The ionosphere poses a range of technological challenges, ranging from satellite positioning errors to HF angle-of-arrival determination and transionospheric signal interruptions. Due to the opening of new shipping lanes in the region, the northern Polar cap is emerging as an increasingly important area of operations. The problem of specifying and forecasting polar ionospheric conditions is addressed here, with specific focus on Sporadic-F. This startling ionospheric phenomenon is frequently observed at high latitudes [
e.g. Meek, 1949;
Hill, 1963]. Over the course of a few minutes, the bulk plasma density increases by up to an order of magnitude, accompanied by horizontal drift speeds in excess of 1 km/s and intense density structuring. Specific forms of Sporadic-F include “tongues of ionization” and “polar cap patches.” Recent analysis by
Xiong et al. [2018] indicates that the annual variability of GPS signal loss onboard Swarm matches that of Sporadic-
F [
e.g. Noja et al., 2013,
Chartier et al., 2018]. It has come to light that current theories on Sporadic-F are incomplete, with the prediction of a summer minimum and winter maximum being totally contradicted by observations made in the southern hemisphere over almost a decade. We apply GPS-based ionospheric tomography in both polar caps to obtain a long-term and systematic perspective on this phenomenon. The predictions of a state-of-the-art first-principles model (SAMI3) are compared against this observational record. A new bistatic, spread-spectrum Antarctic HF radar experiment is presented whose goal is to develop our observational understanding of Sporadic-F and its effects in the southern hemisphere.
References
Chartier, A. T., Mitchell, C. N., and Miller, E. S.: Annual Occurrence Rates of Ionospheric Polar Cap Patches Observed using Swarm, J. Geophys. Res.-Space, https://doi.org/10.1002/2017JA024811, 2018.
Hill, G. E. (1963). Sudden enhancements of F‐layer ionization in polar regions. Journal of the Atmospheric Sciences, 20(6), 492–497. https://doi.org/10.1175/1520-0469(1963)020%3C0492:SEOLII%3E2.0.CO;2
Meek, J.H., (1949) Sporadic Ionization at High Latitudes, Journal of Geophysical Research 54 (4)
Mitchell, C. N., and P. S. J. Spencer (2003), A three‐dimensional time‐dependent algorithm for ionospheric imaging using GPS, Ann. Geophys., 46(4), 687–696.
Noja, M., Stolle, C., Park, J., and Lühr, H.: Long-term analysis of ionospheric polar patches based on CHAMP TEC data, Radio Sci., 48, 289–301, https://doi.org/10.1002/rds.20033, 2013.
Spencer, P. S. J., and C. N. Mitchell (2007), Imaging of fast moving electron‐density structures in the polar cap, Ann. Geophys., 50(3), 427–434, doi:10.4401/ag‐3074.
Xiong, C., C. Stolle and J.-H. Park, Climatology of GPS signal loss observed by Swarm satellites, Annales Geophysicae, 10.5194/angeo-36-679-2018, 36, 2, (679-693), (2018).
