 |
| Titel |
Real-time HF Radio Absorption Maps Incorporating Riometer and Satellite Measurements |
| VerfasserIn |
Neil Rogers, Farideh Honary, Mike Warrington, Alan Stocker, Donald Danskin |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123177
|
| Publikation (Nr.) |
 EGU/EGU2016-2381.pdf |
|
|
|
|
|
| Zusammenfassung |
| A real-time model of HF radio propagation conditions is being developed as a service for
aircraft communications at high latitudes. An essential component of this is a real-time
map of the absorption of HF (3-30 MHz) radio signals in the D-region ionosphere.
Empirical, climatological Polar Cap Absorption (PCA) models in common usage cannot
account for day-to-day variations in ionospheric composition and are inaccurate
during the large changes in recombination rate at twilight. However, parameters of
such models may be optimised using an age-weighted regression to absorption
measurements from riometers in Canada and Scandinavia. Such parameters include the day-
and night-time sensitivity to proton flux as measured on a geostationary satellite
(GOES). Modelling the twilight transition as a linear or Gauss error function over a
range of solar-zenith angles (χl < χ < χu) is found to provide greater accuracy
than ‘Earth shadow’ methods (as applied in the Sodankylä Ionospheric Chemistry
(SIC) model, for example) due to a more gradual ionospheric response for χ <
90˚ . The fitted χl parameter is found to be most variable, with smaller values (as
low as 60˚ ) post-sunrise compared with pre-sunset. Correlation coefficients of
model parameters between riometers are presented and these provide a means of
appropriately weighting individual riometer contributions in an assimilative PCA
model.
At times outside of PCA events, the probability of absorption in the auroral zones is
related to the energetic electron flux inside the precipitation loss cone, as measured on the
polar-orbiting POES satellites. This varies with magnetic local time, magnetic latitude and
geomagnetic activity, and its relation to the real-time solar wind – magnetospheric coupling
function [Newell et al., 2007] will be presented.
Reference: Newell, P. T., T. Sotirelis, K. Liou, C.-I. Meng, and F. J. Rich (2007), A
nearly universal solar wind-magnetosphere coupling function inferred from 10
magnetospheric state variables, J. Geophys. Res., 112, A01206, doi:10.1029/2006JA012015. |
|
|
|
|
|
|