TY - JOUR

T1 - Locations of proton isotropic boundaries as measured by conjugate high-altitude and low-altitude satellites

AU - Ganushkina, N. Yu

AU - Karhunen, T.

AU - Kubyshkina, M. V.

AU - Ebihara, Y.

AU - Sergeev, V. A.

AU - Pulkkinen, T. I.

AU - Fritz, T. A.

PY - 2003

Y1 - 2003

N2 - Polar CAMMICE MICS data of proton pitch angle distributions with energies of 31-80 ke V for the period of 1997-1998 were analyzed to determine the locations where anisotropic pitch angle distributions (perpendicular flux dominating) change to isotropic distributions. We study this high-altitude isotropic distribution boundary (IDB) in terms of its location in L-shell and MLT. Statistical results showed that this boundary is located at lower L-shells on the nightside and at higher L-shells on the dayside with most distant location at dawn. With the increase of magnetic activity, the IDB positions shift towards lower L-shells at all MLT. The locations of IDBs were also determined for different storm phases. A superposed epoch analysis revealed that the L-shells of the IDBs move to lower L-shells with decreasing Dst and to higher L-shells during Dst recovery. We made a comparison between Polar measurements of IDB at high altitudes and DMSP measurements of b2i boundary at low altitudes selecting several events during which simultaneous observations in the same local time sector were available. The magnetic field mapping using the Tsyganenko T01 model with the observed solar wind input parameters showed that Polar and DMSP were placed on nearly the same field lines, which leads us to suggest that the Polar IDB and the b2i boundary at DMSP are related.

AB - Polar CAMMICE MICS data of proton pitch angle distributions with energies of 31-80 ke V for the period of 1997-1998 were analyzed to determine the locations where anisotropic pitch angle distributions (perpendicular flux dominating) change to isotropic distributions. We study this high-altitude isotropic distribution boundary (IDB) in terms of its location in L-shell and MLT. Statistical results showed that this boundary is located at lower L-shells on the nightside and at higher L-shells on the dayside with most distant location at dawn. With the increase of magnetic activity, the IDB positions shift towards lower L-shells at all MLT. The locations of IDBs were also determined for different storm phases. A superposed epoch analysis revealed that the L-shells of the IDBs move to lower L-shells with decreasing Dst and to higher L-shells during Dst recovery. We made a comparison between Polar measurements of IDB at high altitudes and DMSP measurements of b2i boundary at low altitudes selecting several events during which simultaneous observations in the same local time sector were available. The magnetic field mapping using the Tsyganenko T01 model with the observed solar wind input parameters showed that Polar and DMSP were placed on nearly the same field lines, which leads us to suggest that the Polar IDB and the b2i boundary at DMSP are related.

UR - http://www.scopus.com/inward/record.url?scp=0038638240&partnerID=8YFLogxK

U2 - 10.1016/S0273-1177(03)00005-X

DO - 10.1016/S0273-1177(03)00005-X

M3 - Article

AN - SCOPUS:0038638240

VL - 31

SP - 1265

EP - 1270

JO - Advances in Space Research

JF - Advances in Space Research

SN - 0273-1177

IS - 5

ER -