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Cusp energetic particles observed by INTERBALL-tail probe in 1996
Phys. Chem. Earth (C), Vol.26, No. 1-3,pp. 241-245, 2001 © 2001 ElsevierScienceLtd. All fightsreserved 1464-1917/00/$ - see frontmatter
Pergamon
PII: S1464-1917(00)00115-X
Cusp Energetic Particles Observed by INTERBALL-Tail Probe in 1996 N. E Pissarenko ~, I. P. Kirpichev ~, V. N. Lutsenko 1, S. e. Savin 1, E. Yu. Budnick ~, A. R. M o s z h u k i n a ~, E. I. M o r o z o v a 1, A. E. A n t o n o v a 2 and I. SandahP
tSpace Research Institute, Moscow, Russia 2Institute of Nuclear Physics, Moscow State University, Moscow, Russia 3Swedish Institute of Space Physics, Kiruna, Sweden Received 19 December 1999; revised 19 May 2000; accepted 30 June 2000
the particles are accelerated within the Earth's magnetosphere during substorms and due to driftshell branching effect bringing nightside nearequatorial particles to dayside high-latitude regions (Antonova et al., 2000; Delcourt and Sauvaud, 1998, 1999)
The protons with energies of 1 - 3 M e V were observed in the dayside cusp by INTERBALL-Tall Probe. The flux increases lasting for several tens of minutes were recorded up to the magnetopause. These energetic particle enhancements were accompanied by lowfrequency wave turbulence. © 2001 Elsevier Science Ltd. All fightsreserved Abstract.
1
particles are accelerated up to high energy in the diamagnetic cavity inside of the cusp (Chen et al., 1998; Karra and Fritz, 1999)
Introduction
More than 30 years ago V.P. Shabansky and his collaborators showed that the region of local magnetic field minima in the high-latitude dayside outer magnetosphere, resulting from the solar wind - magnetosphere interaction, and involving both closed and open field lines can serve as a trap for energetic charged particles (Shabansky and Antonova, 1968; Shabansky, 1971). These theoretical studies have been confirmed by experiments onboard the ELECTRON, IMP 3 and 5, PROGNOZ 3, 7, and 9 S/C (see, e.g. Vernov et al., 1967; Murayama, 1971; Antonova, 1996). In 1996-1998 in a series of sophisticated experiments onboard the POLAR and INTERBALL-Tail Probe satellites the presence of a new energetic particle component consisting of protons and alpha particles with energies E exceeding 1 M e V has been found in the dayside cusp (Chen et al., 1997, 1998; Savin et al., 1998). Although the existence of energetic particle trapping and quasi-trapping in the cusp region was well established earlier, the particle origin is still unclear. The questions are as follows: where and how do these particles gain their high energy and how do they come into the cusp? There exist several possibilities:
the accelerated particles might come from the vicinity of the near-Earth's quasi-parallel bow shock (Chang et al., 1998). 2
Data analysis
In this work we investigate three events of energetic particle enhancements recorded during INTERBALLTail Probe (INTERBALL-1) passes through the northern cusp region on February 24, March 14, and April 21, 1996. Spring of 1996 was the most convenient period for study of the dayside cusp particle characteristics by the INTERBALL-1. The spacecraft was situated within the cusp for a long time and crossed it during the outbound parts of the orbits which pass from the radiation belts to the bow shock. Figure 1 shows the magnetic field line topology based on the Tsiganenko-96 model in GSM coordinates for March 14. The black circles mark satellite locations for each hour (closest to the Earth diamond corresponds to 00.00 UT). It is can see the INTERBALL-1 was on closed lines until 03.00 UT. It entered the northern cusp at 03.14 UT that was confirmed by detecting the high flux of low-energy ions. The observational results reported here were obtained using the energetic charged particle spectrometers SKA2 and DOK-2 (Pissarenko et al., 1998; Lutsenko et al., 1998); the PROMICS-3, CORALL, and ELECTRON
- the energetic component of the Earth's radiation belts and the ring current might escape into the cusp by diffusion process; Correspondence to: N. F. Pissarenko
241
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N. E Pissarenko et al.: Cusp Energetic Particles Observed by INTERBALL
March 14, 1996
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(Sandahl et al., 1997; Yermolaev et al., 1997; Sauvaud et al., 1997) plasma spectrometers; magnetometers and low-frequency plasma wave instruments ASPI (Klimov et al., 1997). The events of February 24, March 14, and April 21, 1996 are first characterized by a high intensity of charged energetic particle fluxes (Fig. 2, 3a,b). For example, on February 24, 1996, the m a x i m u m fluxes of E > 1 M e V protons exceeded 103 era - 2 s -1 (Fig. 2). The second feature is a strong variation of particle intensity with a characteristic time scale less than a few tens of seconds. Let consider the cusp characteristics for the events of March 14 and April 21, 1996 taken as examples. At March 14 magnetopause was encountered at 05.07 UT. During entire period from 03.14 to 05.07 UT the satel-
lite was situated in the cusp and detected a high inhomogeneity of plasma flux structure. After crossing the magnetopause (05.07 UT) and exit from the exterior cusp/stagnation region (05.07 - 06.45 UT) Tail Probe passes the magnetosheath and reach the bow shock at 09.40 UT. Final exit into the solar wind was at 11.10 UT. It can be noted that the decrease of high-energy particle ( E ,.~ lOOkeV) intensity begins fi'om 09.40 U T and continues up to the exit into the solar wind. The same analysis was made for April 21, 1996. The results are presented below. The cusp (C), magnetopause (MP), exterior cusp/stagnation region (EC/SR), magnetosheath (MSH), bow shock (BS), and solar wind (SW) are distinguishable in all events; for the two events shown in Fig 3(a, b) we find: - March 14: C - 03.14-05.07, MP - 05.07, E C / S R 05.07-06.45, MSH - 06.45-11.10, BS - 11.10 UT; -
April 21: C - 03.40-04.20, MP - 04.20, E C / S R 04.20-05.15, MSH - 05.15-08.02, BS - 08.02, MSH 08.55-09.40 UT.
In contrast to the particles with energies less than tens of k c V , more energetic ( ~ lOOkeV) particles fill the entire cusp region and are relatively uniformly distributed practically up to the Earth's bow shock (Fig. 3a). It can be also seen from a set of spectra for different fragments
N. E Pissarenko et al.: Cusp Energetic Particles Observed by INTERBALL
243
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\,
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The following parameters are displayed on the panels (from top to bottom): (1) By; (2) CORALL E-T spectrogram; (3) the magnetic (Era, shadowed), the ion thermal Et and total energy density; (4) the magnetic field RMS: the shadowed curve presents the RMS of the magnetic field magnitude and upper curve shows the RMS for total one (the sum for three components); and (9) the frequency-time spectrogram of the magnetic field in the range 0.008 to 2 Hz.
N. E Pissarenko et aL: Cusp Energetic Particles Observed by INTERBALL of s a t e l l i t e t r a j e c t o r y (Fig. 4). E n e r g e t i c p a r t i c l e spect r u m s h a p e is v i r t u a l l y i n v a r i a b l e u p t o t h e b o w shock. A t t h e s a m e time, it c a n b e seen t h a t a b e h a v i o r of p a r t i c l e s w i t h energies of a b o u t 1 M e V is m o r e complicated. H i g h i n t e n s i t y v a r i a t i o n s of t h e s e p a r t i c l e s were r e c o r d e d in t h e e n t i r e cusp r e g i o n a n d m a g n e t o s h e a t h u p to BS r e g i o n only d u r i n g M a r c h 14, 1996 event. I n A p r i l 21, 1996 event t h e e n h a n c e d 100 - k e V p a r t i c l e fluxes were o b s e r v e d u p to t h e BS front w h e r e a s t h e 1 M e V p a r t i c l e i n t e n s i t y c o n s i d e r a b l y d e c r e a s e d earlier. O n t h e o t h e r h a n d , t h e e n h a n c e d e n e r g e t i c p a r t i c l e int e n s i t y is c o r r e l a t e d w i t h t h e i n c r e a s e d wave t u r b u l e n c e d e t e c t e d w i t h i n a n d close to t h e cusp (Fig. 5). However t h e m e c h a n i s m r e s p o n s i b l e for this c o r r e l a t i o n is n o t clear now. I t requires f u r t h e r analysis.
3
Summary 1. F o r t h e s t u d i e d events t h e m a x i m u m i n t e n s i t y of 1 M e V p r o t o n s was as h i g h as 103 c m - 2 8 -1 . I t is close to P O L A R r e s u l t s o b t a i n e d for a n u m b e r of events in 1996 ( C h e n a n d Fritz, 1998). 2. O c c a s i o n a l l y e n h a n c e d e n e r g e t i c p a r t i c l e fluxes ( E ,~ 100 k e V ) were o b s e r v e d a l m o s t continuo u s l y from t h e cusp region, to t h e b o w shock w i t h slow c h a n g e d s p e c t r a a n d s m a l l i n t e n s i t y g r a d i e n t . T h e p a r t i c l e s w i t h e n e r g y ,-~ 1 M e V have m o r e complicated distribution. 3. I n m o s t cases t h e e n e r g e t i c p a r t i c l e flux e n h a n c e m e n t in t h e cusp region a r e a c c o m p a n i e d by enh a n c e d wave t u r b u l e n c e , as was e a r l y m e n t i o n e d ( P o t t e l e t e , 1990; W o c h a n d L u n d i n , 1992). 4. M o s t p r o b a b l y , these high e n e r g e t i c p a r t i c l e s come into t h e cusp from t h e different e x t r a - a n d i n t r a m a g n e t o s p h e r i c sources b u t t h e i r r e l a t i v e c o n t r i b u tions a r e still u n k n o w n .
Acknowledgements. We are grateful to A.O. Fedorov for the CORALL data, to N.L. Borodkova for the ELECTRON data, and to S.A. Romanov for the magnetic field data. This work was supported by INTAS 94-2638 grant.
References Antonova, A. E., High-latitude particle traps and related phenomena, Radiation Measurements, 26, 409-411, 1996. Antonova, A. E., Gubar', Yu. I., Kropotkin, A. P., Energetic particle population in the high-latitude geomagnetosphere, Physics and Chemistry of Earth, 25, 47-50, 2000. Chang, S.-W., Scudder, J. D., Fuselier, S. A., Fennell, J. F., Trattner, K. J., Pickett, J. S., Spence, H. E., Menietti, J. D., Peterson, W. K., Lepping, R. P., Friedel, R., Cusp energetic ions: A bow shock source, Geophys. Res. Lett., 25, 3729-3732, 1998. Chen, J., Fritz, T. A., Sheldon, R. B., Spence, H. E., Spjeldvik, W. N., Fennell, J. F., Livi, S., A new temporarily confined population in the polar cap during the August 27, 1996 geomagnetic field distortion period, Geophys. Res. Lett., 24, 1447-1450. 1997.
245
Chen, J., Fritz, T. A., Sheldon, R. B., Spence, H. E., Spjeldvik, W. N., Fennelt, J. F., Livi, S., Russell, C. T., Pickett, J. S., Gurnett, D. A., Cusp energetic particle events: Implications for a major acceleration region of the magnetosphere, J. Geophys. Res., 103, 69-78, 1998. Chen, J., Fritz, T. A., Correlation of cusp MeV helium with turbulent ULF power spectra and its implications, Geophys. Res. Lett., 25, 4113-4116, 1998. Delcourt, D. C., Sauvaud, J.-A., Recirculation of plasma sheet particles into the high-latitude boundary layer, J. Geophys. Res., 103, 26521, 1998. Delcourt, D. C., Sauvaud, J.-A, Populating of the cusp and boundary layers by energetic (hundreds of keV) equatorial particles, J. Geophys. Res., 103, 22635-22648, 1999. Karra, M., Fritz, T. A., Energy dispersion features in the vicinity of the cusp, Geophys. Res. Lett., 26, 3553, 1999. Klimov, S. I., et ai., ASPI experiment: Measurements of field and waves onboard the INTERBALL-1 spacecraft, Ann. Geophysicae, 15, 514-527, 1997. Lutsenko, V. N.~ Kudela, K., Sarris, E. T., DOK-2 experiment to study energetic particles by the Tail Probe and Auroral Probe satellites in the INTERBALL project, Cosmic Research, 1, 98107, 1998. Murayama, T., High latitude boundary of the stably-trapped radiation zone on the day-side of the magnetosphere, J. Geomagn. Geoelec., 23, 205-211, 1971. Pissarenko, N. F., Morozova, E. I., Lutsenko, V. N., Moszhukhina, A. R., Budnick, E. Yu., Sandahl, I., Lundin, R., Pulkkinen, T., Koskinen, H., Structure of the Earth's ring current during a solar minimum, Cosmic Research, 6, 549-558, 1998. Pottelette, R., High-frequency waves in the cusp/cleft region, J. Geophys. Res., 90, 5957, 1990. Sandahl, I., Barabash, S., Dubinin, E. M., Koskinen, H., Lundin, R., Obod, D., Pellinen, R., Pissarenko, N. F., Pulkkinen, T., Toivanen, P., Zakhaxov, A. V., First results from the plasma composition spectrometer PROMICS-3 in the INTERBALL project, Ann. Geophysieae, 15, 542, 1997. Sanvaud, J.-A., et al., The INTERBALL Tail Probe ELECTRON experiment: Initial results on the dawnside magnetosphere, Ann. Geophysieae, 15, 587-595, 1997. Savin, S. P., et al., Interbail Tail Probe measurements in outer cusp and boundary layers, in Geospace Mass and Energy Flows: Results from International Solar-Terrestrial Physics Program. AGU Geophysical Monograph, 104, 25, 1998. Shabansky, V. P., Some processes in the magnetosphere, Space Sci. Rev., 12, 299-418, 1971. Shabansky, V. P., Antonova, A. E., Topology of particle drift shells in the Earth's magnetosphere, Geomagn. Aeron. (English ed.), 8, 844, 1968. Vernov, S. N., Vakulov, P. V., Kuznetsov, S. N., Logachev, Yu. I., Sosnovets, E.N., Stolpovsky, V. G., The boundary of the outer radiation belt and the unstable radiation zone, Geomagn. Aeron. (Russian eel.), 7, 417-422, 1967. Tsyganenko, N. A., Stern, D. P., Modeling the global magnetic field the large-scale Birkeland current systems, J. Geophys. Rcs., 101, 27187-27198, 1996. Woch, J., Lundin, R., Magnetosheath plasma precipitation in the polar cusp and its control by the interplanetary magnetic field, J. Geophys. Res., 97, 1421, 1992. Yermolaev, Yu. I., Fedorov, A. O., Vaisberg, O. L., Ion distribution dynamics near the Earth bow shock: First measurements with 2-D ion energy spectrometer CORALL on INTERBALL Tail Probe satellite, Ann. Geophysicae, 15, 533-541, 1997.
Pergamon
PII: S1464-1917(00)00115-X
Cusp Energetic Particles Observed by INTERBALL-Tail Probe in 1996 N. E Pissarenko ~, I. P. Kirpichev ~, V. N. Lutsenko 1, S. e. Savin 1, E. Yu. Budnick ~, A. R. M o s z h u k i n a ~, E. I. M o r o z o v a 1, A. E. A n t o n o v a 2 and I. SandahP
tSpace Research Institute, Moscow, Russia 2Institute of Nuclear Physics, Moscow State University, Moscow, Russia 3Swedish Institute of Space Physics, Kiruna, Sweden Received 19 December 1999; revised 19 May 2000; accepted 30 June 2000
the particles are accelerated within the Earth's magnetosphere during substorms and due to driftshell branching effect bringing nightside nearequatorial particles to dayside high-latitude regions (Antonova et al., 2000; Delcourt and Sauvaud, 1998, 1999)
The protons with energies of 1 - 3 M e V were observed in the dayside cusp by INTERBALL-Tall Probe. The flux increases lasting for several tens of minutes were recorded up to the magnetopause. These energetic particle enhancements were accompanied by lowfrequency wave turbulence. © 2001 Elsevier Science Ltd. All fightsreserved Abstract.
1
particles are accelerated up to high energy in the diamagnetic cavity inside of the cusp (Chen et al., 1998; Karra and Fritz, 1999)
Introduction
More than 30 years ago V.P. Shabansky and his collaborators showed that the region of local magnetic field minima in the high-latitude dayside outer magnetosphere, resulting from the solar wind - magnetosphere interaction, and involving both closed and open field lines can serve as a trap for energetic charged particles (Shabansky and Antonova, 1968; Shabansky, 1971). These theoretical studies have been confirmed by experiments onboard the ELECTRON, IMP 3 and 5, PROGNOZ 3, 7, and 9 S/C (see, e.g. Vernov et al., 1967; Murayama, 1971; Antonova, 1996). In 1996-1998 in a series of sophisticated experiments onboard the POLAR and INTERBALL-Tail Probe satellites the presence of a new energetic particle component consisting of protons and alpha particles with energies E exceeding 1 M e V has been found in the dayside cusp (Chen et al., 1997, 1998; Savin et al., 1998). Although the existence of energetic particle trapping and quasi-trapping in the cusp region was well established earlier, the particle origin is still unclear. The questions are as follows: where and how do these particles gain their high energy and how do they come into the cusp? There exist several possibilities:
the accelerated particles might come from the vicinity of the near-Earth's quasi-parallel bow shock (Chang et al., 1998). 2
Data analysis
In this work we investigate three events of energetic particle enhancements recorded during INTERBALLTail Probe (INTERBALL-1) passes through the northern cusp region on February 24, March 14, and April 21, 1996. Spring of 1996 was the most convenient period for study of the dayside cusp particle characteristics by the INTERBALL-1. The spacecraft was situated within the cusp for a long time and crossed it during the outbound parts of the orbits which pass from the radiation belts to the bow shock. Figure 1 shows the magnetic field line topology based on the Tsiganenko-96 model in GSM coordinates for March 14. The black circles mark satellite locations for each hour (closest to the Earth diamond corresponds to 00.00 UT). It is can see the INTERBALL-1 was on closed lines until 03.00 UT. It entered the northern cusp at 03.14 UT that was confirmed by detecting the high flux of low-energy ions. The observational results reported here were obtained using the energetic charged particle spectrometers SKA2 and DOK-2 (Pissarenko et al., 1998; Lutsenko et al., 1998); the PROMICS-3, CORALL, and ELECTRON
- the energetic component of the Earth's radiation belts and the ring current might escape into the cusp by diffusion process; Correspondence to: N. F. Pissarenko
241
242
N. E Pissarenko et al.: Cusp Energetic Particles Observed by INTERBALL
March 14, 1996
~-3-t
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1 -
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~ E M - 2 electrons 45 - 90
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(Sandahl et al., 1997; Yermolaev et al., 1997; Sauvaud et al., 1997) plasma spectrometers; magnetometers and low-frequency plasma wave instruments ASPI (Klimov et al., 1997). The events of February 24, March 14, and April 21, 1996 are first characterized by a high intensity of charged energetic particle fluxes (Fig. 2, 3a,b). For example, on February 24, 1996, the m a x i m u m fluxes of E > 1 M e V protons exceeded 103 era - 2 s -1 (Fig. 2). The second feature is a strong variation of particle intensity with a characteristic time scale less than a few tens of seconds. Let consider the cusp characteristics for the events of March 14 and April 21, 1996 taken as examples. At March 14 magnetopause was encountered at 05.07 UT. During entire period from 03.14 to 05.07 UT the satel-
lite was situated in the cusp and detected a high inhomogeneity of plasma flux structure. After crossing the magnetopause (05.07 UT) and exit from the exterior cusp/stagnation region (05.07 - 06.45 UT) Tail Probe passes the magnetosheath and reach the bow shock at 09.40 UT. Final exit into the solar wind was at 11.10 UT. It can be noted that the decrease of high-energy particle ( E ,.~ lOOkeV) intensity begins fi'om 09.40 U T and continues up to the exit into the solar wind. The same analysis was made for April 21, 1996. The results are presented below. The cusp (C), magnetopause (MP), exterior cusp/stagnation region (EC/SR), magnetosheath (MSH), bow shock (BS), and solar wind (SW) are distinguishable in all events; for the two events shown in Fig 3(a, b) we find: - March 14: C - 03.14-05.07, MP - 05.07, E C / S R 05.07-06.45, MSH - 06.45-11.10, BS - 11.10 UT; -
April 21: C - 03.40-04.20, MP - 04.20, E C / S R 04.20-05.15, MSH - 05.15-08.02, BS - 08.02, MSH 08.55-09.40 UT.
In contrast to the particles with energies less than tens of k c V , more energetic ( ~ lOOkeV) particles fill the entire cusp region and are relatively uniformly distributed practically up to the Earth's bow shock (Fig. 3a). It can be also seen from a set of spectra for different fragments
N. E Pissarenko et al.: Cusp Energetic Particles Observed by INTERBALL
243
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1001 I0-I
The following parameters are displayed on the panels (from top to bottom): (1) By; (2) CORALL E-T spectrogram; (3) the magnetic (Era, shadowed), the ion thermal Et and total energy density; (4) the magnetic field RMS: the shadowed curve presents the RMS of the magnetic field magnitude and upper curve shows the RMS for total one (the sum for three components); and (9) the frequency-time spectrogram of the magnetic field in the range 0.008 to 2 Hz.
N. E Pissarenko et aL: Cusp Energetic Particles Observed by INTERBALL of s a t e l l i t e t r a j e c t o r y (Fig. 4). E n e r g e t i c p a r t i c l e spect r u m s h a p e is v i r t u a l l y i n v a r i a b l e u p t o t h e b o w shock. A t t h e s a m e time, it c a n b e seen t h a t a b e h a v i o r of p a r t i c l e s w i t h energies of a b o u t 1 M e V is m o r e complicated. H i g h i n t e n s i t y v a r i a t i o n s of t h e s e p a r t i c l e s were r e c o r d e d in t h e e n t i r e cusp r e g i o n a n d m a g n e t o s h e a t h u p to BS r e g i o n only d u r i n g M a r c h 14, 1996 event. I n A p r i l 21, 1996 event t h e e n h a n c e d 100 - k e V p a r t i c l e fluxes were o b s e r v e d u p to t h e BS front w h e r e a s t h e 1 M e V p a r t i c l e i n t e n s i t y c o n s i d e r a b l y d e c r e a s e d earlier. O n t h e o t h e r h a n d , t h e e n h a n c e d e n e r g e t i c p a r t i c l e int e n s i t y is c o r r e l a t e d w i t h t h e i n c r e a s e d wave t u r b u l e n c e d e t e c t e d w i t h i n a n d close to t h e cusp (Fig. 5). However t h e m e c h a n i s m r e s p o n s i b l e for this c o r r e l a t i o n is n o t clear now. I t requires f u r t h e r analysis.
3
Summary 1. F o r t h e s t u d i e d events t h e m a x i m u m i n t e n s i t y of 1 M e V p r o t o n s was as h i g h as 103 c m - 2 8 -1 . I t is close to P O L A R r e s u l t s o b t a i n e d for a n u m b e r of events in 1996 ( C h e n a n d Fritz, 1998). 2. O c c a s i o n a l l y e n h a n c e d e n e r g e t i c p a r t i c l e fluxes ( E ,~ 100 k e V ) were o b s e r v e d a l m o s t continuo u s l y from t h e cusp region, to t h e b o w shock w i t h slow c h a n g e d s p e c t r a a n d s m a l l i n t e n s i t y g r a d i e n t . T h e p a r t i c l e s w i t h e n e r g y ,-~ 1 M e V have m o r e complicated distribution. 3. I n m o s t cases t h e e n e r g e t i c p a r t i c l e flux e n h a n c e m e n t in t h e cusp region a r e a c c o m p a n i e d by enh a n c e d wave t u r b u l e n c e , as was e a r l y m e n t i o n e d ( P o t t e l e t e , 1990; W o c h a n d L u n d i n , 1992). 4. M o s t p r o b a b l y , these high e n e r g e t i c p a r t i c l e s come into t h e cusp from t h e different e x t r a - a n d i n t r a m a g n e t o s p h e r i c sources b u t t h e i r r e l a t i v e c o n t r i b u tions a r e still u n k n o w n .
Acknowledgements. We are grateful to A.O. Fedorov for the CORALL data, to N.L. Borodkova for the ELECTRON data, and to S.A. Romanov for the magnetic field data. This work was supported by INTAS 94-2638 grant.
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