A Statistical Study of Ion Temperature Anisotropy Using AMISR Data

One of the longstanding problems in ionospheric science is that we typically assume the F-region ion temperature to be an isotropic Maxwellian, meaning the ion temperature is the same in all directions with respect to the magnetic field. However, works from St.-Maurice et al., (1976), and Raman et al., (1981), show that in times of heating due to moderate to strong electric fields (above 50 mV/m), the O+ velocity distribution distorts, and the ion temperature becomes anisotropic. Here, data from advanced modular incoherent scatter radars, or AMISRs, like the resolute bay incoherent scatter radars RISR-N and RISR-C (North and Canada, respectively), and the poker flat incoherent scatter radar, PFISR, taken during strong heating events (generally events consistently above 1500 K for greater than 15 minutes) are used to resolve a temperature perpendicular to the magnetic field and a temperature parallel to the magnetic field. This calculation is performed on radar scanning modes where two or more beams have F-region range gates that overlap in geomagnetic coordinates and have at least 10 degrees difference in their aspect angle This means that the two beams are theoretically scanning the same F-region plasma in the same magnetic flux tube undergoing the same physical processes with similar conditions. Lower beam modes are preferred to reduce error in imaging the plasma. This presentation will provide preliminary results derived through this technique.