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Posted at 01:30 PM ET, 06/21/2011

Understanding space weather forecasts and the risk of solar storms

Part II in series


A solar large flare erupts off the sun June 7, 2011 in space. A large cloud of particles flew up and then was pulled back down to the sun's surface. (NASA/AP)
Part I of this series, “Space weather: Are we ready for a solar strike?” reviewed the background and nature of the threats of space weather.

I concluded that major solar storms have the potential to: 1) occur with limited advanced warning, 2) strike with insufficient means to protect vital earth and satellite based systems, 3) be disastrous to technology dependent societies and 4) leave in their wake totally inadequate resources and capabilities to recover for a periods ranging from weeks to years – at a cost of trillions of dollars.

In light of the severity of threat, understanding the basics of solar weather phenomena becomes important. Such basic information is the focus of this post, the second part in my three-part series. It should help you understand the nature of the threat if and when it becomes real. Although a solar strike may not happen tomorrow, it is clearly in the realm of possibilities anytime over the next few years.

Important terms to be familiar with

Let’s begin by defining some key terms, which will be referenced later...

Space weather: conditions in space that effect Earth and its technological systems. Unlike the terrestrial weather elements we are all familiar with (moisture, temperature, pressure, etc.), the key players are electromagnetic energy (light, x-rays, etc), magnetic fields, and plasma consisting of ionized or charged atomic particles permeated by a magnetic field separate from that of the sun and earth.

Sunspots: cooler and darker areas on the surface of the sun which become most and less numerous (sun spot number), respectively, which follow an approximately 11 year cycle from minimum to maximum and back to minimum.

Solar Wind: persistent, normal background stream of high-speed, ionized particles (mainly electrons and protons) ejected from the sun in all directions into interplanetary space.

Solar flares: short explosive releases of energy seen as bright areas on the sun that radiate throughout the electromagnetic spectrum, including x-rays and radio wave lengths particularly relevant to earth and technological system vulnerabilities.

Coronal Mass Ejection (CME): cloud of highly magnetized atomic particles (plasma) violently propelled from the upper layer of the sun’s atmosphere (corona) and sometimes associated with a sunspot group and/or solar flare. These disturbances are superimposed upon the background solar wind and, if directed towards earth, are the proximate causes of potentially disastrous geomagnetic storms 2-6 days after leaving the sun.

Geomagnetic storm: large spikes in electrical currents in the atmosphere and on the ground induced by induced by interaction of Earth’s magnetic field with the solar wind supercharged by CMEs.

Monitoring and forecasting space weather


The NOAA and NASA space weather observation network
A fleet of NOAA and NASA satellites, as well as ground-based systems, continually monitor solar events and provide the observations for analysis of solar activity and necessary for input to forecast models to predict the nature, path, and intensity of solar storms that might impact Earth. Despite recent improvements, observational systems and, especially prediction models, are in their early stages of development – comparable to when modern weather prediction analysis and forecast systems on Earth were in their infancy some 50+ years ago.

Current space weather forecasts are statistically-based on relationships of past solar activity and related phenomena (space weather climatology). They currently provide the basis for the one to three day official predictions of relevant phenomena issued by the Space Weather Prediction Center (SWPC), but are of questionable accuracy. The first large-scale, physics-based space weather prediction model is scheduled to fully transition form research to operations at SWPC in December. It remains to be seen to what extent the model adds value.

Looking further into the future, United Kingdom Prime Minister David Cameron and President Barack Obama recently signed a memorandum of understanding for a coordinated US-UK partnership in delivery of space weather alerts. It is an ambitious program to create the world’s first space weather model capable of forecasting terrestrial weather as well as indicating where, when, and for how long space weather effects will persist in the upper atmosphere.

At present, even if we know for sure that a CME plasma cloud is directed towards Earth some days ahead, the effects on power grids, satellites, etc, depend upon the relative orientation (polarity) of the magnetic fields of the plasma and Earth. Under certain alignments, even the most intense plasma disturbance will pass earth with virtually no effect whereas, under others, the threat is real and potentially disastrous. Intermediate levels of danger depend upon the relative polarity of Earth and plasma magnetic fields between these two extremes.

Critically, the only source of information on the alignment of the magnetic fields is NASA’s Advanced Composition Explorer (ACE) satellite and, therefore, the only system able to provide advanced warning of geomagnetic storms. Given the position of ACE in space between the Earth and Sun (L1 point), however, only short term advance notice (1 hour at most) is possible.

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Sidebar: Are the days of the ACE space weather satellite numbered?

ACE is not only an integral component of the short term warnings, it is invaluable for providing observations for assessing the accuracy of current and prospective space weather prediction models (such as the physics based model mentioned above).

Unfortunately and dangerously so, ACE is operating now 12-years past its design life with decreasing reliability of its sensors with a high risk of a complete failure without backup capability for two years at the very least. ). Its loss would be comparable to losing critical radar data for specific short-term tornado warnings and knowing only the general area and time frame tornadoes are possible.

NOAA acknowledges the possible loss of ACE would constitute the ‘most serious gap’ in its space weather services by leaving the world without a vital early-warning system against a devastating solar storm. It’s something which Tom Bogdan, Director of SWPC, admits keeps him awake at night.

Note: The White House budget request for 2012 includes funding for NOAA to convert a satellite, the Deep Space Climate Observatory (DSCOVR), initially slated for climate research (but grounded by politics) to a space weather system able to replace ACE in providing warnings of solar storms. If NOAA does get full funding (likely a big if), DSCOVR would be ready for launch by late 2013, probably too late for the spin up to the maximum in the current solar cycle. (I can’t help but wonder why so much justifiable media attention was given recently to the potential loss of a polar weather satellite, while the potential loss of ACE and need for DSCOVR seems too go unnoticed. In my humble opinion, although the loss of a polar satellite would be felt, the weather community can get by without it. Not so without ACE and its follow on, DSCOVR.)

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Understanding space weather forecasts

While far less than adequate, SPWC products and services are valuable to a wide array of customers responsible for space weather dependent systems such as satellites, GPS, power companies, airlines, and companies insuring against losses due to solar storms (Lloyds of London recently began offering coverage for damages due to space weather).

For the general user of space weather “situational awareness” SWPC issues current and forecast information in the form of scaled indices for three categories which are most relevant to the possible effects on electric power grids and satellite-based systems

Geomagnetic Storms: disturbances in the geomagnetic field caused by gusts in the solar wind that blows by Earth. Solar Radiation Storms: elevated levels of radiation that occur when the numbers of energetic particles increase. Radio Blackouts: disturbances of the ionosphere caused by X-ray emissions from the Sun.
G1 S1 R1
G2 S2 R2
G3 S3 R3
G4 S4 R4
G5 S5 R5

The scale for each range from 1 (minimal activity) to 5 (maximum hazard) and are similar to the Saffir-Simpson scale for categorizing hurricane intensity and Enhanced Fujita scale for measuring the strength of tornadoes. A description and effects for each of three categories used to assign the numbered value to indices is available on the SWPC website (no need to be concerned with the actual physical variable and frequency also shown).

Geomagnetic storms are the most important of the three items with regard to the question of “life as we know it” , endangerinh both power grids and satellites. In the scale for geomagnetic storms, G1 is considered “minor” with minimal effects on power systems and satellites. Effects become “severe” at the G4 level and “extreme” when reaching G5.

Radiation storms, as seen from chart, can render satellite systems useless and thereby satellite-dependent technology we now take for granted (most notably GPS).

A near simultaneous “extreme” hit on both power grids and satellites would be disastrous and unforgiving over extended periods and globally for whatever one views as the “normal” way of life.

Radio blackouts are consequential primarily only to a relatively few dependent concerns and effects are short-lived (a few days or less).

As mentioned, there would be at most only one hour warning of a certain G4/5 event from ACE. Even if action is taken a few days ahead on the basis of a probabilistic estimate (provided by SWPC with unknown reliability) of a possible G4/5 geomagnetic storm, the ability to prepare and protect technologically vulnerable systems is currently extremely limited, to say nothing of the woeful lack of resources necessary to recover from disaster.

My forthcoming post, Part III in this series, will examine more closely the potential effects and consequences of solar storms, as well as what can and cannot be done to protect, prepare and recover from a major event.

Additional Reading:

As the sun awakens, the power grid stands vulnerable and Space weather graphic (from today’s Washington Post print edition)
Solar flare photo gallery
Do solar storms threaten life as we know it?
2008 report on space weather by the National Academy of Sciences

By  |  01:30 PM ET, 06/21/2011

Categories:  Astronomy, Tracton, Latest, Space

 
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