The polar wind is an ambipolar plasma outflow from the terrestrial ionosphere at high latitudes. As the ions drift upward along geomagnetic flux tubes, they move from collision-dominated (ion barosphere) to collision less (ion exosphere) regions. A transition layer is embedded between these two regions where the ion characteristics change rapidly. So, this thesis deals with modeling of major ions outflow in the polar cap at altitudes higher than 400km. Different ion outflow models are numerical investigated and the pros and cons of these models are discussed. Observations are crucial for...