Space weather

Space weather is a consequence of the behaviour of the Sun, the nature of Earth’s magnetic field and atmosphere, and our location in the solar system. There are various phenomena that originate from the Sun that can result in space weather storms. Outbursts from huge explosions on the Sun - Solar Flares and Coronal Mass Ejections (CME) - send space weather storms hurling outward through our solar system. The Sun also emits a continuous stream of radiation in the form of charged particles that make up the plasma of the solar wind.

From an operations perspective, space weather events occur when the Sun causes disruptions to aviation communications, navigation and surveillance systems, radiation-sensitive electronics and elevates radiation dose levels at flight altitudes. Space weather events may occur on short time scales, with the effects occurring from seemingly instantaneous to a few days hence.

Space weather advisories for international air navigation address particular types of disturbances, such as solar radiation storms, geomagnetic storms, ionospheric storms, and solar flares. These advisories enable operators to maintain awareness of potential hazards and to formulate alternative plans should the impending conditions be of a magnitude and/or type that could disrupt normal operations.

Space weather for aviation impacts on communications, navigation, surveillance, radiation-sensitive electronics, and human exposure. The impacts may include:

• Unexpected loss of communications;
• HF voice and HF data link, i.e. Controller Pilot Data Link Communications (CPDLC), on routes where HF is employed;
• Poor or unusable performance of L-band SATCOM.
• Degraded performance of navigation and surveillance that rely on GNSS;
• Automatic Dependent Surveillance – Broadcast (ADS-B) and/or Automatic Dependent Surveillance – Contract (ADS-C) anomalies;
• Sporadic loss-of-lock of GNSS, especially near the equator, post- sunset.
• Unanticipated non-standard performance of on-board electronics.
• Issues related to radiation exposure by aircrew and passengers.

Global centres

ACFJ Consortium - Australia, Canada, Japan & France

Two centres – Melbourne, Australia:  will issue HF Advisories; and Toulouse, France: will issue all other SWX advisories.

PECASUS Consortium - Austria, Belgium, Cyprus, Finland, Germany, Italy, Netherlands, Poland and the United Kingdom

Lead centre in Finland supported by UK (backup) and Belgium (data hub).

United States: Centre based in Boulder, Colorado, USA

Regional centres

1.      China/Russian Federation consortium (may become a global centre in the future)

2.      South Africa

Operation of the global centres

Each of the three global centres will operate for a two-week period every six weeks and when not active they will operate as a backup centre or secondary backup centre for two-weeks each respectively.  This is referred to as a rotational (or roster) arrangement.

SWX advisories are issued when impacts to HF communications, communications via satellite, GNSS-based navigation and surveillance systems, or heightened radiation occurs or is expected to occur.

The advisory message informs users of:

• The type of impact;
• The expected onset, or if the event is already in progress;
• The duration of the event;
• A generalized description of the spatial extent affected for the next 24 hours;
• A description of the severity of the impact in moderate (MOD) or severe (SEV) categories.

Forecasts included in SWXA are for 6, 12, 18 and 24 hours beyond the observed time, i.e., +6 HR, +12 HR, +18 HR and +24 HR.

SWX SIGMETs will not be issued by MWOs.

SWXA for GNSS and HFCOM effects

SWX ADVISORY
DTG: 20161108/0100Z
SWXC: DONLON*
ADVISORY NR: 2016/2
NR RPLC: 2016/1
SWX EFFECT: HF COM MOD AND GNSS MOD
OBS SWX: 08/0100Z HNH HSH E18000 – W18000
FCST SWX +6 HR: 08/0700Z HNH HSH E18000 – W18000
FCST SWX +12 HR: 08/1300Z HNH HSH E18000 – W18000
FCST SWX +18 HR: 08/1900Z HNH HSH E18000 – W18000
FCST SWX +24 HR: 09/0100Z NO SWX EXP
RMK: LOW LVL GEOMAGNETIC STORMING CAUSING INCREASED AURORAL ACT AND SUBSEQUENT MOD DEGRADATION OF GNSS AND HF COM AVBL IN THE AURORAL ZONE. THIS STORMING EXP TO SUBSIDE IN THE FCST PERIOD. SEE WWW. SPACEWEATHERPROVIDER.WEB 
NXT ADVISORY: NO FURTHER ADVISORIES

SWXA for RADIATION effects

SWX ADVISORY
DTG: 20161108/0000Z
SWXC: DONLON*
ADVISORY NR: 2016/2 NR
RPLC: 2016/1
SWX EFFECT: RADIATION MOD
FCST SWX: 08/0100Z HNH HSH E18000 – W18000 ABV FL 350
FCST SWX +6 HR: 08/0700Z HNH HSH E18000 – W18000 ABV FL 350
FCST SWX +12 HR: 08/1300Z HNH HSH E18000 – W18000 ABV FL 350
FCST SWX +18 HR: 08/1900Z HNH HSH E18000 – W18000 ABV FL 350
FCST SWX +24 HR: 09/0100Z NO SWX EXP
RMK: RADIATION LVL EXCEEDED 100 PCT OF BACKGROUND LVL AT FL350 AND ABV.THE CURRENT EVENT HAS PEAKED AND LVL SLW RTN TO BACKGROUND LVL. SEE WWW.SPACEWEATHERPROVIDER.WEB
NXT ADVISORY: NO FURTHER ADVISORIES

SWXA for HFCOM effects

SWX ADVISORY 

DTG: 20161108/0100Z

SWXC: DONLON*

ADVISORY NR: 2016/1

SWX EFFECT: HF COM SEV 

OBS SWX: 08/0100Z DAYLIGHT SIDE

FCST SWX +6 HR: 08/0700Z DAYLIGHT SIDE

FCST SWX +12 HR: 08/1300Z DAYLIGHT SIDE

FCST SWX +18 HR: 08/1900Z DAYLIGHT SIDE

FCST SWX +24 HR: 09/0100Z NO SWX EXP

RMK: PERIODIC HF COM ABSORPTION AND LIKELY TO CONT IN THE NEAR TERM. CMPL AND PERIODIC LOSS OF HF ON THE SUNLIT SIDE OF THE EARTH EXP. CONT HF COM DEGRADATION LIKELY OVER THE NXT 7 DAYS. SEE WWW. SPACEWEATHERPROVIDER.WEB

NXT ADVISORY: 20161108/0700Z

* fictitious location

FNXX01 KWNP 020100
SWX ADVISORY
DTG: 20190502/0100Z
SWXC: DONLON*
ADVISORY NR: 2019/59
NR RPLC: 2019/58
SWX EFFECT: GNSS MOD
OBS SWX: 02/0100Z HNH HSH E18000-W18000
FCST SWX + 6 HR: 02/0700Z HNH HSH E18000-W18000
FCST SWX + 12 HR: 02/1300Z HNH HSH E18000-W18000
FCST SWX + 18 HR: 02/1900Z NO SWX EXP
FCST SWX + 24 HR: 03/0100Z NO SWX EXP
RMK: IONOSPHERIC STORM CONTINUES TO CAUSE LOSS-OF-LOCK OF GNSS IN AURORAL ZONE. THIS ACTIVITY IS EXPECTED TO SUBSIDE IN THE FORECAST PERIOD
NXT ADVISORY: 20190502/0700Z=

* Note DONLON is a fictional centre.
** Note that there is no vertical extent description possible for SWX, except for radiation events.

The area affected may also be described as DAYLIGHT SIDE, meaning the extent of the planet that is in daylight (used for short wave fadeout events).

SWX Advisories will be disseminated to users via the ROBEX distribution mechanisms rather than directly to end users via AFTN/AMHS.

SWXCs will send advisories to their National OPMET Centre (NOC), who will forward the message to their Regional OPMET Centre (ROC). The ROCs will forward the message to the Inter-regional OPMET Gateway (IROGs) and other regional ROCs (who will make SWXA available to NOCs within their area of responsibility). The IROGs will distribute the message to their neighbouring IROGs and internet-based services (SADIS and WIFS).

Users will access Space Weather Advisories through their normal national aviation briefing service but it should be noted that airlines may request their NOCs to deliver SWXAs directly to the airline, via AFTN/AMHS, like other OPMET.

The ICAO Global Space Weather Service does not specifically define the operational responses to space weather events and the receipt of SWA.  Such responses are the responsibility of aircraft operators, which may choose to have operational procedures in place in order to be ready in case of space weather events.

The following general guidelines may however be useful:

1. Depending on the intensity of the phenomena, aircraft operators might choose to fly less exposed routes, or delay their flights until the phenomena have abated.
2. They might also wish to use alternate means of communication and/or navigation.
   1. HF absorption on the daylight side of Earth, in equatorial areas, and in polar areas tend to affect the lowest frequencies in the HF band. The upper part of the HF band might be less affected.
   2. The arrival of magnetic material may result in physical processes that may impact the upper part of the HF band (Maximum Usable Frequency depression) from hours to days. In that case, the lower HF frequencies might be less affected.
3. Impacts on GNSS may result in reduced availability of specific GNSS services. This may require, during rare and particularly strong events, the use of alternate navigation means to GNSS SBAS and/or GNSS GBAS approaches with vertical guidance (i.e. for 3D instrument approaches down to LPV minima and/or to GLS minima). For enroute, terminal and 2D instrument approaches, it is unlikely that space weather induced positioning errors would exceed lateral GNSS guidance margins. GNSS and SATCOM signals may also be degraded (amplitude and/or phase signal scintillations) in all phases of flight, to the point where the signals can no longer be processed by receivers, which lose lock.
4. Flying at lower altitude and/or latitude decreases radiation aboard aircraft. It should be noted however that solar events which are able to accelerate particles enough for them to result in a significant radiation increase at aircraft altitudes are rare. Since 2000, the 4 radiation events which led to a significant radiation increase at aircraft altitudes occurred on 14 July 2000, 15 April 2001, 20 January 2005, and 13 December 2006. During those events, it is estimated that the radiation dose received during a long-haul flight reaching high latitudes was equivalent to that usually received (from galactic cosmic rays) during a couple of similar long-haul flights.

The following European Union Aviation Safety Agency (EASA) Safety Information Bulletins may also be of interest:

• EASA SIB 2012-09R1 - Effects of Space Weather on Aviation(external link)
• EASA SIB 2012-10R1 - Single Event Effects on Aircraft Systems caused by Atmospheric Radiation(external link)

For further information on space weather, see the Australian Bureau of Meteorology’s brochures on space weather and space weather advisories. The advisories are expected to be issued, when necessary, from 07 November 2019.

Australian Bureau of Meteorology – Space weather(external link)

Australian Bureau of Meteorology – Space weather advisories(external link)

For more detailed information, including how MOD and SEV SWX intensities are defined, see:
ICAO Doc 10100 - Manual on Space Weather Information in Support of International Air Navigation(external link).