The New Daily Ionospheric Forecast Service (DIFs)
For nearly 30 years the Advanced Technology Centre - Gt Baddow has produced
and issued a daily ionospheric forecast.
A recently enhanced service has
been implemented under co-funding through the ESA Space Weather Applications
Pilot Project and is part of the Space Weather European Network (SWENET).
The service now offers three HF Forecasts, two 24 hourly forecasts for
- high latitudes (polar and auroral regions)
- low latitudes (equatorial region)
- and a 12 hourly forecast for mid latitudes.
These are aimed at HF sky-wave users who suffer from degraded performance
during solar & geomagnetic storms and wish to have advance warning of poor
propagation conditions.
A SATCOM disturbance warning service has been introduced to provide SATCOM
users with an advance forecast of conditions on Earth to space
communications links for latitudinal regions and timezones.
During the severest events (e.g. Oct 28th 2003) HF sky-wave circuits can
disappear completely. Many commercial airlines use HF on transatlantic
services to provide position reports to air traffic control.
On the 28/29th
Oct, HF circuits were unworkable leading to air traffic control restricting
flights to mid-latitudes (rather than the usual polar routes) and increasing
the spacing between aircraft. This lead to delays to all flights across the
Atlantic. The SATCOM disturbance warning forecast provided to SATCOM
operators has been developed to give users an indication of scintillation
activity.
Under moderate and severe scintillation SATCOMs equipment can
suffer loss of lock & synchronisation. GPS users will also suffer
degradation in location accuracy and even lose position completely through
the inability of the RF receivers to lock onto the signals.
We can now provide our HF users with a 6 hourly up-dated forecast, 7 days a
week, 365 days a year service and is available via email and web access.
SATCOM operators receive a daily forecast of scintillation (fading) as a
function of local time for different latitude bands.
The HF forecast Daily Ionospheric forecast has two sections.
1) A summary of the solar, geophysical and ionospheric environment and HF
propagation conditions for the previous 24 hour period.
2) A forecast of the HF propagation conditions together with predicted
indices.
The DIF provides an ionospheric correction factor (ICF) which links directly
into WinHF - our proprietary HF propagation prediction programme.
The new SATCOM forecast provides users with a forecast of the expected
scintillation quantified at three levels of fade depth.
For details of acronyms, definitions and forecast descriptions please click
http://www.sflorg. com/BAE_Systems_ DIFS/glossary. html
These forecasts may also be viewed via the following links:
Mid-Latitude forecast
http://www.esa- spaceweather. net/swenet/ login?cmd= swenet_motd_ preview&sda= difs&report_ type=midlats
High-Latitude forecast
http://www.esa- spaceweather. net/swenet/ login?cmd= swenet_motd_ preview&sda= difs&report_ type=highlats
Low-Latitude forecast
http://www.esa- spaceweather. net/swenet/ login?cmd= swenet_motd_ preview&sda= difs&report_ type=lowlats
SATCOM forecast
http://www.esa- spaceweather. net/swenet/ login?cmd= swenet_motd_ preview&sda= difs&report_ type=satcom
For more details on receiving the Daily Ionospheric Forecast, the SATCOM
forecast or the HF propagation prediction program see
http://www.sflorg. com:80/BAE_ Systems_DIFS/
With thanks to Mike Terry
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