Space Weather Impacts to Mariners
Don't throw away that sextant just yet....read on
From the National Geospatial-Intelligence Agency's (NGA), Notices to Mariners, Special Paragraphs:
"(73) SPACE WEATHER IMPACTS.
There is a growing potential that space weather events including geomagnetic and solar radiation storms will adversely impact
mariners as the 11-year sunspot cycle nears its projected peak in 2013. Such events can disrupt satellite communication and
navigation systems including Inmarsat and GPS, HF radio, and very occasionally VHF radio. There is also the potential that
these systems can be interrupted indirectly as terrestrial networks and power systems can be affected as well. Conversely,
some HF communications can improve, usually for those frequencies above 15 MHz. The impacts will usually be greater at
higher latitudes. The northern lights are a phenomenon related to space weather. For an introduction to space weather activity,
see NOAA's Space Weather Prediction Center's (SWPC) primer at www.swpc.noaa.gov/primer/primer_2010.pdf . Notice of these and other events may be issued on an experimental basis within NOAA marine weather forecasts at a frequency intended
to minimize the number of false alerts. Mariners should keep in mind that the state of science is such that neither these events
nor the actual impacts can be forecast with certainty. For further information on space weather see www.swpc.noaa.gov"
The UK Maritime and Coastguard Agency's Marine Information Note "Navigation: Global Navigation Satellite Systems
(GNSS) - Availability During Increased Sunspot Activity" contains some very helpful information of value to mariners
A handy reference containing propagation charts to get some idea on how sunspots are impacting HF radio communication is available courtesy of the American Radio Relay League (ARRL).
Sampling of data available from NOAA's Space Weather Prediction Center: