Comparison of Joule heating associated with high-speed solar wind between different models and observations

To gain an improved quantitative understanding of the solar wind/magnetosphere/ionosphere coupling processes, the capabilities of different models and observations to represent the variations of ionospheric forcing associated with high-speed solar wind streams are compared for year 2005. We investigate the high-latitude forcing from the measurements of DMSP satellite, empirical model Weimer05 and Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure, with ground magnetometer data only (AMIE 1) or with both ground magnetometer and DMSP convection data (AMIE 2). The yearly averages of the northern hemisphere integrated Joule heating (IJH) calculated from AMIE 1 and 2 are about 41% and 85% larger than that from Weimer05, respectively. A consistent 9-day periodicity is shown in both the cross polar cap potential and IJH, which corresponds to the 9-day oscillation in the high-speed solar wind streams. A band-pass filter centered at 9 day is used to examine the sensitivity of the IJH calculated from different sources to the solar wind condition. The comparison shows that the sensitivity of IJH from AMIE 1 and 2 are about 2.2 and 2.5 times larger than that from Weimer05, respectively.