Riding On the Tail of A CME

Solar storms more severe when two events ‘slipstream’ behind each other

Solar storms more severe when two events 'slipstream' behind each other

A research team led by Imperial College London has presented in a new study that Coronal Mass Ejections (CMEs) or solar storms could be more extreme than previously believed when they “slipstream” each other or when two such events follow each other. Modeling of an extreme space weather event that missed the Earth narrowly in 2012 shows that it could have been worse if another one occurred.

Coronal Mass Ejections (CMEs) are explosions of vast amounts of magnetized material from the Sun, which travel at high speeds and release a large amount of energy in a short period. When the CMEs reach the Earth, they trigger auroras, but they can also disrupt satellites and communications.

The most extreme of space weather events are likely to be catastrophic, causing power blackouts that would damage transformers, and it could take years to repair. Therefore, precise monitoring and forecasting are important to reduce possible damage.

The research team analyzed a large CME that happened on July 23, 2012, which narrowly missed the Earth by a couple of days. It traveled at around 2 250 km/s (1 400 mps), making it comparable to one of the biggest events on record– the 1859 Carrington event.

“The 23 July 2012 event is the most extreme space weather event of the space age, and if this event struck the Earth, the consequences could cause technological blackouts and severely disrupt society, as we are ever more reliant on modern technologies for our day-to-day lives,” said lead author Dr. Ravindra Desai from the Department of Physics at Imperial.

“We find however that this event could actually have been even more extreme– faster and more intense– if it had been launched several days earlier directly behind another event.”

The team studied one of the possible causes to identify what made the storm so extreme, and determined that it was the release of another CME — on July 19, just a few days before — that ‘cleared’ the path for another.

CMEs travel faster than the ambient solar wind, the stream of charged particles constantly flowing from the sun. This means the solar wind exerts drag on the traveling CME, slowing it down.

However, if a previous CME has recently passed through, the solar wind will be affected in such a way that it will not slow down the subsequent CME as much. This is similar to how race car drivers ‘slipstream’ behind one another to gain a speed advantage.


The July 23 event. Image credit: NASA/STEREO

The team developed a model that accurately represented the traits of the July 23 event, then simulated what would happen if it had happened earlier or later, or closer to the July 19 event.

The researchers found that by the time of the July 23 event, the solar wind had recovered from the July 19 event, thus, the previous event had a small impact. However, the model showed that if the latter event happened earlier– nearer the July 19 event– it could have been more extreme and could have possibly reached up to 2 750 km/s (1 700 mps).

“We show that the phenomenon of ‘solar wind preconditioning’, where an initial CME causes a subsequent CME to travel faster, is important for magnifying extreme space weather events,” said co-author Han Zhang.

“Our model results, showing the magnitude of the effect and how long the effect lasts, can contribute to current space weather forecasting efforts.”

“There have been previous instances of successive solar storms bombarding the Earth, such as the Halloween Storms of 2003,” co-author Emma Davies added.

“During this period, the sun produced many solar flares, with accompanying CMEs of speeds around 2 000 km/s. These events damaged satellites and communication systems, caused aircraft to be re-routed, and a power outage in Sweden.”

“There is always the possibility of similar or worse scenarios occurring this next solar cycle, therefore accurate models for prediction are vital to helping mitigate their effects.”


“Three-Dimensional Simulations of Solar Wind Preconditioning and the 23 July 2012 Interplanetary Coronal Mass Ejection” – Desai, R. T. et al. – Solar Physics – DOI: 10.1007/s11207-020-01700-5 – OPEN ACCESS


Predicting the large-scale eruptions from the solar corona and their propagation through interplanetary space remains an outstanding challenge in solar- and helio-physics research. In this article, we describe three-dimensional magnetohydrodynamic simulations of the inner heliosphere leading up to and including the extreme interplanetary coronal mass ejection (ICME) of 23 July 2012, developed using the code PLUTO. The simulations are driven using the output of coronal models for Carrington rotations 2125 and 2126 and, given the uncertainties in the initial conditions, are able to reproduce an event of comparable magnitude to the 23 July ICME, with similar velocity and density profiles at 1 au. The launch time of this event is then varied with regards to an initial 19 July ICME and the effects of solar wind preconditioning are found to be significant for an event of this magnitude and to decrease over a time-window consistent with the ballistic refilling of the depleted heliospheric sector. These results indicate that the 23 July ICME was mostly unaffected by events prior, but would have traveled even faster had it erupted closer in time to the 19 July event where it would have experienced even lower drag forces. We discuss this systematic study of solar wind preconditioning in the context of space weather forecasting.

Featured image credit: NASA/STEREO

from:    https://watchers.news/2020/10/04/cme-slipstream-research/

What do They Know?

Executive Order — Coordinating Efforts to Prepare the Nation for Space Weather Events

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By the authority vested in me as President by the Constitution and the laws of the United States of America, and to prepare the Nation for space weather events, it is hereby ordered as follows:

Section 1. Policy. Space weather events, in the form of solar flares, solar energetic particles, and geomagnetic disturbances, occur regularly, some with measurable effects on critical infrastructure systems and technologies, such as the Global Positioning System (GPS), satellite operations and communication, aviation, and the electrical power grid. Extreme space weather events — those that could significantly degrade critical infrastructure — could disable large portions of the electrical power grid, resulting in cascading failures that would affect key services such as water supply, healthcare, and transportation. Space weather has the potential to simultaneously affect and disrupt health and safety across entire continents. Successfully preparing for space weather events is an all-of-nation endeavor that requires partnerships across governments, emergency managers, academia, the media, the insurance industry, non-profits, and the private sector.

It is the policy of the United States to prepare for space weather events to minimize the extent of economic loss and human hardship. The Federal Government must have (1) the capability to predict and detect a space weather event, (2) the plans and programs necessary to alert the public and private sectors to enable mitigating actions for an impending space weather event, (3) the protection and mitigation plans, protocols, and standards required to reduce risks to critical infrastructure prior to and during a credible threat, and (4) the ability to respond to and recover from the effects of space weather. Executive departments and agencies (agencies) must coordinate their efforts to prepare for the effects of space weather events.

Sec. 2. Objectives. This order defines agency roles and responsibilities and directs agencies to take specific actions to prepare the Nation for the hazardous effects of space weather. These activities are to be implemented in conjunction with those identified in the 2015 National Space Weather Action Plan (Action Plan) and any subsequent updates. Implementing this order and the Action Plan will require the Federal Government to work across agencies and to develop, as appropriate, enhanced and innovative partnerships with State, tribal, and local governments; academia; non-profits; the private sector; and international partners. These efforts will enhance national preparedness and speed the creation of a space-weather-ready Nation.

Sec. 3. Coordination. (a) The Director of the Office of Science and Technology Policy (OSTP), in consultation with the Assistant to the President for Homeland Security and Counterterrorism and the Director of the Office of Management and Budget (OMB), shall coordinate the development and implementation of Federal Government activities to prepare the Nation for space weather events, including the activities established in section 5 of this order and the recommendations of the National Science and Technology Council (NSTC), established by Executive Order 12881 of November 23, 1993 (Establishment of the National Science and Technology Council).

(b) To ensure accountability for and coordination of research, development, and implementation of activities identified in this order and in the Action Plan, the NSTC shall establish a Space Weather Operations, Research, and Mitigation Subcommittee (Subcommittee). The Subcommittee member agencies shall conduct activities to advance the implementation of this order, to achieve the goals identified in the 2015 National Space Weather Strategy and any subsequent updates, and to coordinate and monitor the implementation of the activities specified in the Action Plan and provide subsequent updates.

Sec. 4. Roles and Responsibilities. To the extent permitted by law, the agencies below shall adopt the following roles and responsibilities, which are key to ensuring enhanced space weather forecasting, situational awareness, space weather preparedness, and continuous Federal Government operations during and after space weather events.

(a) The Secretary of Defense shall ensure the timely provision of operational space weather observations, analyses, forecasts, and other products to support the mission of the Department of Defense and coalition partners, including the provision of alerts and warnings for space weather phenomena that may affect weapons systems, military operations, or the defense of the United States.

(b) The Secretary of the Interior shall support the research, development, deployment, and operation of capabilities that enhance the understanding of variations of the Earth’s magnetic field associated with solar-terrestrial interactions.

(c) The Secretary of Commerce shall:

(i) provide timely and accurate operational space weather forecasts, watches, warnings, alerts, and real-time space weather monitoring for the government, civilian, and commercial sectors, exclusive of the responsibilities of the Secretary of Defense; and

(ii) ensure the continuous improvement of operational space weather services, utilizing partnerships, as appropriate, with the research community, including academia and the private sector, and relevant agencies to develop, validate, test, and transition space weather observation platforms and models from research to operations and from operations to research.

(d) The Secretary of Energy shall facilitate the protection and restoration of the reliability of the electrical power grid during a presidentially declared grid security emergency associated with a geomagnetic disturbance pursuant to 16 U.S.C. 824o-1.

(e) The Secretary of Homeland Security shall:

(i) ensure the timely redistribution of space weather alerts and warnings that support national preparedness, continuity of government, and continuity of operations; and

(ii) coordinate response and recovery from the effects of space weather events on critical infrastructure and the broader community.

(f) The Administrator of the National Aeronautics and Space Administration (NASA) shall:

(i) implement and support a national research program to understand the Sun and its interactions with Earth and the solar system to advance space weather modeling and prediction capabilities applicable to space weather forecasting;

(ii) develop and operate space-weather-related research missions, instrument capabilities, and models; and

(iii) support the transition of space weather models and technology from research to operations and from operations to research.

(g) The Director of the National Science Foundation (NSF) shall support fundamental research linked to societal needs for space weather information through investments and partnerships, as appropriate.

(h) The Secretary of State, in consultation with the heads of relevant agencies, shall carry out diplomatic and public diplomacy efforts to strengthen global capacity to respond to space weather events.

(i) The Secretaries of Defense, the Interior, Commerce, Transportation, Energy, and Homeland Security, along with the Administrator of NASA and the Director of NSF, shall work together, consistent with their ongoing activities, to develop models, observation systems, technologies, and approaches that inform and enhance national preparedness for the effects of space weather events, including how space weather events may affect critical infrastructure and change the threat landscape with respect to other hazards.

(j) The heads of all agencies that support National Essential Functions, defined by Presidential Policy Directive 40 (PPD-40) of July 15, 2016 (National Continuity Policy), shall ensure that space weather events are adequately addressed in their all-hazards preparedness planning, including mitigation, response, and recovery, as directed by PPD-8 of March 30, 2011 (National Preparedness).

(k) NSTC member agencies shall coordinate through the NSTC to establish roles and responsibilities beyond those identified in section 4 of this order to enhance space weather preparedness, consistent with each agency’s legal authority.

Sec. 5. Implementation. (a) Within 120 days of the date of this order, the Secretary of Energy, in consultation with the Secretary of Homeland Security, shall develop a plan to test and evaluate available devices that mitigate the effects of geomagnetic disturbances on the electrical power grid through the development of a pilot program that deploys such devices, in situ, in the electrical power grid. After the development of the plan, the Secretary shall implement the plan in collaboration with industry. In taking action pursuant to this subsection, the Secretaries of Energy and Homeland Security shall consult with the Chairman of the Federal Energy Regulatory Commission.

(b) Within 120 days of the date of this order, the heads of the sector-specific agencies that oversee the lifeline critical infrastructure functions as defined by the National Infrastructure Protection Plan of 2013 — including communications, energy, transportation, and water and wastewater systems — as well as the Nuclear Reactors, Materials, and Waste Sector, shall assess their executive and statutory authority, and limits of that authority, to direct, suspend, or control critical infrastructure operations, functions, and services before, during, and after a space weather event. The heads of each sector-specific agency shall provide a summary of these assessments to the Subcommittee.

(c) Within 90 days of receipt of the assessments ordered in section 5(b) of this order, the Subcommittee shall provide a report on the findings of these assessments with recommendations to the Director of OSTP, the Assistant to the President for Homeland Security and Counterterrorism, and the Director of OMB. The assessments may be used to inform the development and implementation of policy establishing authorities and responsibilities for agencies in response to a space weather event.

(d) Within 60 days of the date of this order, the Secretaries of Defense and Commerce, the Administrator of NASA, and the Director of NSF, in collaboration with other agencies as appropriate, shall identify mechanisms for advancing space weather observations, models, and predictions, and for sustaining and transitioning appropriate capabilities from research to operations and operations to research, collaborating with industry and academia to the extent possible.

(e) Within 120 days of the date of this order, the Secretaries of Defense and Commerce shall make historical data from the GPS constellation and other U.S. Government satellites publicly available, in accordance with Executive Order 13642 of May 9, 2013 (Making Open and Machine Readable the New Default for Government Information), to enhance model validation and improvements in space weather forecasting and situational awareness.

(f) Within 120 days of the date of this order, the Secretary of Homeland Security, through the Administrator of the Federal Emergency Management Agency and in coordination with relevant agencies, shall lead the development of a coordinated Federal operating concept and associated checklist to coordinate Federal assets and activities to respond to notification of, and protect against, impending space weather events. Within 180 days of the publication of the operating concept and checklist, agencies shall develop operational plans documenting their procedures and responsibilities to prepare for, protect against, and mitigate the effects of impending space weather events, in support of the Federal operating concept and compatible with the National Preparedness System described in PPD-8.

Sec. 6. Stakeholder Engagement. The agencies identified in this order shall seek public-private and international collaborations to enhance observation networks, conduct research, develop prediction models and mitigation approaches, enhance community resilience and preparedness, and supply the services necessary to protect life and property and promote economic prosperity, as consistent with law.

Sec. 7. Definitions. As used in this order:

(a) “Prepare” and “preparedness” have the same meaning they have in PPD-8. They refer to the actions taken to plan, organize, equip, train, and exercise to build and sustain the capabilities necessary to prevent, protect against, mitigate the effects of, respond to, and recover from those threats that pose the greatest risk to the security of the Nation. This includes the prediction and notification of space weather events.

(b) “Space weather” means variations in the space environment between the Sun and Earth (and throughout the solar system) that can affect technologies in space and on Earth. The primary types of space weather events are solar flares, solar energetic particles, and geomagnetic disturbances.

(c) “Solar flare” means a brief eruption of intense energy on or near the Sun’s surface that is typically associated with sunspots.

(d) “Solar energetic particles” means ions and electrons ejected from the Sun that are typically associated with solar eruptions.

(e) “Geomagnetic disturbance” means a temporary disturbance of Earth’s magnetic field resulting from solar activity.

(f) “Critical infrastructure” has the meaning provided in section 1016(e) of the USA Patriot Act of 2001 (42 U.S.C. 5195c(e)), namely systems and assets, whether physical or virtual, so vital to the United States that the incapacity or destruction of such systems and assets would have a debilitating impact on security, national economic security, national public health or safety, or any combination of those matters.

(g) “Sector-Specific Agency” means the agencies designated under PPD-21 of February 12, 2013 (Critical Infrastructure Security and Resilience), or any successor directive, to be responsible for providing institutional knowledge and specialized expertise as well as leading, facilitating, or supporting the security and resilience programs and associated activities of its designated critical infrastructure sector in the all-hazards environment. Sec. 8. General Provisions.

(a) Nothing in this order shall be construed to impair or otherwise affect:

(i) the authority granted by law to an agency, or the head thereof; or (ii) the functions of the Director of OMB relating to budgetary, administrative, or legislative proposals.

(b) This order shall be implemented consistent with applicable law and subject to the availability of appropriations.

(c) This order is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by any party against the United States, its departments, agencies, or entities, its officers, employees, or agents, or any other person.




October 13, 2016.

from:    https://www.whitehouse.gov/the-press-office/2016/10/13/executive-order-coordinating-efforts-prepare-nation-space-weather-events

More on ROSAT Re-Entry Dates & Conditions

SATELLITE RE-ENTRY: The ROSAT X-ray observatory, launched in 1990 by NASA and managed for years by the German Aerospace Center (DLR), will return to Earth within the next two weeks. Current best estimates place the re-entry between Oct. 22nd and 24th over an unknown part of Earth. Although ROSAT is smaller and less massive than UARS, which grabbed headlines when it re-entered on Sept. 24th, more of ROSAT could reach the planet’s surface. This is because the observatory is made of heat-tolerant materials. According to a DLR study, as many as 30 individual pieces could survive the fires of re-entry. The largest single fragment would likely be the telescope’s mirror, which is very heat resistant and may weigh as much as 1.7 tons.

ROSAT is coming, but it’s not here yet. On Oct. 13th, Marco Langbroek photographed the observatory still in orbit over Leiden, the Netherlands:

Photo details: 5 second exposure, Canon EOS 450D, ISO 400

“I observed ROSAT this evening in deep twilight,” says Langbroek. “It was bright, magnitude +1, and an easy naked-eye object zipping across the sky where the first stars just had become visible.”

Update: Scott Tilley of Roberts Creek, British Columbia, made a video of ROSATon Oct. 15th: “It did get pretty bright, at least 1st magnitude, as it passed overhead after sunset.”

ROSAT will become even brighter in the nights ahead as it descends toward Earth. Local flyby times may be found on the web or on your smartphone.

Also, check the German ROSAT re-entry page for updates.

The role of space weather: Solar activity has strongly affected ROSAT’s decay. Only a few months ago, experts expected the satellite to re-enter in December. However, they did not anticipate the recent increase in sunspot count. Extreme ultraviolet radiation from sunspots has heated and “puffed up” Earth’s atmosphere, accelerating the rate of orbital decay. The massive observatory now has a date with its home planet in October.

from:    spaceweather.com

Mercury Receiving CME

MERCURY-DIRECTED CME: On Sept 8th around 2300 UT, the SOHO and STEREO spacecraft detected a significant CME emerging from the farside of the sun. Earth is not in the line of fire, but the planet Mercury is. Analysts at the Goddard Space Weather Lab estimate that the cloud will reach the innermost planet on Sept. 9th at 12:00 UT (plus minus 7 hours). Click to view a movie of their CME model:


NASA’s MESSENGER spacecraft is in orbit around Mercury, so it will have a front row seat for the impact. Researchers are keen to learn how Mercury’s magnetosphere responds to CMEs. In particular, they wonder if CMEs can overpower Mercury’s magnetic field and sputter atoms right off the planet’s surface. Thanks to the Goddard forecast, MESSENGER’s controllers know the CME is coming, and they can prepare to observe the impact.

Interplanetary space weather forecasting is a new thing. It became possible in 2010-2011 when NASA and ESA spacecraft surrounded the sun. Working together, SOHO, the Solar Dynamics Observatory, STEREO-A and STEREO-B now have the entire star under surveillance. CMEs can be tracked no matter where they go, which means space weather isn’t just for Earth anymore.