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Until recently, theoretical models of the polar wind were one-dimensional. In these models, reasonable but ad hoc boundary conditions were fed to a mathematical model, which was then solved to provide either a steady state or time-dependent description of the plasma along a particular field line. These models were inherently unable to address the three-dimensional structure of the polar wind. Now, a truly global model of the polar wind has been developed. This model is a three-dimensional, time-dependent, fluid model that self-consistently couples the ionosphere and the polar wind. It describes the plasma dynamics in a large number of high-latitude flux tubes as they move under the combined influence of corotational and convection electric fields. The model incorporates realistic models of the high-latitude convection and auroral electron precipitation. In this study, the global model of the ionosphere and polar wind was used to illuminate the seasonal and solar cycle variability of the polar wind's three-dimensional structure. In particular, the three-dimensional distribution of both H+ and O+ ions in the polar wind was examined for both solar maximum and minimum conditions and for both summer and winter solstices, as well as for various levels of geomagnetic activity. Over 1000 flux tubes of plasma are modeled for each set of geophysical conditions considered in this study, providing a horizontal resolution that is much finer than in previous applications of the global model. The modeling results are compared with relevant observational databases. ¿ 2001 American Geophysical Union |