Near real‐time input to a propagation model for nowcasting of HF communications with aircraft on polar routes

Abstract

There is a need for improved techniques for nowcasting and forecasting (over several hours) HF propagation at northerly latitudes to support airlines operating over the increasingly popular trans-polar routes. In this paper the assimilation of real-time measurements into a propagation model developed by the authors is described, including ionosonde measurements The model incorporates various features (e.g. convecting patches of enhanced plasma density) of the polar ionosphere that are, in particular, responsible for off-great circle propagation and lead to propagation at times and frequencies not expected from on-great circle propagation alone. The model development is supported by the collection of HF propagation measurements over several paths within the polar cap, crossing the auroral oval, and along the mid-latitude trough.

Global Diagnostics of Ionospheric Absorption During X‐Ray Solar Flares Based on 8‐ to 20‐MHz Noise Measured by Over‐the‐Horizon Radars

“…It is known that the lower part of the ionosphere (layers D and E) is ionized by wavelengths <100 Å (Banks & Kockarts, 1973) as well as by Lyman-line (about 1,200 Å). Most often, researchers analyze the association of absorption with X-ray radiation 1-8 Å only, measured by GOES/XRS and associated with the ionization of the D layer (Rogers & Honary, 2015;Warrington et al, 2016), see Figure 1d. However, the absorption is important not only in the D layer but also in the E layer, the ionization of which is caused by other components of the solar radiation.…”

Space weather impact on radio device operation

“…При распространении КВ-радиоволн возникно-вение дополнительных ионосферных слоев приво-дит к возникновению дополнительных траекторий распространения и, как след-ствие, к усложнению привязки радиолокационной дальности (групповой задержки сигнала) и азимута к реальным положениям рассеивающих объектов или направлениям на них [Reinisch et al, 1997;Chen et al, 2016;Warrington et al, 2016]. Зависимость траекторий распростране-ния от частоты приводит к сильным фазовым иска-жениям сигнала, что дополнительно усложняет де-тектирование сложных сигналов на дальних трассах.…”

“…Для поддержки функционирования загоризонт-ных радиосредств используются системы моделиро-вания распространения радиосигнала в неоднород-ной замагниченной ионосферной плазме [Fridman et al, 2016;Landeau et al, 1997;Reinisch et al, 1997;Warrington et al, 2016], поскольку если их не использовать, то ошибки, вносимые ионосферой, будут очень велики [Reinisch et al, 1997;Berngardt et al, 2015b]. Для корректного ре-шения задачи распространения сигнала необходимо знать среду распространения или по крайней мере иметь хорошую ее модель.…”

Developments in an HF nowcasting model for trans-polar airline routes

“…to define the background ionosphere in the raytracing model. Whilst there is a lack of information to deal with the IG and RZ parameters separately, their relationship has been fixed to that given by fitting a curve to the historical values relating the two parameters [3].…”

“…solar flares, solar wind, etc.). Ongoing work, which uses a ray-tracing model [1,2] to estimate the signal coverage [3,4], has previously been reported. In this model, a background ionosphere is generated, which is then perturbed with electron density variations associated with the presence of various high latitude ionospheric features (patches, arcs, auroral oval irregularities and the mid-latitude trough).…”