Space Physics and Aeronomy, Ionosphere Dynamics and Applications. Группа авторов
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СКАЧАТЬ rel="nofollow" href="#ulink_fbf4420a-72c8-5847-b68b-5196565414c4">(1.5)equation

      where σ is the conductivity (Banks et al., 1981). Radar measurements of the ion convection determine E. Combining E with models of the conductivity, Q, can be calculated. A comparison of the electromagnetic to particle power shows a ratio ranging from 1 (Brekke, 1976; Banks, 1977) to 4 (Ahn et al., 1983b). In these studies, there is a focus on the auroral zone due to the location of radar observatories, which determine not only E but, to a large extent, σ as well (Ahn et al., 1983a).

      Ionospheric conductivites are described by Maeda (1977) and in the World Data Center A (Kyoto) website (http://wdc.kugi.kyoto‐u.ac.jp/ionocond/exp/icexp.html). A number of models of conductivity and conductance have been derived based on particle precipitation (Fuller‐Rowell & Evans, 1987; Wallis & Budzinski, 1981; Spiro et al., 1982; Roble & Ridley, 1987; Hardy et al., 1987; Robinson et al., 1987; Gjerloev & Hoffman, 2000; McGranaghan et al., 2016, & others). Models have also been developed, which are based on UV observations (e.g., Lummerzheim et al.,1991; Coumans et al., 2004), and which account for proton precipitation (Galand & Richmond, 2001; Coumans et al., 2004). The complexity of the conductivity resulting from particle precipitation has been emphasized by McGranaghan et al. (2016), who point out that three‐dimensional spatial variations in even the average precipitation patterns are normal. When temporal variability is added, the task of capturing conductivity accurately becomes even more challenging.

      1.2.2 The Weimer Model

Schematic illustrations of (a)–(i) Polar cap electric potentials in the Northern Hemisphere, mapped as a function of AACGM latitude and MLT. Figures (a)–(d) and (f)–(i) show the patterns for eight different clock angle orientations of the IMF vector in the GSM Y-Z plane; the angle in degrees is indicated in the top left corner of each map. Figure (e) shows the potential for zero IMF, with the same solar wind conditions.

      (reproduced from Fig. 2, Weimer et al., 2005. Reproduced with permission of John Wiley & Sons).

Schematic illustrations of (a)–(i) Polar cap electric potentials in the Northern Hemisphere, mapped as a function of AACGM latitude and MLT. Figures (a)–(d) and (f)–(i) show the patterns for eight different clock angle orientations of the IMF vector in the GSM Y-Z plane; the angle in degrees is indicated in the top left corner of each map. Figure (e) shows the potential for zero IMF, with the same solar wind conditions.

      (reproduced from Fig. 3, Weimer et al., 2005. Reproduced with permission of John Wiley & Sons).

      As in any empirical model, the results are obtained by averaging over observations. In the case of the Weimer model, the observations are obtained from the approximately 18‐month lifetime of the DE2 mission. Despite the sparseness of the original data set, the model has been highly successful in providing high‐latitude electric fields required to model the IT response to magnetospheric energy input. While W05 can be used to specify the Joule heat as a standalone model, the major application of the code is in providing the high‐latitude electric field required by the General Circulation Models (GCMs), which will be discussed below.