| Title | A modeling framework to estimate ionospheric HF absorption produced by solar flares |
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| Author | Chakrabory, S ;
Baker, J B H; Fiori, R A D; Ruohoniemi, J M; Zawdie, K A |
| Source | Radio Science vol. 56, issue 10, 2021 p. 1-15, https://doi.org/10.1029/2021RS007285 |
| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210453 |
| Publisher | John Wiley and Sons Inc |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Canada; Canada; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon;
Nunavut |
| NTS | 1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65;
66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560 |
| Lat/Long WENS | -141.0000 -50.0000 90.0000 41.7500 |
| Subjects | geophysics; Science and Technology; Information and Communications; ionosphere; absorption; solar variations; geomagnetism; geomagnetic fields; modelling; solar variations; electromagnetic fields;
Irradiation; Communications equipment |
| Illustrations | location maps; tables; models; profiles; graphs; plots |
| Program | Public Safety Geoscience Assessing space weather hazards |
| Released | 2021 09 23 |
| Abstract | Over-the-Horizon communication is strongly dependent on the state of the ionosphere, which is susceptible to solar flares. Trans-ionospheric high frequency (HF, 3-30 MHz) signals can experience strong
attenuation following a solar flare that lasts typically for an hour, commonly referred to as shortwave fadeout (SWF). In this study, we examine the role of dispersion relation and collision frequency formulations on the estimation of SWF in riometer
observations using a new physics-based model framework. The new framework first uses modified solar irradiance models incorporating high-resolution solar flux data from the GOES satellite X-ray sensors as input to compute the enhanced ionization
produced during a flare event. The framework then uses different dispersion relation and collision frequency formulations to estimate the enhanced HF absorption. The modeled HF absorption is compared with riometer data to determine which formulation
best reproduces the observations. We find the Appleton-Hartree dispersion relation in combination with the averaged collision frequency profile reproduces riometer observations with an average skill score of 0.4, representing 40% better forecast
ability than the existing D-region Absorption Prediction model. Our modeling results also indicate that electron temperature plays an important role in controlling HF absorption. We suggest that adoption of the Appleton-Hartree dispersion relation in
combination with the averaged collision frequency be considered for improved forecasting of ionospheric absorption following solar flares. |
| Summary | (Plain Language Summary, not published)
Space weather refers to the dynamic conditions on the Sun and in the space environment, in particular, in the near-Earth environment, that can affect
critical infrastructure. NRCan operates the Canadian Space Weather Forecast Centre and conducts research into space weather effects on power systems, pipelines, radio communications and GNSS positioning to help Canadian industry understand and
mitigate the effects of space weather. Sudden bursts of electromagnetic radiation from the Sun, also known as solar flares, alter the physical properties of the ionosphere. The sudden enhancement in solar radiation affects radio communication. This
study describes a new approach to model the affects on radio communication. |
| GEOSCAN ID | 329303 |
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