (at ) and worse in the tail ( 0): on the dayside the MP is located by 1-2 closer to the Earth and in the tail the scatter is from -5 to +2 . Our statistics do not allow us to compare quantitatively both models with sufficient reliability. However, the larger scatter of MP crossing with respect to model predictions testifies that the MP motion during MC passage is more complicated than it is predicted by empirical models which

were mainly constructed for the conditions of weakly disturbed SW. Table 3 presents the results of comparison of the MP location with predictions of the model by Shue et al. (1998) as well as the comparison of BS location with its average position. Similar statistical models for BS, which take into account the conditions in the interplanetary space, are absent now; by this reason, the real BS crossing was compared with average BS location. However, since the MP is obstacle for SW in forming BS, we plan to take into account the MP motion depending on conditions in the SW and to investigate the correlation between changes of BS and MP location. Now we can only notice that the deviation of BS from average location is approximately the same as that for MP. The MP shape and motion for MC of January 10-11, 1997 were studied, in particular, by Nikolaeva et al. (1998) and Safrankova et al. (1998). The results indicated that the change of magnetosphere size was accompanied by more complicated deformations than a simple compression when different parts of the magnetosphere simultaneously undergo proportional displacement, by surface waves on the boundaries and

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

Fig. 5. Time dependences of the auroral indices Contracted Oval, Standard Oval, and Expanded Oval on January 11, 1997.

by oscillation of the tail (Yermolaev et al., 1997a; Nikolaeva et al., 1998). More complicated character of MS compression follows also from observations on October 18-19, 1995, since these data were interpreted as a result of reconnection of magnetic field not in the subsolar region or near the cusp but rather on the MP in the far tail at distances larger than 20 (Savin et al., 1997). 5 Magnetosphere state. As was shown in previous Section, the MC passage to the Earth is accompanied by the displacement of MS boundaries. This implies partially that the place where one physical region of space is usually observed (which is characterized by typical values of plasma and magnetic field parameters) occurs to be occupied by another region which is observed far from this place under normal conditions. Though small displacement of various regions is a rather frequent phenomenon in such a dynamical system as MS, displacements to distance comparable with the size of regions or even greater are quite rare phenomena. This fact should be taken into account when

comparing the parameters of the usual magnetosheath, for instance, with those magnetosheath-like plasmas which we observed in the region of usual plasma sheet observations. Such an analysis is very important since it provides additional information on the dynamics and mechanisms of different MS region formation. We have considered only several examples from the large set of various cases of anomalous location of MS regions, and the results presented below can be considered only as a first step in this direction. Figure 9 shows the dynamic energy spectrograms of ions (the abscissa is time, the ordinate is energy, the color from blue to red indicates increasing value of ion flux) for three successive orbits of INTERBALL-1 during the period of January 6-15, 1997. In this case the data, placed on the same vertical straight line, were obtained approximately at the same satellite coordinates. (Due to annual satellite orbit evolution with respect to the Sun-Earth axis the planes of successive orbits in GSE frame are displaced relative to each other by an angle of .) These data were obtained by the CORALL instrument (Yermolaev et al., 1997b) with the help of a sen-



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9

Date 1995 Aug. 22-23 Oct. 18-19 1996 Dec. 23-25 1997 Jan. 10-11 Feb. 8-11 Apr. 10-11 Apr. 21-23 May 15-16 June 8-9 June 19 July 15-16 Aug. 3-4 Sept. 2-3 Sept. 18-20 Sept. 21 Sept. 21-22 Oct. 1-2 Oct. 10-12 Nov. 7-8 Nov. 22-23 Dec. 10-11 Dec. 30-31 1998 Jan. 7-8 Feb. 4-5 Feb. 17-18 Mar. 4-5 May 2-3 May 4-5 June 2 June 24-25 Sept. 25-26 Oct. 18-20 Nov. 7-8 Nov. 8-10 Nov. 13-14 Total Avarage

Dst, nT Total -61 -127 -33 -78 -68 -82 -107 -115 -84 -36 -45 -49 -98 -56 -24 -30 -98 -130 -110 -108 -60 -77 -83 -34 -100 -36 -85 -205 -1 -25 -207 -139 -148 -148 -133 -86 3 9 2 9 15 4 2 6 5 0 4 5 3 5 2 2 7 4 6 10 4 5 10 2 5 4 12 7 1 7 14 9 11 23 20 237 7 IS1 0/1 1/1 0/1 0/1 1/1 0/1 1/1 0/1 1/1 0/1 0/1 0/0 0/1 1/1 0/1 1/1 1/1 1/1 1/1 1/1 0/1 0/1 0/1 1/1 0/1 1/1 1/1 1/1 0/0 0/1 1/1 0/1 0/1 1/1 1/1 17/33

Number of substorms and activations LE B jump B 0 Pjump 0/1 1/1 0/1 1/1 1/1 1/1 0/1 1/1 0/1 0/1 1/1 1/1 1/1 0/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 0/1 1/1 0/1 1/1 0/1 1/1 1/1 1/1 1/1 1/1 0/0 1/1 25/34 3/5 1/1 0/5 2/3 2/4 1/2 0/5 2/6 0/5 0/0 0/0 1/1 0/0 1/3 0/1 0/0 1/1 1/2 1/3 1/1 1/3 1/1 4/6 0/0 1/1 2/6 0/3 1/3 0/1 0/4 1/2 6/10 7/17 10/12 ? 51/117

IS2 0/0 1/1 0/0 0/1 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/1 0/0 0/0 1/1 0/0 1/1 0/0 0/0 0/1 0/0 0/0 0/0 0/0 0/0 3/6

TE 0/1 0/1 0/1 0/1 1/1 1/1 0/0 1/1 0/0 0/0 0/0 0/1 1/1 1/1 1/1 0/1 0/1 0/1 0/1 1/1 1/1 0/1 0/1 0/1 0/1 0/1 0/0 0/1 0/1 0/1 1/1 0/1 0/0 1/1 1/1 8/28







sor oriented perpendicular to the satellite spin axis, i.e., in the plane normal to the Sun-Earth direction. The upper panel, whose data were obtained before the MC passage, shows at first a hot and low density plasma of the plasma sheet. During interval from 22 UT on January 6 to 02 UT on January 7, when satellite was close to geomagnetic equator ( -17 and ) the plasma of a low-latitude boundary layer (LLBL) was observed. After this the satellite began to approach the Earth while crossing the

plasma mantle several times and the tail lobes and the satellite reached the radiation belt at 23 UT. Before the MC passage on January 10 the plasma sheet ions (more precisely PSBL ions) were observed. However, at about 01:20 UT the satellite crossed the MP and entered the very hot magnetosheath. Then, from 06 to 20 UT, the instrument recorded both long (for 1-2 h) intervals and short (a few minutes) bursts of plasma sheet with lower density and higher energy than on the previous orbit. The plasma sheet

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0 2 1 2 3 0 0 3 0 0 3 0 0 0 0 0 0 1 2 6 1 3 0 0 1 1 8 1 0 5 6 2 2 11 ? 64

0/2 1/3 1/1 1/3 3/5 0/0 1/1 0/1 1/6 0/0 0/0 1/1 1/2 1/3 0/3 0/1 1/2 0/2 0/1 0/1 0/0 0/0 0/1 0/6 0/0 0/0 0/1 0/0 0/0 2/6 0/1 1/2 1/4 1/4 ? 17/65

r V a y

q


10

Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

Fig. 9. The ion energy spectrograms during 3 successive orbits of INTERBALL-1 on January 6-15, 1997.

observations were interrupted by satellite entering the lobes which connected with fast tail motion with respect to a rather slowly moving satellite. After MC trailing edge passage at about 01:20 UT on January 11, the satellite from the plasma sheet quickly entered a very dense and hot magnetosheath, then at 02 UT it was in the LLBL (at a rather large distance ) and then from geomagnetic equator with in the plasma sheet.

On the third panel of figure the ion measurements are shown after MC passage on January, 13-15, 1997. Till 18:30 the CORALL instrument was switched off. First the satellite consistently crossed MSH, PSBL and LLBL, and at 07:30 UT has come PS. As a whole the boundaries of magnetospheric regions are located near to their average positions, and fluxes of plasma in all regions are appreciably lower, than on two previous panels, especially low density of ions in PS. Also it

r eF D d




Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds Table 3. Magnetospheric boundary locations.
20

11

R yz, R e

10

0 -2 0 -1 0 0 10 20

20

10

ZGSM , Re

0

-1 0

-2 0

-2 0

-1 0

0

10

20

YGSM , Re

Fig. 7. INTERBALL-1 magnetopause crossings during magnetic and (b) planes. cloud passages in the (a)

6 5 4 3 2

S h u e et al, 1 9 9 7 S h u e e t a l, 1 9 9 8

D i s t, R e

1 0 -1 -2 -3 -4 -5 -6 -2 5 -2 0 -1 5 -1 0 -5 0 5

in s id e M P o u ts id e M P

10

X, Re

Fig. 8. Comparison of magnetopause crossings with model (Shue et al., 1997) (circles) and (Shue et al., 1998) (diamonds) predictions.

is possible to note, that variability in PS is significantly lower, than on the previous orbit, and it basically is connected not with memory of magnetosphere about passage of the magnetic cloud, and with current variations of SW and IMF parameters. The dynamic energy spectrograms of electrons, measured by ION instrument (Sauvaud et al., 1997) on subsequent orbits of the INTERBALL-2 satellite, are presented in Figure 10. Before the MC passage in the polar cap (invariant ) the fluxes of electrons had low energy of latitude several tens of electronovolts and too low intensity to be observed. However after the MC TE passage on January 11, 1997, high fluxes of electron with energy 100-300 eV were detected in the polar cap. This interval coincides with the INTERBALL-1 exit from the plasma sheet into the magnetosheath and LLBL, i.e., the disturbance of distant tail of MS coincided with electron precipitation in the polar cap. Thus, several features of the magnetosphere and magnetosheath plasma observed during the MC passage can be summarized as follows. The magnetosheath ion temperature (or ion energy) is usually higher than in the average MSH. This effect is stronger during passage of pressure jumps on the IS, LE and TE. Density in MSH correlates with SW density. Simulta-

$

XGSM , Re

1995 Oct. 18 -2.4 ... 1.4 Oct. 19 -4.4 ... 0.6 1996 Dec.25 5 1997 Jan. 10 -0.9 ... 1.4 Jan. 11 0.0 ... 1.5 Feb. 8 3 Feb. 9 2 ... 3 Feb. 10 4 -3.2 Feb. 11 3 ... 6 June 9 -5 ... -6 -0.5 July 3 -2 ... -4 July 4 2 Sept. 03 2 1.0 ... 2.8 Sept. 18 7 -3.5 Sept. 20 7 Sept. 21 7 1998 Feb. 3 -0.9 Feb. 4 -4.7 ... -2.0 Feb. 18 1.7 Mar. 4 -3 ... 3 3.5 Mar. 5 3 ... 4 1.0 May 4 0 1.7 * Distance is possitive if the boundary is located closer to the Earth than the model boundary

q j p

Date

Distance ( ) between boundary crossing and Bow Shock Magnetopause

uc V ts r

gh gf o n ml k жj i


12

Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

Fig. 10. The electron energy spectrograms during 3 orbits of INTERBALL-2 on January 10-12, 1997.

neous observations on GEOTAIL and INTERBALL-1 satellites showed that during large increasing in MSH density (for example, on 11 January, 1997 when the density in MSH in150 cm ) the change in PS density was creased up to small (Yermolaev et al., 1997a). The MC passages result in observations of different magnetospheric regions far from their average locations and multiple crossings of boundaries between them. These observations allow us to suggest a large-scale geomagnetic tail oscillations relative to the satellite, so that the displacements of some magnetospheric regions are comparable to characteristic size of the regions. These motions can result in the development of disturbances and acceleration of ions and electrons in the plasma sheet, their subsequent injection and precipitation in polar regions of the magnetosphere (Yermolaev et al., 1997a, 2000a,b).

6 Conclusions. The results on the analysis of magnetic clouds observed on interplanetary spacecraft and INTERBALL-1,2 satellites during August, 1995 - December, 1998 (near minimum of solar cycle), allow us to make several conclusions about the magnetospheric response to these events. The geoefectiveness of magnetic clouds depends on the value of parameter variations in the magnetic cloud. For low, medium, or moderately high variations of plasma and magnetic field in the cloud, the magnetospheric response is the same as for similar variations in the interplanetary space in the absence of magnetic clouds, and strongly depends on the interplanetary magnetic field prehistory: -after prolonged energy transfer to the magnetosphere (at the southward IMF) practically all changes in the solar wind

w v

@


Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds

13 shock disturbances and coronal mass ejections, J.Geophys.Res., 96, 7831, 1991. Kamide, Y., W. Baumjohann, I. A. Daglis, W. D. Gonzalez, M. Grade, J. A. Joselyn, R. L. McPherron, J. L. Phillips, E. G. D. Reeves, G. Rostoker, A. S. Sharma, H. J. Singer, B. T. Tsurutani, and V. M. Vasyliunas, Current understanding of magnetic storm: Storm-substorm relationships, J.Geophys.Res.,103, 17705, 1998. Kuznetsov, S. N., ans A. N. Suvorova, The magnetopause shape in the region of geosynchronous orbit, Geomagn. Aeronom., 37, 1, 1997. Lepping, R. P., M. H. Acuna, L. F. Burlaga, W. M. Farrel, J. A. Slavin, K. H. Schatten, F. Mariani, N. F. Ness, F. M. Neubauer, Y. C. Whang, J. B. Byrnes, R. S. Kennon, P. V. Panetta, J. Scheifele, and E. M. Worley, The WIND magnetic field investigation, Space Sci.Rev., 71, 207, 1995. Nikolaeva, N. S., G. N. Zastenker, M. N. Nozdrachev, A. A. Skalsky, N. A. Eismont, J. Safrankova, Z. Nemecek, O. Santolik, J. Steinberg, A. Lazarus, A. Szabo, R. Lepping, J.-H. Shue, J. Borovsky, M. Tomsen, and L. Frank, Position and motion of the magnetopause during arrival of a magnetic cloud to the Earth on January 10 and 11, 1997, Kosmich.Issled., 36, 563, 1998 (in Russian). Ogilvie, K. W., D. J. Chornay, R. J. Fritzenreiter, F. Hunsaker, J. Keller, J. Lobell, G. Miller, J. D. Scudder, E. C. Sittler Jr., R. B. Torbert, D. Bodet, G. Needell, A. J. Lazarus, J. T. Steiberg, J. H. Tappan, A. Mavretic, and E. Gergin, A comprehensive plasma instrument for the WIND spacecraft, Space Sci.Rev., 71, 55, 1995. Petrinec, S. M., and C. T. Russell, Near-Earth magnetotail shape and size as determined from the magnetopause flaring angle, J.Geophys.Res., 101, 137, 1996. Petrukovich A. A., and S. I. Klimov, The use of solar wind measurements for the analysis and prediction of geomagnetic activity, Kosmich.Issled., 38, 463, 2000 (in Russian). Roelof E. C., and D. G. Sibeck, Magnetopause shape as bivariate function of interplanetary magnetic field Bz and solar wind dynamic pressure, J.Geophys.Res., 98, 21421, 1993. Safrankova, J., Z. Nemecek, L. Prech, G. Zastenker, K. I. Paularena, N. Nikolaeva, M. Nozdrachev, A. Skalsky, and T. Mukai, The January 10-11, 1997, magnetic cloud: Multipoint measurements, Geophys.Res. Lett., 25, 2545, 1998. Sauvaud J.-A., H. Barthe, C. Aoustin, J. J. Thocaven, J. Rouzaud, E. Penou, R. A. Kovrazhkin, and K. G. Afanasiev, The ION experiment onboard the INTERBALL-AURORA satellite; initial results on velocity dispersed structures in the cleft and inside the auroral oval, Ann. Geophys., 16, 1056, 1998. Savin S., O. Balan, N. Borodkova, E. Budnik, N. Nikolaeva, V. Prokhorenko, T. Pulkkinen, N. Rybjeva, J. Safrankova, I. Sandahl, E. Amata, U. Auster, G. Bellucci, A. Blagau, J. Blecki, J. Buechner, M. Ciobanu, E. Dubinin, Yu. Yermolaev, M. Echim, A. Fedorov, V. Formisano, R. Grard, V. Ivchenko, F. Jiricek, J. Juchniewicz, S. Klimov, V. Korepanov, H. Koskinen, K. Kudela, R. Lundin, V. Lutsenko, O. Marghitu, Z. Nemecek, B. Nikutowski, M. Nozdrachev, S. Orsini, M. Parrot, A. Petrukovich, N. Pissarenko, S. Romanov, J. Rauch, J. Rustenbach, J.-A. Sauvaud, E. T. Sarris, A. Skalsky, J. Smilauer, P. Triska, J. G. Trotignon, J. Vojta, G. Zastenker, L. Zelenyi, Yu. Agafonov, V. Grushin, V. Khrapchenkov, L. Prech, and O. Santolik, INTERBALL magnetotail boundary case studies, Adv.Space Res., 20, N 4/5, 999, 1997 Shue J.-H, J. K. Chao, H.C. Fu, C. T. Russell, P. Song, K. K. Kharana, and H. J. Singer, A new functional form to study the solar wind control of the magnetopause size and shape, J.Geophys.Res., 102, 9497, 1997. Shue J.-H., P. Song, C. T. Russell, J. T. Steinberg, J. K. Chao, G. Zastenker, O. L. Vaisberg, S. Kokubun, H. J. Singer, T. R. Detman, and H. Kawano, Magnetopause location under ex-

pressure or in the IMF magnitude and orientation can result in auroral activations, substorms and magnetic storms; -with prolonged northward IMF all changes in magnetic cloud parameters are not geoeffective and do not have significant influence on the state of the magnetosphere and on the geomagnetic field. Extremely high jumps of parameters in magnetic clouds (mainly near their boundaries: in shocks, at leading and trailing edges) can result in the unusual behavior of the magnetosphere: -strong and rather complicated compression and deformation (with large and disproportional displacement of boundaries) of the magnetosphere relative to its usual position; -large-scale oscillations of geomagnetic tail structures relative to satellite; -the development of disturbances in the plasma sheet, which result in acceleration of ions and electrons and their injections in the polar cap. The magnetic clouds resulting in a greater number of polar disturbances like substorms are accompanied, as a rule, by stronger global disturbance like magnetic storms.
Acknowledgements. The key parameters of plasma and magnetic field in the interplanetary space (PIs of experiments K.W.Ogilvie and R.P.Lepping) were obtained from NASA/GSPC via CDAWeb, the data on Auroral Oval Indices from the Cluster/Ground-Based Data Center. We thank S.I.Klimov, S.A.Romanov, M.N.Nozdrachev and A.A.Skalsky for results of INTERBALL magnetic field measurements, A.O.Fedorov for his participation in CORALL data processing, R.A.Kovrazhkin and N.L.Borodkova for help in ION and ELECTRON data preparation, V.I.Prokhorenko for calculations of INTERBALL orbits, S.P.Savin, L.M.Zelenyi, P.E.Eiges, Z.Nemecek, J.Safrankova, and Yu.I.Galperin for assistance and useful discussions. The work was partially supported by the RFBR, grants 97-02-16489, 98-02-16297 and 98-05-64508, and by the INTAS, grants 97-1612 and 99-0078.

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Yu. I. Yermolaev et al.: Magnetospheric response to magnetic clouds