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In a previous study, Blockx et al. (2005) showed that the SI12 camera on board the IMAGE\udspacecraft is an excellent tool to remotely determine the position of the\udisotropy boundary (IB) in the ionosphere, and thus is able to provide a\udreasonable estimate of the amount of stretching of the magnetic field lines\udin the magetotail. By combining an empirical model of the magnetospheric\udconfiguration with Sergeev's criterion for non-adiabatic motion, it is also\udpossible to obtain a theoretical position of IB in the ionosphere, for known\udconditions in the solar wind. Earlier studies have demonstrated the\udinadequacy of the Tsyganenko-1989 (T89) model to quantitatively reproduce\udthe field line stretching, particularly during growth phases. In this study,\udwe reexamine this question using the T01 model which considers the time\udhistory of the solar wind parameters. We compare the latitude of IB derived\udfrom SI12 global images near local midnight with that calculated from the\udT01 model and the Sergeev's criterion. Observational and theoretical results\udare found to frequently disagree. We use in situ measurements of the magnetic field\udwith the GOES-8 satellite to discriminate which of the two components in the\udcalculation of the theoretical position of the IB (the T01 model or\udSergeev's criterion) induces the discrepancy. For very quiet magnetic\udconditions, we find that statistically the T01 model approximately predicts\udthe correct location of the maximum proton precipitation. However, large\uddiscrepancies are observed in individual cases, as demonstrated by the large\udscatter of predicted latitudes. For larger values of the AE index, the model\udfails to predict the observed latitude of the maximum proton intensity, as a\udconsequence of the lack of consideration of the cross-tail current component\udwhich produces a more elongated field configuration at the location of the\udproton injection along the field lines. We show that it is possible to match\udthe observed location of the maximum proton precipitation by decreasing the\udcurrent sheet half-thickness <I>D</I> parameter. We thus conclude that\udunderestimation of the field line stretching leads to inadequately\udprediction of the boundary latitude of the non-adiabatic proton\udprecipitation region

A comparison between FUV remote sensing of magnetotail stretching and the T01 model during quiet conditions and growth phases