Observations of ionospheric heating during the passage of solar coronal hole fast streams

[1] Using ionospheric temperature measurements made continuously by the Poker Flat Incoherent Scatter Radar (PFISR) and EISCAT Svalbard Radar (ESR) during the International Polar Year (IPY), we provide evidence for directly driven ionospheric heating associated with the solar wind corotating interaction region (CIR). Both ESR and PFISR operated almost continuously during the IPY, which began on 1 March 2007. During this period 55 CIR events occurred and when ISR observations were available during these events ionospheric heating was observed. This study is the first comprehensive observation of ionospheric heating by CIRs demonstrated through case study comparisons and statistically over the 1-year IPY period. These multiple-day heating events are present in both the auroral and polar regions. The quantitative one-to-one correlation between ACE-CIR observations and ISR-ionosphere observations leads to a database that will enable the ionospheric heating efficiency of CIR events to be determined.