Due to its large inertia, a simplified view of the thermosphere is that it is a relatively smoothly varying (large spatial and temporal scales of 1000km and hours, respectively) medium which hosts the dynamic ionosphere. However, there is increasing evidence that small-scale spatial and temporal structure is a typical attribute of the thermosphere. Significant small-scale structure is often reported (e.g., Aruliah and Griffin, 2001; Conde and Smith, 1998) and the thermosphere is found to be readily responsive to the ionospheric forcings. It is important to understand the full extent of the variability of the neutral atmosphere as the di
fference in the ion and neutral flow is a useful quantity in calculating crucial parameters concerning upper atmospheric energetics such as ion drag and Joule heating. It is important we understand the energetics and dynamics of the thermosphere to improve high-precision satellite orbit determination which can cost millions of pounds if errors are made.

UCL's all-sky SCANning Doppler Imager (SCANDI) has been making observations of the 630nm atomic O red line emission since 2007, which peaks at 250km altitude. From these observations, the horizontal wind field can be derived at many locations across a 1000km field of view on scales of 100km with a cadance of 7 minutes providing evidence of small scale variability.

SCANDI's database it used to create climatological maps of the polar thermospheric wind field. For comparison, climatologies of the SuperDARN plasma drift maps have been created. These give an insight into the balance of forces which drive the winds. The pressure gradient force and the ion-drag are shown to have a significant effect on the wind field. Climatological Joule heating calculations are presented.