TY - JOUR

T1 - Statistical study of the proton isotropy boundary

AU - Lvova, E. A.

AU - Sergeev, V. A.

AU - Bagautdinova, G. R.

PY - 2005

Y1 - 2005

N2 - Based on a large data set of polar NOAA-type satellite observations we studied the latitude-MLT shape of the 80 keV proton isotropy boundary (IB) as a function of the solar wind parameters and magnetic activity. Using "snapshots" of isotropy boundaries near-simultaneously crossed at four points we found that its equatorward expansion, as well as its dawn-dusk shift, depends mostly on the AE-index and on the corrected Dst*, whereas the amplitude of the IB daily variation is mostly controlled by the solar wind dynamic pressure. Applying a nonlinear, multi-parametric, least-square regression procedure, the empirical relationship describing the IB latitude as a function of MLT and AE, Pd, Dst * parameters was obtained. Comparing it with the predictions from the Tsyganenko-2001 model we found a good agreement during the quiet time but some important differences during the disturbed periods. Interpretation of these results in terms of the properties of the magnetospheric configuration is briefly discussed.

AB - Based on a large data set of polar NOAA-type satellite observations we studied the latitude-MLT shape of the 80 keV proton isotropy boundary (IB) as a function of the solar wind parameters and magnetic activity. Using "snapshots" of isotropy boundaries near-simultaneously crossed at four points we found that its equatorward expansion, as well as its dawn-dusk shift, depends mostly on the AE-index and on the corrected Dst*, whereas the amplitude of the IB daily variation is mostly controlled by the solar wind dynamic pressure. Applying a nonlinear, multi-parametric, least-square regression procedure, the empirical relationship describing the IB latitude as a function of MLT and AE, Pd, Dst * parameters was obtained. Comparing it with the predictions from the Tsyganenko-2001 model we found a good agreement during the quiet time but some important differences during the disturbed periods. Interpretation of these results in terms of the properties of the magnetospheric configuration is briefly discussed.

KW - Magnetospheric physics (Energetic particles, precipitating; energetic particles, trapped; solar wind-magnetosphere interactions)

UR - http://www.scopus.com/inward/record.url?scp=23744500396&partnerID=8YFLogxK

U2 - 10.5194/angeo-23-1311-2005

DO - 10.5194/angeo-23-1311-2005

M3 - Article

VL - 23

SP - 1311

EP - 1316

JO - Annales Geophysicae

JF - Annales Geophysicae

SN - 0992-7689

IS - 4

ER -