New Study Highlights Charged Particles Role In Creating Upper Atmosphere Discharge Similar to Terrestrial Lightning

Scientists from NASA and three universities have presented new discoveries about the way heat and energy move and manifest in the ionosphere, a region of Earth’s atmosphere that reacts to changes from both space above and Earth below.

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Far above Earth’s surface, within the tenuous upper atmosphere, is a sea of particles that have been split into positive and negative ions by the Sun’s harsh ultraviolet radiation. Called the ionosphere, this is Earth’s interface to space, the area where Earth’s neutral atmosphere and terrestrial weather give way to the space environment that dominates most of the rest of the universe – an environment that hosts charged particles and a complex system of electric and magnetic fields. The ionosphere is both shaped by waves from the atmosphere below and uniquely responsive to the changing conditions in space, conveying such space weather into observable, Earth-effective phenomena creating the aurora, disrupting communications signals, and sometimes causing satellite problems.

Many of these effects are not well-understood, leaving the ionosphere, for the most part, a region of mystery. Scientists from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the Catholic University of America in Washington, D.C., the University of Colorado Boulder, and the University of California, Berkeley, presented new results on the ionosphere at the fall meeting of the American Geophysical Union on Dec. 14, 2016, in San Francisco.

One researcher explained how the interaction between the ionosphere and another layer in the atmosphere, the thermosphere, counteract heating in the thermosphere – heating that leads to expansion of the upper atmosphere, which can cause premature orbital decay. Another researcher described how energy outside the ionosphere accumulates until it discharges – not unlike lightning – offering an explanation for how energy from space weather crosses over into the ionosphere. A third scientist discussed two upcoming NASA missions that will provide key observations of this region, helping us better understand how the ionosphere reacts both to space weather and to terrestrial weather.

Changes in the ionosphere are primarily driven by the Sun’s activity. Though it may appear unchanging to us on the ground, our Sun is, in fact, a very dynamic, active star. Watching the Sun in ultraviolet wavelengths of light from space – above our UV light-blocking atmosphere – reveals constant activity, including bursts of light, particles, and magnetic fields.

Occasionally, the Sun releases huge clouds of particles and magnetic fields that explode out from the Sun at more than a million miles per hour. These are called coronal mass ejections, or CMEs. When a CME reaches Earth, its embedded magnetic fields can interact with Earth’s natural magnetic field – called the magnetosphere – sometimes compressing it or even causing parts of it to realign.

It is this realignment that transfers energy into Earth’s atmospheric system, by setting off a chain reaction of shifting electric and magnetic fields that can send the particles already trapped near Earth skittering in all directions. These particles can then create one of the most recognizable and awe-inspiring space weather events – the aurora, otherwise known as the Northern Lights.

But the transfer of energy into the atmosphere isn’t always so innocuous. It can also heat the upper atmosphere – where low-Earth satellites orbit – causing it to expand like a hot-air balloon.

“This swelling means there’s more stuff at higher altitudes than we would otherwise expect,” said Delores Knipp, a space scientist at the University of Colorado Boulder. “That extra stuff can drag on satellites, disrupting their orbits and making them harder to track.”

This phenomenon is called satellite drag. New research shows that this understanding of the upper atmosphere’s response to solar storms – and the resulting satellite drag – may not always hold true.

“Our basic understanding has been that geomagnetic storms put energy into the Earth system, which leads to swelling of the thermosphere, which can pull satellites down into lower orbits,” said Knipp, lead researcher on these new results. “But that isn’t always the case.”

Sometimes, the energy from solar storms can trigger a chemical reaction that produces a compound called nitric oxide in the upper atmosphere. Nitric oxide acts as a cooling agent at very high altitudes, promoting energy loss to space, so a significant increase in this compound can cause a phenomenon called overcooling.

“Overcooling causes the atmosphere to quickly shed energy from the geomagnetic storm much quicker than anticipated,” said Knipp. “It’s like the thermostat for the upper atmosphere got stuck on the ‘cool’ setting.”

That quick loss of energy counteracts the previous expansion, causing the upper atmosphere to collapse back down – sometimes to an even smaller state than it started in, leaving satellites traveling through lower-density regions than anticipated.

A new analysis by Knipp and her team classifies the types of storms that are likely to lead to this overcooling and rapid upper atmosphere collapse. By comparing over a decade of measurements from Department of Defense satellites and NASA’s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics, or TIMED, mission, the researchers were able to spot patterns in energy moving throughout the upper atmosphere.

“Overcooling is most likely to happen when very fast and magnetically-organized ejecta from the Sun rattle Earth’s magnetic field,” said Knipp. “Slow clouds or poorly-organized clouds just don’t have the same effect.”

This means that, counterintuitively, the most energetic solar storms are likely to provide a net cooling and shrinking effect on the upper atmosphere, rather than heating and expanding it as had been previously understood.

Competing with this cooling process is the heating that caused by solar storm energy making its way into Earth’s atmosphere. Though scientists have known that solar wind energy eventually reaches the ionosphere, they have understood little about where, when and how this transfer takes place. New observations show that the process is localized and impulsive, and partly dependent on the state of the ionosphere itself.

Traditionally, scientists have thought that the way energy moves throughout Earth’s magnetosphere and atmosphere is determined by the characteristics of the incoming particles and magnetic fields of the solar wind – for instance, a long, steady stream of solar particles would produce different effects than a faster, less consistent stream. However, new data shows that the way energy moves is much more closely tied to the mechanisms by which the magnetosphere and ionosphere are linked.

“The energy transfer process turns out to be very similar to the way lightning forms during a thunderstorm,” said Bob Robinson, a space scientist at NASA Goddard and the Catholic University of America.

During a thunderstorm, a buildup of electric potential difference – called voltage – between a cloud and the ground leads to a sudden, violent discharge of that electric energy in the form of lightning. This discharge can only happen if there’s an electrically conducting pathway between the cloud and the ground, called a leader.

Similarly, the solar wind striking the magnetosphere can build up a voltage difference between different regions of the ionosphere and the magnetosphere. Electric currents can form between these regions, creating the conducting pathway needed for that built-up electric energy to discharge into the ionosphere as a kind of lightning.

“Terrestrial lightning takes several milliseconds to occur, while this magnetosphere-ionosphere ‘lightning’ lasts for several hours – and the amount of energy transferred is hundreds to thousands of times greater,” said Robinson, lead researcher on these new results. These results are based on data from the global Iridium satellite communications constellation.

Because solar storms enhance the electric currents that let this magnetosphere-ionosphere lightning take place, this type of energy transfer is much more likely when Earth’s magnetic field is jostled by a solar event.

The huge energy transfer from this magnetosphere-ionosphere lightning is associated with heating of the ionosphere and upper atmosphere, as well as increased aurora.

Looking Forward

Though scientists are making progress in understanding the key processes that drive changes in the ionosphere and, in turn, on Earth, there is still much to be understood. In 2017, NASA is launching two missions to investigate this dynamic region: the Ionospheric Connection Explorer, or ICON, and Global Observations of the Limb and Disk, or GOLD.

“The ionosphere doesn’t only react to energy input by solar storms,” said Scott England, a space scientist at the University of California, Berkeley, who works on both the ICON and GOLD missions. “Terrestrial weather, like hurricanes and wind patterns, can shape the atmosphere and ionosphere, changing how they react to space weather.”

ICON will simultaneously measure the characteristics of charged particles in the ionosphere and neutral particles in the atmosphere – including those shaped by terrestrial weather – to understand how they interact. GOLD will take many of the same measurements, but from geostationary orbit, which gives a global view of how the ionosphere changes.

Both ICON and GOLD will take advantage of a phenomenon called airglow – the light emitted by gas that is excited or ionized by solar radiation – to study the ionosphere. By measuring the light from airglow, scientists can track the changing composition, density, and even temperature of particles in the ionosphere and neutral atmosphere.

ICON’s position 350 miles above Earth will enable it to study the atmosphere in profile, giving scientists an unprecedented look at the state of the ionosphere at a range of altitudes. Meanwhile, GOLD’s position 22,000 miles above Earth will give it the chance to track changes in the ionosphere as they move across the globe, similar to how a weather satellite tracks a storm.

“We will be using these two missions together to understand how dynamic weather systems are reflected in the upper atmosphere, and how these changes impact the ionosphere,” said England.

Satellite Observations of Magnetic Fields to Measure Ocean Temperatures

A surprising feature of the tides could help, however. Scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are developing a new way to use satellite observations of magnetic fields to measure heat stored in the ocean.

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“If you’re concerned about understanding global warming, or Earth’s energy balance, a big unknown is what’s going into the ocean,” said Robert Tyler, a research scientist at Goddard. “We know the surfaces of the oceans are heating up, but we don’t have a good handle on how much heat is being stored deep in the ocean.”

Despite the significance of ocean heat to Earth’s climate, it remains a variable that has substantial uncertainty when scientists measure it globally. Current measurements are made mainly by Argo floats, but these do not provide complete coverage in time or space. If it is successful, this new method could be the first to provide global ocean heat measurements, integrated over all depths, using satellite observations.

Tyler’s method depends on several geophysical features of the ocean. Seawater is a good electrical conductor, so as saltwater sloshes around the ocean basins it causes slight fluctuations in Earth’s magnetic field lines. The ocean flow attempts to drag the field lines around, Tyler said. The resulting magnetic fluctuations are relatively small, but have been detected from an increasing number of events including swells, eddies, tsunamis and tides.

“The recent launch of the European Space Agency’s Swarm satellites, and their magnetic survey, are providing unprecedented observational data of the magnetic fluctuations,” Tyler said. “With this comes new opportunities.”

Researchers know where and when the tides are moving ocean water, and with the high-resolution data from the Swarm satellites, they can pick out the magnetic fluctuations due to these regular ocean movements.

That’s where another geophysical feature comes in. The magnetic fluctuations of the tides depend on the electrical conductivity of the water- and the electrical conductivity of the water depends on its temperature.

For Tyler, the question then is: “By monitoring these magnetic fluctuations, can we monitor the ocean temperature?”

At the American Geophysical Union meeting in San Francisco this week, Tyler and collaborator Terence Sabaka, also at Goddard, presented the first results. They provide a key proof-of-concept of the method by demonstrating that global ocean heat content can be recovered from “noise-free” ocean tidal magnetic signals generated by a computer model. When they try to do this with the “noisy” observed signals, it does not yet provide the accuracy needed to monitor changes in the heat content.

But, Tyler said, there is much room for improvement in how the data are processed and modeled, and the Swarm satellites continue to collect magnetic data. This is a first attempt at using satellite magnetic data to monitor ocean heat, he said, and there is still much more to be done before the technique could successfully resolve this key variable. For example, by identifying fluctuations caused by other ocean movements, like eddies or other tidal components, scientists can extract even more information and get more refined measurements of ocean heat content and how it’s changing.

More than 90 percent of the excess heat in the Earth system goes into the ocean, said Tim Boyer, a scientist with the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information. Scientists currently monitor ocean heat with shipboard measurements and Argo floats. While these measurements and others have seen a steady increase in heat since 1955, researchers still need more complete information, he said.

“Even with the massive effort with the Argo floats, we still don’t have as much coverage of the ocean as we would really like in order to lower the uncertainties,” Boyer said. “If you’re able to measure global ocean heat content directly and completely from satellites, that would be fantastic.”

Changing ocean temperatures have impacts that stretch across the globe. In Antarctica, floating sections of the ice sheet are retreating in ways that can’t be explained only by changes in atmospheric temperatures, said Catherine Walker, an ice scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

She and her colleagues studied glaciers in Antarctica that lose an average of 6.5 to 13 feet (2 to 4 meters) of elevation per year. They looked at different options to explain the variability in melting – surrounding sea ice, winds, salinity, air temperatures – and what correlated most was influxes of warmer ocean water.

“These big influxes of warm water come onto the continental shelf in some years and affect the rate at which ice melts,” Walker said. She and her colleagues are presenting the research at the AGU meeting.

Walker’s team has identified an area on the Antarctic Peninsula where warmer waters may have infiltrated inland, under the ice shelf – which could have impacts on sea level rise.

Float and ship measurements around Antarctica are scarce, but deep water temperature measurements can be achieved using tagged seals. That has its drawbacks, however: “It’s random, and we can’t control where they go,” Walker said. Satellite measurements of ocean heat content and temperatures would be very useful for the Southern Ocean, she added.

Ocean temperatures also impact life in the ocean – from microscopic phytoplankton on up the food chain. Different phytoplankton thrive at different temperatures and need different nutrients.

“Increased stratification in the ocean due to increased heating is going to lead to winners and losers within the phytoplankton communities,” said Stephanie Schollaert Uz, a scientist at Goddard.

In research presented this week at AGU, she took a look 50 years back. Using temperature, sea level and other physical properties of the ocean, she generated a history of phytoplankton extent in the tropical Pacific Ocean, between 1958 and 2008. Looking over those five decades, she found that phytoplankton extent varied between years and decades. Most notably, during El Niño years, water currents and temperatures prevented phytoplankton communities from reaching as far west in the Pacific as they typically do.

Digging further into the data, she found that where the El Niño was centered has an impact on phytoplankton. When the warmer waters of El Niño are centered over the Eastern Pacific, it suppresses nutrients across the basin, and therefore depresses phytoplankton growth more so than a central Pacific El Niño.

“For the first time, we have a basin-wide view of the impact on biology of interannual and decadal forcing by many El Niño events over 50 years,” Uz said.

As ocean temperatures impact processes across the Earth system, from climate to biodiversity, Tyler will continue to improve this novel magnetic remote sensing technique, to improve our future understanding of the planet.

BREAKING NEWS: New Discovery of Mysterious Alignment of Black Holes

Deep radio imaging by researchers in the University of Cape Town and University of the Western Cape, in South Africa, has revealed that supermassive black holes in a region of the distant universe are all spinning out radio jets in the same direction. The astronomers publish their results to the Royal Astronomical Society.

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The jets are produced by the supermassive black holes at the center of these galaxies, and the only way for this alignment to exist is if supermassive black holes are all spinning in the same direction, says Prof Andrew Russ Taylor, joint UWC/UCT SKA Chair, Director of the recently-launched Inter-University Institute for Data Intensive Astronomy, and principal author of the Monthly Notices study.

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Earlier observational studies had previously detected deviations from uniformity (so-called isotropy) in the orientations of galaxies. But these sensitive radio images offer a first opportunity to use jets to reveal alignments of galaxies on physical scales of up to 100 Mpc. And measurements from the total intensity radio emission of galaxy jets have the advantage of not being affected by effects such as scattering, extinction and Faraday Radiation, which may be an issue for other studies.

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So what could these large-scale environmental influences during galaxy formation or evolution have been? There are several options: cosmic magnetic fields; fields associated with exotic particles (axions); and cosmic strings are only some of the possible candidates that could create an alignment in galaxies even on scales larger than galaxy clusters. It’s a mystery, and it’s going to take a while for technology and theory alike to catch up.

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New Equation:
Increase Charged Particles  and Decreased Magnetic Field → Increase Outer Core Convection → Increase of Mantle Plumes → Increase in Earthquake and Volcanoes → Cools Mantle and Outer Core → Return of Outer Core Convection (Mitch Battros – July 2012)

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The finding wasn’t planned for: the initial investigation was to explore the faintest radio sources in the universe, using the best available telescopes – a first view into the kind of universe that will be revealed by the South African MeerKAT radio telescope and the Square Kilometer Array (SKA), the world’s most powerful radio telescope and one of the biggest scientific instruments ever devised.

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UWC Prof Romeel Dave, SARChI Chair in Cosmology with Multi-Wavelength Data, who leads a team developing plans for universe simulations that could explore the growth of large-scale structure from a theoretical perspective, agrees: “This is not obviously expected based on our current understanding of cosmology. It’s a bizarre finding.”
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New Theories on Stellar Winds – Pulsating Magnetically Driven Radiative Energy

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A new study of the mechanism that drives stellar winds from the upper atmosphere of a star has shed new light. Astronomers think there are three possibilities: radiative, in which the pressure of the light pushes out the grains, magnetically driven, in which the stellar magnetic field plays a role in powering the flow, and pulsation driven, in which a periodic build-up of radiative energy in the stellar interior is suddenly released.

A new study of the mechanism that drives stellar winds from the upper atmosphere of a star has shed new light. Astronomers think there are three possibilities: radiative, in which the pressure of the light pushes out the grains, magnetically driven, in which the stellar magnetic field plays a role in powering the flow, and pulsation driven, in which a periodic build-up of radiative energy in the stellar interior is suddenly released.

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The winds of stars more evolved than the Sun (like the so-called giant stars that are cooler and larger in diameter than the Sun) often contain dust particles which enrich the interstellar medium with heavy elements. These winds also contain small grains on whose surfaces chemical reactions produce complex molecules. The dust also absorbs radiation and obscures visible light. Understanding the mechanism(s) that produce these winds in evolved stars is important both for modeling the wind and the character of the stellar environment, and for predicting the future evolution of the star.

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Nearly all stars have winds. The Sun’s wind, which originates from its hot outer layer (corona), contains charged particles emitted at a rate equivalent to about one-millionth of the moon’s mass each year. Some of these particles bombard the Earth, producing radio static, auroral glows, and (in extreme cases) disrupted global communications.

NASA'S Chandra Finds Fastest Wind From Stellar-Mass Black Hole
NASA’S Chandra Finds Fastest Wind From Stellar-Mass Black Hole

Over the years scientific opinion has varied among these alternatives, depending on each particular stellar example. Harvard–Smithsonian Center for Astrophysics Chris Johnson, and his colleagues explored the problem of wind-driving mechanism in giant stars by measuring the motion of the outflowing CO (carbon monoxide) gas around one the nearest and brightest giant stars, EU Del, which is only about 380 light-years away and shines with 1600 solar-luminosities.

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New Equation:
Increase Charged Particles and Decreased Magnetic Field → Increase Outer Core Convection → Increase of Mantle Plumes → Increase in Earthquake and Volcanoes → Cools Mantle and Outer Core → Return of Outer Core Convection (Mitch Battros – July 2012)

Its radius, if the star were placed at the position of the Sun, would extend past the orbit of Venus. EU Del is known to be a semi-regular variable star which pulses every sixty days or so (but with some secondary periods as well), and infrared observations suggest it has a circumstellar dust shell.

The astronomers used the submillimeter APEX (Atacama Pathfinder Experiment) telescope to look at warm CO gas in the wind, making EU Del one of the first stars of its class to be studied with this relatively new tool. The team reports finding the CO moving at about ten kilometers per second (twenty two thousand miles per hour) with a total mass-loss rate equal to about the mass of the Moon each year.