Large Volcanic Eruptions Can Alter Hurricane Strength And Frequency

A new study led by Lamont-Doherty Earth Observatory researcher Suzana Camargo and Université du Québec à Montréal’s Francesco Pausata provides deeper insight into how large volcanic eruptions affect hurricane activity. Previous studies could not clearly determine the effects of volcanic eruptions on hurricanes, because the few large volcanic eruptions in the last century coincided with El Niño-Southern Oscillation events, which also influence hurricane activity. In the study published today in the Proceedings of the National Academy of Sciences of the United States of America, Camargo and Pausata approached this relationship by simulating very large volcanic eruptions in the tropics multiple times. Their modeling told a more complex story than previous papers had indicated.

“This is the first study to explain the mechanism of how large volcanic eruptions influences hurricanes globally,” said Camargo.

According to their findings, large tropical volcanic eruptions can affect hurricanes by shifting the Intertropical Convergence Zone, a region that circles the Earth near the Equator and greatly influences rainfall and hurricane activity. As the Intertropical Convergence Zone moves after a large volcanic eruption, it affects both the intensity and frequency of hurricanes, causing some regions to experience an increase in activity and other regions to experience a decrease. For example, a large eruption in the tropical regions of the Northern Hemisphere leads to a southward shift of the Intertropical Convergence Zone. This results in an increase in hurricane activity between the Equator and the 10°N line, and a decrease further north. The zone’s southward shift has further effects in the Southern Hemisphere, causing a decrease in activity on the coasts of Australia, Indonesia, and Tanzania, while Madagascar and Mozambique experience an increase. These changes can last for up to four years following the eruption.

Camargo and Pausata were able to separate the effects of volcanic eruptions and El Niño-Southern Oscillation on hurricane activity and show the different impacts that the two factors have on hurricanes globally. Their findings are important in helping scientists better understand the relationship between volcanoes and hurricanes.

Driving Force Of Volcanic Super-Hazards Uncovered

Massey volcanologists have discovered the driving force behind superheated gas-and-ash clouds from volcanic eruptions, which may help save lives and infrastructure around the globe.

Endangering 500 million people worldwide, pyroclastic density currents (or pyroclastic flows) are the most common and lethal volcanic threat, causing 50 per cent of fatalities caused by volcanic activity. During volcanic events, these currents transport hot mixtures of volcanic particles and gas over tens of kilometres, causing damage to infrastructure and loss of life.

One of the issues to studying these phenomena is that they are impossible to measure in real life. Using Massey’s Pyroclastic flow Eruption Large-scale Experiment (PELE) eruption simulator facility, the team were able to synthesize the natural behaviour of volcanic super-hazards and generate these flows as they occur in nature, but on a smaller scale.

Until now, scientists could not find the mechanism responsible for the super-mobility of these flows, and previous models were unable to accurately predict their velocity, runout and spread through hazard models, which put lives and infrastructure at risk.

Massey University’s Associate Professor Gert Lube says that through their unique experiments, the enigmatic friction-cheating mechanism was found.

“With several tonnes of pumice and gas in motion, our large-scale eruption simulations uncovered the flow enigma that has been baffling researchers for decades. We measured a low-friction air cushion that is self-generated in these flows and perpetuates their motion. We were able to mathematically describe the resulting flow behavior. There is an internal process that counters granular friction, where air lubrication develops under high basal shear when air is locally forced downwards by reversed pressure gradients and displaces particles upward.

“This explains how the currents are able to propagate over slopes, bypass tortuous flow paths, and ignore rough substrates and flat and upsloping terrain, without slowing down.”

“The discovery necessitates a re-evaluation of global hazard mitigation strategies and models that aim to predict the velocity, runout and spreading of these flows. Discovery of this air-lubrication mechanism opens a new path towards reliable predictions of pyroclastic flow motion and the extreme runout potential of these lethal currents, thereby reducing future casualties. It will be used by hazard scientists, as well as decision makers, and is envisaged to lead to major revisions of volcanic hazard forecasts.”

Unexpected Coronal Rain On Sun Links Two Solar Mysteries

For five months in mid 2017, Emily Mason did the same thing every day. Arriving to her office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, she sat at her desk, opened up her computer, and stared at images of the Sun — all day, every day. “I probably looked through three or five years’ worth of data,” Mason estimated. Then, in October 2017, she stopped. She realized she had been looking at the wrong thing all along.

Mason, a graduate student at The Catholic University of America in Washington, D.C., was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun’s outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops — named for their resemblance to a knight’s pointy helmet — that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening. And if she could just find it, the underlying rain-making physics would have major implications for the 70-year-old mystery of why the Sun’s outer atmosphere, known as the corona, is so much hotter than its surface. But after nearly half a year of searching, Mason just couldn’t find it. “It was a lot of looking,” Mason said, “for something that never ultimately happened.”

The problem, it turned out, wasn’t what she was looking for, but where. In a paper published today in the Astrophysical Journal Letters, Mason and her coauthors describe the first observations of coronal rain in a smaller, previously overlooked kind of magnetic loop on the Sun. After a long, winding search in the wrong direction, the findings forge a new link between the anomalous heating of the corona and the source of the slow solar wind — two of the biggest mysteries facing solar science today.

How It Rains on the Sun

Observed through the high-resolution telescopes mounted on NASA’s SDO spacecraft, the Sun — a hot ball of plasma, teeming with magnetic field lines traced by giant, fiery loops — seems to have few physical similarities with Earth. But our home planet provides a few useful guides in parsing the Sun’s chaotic tumult: among them, rain.

On Earth, rain is just one part of the larger water cycle, an endless tug-of-war between the push of heat and pull of gravity. It begins when liquid water, pooled on the planet’s surface in oceans, lakes, or streams, is heated by the Sun. Some of it evaporates and rises into the atmosphere, where it cools and condenses into clouds. Eventually, those clouds become heavy enough that gravity’s pull becomes irresistible and the water falls back to Earth as rain, before the process starts anew.

On the Sun, Mason said, coronal rain works similarly, “but instead of 60-degree water you’re dealing with a million-degree plasma.” Plasma, an electrically-charged gas, doesn’t pool like water, but instead traces the magnetic loops that emerge from the Sun’s surface like a rollercoaster on tracks. At the loop’s foot points, where it attaches to the Sun’s surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop’s legs as coronal rain.

Mason was looking for coronal rain in helmet streamers, but her motivation for looking there had more to do with this underlying heating and cooling cycle than the rain itself. Since at least the mid-1990s, scientists have known that helmet streamers are one source of the slow solar wind, a comparatively slow, dense stream of gas that escapes the Sun separately from its fast-moving counterpart. But measurements of the slow solar wind gas revealed that it had once been heated to an extreme degree before cooling and escaping the Sun. The cyclical process of heating and cooling behind coronal rain, if it was happening inside the helmet streamers, would be one piece of the puzzle.

The other reason connects to the coronal heating problem — the mystery of how and why the Sun’s outer atmosphere is some 300 times hotter than its surface. Strikingly, simulations have shown that coronal rain only forms when heat is applied to the very bottom of the loop. “If a loop has coronal rain on it, that means that the bottom 10% of it, or less, is where coronal heating is happening,” said Mason. Raining loops provide a measuring rod, a cutoff point to determine where the corona gets heated. Starting their search in the largest loops they could find — giant helmet streamers — seemed like a modest goal, and one that would maximize their chances of success.

She had the best data for the job: Images taken by NASA’s Solar Dynamics Observatory, or SDO, a spacecraft that has photographed the Sun every twelve seconds since its launch in 2010. But nearly half a year into the search, Mason still hadn’t observed a single drop of rain in a helmet streamer. She had, however, noticed a slew of tiny magnetic structures, ones she wasn’t familiar with. “They were really bright and they kept drawing my eye,” said Mason. “When I finally took a look at them, sure enough they had tens of hours of rain at a time.”

At first, Mason was so focused on her helmet streamer quest that she made nothing of the observations. “She came to group meeting and said, ‘I never found it — I see it all the time in these other structures, but they’re not helmet streamers,'” said Nicholeen Viall, a solar scientist at Goddard, and a coauthor of the paper. “And I said, ‘Wait…hold on. Where do you see it? I don’t think anybody’s ever seen that before!'”

A Measuring Rod for Heating

These structures differed from helmet streamers in several ways. But the most striking thing about them was their size.

“These loops were much smaller than what we were looking for,” said Spiro Antiochos, who is also a solar physicist at Goddard and a coauthor of the paper. “So that tells you that the heating of the corona is much more localized than we were thinking.”

While the findings don’t say exactly how the corona is heated, “they do push down the floor of where coronal heating could happen,” said Mason. She had found raining loops that were some 30,000 miles high, a mere two percent the height of some of the helmet streamers she was originally looking for. And the rain condenses the region where the key coronal heating can be happening. “We still don’t know exactly what’s heating the corona, but we know it has to happen in this layer,” said Mason.

A New Source for the Slow Solar Wind

But one part of the observations didn’t jibe with previous theories. According to the current understanding, coronal rain only forms on closed loops, where the plasma can gather and cool without any means of escape. But as Mason sifted through the data, she found cases where rain was forming on open magnetic field lines. Anchored to the Sun at only one end, the other end of these open field lines fed out into space, and plasma there could escape into the solar wind. To explain the anomaly, Mason and the team developed an alternative explanation — one that connected rain on these tiny magnetic structures to the origins of the slow solar wind.

In the new explanation, the raining plasma begins its journey on a closed loop, but switches — through a process known as magnetic reconnection — to an open one. The phenomenon happens frequently on the Sun, when a closed loop bumps into an open field line and the system rewires itself. Suddenly, the superheated plasma on the closed loop finds itself on an open field line, like a train that has switched tracks. Some of that plasma will rapidly expand, cool down, and fall back to the Sun as coronal rain. But other parts of it will escape — forming, they suspect, one part of the slow solar wind.

Mason is currently working on a computer simulation of the new explanation, but she also hopes that soon-to-come observational evidence may confirm it. Now that Parker Solar Probe, launched in 2018, is traveling closer to the Sun than any spacecraft before it, it can fly through bursts of slow solar wind that can be traced back to the Sun — potentially, to one of Mason’s coronal rain events. After observing coronal rain on an open field line, the outgoing plasma, escaping to the solar wind, would normally be lost to posterity. But no longer. “Potentially we can make that connection with Parker Solar Probe and say, that was it,” said Viall.

Digging Through the Data

As for finding coronal rain in helmet streamers? The search continues. The simulations are clear: the rain should be there. “Maybe it’s so small you can’t see it?” said Antiochos. “We really don’t know.”

But then again, if Mason had found what she was looking for she might not have made the discovery — or have spent all that time learning the ins and outs of solar data.

“It sounds like a slog, but honestly it’s my favorite thing,” said Mason. “I mean that’s why we built something that takes that many images of the Sun: So we can look at them and figure it out.”

Massive Storm Sparks Blizzard Warnings From Colorado To Minnesota

A potentially record-breaking storm is squeezing the warmth from spring as it brings snow and howling winds across the U.S. Great Plains and threatens to flood rivers from Canada to the Gulf of Mexico.

The giant system, set to strengthen Wednesday, has sparked blizzard warnings from Colorado to Minnesota and could drop more than 2 feet of snow in South Dakota and as much as 8 inches in Minneapolis, the National Weather Service said. Severe thunderstorms will hit Texas and the Mississippi Valley. The system threatens to delay wheat and corn planting.

“It is pretty extensive,” David Roth, a senior branch forecaster at the U.S. Weather Prediction Center, said by telephone.

The storm, which will pack near-record low pressure, could be on par with the massive system that triggered flooding across Nebraska and Iowa last month. Snow and rain area already falling across the Great Plains and Midwest. The storm will build over Wyoming on Wednesday, cross Nebraska on Thursday and then hit Minneapolis, said Rob Carolan, owner of Hometown Forecast Services.

Farther south, the storm will push dry winds across Kansas, Oklahoma, New Mexico and Texas — raising the risk of wildfires.

The Mississippi River is already at moderate-to-major flood stage in Wisconsin, Illinois and Iowa. The Red River is at major flood stage in Fargo, N.D.

“Because the Mississippi is flooding — none of this is welcome,” Roth said.

Nonetheless, the Mississippi should be able to handle this week’s storm, because water levels are currently falling, said Matt Roe, spokesman for the Army Corps of Engineers in New Orleans. The Corps has begun to close the Bonnet Carre spillway upstream from New Orleans, designed to prevent flooding.

High water has restricted Mississippi barge traffic to daylight and has limited the amount of freight that can be hauled, said Austin Golding, president of Golding Barge Line in Vicksburg, Miss. Right now, the river is entirely navigable, but the hardest parts to traverse are the bridges in Vicksburg and Baton Rouge.

“May will be nasty if it gets hot up north and the snow melt accelerates after this winter system they are encountering now,” Golding said.

This system’s icy reach won’t extend to Chicago, which will get rain and have a low of 39 degrees Wednesday before temperatures rebound into the 60s by Thursday. Detroit and Toronto will also be spared, Carolan said.

As the storm passes, weather will whiplash between extremes in many places. On Tuesday, Denver’s temperature reached 78 degrees. Wednesday, however, the city is under a blizzard warning with readings set to plunge to 21, the weather service said. Cheyenne, Wyo., will go from 71 on Tuesday to 18 degrees late Wednesday.

While the storm bulldozes across the central U.S., mild air on the East Coast will keep temperatures in New York in the high 50s and low 60s through the rest of the week, the weather service said.

The snow and rain across the northern Midwest will delay corn and wheat planting, said Dan Hicks, a meteorologist with Freese-Notis Weather Services in Des Moines, Iowa. Farther south, from Kansas to Southern Illinois, planting is unlikely to be interrupted.

‘Strange Blue Lights’ Spotted Over Arctic Circle Explained By NASA

Those observing the Northern Lights in Norway over the weekend were treated not only to the spectacular aurora, but also reported strange configurations of colourful lights moving through the sky.

While those who witnessed it could be forgiven for preparing to pledge allegiance to some new extra-terrestrial conquistadors, Nasa has owned up and explained it was in fact a pair of their rockets which created the unusual phenomenon.

The stunning geometric lights, made up of dark blue clouds, turquoise dots and pale orange vapour trails, lit up the sky over the Norwegian Sea on April 5.

They were the result of an experiment designed to study the processes inside the Earth’s “polar cusp”, where the planet’s magnetic field lines bend down through the atmosphere.

It is here that the charged particles from solar wind cause aurora – the colourful natural light displays which appear over the poles during periods of solar activity.

Scientists want to study exactly what happens during an aurora in the electrically charged and turbulent layer of the outer atmosphere which Nasa describes as a “tumultuous particle soup”.

Their pair of rockets were carrying scientific instruments for studying the energy exchange during the phenomenon, and also deployed what they called “visible gas tracers”, between 71 and 150 miles altitude.

The mixture of substances are similar to those found in fireworks, with chemicals which ionize when exposed to sunlight.

The multi-coloured vapours produced “allow researchers to track the flow of neutral and charged particles with the auroral wind,” Nasa said.

The project is called AZURE, which stands for Auroral Zone Upwelling Rocket Experiment, and was carried out by two black Brant I-A sounding rockets, which were launched from the Andøya Space Centre in north-west Norway.

Michael Theusner who captured a stunning time lapse of the kaleidoscopic illuminations, said: “While we were watching the after-effects of a beautiful northern lights display, the rockets were launched from the Andøya Space Centre only about 180 km away to the north.

“We saw two orange dots rise into the sky and disappear. A short while later strange lights and colourful, expanding clouds appeared I first did not have an explanation for. It looked like an alien attack.”

Strong Earthquake Hits The Atlantic Ocean Near The South Sandwich Islands

A strong earthquake with a preliminary magnitude of 6.5 has struck the South Atlantic Ocean near the South Sandwich Islands, seismologists say, just days after the region was struck by a similar earthquake. There is no threat of a tsunami.

The earthquake happened at 3:54 p.m. on Tuesday and was centered about 56 kilometers (35 miles) southeast of Montagu Island, which is part of a British overseas territory that is known as South Georgia and the South Sandwich Islands.

The earthquake was initially measured at 6.7, but the magnitude was later downgraded to 6.5, according to the U.S. Geological Survey (USGS). It said the earthquake struck about 47 kilometers (29 miles) below the seabed, making it a shallow earthquake.

“Based on all available data, there is no tsunami threat from this earthquake. No action is required,” the Pacific Tsunami Warning Center said in a bulletin.

Injuries are unlikely because the British overseas territory is uninhabited, although a few dozen staff members stay year-round at scientific bases on Bird Island and South Georgia Island. There are no reports of damage.

Tuesday’s earthquake comes less than a week after a similar earthquake struck the same region. On Friday afternoon, an earthquake measuring 6.5 struck near Zavodovski Island, which is also part of the South Sandwich Islands.

Yellowstone Scientists Find New Thermal Area

Yellowstone National Park has a new thermal area that scientists think has been growing for the past 20 years.

The new area is deep in Yellowstone’s backcountry between West Tern Lake and the previously mapped Tern Lake thermal area, the U.S. Geological Survey announced earlier this month.

“This is exactly the sort of behavior we expect from Yellowstone’s dynamic hydrothermal activity,” R. Greg Vaughan, a research scientist with USGS, wrote in a blog post, “and it highlights that changes are always taking place, sometimes in remote and generally inaccessible areas of the park.”

A thermal area is the visible result on the Earth’s surface of magma activity underground. They can include geysers, like Yellowstone’s Old Faithful; hot springs; and fumaroles, which are vents that allow volcanic gases to escape. They are surrounded by hydrothermal mineral deposits, geothermal gas emissions, heated ground and lack of vegetation, the USGS says

Yellowstone has about 10,000 thermal areas concentrated into about 120 distinct areas.

The new thermal area, about half a mile from the nearest trail, and about 11 miles from the nearest trailhead, was first noticed in an infrared satellite image acquired in April 2017. The area showed up as a bright spot between the Tern Lake thermal area and the western edge of West Tern Lake.

High-resolution aerial images later confirmed a large area of dead trees and bright soil, USGS said, the type of scene expected over a thermal area.

Historical images showed the area began forming in the late 1990s or early 2000s. Those images also showed that the Tern Lake Thermal Area had grown on its northern side.

“Yellowstone’s thermal areas are the surface expression of the deeper magmatic system, and they are always changing,” Vaughn wrote. “They heat up, they cool down, and they can move around.”

A recent example was the eruption of the Ear Spring thermal spring for the first time in 60 years. The eruption this past September sent water and steam 20 to 30 feet in the air. Several other thermal features formed at the same time.

Any geological changes at Yellowstone tend to make headlines because the park sits atop an underground supervolcano that is 44 miles across and last erupted more than 630,000 years ago. However, scientists with the Yellowstone Volcano Observatory say there is nothing to worry about.

“We’ve heard many statements that Yellowstone is overdue — that it has a major eruption every 600,000 years on average, and since the last eruption was 631,000 years ago… well… you can see where this is going,” Michael Poland, scientist-in-charge of the Yellowstone Volcano Observatory, recently wrote in a blog post. “Is this true? In a word, no. In two words, no way. In three words, not even close. Yellowstone doesn’t work that way.”