This is a two-year award to continue efforts to document and understand the causes of different types of auroral disturbances. The project relates to the ultimate goal of establishing the relationships between changes in the solar wind and interplanetary magnetic field, changes in the reconnection related ionospheric flows on the dayside, and the resulting types of auroral disturbances. Understanding these relationships is essential to improve specification and forecasting of the auroral disturbances, which can cause disruption of radio transmission and satellite communications, including the Global Positioning System. The main objective of the project is to derive and verify observational techniques based on recent investments in polar observation technology to identify the various auroral disturbances. Specific focus is on the determination of the nightside electric field reversal in the Harang discontinuity. The research work will be carried out mainly by graduate students.