Electromagnetic waves linked to particle fallout in Earth's atmosphere, new study finds

In a new study that sheds light on space weather's impact on Earth, Dartmouth researchers and their colleagues show for the first time that plasma waves buffeting the planet's radiation belts are responsible for scattering charged particles into the atmosphere.

The study is the most detailed analysis so far of the link between these waves and the fallout of electrons from the planet's radiation belts. The belts are impacted by fluctuations in "space weather" caused by solar activity that can disrupt GPS satellites, communication systems, power grids and manned space exploration.

The results appear in the journal Geophysical Research Letters. A PDF is available on request.

The Dartmouth space physicists are part of a NASA-sponsored team that studies the Van Allen radiation belts, which are donut-shaped belts of charged particles held in place by Earth's magnetosphere, the magnetic field surrounding our planet. In a quest to better predict space weather, the Dartmouth researchers study the radiation belts from above and below in complementary approaches -- through satellites (the twin NASA Van Allen Probes) high over Earth and through dozens of instrument-laden balloons (BARREL, or Balloon Array for Radiation belt Relativistic Electron Losses) at lower altitudes to assess the particles that rain down.

The Van Allen Probes measure particle, electric and magnetic fields, or basically everything in the radiation belt environment, including the electrons, which descend following Earth's magnetic field lines that converge at the poles. This is why the balloons are launched from Antarctica, where some of the best observations can be made. As the falling electrons collide with the atmosphere, they produce X-rays and that is what the balloon instruments are actually recording.

"We are measuring those atmospheric losses and trying to understand how the particles are getting kicked into the atmosphere," says co-author Robyn Millan, an associate professor in Dartmouth's Department of Physics and Astronomy and the principal investigator of BARREL. "Our main focus has been really on the processes that are occurring out in space. Particles in the Van Allen belts never reach the ground, so they don't constitute a health threat. Even the X-rays get absorbed, which is why we have to go to balloon altitudes to see them."

In their new study, the BARREL researchers' major objective was to obtain simultaneous measurements of the scattered particles and of ionoized gas called plasma out in space near Earth's equator. They were particularly interested in simultaneous measurements of a particular kind of plasma wave called electromagnetic ion cyclotron waves and whether these waves were responsible for scattering the particles, which has been an open question for years.

The researchers obtained measurements in Antarctica in 2013 when the balloons and both the Geostationary Operational Environmental Satellite (GOES) and Van Allen Probe satellites were near the same magnetic field line. They put the satellite data into their model that tests the wave-particle interaction theory, and the results suggest the wave scattering was the cause of the particle fallout. "This is the first real quantitative test of the theory," Millan says.

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Temperature anomalies are warming faster than Earth's average, study finds

It's widely known that Earth's average temperature has been rising. But research by an Indiana University geographer and colleagues finds that spatial patterns of extreme temperature anomalies -- readings well above or below the mean -- are warming even faster than the overall average.

And trends in extreme heat and cold are important, said Scott M. Robeson, professor of geography in the College of Arts and Sciences at IU Bloomington. They have an outsized impact on water supplies, agricultural productivity and other factors related to human health and well-being.

"Average temperatures don't tell us everything we need to know about climate change," he said. "Arguably, these cold extremes and warm extremes are the most important factors for human society."

Robeson is the lead author of the article "Trends in hemispheric warm and cold anomalies," which will be published in the journal Geophysical Research Letters and is available online. Co-authors are Cort J. Willmott of the University of Delaware and Phil D. Jones of the University of East Anglia.

The researchers analyzed temperature records for the years 1881 to 2013 from HadCRUT4, a widely used data set for land and sea locations compiled by the University of East Anglia and the U.K. Met Office. Using monthly average temperatures at points across the globe, they sorted them into "spatial percentiles," which represent how unusual they are by their geographic size.

Their findings include:

Temperatures at the cold and warm "tails" of the spatial distribution -- the 5th and 95th percentiles -- increased more than the overall average Earth temperature.Over the 130-year record, cold anomalies increased more than warm anomalies, resulting in an overall narrowing of the range of Earth's temperatures.In the past 30 years, however, that pattern reversed, with warm anomalies increasing at a faster rate than cold anomalies. "Earth's temperature was becoming more homogenous with time," Robeson said, "but now it's not."

The study records separate results for the Northern and Southern Hemispheres. Temperatures are considerably more volatile in the Northern Hemisphere, an expected result because there's considerably less land mass in the South to add complexity to weather systems.

The study also examined anomalies during the "pause" in global warming that scientists have observed since 1998. While a 16-year-period is too short a time to draw conclusions about trends, the researchers found that warming continued at most locations on the planet and during much of the year, but that warming was offset by strong cooling during winter months in the Northern Hemisphere.

"There really hasn't been a pause in global warming," Robeson said. "There's been a pause in Northern Hemisphere winter warming."

Co-author Jones of the University of East Anglia said the study provides scientists with better knowledge about what's taking place with Earth's climate. "Improved understanding of the spatial patterns of change over the three periods studied are vital for understanding the causes of recent events," he said.

It may seem counterintuitive that global warming would be accompanied by colder winter weather at some locales. But Robeson said the observation aligns with theories about climate change, which hold that amplified warming in the Arctic region produces changes in the jet stream, which can result in extended periods of cold weather at some locations in the mid-northern latitudes.

And while the rate of planetary warming has slowed in the past 16 years, it hasn't stopped. The World Meteorological Organization announced this month that 2014 is on track to be one of the warmest, if not the warmest, years on record as measured by global average temperatures.

In the U.S., the East has been unusually cold and snowy in recent years, but much of the West has been unusually warm and has experienced drought. And what happens here doesn't necessarily reflect conditions on the rest of the planet. Robeson points out that the United States, including Alaska, makes up only 2 percent of Earth's surface.

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Seasonal Arctic summer ice extent still hard to forecast, study says

Will next year's summer Arctic ice extent be high or low? Can ship captains plan on navigating the famed Northwest Passage -- a direct shipping route from Europe to Asia across the Arctic Ocean -- to save on time and fuel? A new study says year-to-year forecasts of the Arctic's summer ice extent are not yet reliable.

Scientists at the National Snow and Ice Data Center (NSIDC), University College London, University of New Hampshire and University of Washington analyzed 300 summer Arctic sea ice forecasts from 2008 to 2013 and found that forecasts are quite accurate when sea ice conditions are close to the downward trend that has been observed in Arctic sea ice for the last 30 years. However, forecasts are not so accurate when sea ice conditions are unusually higher or lower compared to this trend.

"We found that in years when the sea ice extent departed strongly from the trend, such as in 2012 and 2013, predictions failed regardless of the method used to forecast the September sea ice extent," said Julienne Stroeve, a senior scientist at NSIDC and professor at University of College London. Stroeve is lead author of the study, published recently in Geophysical Research Letters.

"That downward trend reflects Arctic climate change, but the causes of yearly variations around the trend are harder to pin down," said Lawrence Hamilton, co-author and a researcher at the University of New Hampshire. "This collection of forecasts from many different sources highlights where they do well, and where more work is needed."

Arctic sea ice cover grows each winter as the sun sets for several months, and shrinks each summer as the sun rises higher in the northern sky. Each year, the Arctic sea ice reaches its minimum extent in September. Scientists consider Arctic sea ice as a sensitive climate indicator and track this minimum extent every year to see if any trends emerge.

Multi-channel passive microwave satellite instruments have been tracking sea ice extent since 1979. According to the data, September sea ice extent from 1979 to 2013 has declined 13.7 percent per decade. The recent years have shown an even more dramatic reduction in Arctic ice. In September 2012, Arctic sea ice reached a record minimum: 16 percent lower than any previous September since 1979, and 45 percent lower than the average ice extent from 1981 to 2010.

Long-term predictions of summer Arctic extent made by global climate models (GCMs) suggest that the downward trend will likely lead to an ice-free Arctic summer in the middle of the century. GCMs are in overall agreement on loss of Arctic summer sea ice as a result of anticipated warming from the rise in greenhouse gases this century.

Shorter-term forecasts of summer ice extent are harder to make but are now in high demand. The shrinking ice has caught the attention of coastal communities in the Arctic and industries interested in extracting resources and in a shorter shipping route between Europe and Asia.

Many of the forecasts analyzed in the study focused on the state of the ice cover prior to the summer melt season. According to the study, including sea ice thickness and concentration could improve the seasonal forecasts.

"It may even be possible to predict sea ice cover a year in advance with high-quality observations of sea ice thickness and snow cover over the whole Arctic," said Cecilia Bitz, co-author and professor of atmospheric sciences at the University of Washington.

"Short term predictions are achievable, but challenges remain in predicting anomalous years, and there is a need for better data for initialization of forecast models," Stroeve said. "Of course there is always the issue that we cannot predict the weather, and summer weather patterns remain important."

The study analyzed forecasts from the Study of Environmental Arctic Change (SEARCH) Sea Ice Outlook, a project that gathers and summarizes sea ice forecasts made by sea ice researchers and prediction centers. Contributors to the SEARCH Sea Ice Outlook project employ a variety of techniques to forecast the September sea ice extent, ranging from heuristic, to statistical, to sophisticated modeling approaches.

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Solar activity not a key cause of climate change, study shows

Climate change has not been strongly influenced by variations in heat from the sun, a new scientific study shows.

The findings overturn a widely held scientific view that lengthy periods of warm and cold weather in the past might have been caused by periodic fluctuations in solar activity.

Research examining the causes of climate change in the northern hemisphere over the past 1000 years has shown that until the year 1800, the key driver of periodic changes in climate was volcanic eruptions. These tend to prevent sunlight reaching Earth, causing cool, drier weather. Since 1900, greenhouse gases have been the primary cause of climate change.

The findings show that periods of low sun activity should not be expected to have a large impact on temperatures on Earth, and are expected to improve scientists' understanding and help climate forecasting.

Scientists at the University of Edinburgh carried out the study using records of past temperatures constructed with data from tree rings and other historical sources. They compared this data record with computer-based models of past climate, featuring both significant and minor changes in the sun.

They found that their model of weak changes in the sun gave the best correlation with temperature records, indicating that solar activity has had a minimal impact on temperature in the past millennium.

The study, published in Nature GeoScience, was supported by the Natural Environment Research Council.

Dr Andrew Schurer, of the University of Edinburgh's School of GeoSciences, said: "Until now, the influence of the sun on past climate has been poorly understood. We hope that our new discoveries will help improve our understanding of how temperatures have changed over the past few centuries, and improve predictions for how they might develop in future. Links between the sun and anomalously cold winters in the UK are still being explored."

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New study suggests coral reefs may be able to adapt to moderate climate change

October 29, 2013

A new modeling study shows that widespread bleaching events like this one in Thailand in 2010 will become more common in the future. However, the study also found signs corals may be adapting to warming -- the question is if it can be fast enough to keep up with the rate humans are burning fossil fuels.

High resolution (Credit:C. Mark Eakin/NOAA )

Coral reefs may be able to adapt to moderate climate warming, improving their chance of surviving through the end of this century, if there are large reductions in carbon dioxide emissions, according to a study funded by NOAA and conducted by the agency’s scientists and its academic partners. Results further suggest corals have already adapted to part of the warming that has occurred.

“Earlier modeling work suggested that coral reefs would be gone by the middle of this century. Our study shows that if corals can adapt to warming that has occurred over the past 40 to 60 years, some coral reefs may persist through the end of this century,” said study lead author Cheryl Logan, Ph.D., an assistant professor in California State University Monterey Bay’s Division of Science and Environmental Policy. The scientists from the university, and from the University of British Columbia, were NOAA’s partners in the study.

Warm water can contribute to a potentially fatal process known as coral “bleaching,” in which reef-building corals eject algae living inside their tissues. Corals bleach when oceans warm only 1-2°C (2-4°F) above normal summertime temperatures. Because those algae supply the coral with most of its food, prolonged bleaching and associated disease often kills corals.

The study, published online in the journal Global Change Biology, explores a range of possible coral adaptive responses to thermal stress previously identified by the scientific community. It suggests that coral reefs may be more resilient than previously thought due to past studies that did not consider effects of possible adaptation.

The study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100, if there are large reductions in carbon dioxide emissions.

“The hope this work brings is only achieved if there is significant reduction of human-related  emissions of heat-trapping gases,” said Mark Eakin, Ph.D., who serves as director of the NOAA Coral Reef Watch monitoring program, which tracks bleaching events worldwide. “Adaptation provides no significant slowing in the loss of coral reefs if we continue to increase our rate of fossil fuel use.”

“Not all species will be able to adapt fast enough or to the same extent, so coral communities will look and function differently than they do today,” CalState’s Logan said.

While this paper focuses on ocean warming, many other general threats to coral species have been documented to exist that affect their long-term survival, such as coral disease, acidification, and sedimentation. Other threats to corals are sea-level rise, pollution, storm damage, destructive fishing practices, and direct harvest for ornamental trade.

According to the Status of Coral Reefs of the World: 2000 report, coral reefs have been lost around the world in recent decades with almost 20 percent of reefs lost globally to high temperatures during the 1998-1999 El Niño and La Niña and an 80 percent percent loss of coral cover in the Caribbean was documented in a 2003 Science paper. Both rates of decline have subsequently been documented in numerous other studies as an on-going trend.

Tropical coral reef ecosystems are among the most diverse ecosystems in the world, and provide economic and social stability to many nations in the form of food security, where reef fish provide both food and fishing jobs, and economic revenue from tourism. Mass coral bleaching and reef death has increased around the world over the past three decades, raising questions about the future of coral reef ecosystems.

In the study, researchers used global sea surface temperature output from the NOAA/GFDL Earth System Model-2 for the pre-industrial period though 2100 to project rates of coral bleaching.

Because initial results showed that past temperature increases should have bleached reefs more often than has actually occurred, researchers looked into ways that corals may be able to adapt to warming and delay the bleaching process.

The article calls for further research to test the rate and limit of different adaptive responses for coral species across latitudes and ocean basins to determine if, and how much, corals can actually respond to increasing thermal stress.

In addition to Logan, the other authors of the paper were John Dunne, NOAA Geophysical Fluid Dynamics Laboratory; Eakin, NOAA’s Coral Reef Watch; and Simon Donner, Department of Geography at the University of British Columbia. NOAA’s Coral Reef Conservation Program funded the study.

NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter, Instagram and our other social media channels.

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Study finds fishing tops U.S. lightning death activities

June 24, 2013

NOAA's National Weather Service has discovered that 64 percent of lightning deaths since 2006 occurred while people were participating in leisure activities, with fishing topping the list at 26 deaths. John Jensenius, a lightning safety specialist with the National Weather Service, conducted the study by examining demographic information for 238 deaths attributed to lightning over the last seven years. NOAA released these findings on the first day of National Lightning Safety Awareness Week to call attention to the danger of outdoor activities during a thunderstorm.

Of the 152 deaths associated with leisure activities, fishing is followed by camping (15 deaths), boating (14 deaths), soccer (12 deaths) and golf (8 deaths). The remaining 77 people were struck by lightning while participating in a number of other leisure activities like enjoying the beach, swimming, walking and running, riding recreational vehicles, and picnicking or relaxing in their yard. Between 2006 and 2012, 82 percent of people killed by lightning were male.

“When people think of lightning deaths, they usually think of golf,” Jensenius said. “While every outdoor activity is dangerous when a thunderstorm is in the area, outdoor activities other than golf lead to more lightning deaths. NOAA has made a concerted effort to raise lightning awareness in the golf community since we began the campaign in 2001, and we believe our outreach has made a huge difference since lightning-related deaths on golf courses have decreased by 75 percent.”

Jensenius said the large number of fishing, camping and boating lightning deaths may occur because these activities require extra time to get to a safe place. “People often wait far too long to head to safety when a storm is approaching, and that puts them in a dangerous and potentially deadly situation,” he said.

Prior to the lightning safety campaign, lightning killed an average of 73 people each year in the United States. Since the National Weather Service launched the campaign, the average has dropped to 37. Seven people have died from lightning strikes so far this year.

The best way for people to protect themselves against lightning injury or death is to monitor the weather and postpone or cancel outdoor activities when thunderstorms are in the forecast. Lightning can strike from 10 miles away, so if people can hear thunder, they are in danger of being struck by lightning. The only safe places to be during a thunderstorm are in a building with four walls and a roof or in a car. A hut, cabana, tent, or other rain shelter will not protect a person from being struck by lightning.

National Weather Service forecast offices throughout the country will promote lightning safety at local events all week. Here are a few highlights:

Lightning Safety Awareness Week kicked off on Friday, June 21 in Parker, Colorado. NOAA experts joined partners from the Lightning Protection Institute, the Colorado Department of Homeland Security, local fire officials, other lightning safety partners and local TV meteorologist Jeff Womack for a public open house safety event at South Metro Fire Station #45. After hearing lightning safety education talks, visitors toured the fire station and spoke with lightning experts.On June 22, the Binghamton, NY, forecast office participated in the Moscow Country Run in Moscow, PA, by announcing the starting commands of the race. The run was a combination lightning safety event and fundraiser for Jason Penecek, who was struck by lightning while attending the Pocono 400 NASCAR race at Pocono Raceway last August. Jason, who lost his best friend of almost 20 years during the storm, continues to struggle with debilitating injuries. The run consisted of three events: The Lightning Bolt 5k, the One-Mile Shock Walk and the Kids Thunder Run. Jason’s experience as a lightning strike victim and journey back to health inspired his sister and fellow runner, Kimberly McHale, to create a local Lightning Awareness Group, which visits local schools and community events to promote lightning safety awareness.On June 28, the National Weather Service will team up with the Boston Red Sox at Fenway Park to promote lightning safety awareness at the major league baseball game. Meteorologists from the NWS Boston Forecast Office will host an information booth, and lightning safety information will appear on the video board during the 5th inning of the game against the Toronto Blue Jays. Yellow lightning safety foam visors will go to 300 young fans.

NOAA's mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook , Twitter and our other social media channels.

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Study shows deeper meltdown at Japan nuke reactor (AP)

TOKYO – Radioactive debris from melted fuel rods may have seeped deeper into the floor of a Japan's tsunami-hit nuclear reactor than previously thought, to within a foot from breaching the crucial steel barrier, a new simulation showed Wednesday.

The findings will not change the ongoing efforts to stabilize the reactors more than eight months after the Fukushima Dai-ichi plant was disabled, but they harshly depict the meltdowns that occurred and conditions within the reactors, which will be off-limits for years.

The plant operator Tokyo Electric Power Co. said its latest simulation showed fuel at the No. 1 reactor may have eroded part of the primary containment vessel's thick concrete floor. The vessel is a beaker-shaped steel container, set into the floor. A concrete foundation below that is the last manmade barrier before earth.

The fuel came within a foot of the container's steel bottom in the worst-case scenario but has been somewhat cooled, TEPCO's nuclear safety official Yoshihiro Oyama said at a government workshop. He said fuel rods in the No. 1 reactor were the worst damaged because it lost cooling capacity before the other two reactors, leaving its rods dry and overheated for hours before water was pumped in.

The nuclear crisis following the March 11 earthquake and tsunami caused massive radiation leaks and the relocation of some 100,000 people.

Another simulation on the structure released by the government-funded Japan Nuclear Energy Safety Organization, or JNES, said the erosion of the concrete could be deeper and the possibility of structural damage to the reactor's foundation needs to be studied.

JNES official Masanori Naito said the melting fuel rods lost their shape as they collapsed to the bottom of the vessel, then deteriorated into drops when water pumping resumed, and the fuel drops spattered and smashed against the concrete as they fell, Naito said.

TEPCO and government officials are aiming to achieve "cold shutdown" by the end of the year — a first step toward creating a stable enough environment for work to proceed on removing the reactors' nuclear fuel and closing the plant altogether.

The government estimates it will take 30 years or more to safely decommission Fukushima Dai-ichi.

Wednesday's simulations depict what happened early in the crisis and do not mean a recent deterioration of the No. 1 reactor. Oyama said, however, the results are based only on available data and may not match the actual conditions inside the reactors, which cannot be opened for years.

Some experts have raised questions about achieving the "cold shutdown," which means bringing the temperature of the pressure vessel containing healthy fuel rods to way below the benchmark 100 Celsius (212 Fahrenheit). They say the fuel is no longer there and measuring the temperature of empty cores is meaningless, while nobody knows where and how hot the melted fuel really is.

Kiyoharu Abe, a nuclear expert at JNES, said it's too early to make a conclusion and more simulations should be done to get accurate estimates.

"I don't think the simulation today was wrong, but we should look at this from various viewpoints rather than making a conclusion from one simulation," Abe said. "It's just the beginning of a long process."

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