vendredi 25 mai 2018

World’s first crabbing of a proton beam












CERN - European Organization for Nuclear Research logo.

25 May 2018


Image above: Test bench of the first two prototype crab cavities in the Super Proton Synchrotron (SPS) accelerator. The cryomodule containing the cavities is installed on a mobile table that allows it to be moved into the beam line as needed (Image: M. Brice/CERN).

CERN has successfully tested “crab cavities” to rotate a beam of protons – a world first. The test took place on 23 May using a beam from CERN’s Super Proton Synchrotron (SPS) accelerator and showed that bunches of protons could be tilted using these superconducting transverse radiofrequency cavities. These cavities are a key component of the High-Luminosity Large Hadron Collider (HL-LHC), the future upgrade of the LHC.

The HL-LHC, which will be commissioned after 2025, will increase the luminosity of the LHC by a factor of five to ten. Luminosity is a crucial indicator of a collider’s performance: it gives the number of potential collisions per surface unit over a given period of time. In other words, the higher the luminosity, the higher the number of collisions and the more data the experiments can gather. This will allow researchers to observe rare processes that occur beyond the LHC’s present sensitivity level. Physicists will also be able to perform precise studies of the new particles observed at the LHC, such as the Higgs boson. The newly developed crab cavities will play an important role to increase the luminosity.

In the LHC, the two counter-rotating beams are not a continuous stream of particles but are made up of “bunches” of protons a few centimetres long, each containing billions of protons. These bunches meet at a small angle at each collision point of the experiments. When installed at each side of the ATLAS and CMS experiments, the crab cavities will “tilt” bunches of protons in each beam to maximise their overlap at the collision point. Тhis way every proton in the bunch will be forced to pass through the whole length of the opposite bunch, increasing the probability of collisions and hence more luminosity. After being tilted, the motion of the proton bunches appears to be sideways – just like a crab. Crab cavities were already used in the KEKB collider in Japan for electrons and positrons, but never with protons, which are more massive and at significantly higher energies. “The crab cavities are expected to increase the overall luminosity by 15 to 20%,” explains Rama Calaga, leader of the crab cavity project.


Image above: The first prototype crab cavities being assembled during summer 2017 (Image: Julien Ordan/CERN).

The two first crab cavity prototypes were manufactured at CERN in 2017 in collaboration with Lancaster University and the Science and Technology Facilities Council (STFC) in the United Kingdom, as well as the U.S. LHC Accelerator Research Program (USLARP). The cavities were assembled in a cryostat and tested at CERN. They are made of high-purity niobium superconducting material, operating at 2 kelvins (-271°C), in order to generate very high transverse voltage of 3-4 million volts. The cavities were installed in the SPS accelerator during the last winter technical stop to undergo validation tests with proton beams.

The first beam tests on 23 May lasted for more than 5 hours at a temperature of 4.2 K with a single proton bunch accelerated to 26 GeV and containing between 20 and 80 billion protons, almost the intensity of the LHC bunches. The crab cavities were powered to about 10% of their nominal voltage. The “crabbing” was observed using a special monitor to observe the tilt along the length of the bunch.  “These tests mark the start-up of a unique facility for testing superconducting cavities on a high-current, high-energy proton beam,” explains Lucio Rossi, leader of the HL-LHC project. “The results are impressive and crucial to prove the feasibility of using such cavities for increasing the luminosity in the LHC.”

How to get more collisions at the LHC: crab cavities

Video above: Watch this short video to learn more about how the crab cavities work (Video: Polar Media/CERN).

In the coming months, the cavities will be commissioned to their nominal voltage of 3.4 million volts and will undergo a series of tests to fully validate their operation for the HL-LHC era. A total of 16 such cavities will be installed in the HL-LHC – eight near ATLAS and eight near CMS. 

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related links:

Super Proton Synchrotron (SPS): https://home.cern/about/accelerators/super-proton-synchrotron

High-Luminosity Large Hadron Collider (HL-LHC): https://home.cern/topics/high-luminosity-lhc

Large Hadron Collider (LHC): https://home.cern/topics/large-hadron-collider

ATLAS experiment: https://home.cern/about/experiments/atlas

CMS experiment: https://home.cern/about/experiments/cms

Higgs boson: http://home.web.cern.ch/topics/higgs-boson

For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/

Images (mentioned), Video (mentioned), Text, Credits: CERN/Corinne Pralavorio.

Best regards, Orbiter.ch

Crew Begins Unloading Cygnus, Works Science Ahead of June Crew Swap











ISS - Expedition 55 Mission patch.

May 25, 2018

The Cygnus resupply ship from Orbital ATK is now open for business and the Expedition 55 crew has begun unloading the 7,400 pounds of cargo it delivered Thursday morning. The orbital residents are also conducting space research and preparing for a crew swap in early June.

There are now four spaceships parked at the International Space Station, the newest one having arrived to resupply the crew early Thursday morning. Astronauts Drew Feustel and Norishige Kanai opened Cygnus’ hatches shortly after it was installed to the Unity module. The cargo carrier will remain attached to the station until July so the astronauts can offload new supplies and repack Cygnus with trash.

NASA astronaut Scott Tingle, who caught Cygnus with the Canadarm2 robotic arm, swapped out gear inside a small life science research facility today called TangoLab-1. Tingle also joined Kanai later in the day transferring frozen biological samples from the Destiny lab module to the Kibo lab module.


Image above: This view taken from inside the Cupola shows the Orbital ATK space freighter moments before it was grappled with the Canadarm2 robotic arm on May 24, 2018. Image Credit: NASA.

The duo also joined Commander Anton Shkaplerov and continued to pack gear and check spacesuits ahead of their return to Earth on June 3 inside the Soyuz MS-07 spaceship. When the three crewmates land in Kazakhstan, about three and a half hours after undocking, the trio will have spent 168 days in space and conducted one spacewalk each.

Three new Expedition 56-57 crew members, waiting to replace the homebound station crew, are counting down to a June 6 launch to space. Astronauts Serena Auñón-Chancellor and Alexander Gerst will take a two-day ride to the space station with cosmonaut Sergey Prokopyev inside the Soyuz MS-09 spacecraft for a six-month mission aboard the orbital laboratory.

Related links:

TangoLab-1: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1660

Orbital ATK: https://www.nasa.gov/orbital

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

Commercial Resupply: http://www.nasa.gov/mission_pages/station/structure/launch/index.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Image (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

NASA Tracks Lava from Kilauea Volcano












NASA & NOAA - Suomi NPP Mission patch.

May 25, 2018


Image above: At 10:41 a.m. local time (20:41 Universal Time) on May 14, 2018, the Operational Land Imager (OLI) on Landsat 8 acquired a natural-color image of the volcano. Image Credits: NASA Earth Observatory.

NASA is tracking lava flows from Hawaii Island’s Kilauea volcano as fissures erupt and lava makes its way to the ocean.

Using data from the Visible Infrared Imaging Radiometer, or VIIRS, instrument aboard the NASA-NOAA Suomi NPP satellite, NASA’s Disaster Program has been tracking thermal anomalies, or hot spots, indicative of lava flow. VIIRS is the only instrument from space that can track lava flows through hot spots, making it an important additional source of information for the U.S. Geological Survey as it monitors and informs the public of the ongoing volcanic activity, which has produced everything from earthquakes and giant rock projectiles from eruptions to blankets of ash clouds and volcanic smog, or vog.


Image Credit: NASA.

For example, VIIRS captured the above enhanced nighttime image on May 14, 2018, superimposed with hot spots highlighted in red. Multiple hot spots were observed on this satellite overpass near the southeast tip of Hawaii Island. Kilauea volcano is represented by the hot spot to the west.


Image Credit: NASA.

Zooming in over this area shows that those hot spots were located farther east from Leilani area and were consistent with new fissures observed on the ground.


Image Credit: NASA.

This VIIRS image from May 22, 2018, shows the extension of the hot spots toward the ocean, indicating that lava is moving toward and warming the ocean upon contact.

In addition to VIIRS, NASA provides other information on volcanic activity, including aerosol and sulfur dioxide measurements derived from the Ozone Monitoring Instrument (OMI) aboard NASA’s Aura satellite as well as the Ozone Mapping Profiler Suite aboard NASA-NOAA Suomi NPP satellite, and ground deformation and movement with synthetic aperture radar data.

NASA also organized a field mission with airborne radar to provide accurate digital elevation maps that USGS can use to predict lava path flows. Flown on the G-III research aircraft, the Jet Propulsion Laboratory’s Glacier and Ice Surface Topography Interferometer (GLISTIN) instrument is detecting changes in Kilauea’s topography associated with the new lava flows, with the goal of measuring the erupted volume as a function of time and ultimately the total volume of the event.

Related links:

NASA’s Disaster Program: http://disasters.nasa.gov/

NASA’s Aura satellite: https://aura.gsfc.nasa.gov/

Ozone Monitoring Instrument (OMI): https://aura.gsfc.nasa.gov/omi.html

Ozone Mapping Profiler Suite: https://jointmission.gsfc.nasa.gov/omps.html

NASA-NOAA Suomi NPP satellite: https://www.nasa.gov/mission_pages/NPP/main/index.html

Glacier and Ice Surface Topography Interferometer (GLISTIN): https://www.nasa.gov/feature/help-from-above-nasa-aids-kilauea-disaster-response-1

Images (mentioned), Text, Credits: NASA/sreiny.

Greetings, Orbiter.ch

Scientists Shrink Chemistry Lab to Seek Evidence of Life on Mars









ESA & ROSCOSMOS - ExoMars Mission patch.

May 25, 2018

An international team of scientists has created a tiny chemistry lab for a rover that will drill beneath the Martian surface looking for signs of past or present life. The toaster oven-sized lab, called the Mars Organic Molecule Analyzer or MOMA, is a key instrument on the ExoMars Rover, a joint mission between the European Space Agency and the Russian space agency Roscosmos, with a significant contribution to MOMA from NASA. It will be launched toward the Red Planet in July 2020.

“The ExoMars Rover’s two-meter deep drill will provide MOMA with unique samples that may contain complex organic compounds preserved from an ancient era, when life might have gotten started on Mars,” said MOMA Project Scientist Will Brinckerhoff of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Searching for Signs of Life on Mars

Video above: The ExoMars rover will search the Red Planet for signs of life, using an instrument called MOMA. Video Credits: NASA's Goddard Space Flight Center/Dan Gallagher.

Although the surface of Mars is inhospitable to known forms of life today, there is evidence that in the distant past, the Martian climate allowed the presence of liquid water – an essential ingredient for life – at the surface. This evidence includes features that resemble dry riverbeds and mineral deposits that only form in the presence of liquid water. NASA has sent rovers to Mars that have found additional signs of past habitable environments, such as the Opportunity and Curiosity rovers both currently exploring the Martian terrain.


Image above: Precision assembly and mechanical technician Ryan Wilkinson inspects MOMA during thermal vacuum testing at Goddard. Image Credit: NASA.

The MOMA instrument will be capable of detecting a wide variety of organic molecules. Organic compounds are commonly associated with life, although they can be created by non-biological processes as well. Organic molecules contain carbon and hydrogen, and can include oxygen, nitrogen, and other elements. To find these molecules on Mars, the MOMA team had to take instruments that would normally occupy a couple of workbenches in a chemistry lab and shrink them down to roughly the size of a toaster oven so they would be practical to install on a rover.


Image above: A close-up of the MOMA instrument. Image Credit: NASA.

While the instrument is complex, MOMA is built around a single, very small mass spectrometer that separates charged atoms and molecules by mass. The basic process for finding Martian organic compounds can be boiled down to two steps: separate organic molecules from the Martian rocks and sediments and give them an electric charge (ionized) so they can be detected and identified by the mass spectrometer. MOMA has two methods for distinguishing as many different kinds of organic molecules as possible. The first method uses an oven to heat a sample—this baking process vaporizes the organic molecules and sends them to a thin column that separates mixtures of compounds into their individual constituents. The compounds sequentially pass into the mass spectrometer, where they are given an electric charge and sorted by mass using electric fields. Each type of molecule has a set of distinct mass-to-electric-charge ratios. The mass spectrometer instrument uses this pattern called a mass spectrum to identify the molecules.

Some larger organic molecules are fragile and would be broken apart during the high-temperature vaporization in the oven, so MOMA has a second method to find them: It zaps the sample with a laser. Since just a quick burst of laser light is used, it vaporizes some types of larger organic molecules without totally breaking them apart. The laser also gives these molecules an electric charge, so they are sent directly from the sample to the mass spectrometer to be sorted and identified.

Certain organic molecules have a property that could potentially be used as a strong hint that they were created by life: their handedness, or chirality. Some organic molecules used by life come in two varieties that are mirror images of each other, like your hands. On Earth, life uses all left-handed amino acids and all right-handed sugars to build larger molecules needed for life, like proteins from amino acids and DNA from sugars. Life based on right-handed amino acids (and left-handed sugars) could work, but a mix of right- and left-handed for either will not. This is because these molecules need to come together with the correct orientation, like puzzle pieces, to build other molecules necessary for life to function.

MOMA is capable of detecting the chirality of organic molecules. If it finds an organic molecule is primarily of the left-hand or right-hand variety (called “homochirality”) that can be evidence that life produced the molecules, since non-biological processes tend to make an equal mix of varieties. This is known as a biosignature.

Mars rovers face another challenge when searching for evidence of life: Contamination. Earth is saturated with life, and scientists have to be very careful that the organic material they detect wasn’t simply carried with the instrument from Earth. To ensure this, the MOMA team has taken great care to make sure that the instrument is as free as possible from terrestrial molecules that are signatures of life.

The ExoMars rover will be the first to explore deep beneath the surface, with a drill capable of taking samples from as deep as two meters (over six feet). This is important because Mars’ thin atmosphere and spotty magnetic field offer insufficient protection from space radiation, which can gradually destroy organic molecules left exposed on the surface. However, Martian sediment is an effective shield, and the team expects to find greater abundances of organic molecules in samples from beneath the surface.

NASA Goddard is developing the mass spectrometer and electronics boxes for MOMA, while LATMOS (Laboratory for Atmospheres, Environments, and Space Observations), Guyancourt, France and Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA or Interuniversity Laboratory of Atmospheric Systems) Paris, France, make MOMA’s gas chromatograph, and the Max Plank Institute for Solar System Research, Gottingen, Germany and Laser Zentrum Hannover, Hannover, Germany, build the instrument’s laser, ovens, and tapping (oven sealing) station.

MOMA recently completed both ESA and NASA pre-delivery reviews that cleared the path for the flight instrument to be delivered to the mission. On Wednesday, May 16, the MOMA mass spectrometer team gathered at Goddard to see off their one-of-a-kind science instrument on the first leg of its journey to Mars: delivery to Thales Alenia Space, in Turin, Italy, where it will be integrated into the rover’s analytical laboratory drawer during upcoming mission-level activities this summer. Following subsequent higher-level rover and spacecraft-level integration activities in 2019, the ExoMars Rover is scheduled to launch to Mars in July, 2020 from the Baikonur Cosmodrome in Kazakhstan.

Related links:

ExoMars Rover: http://exploration.esa.int/mars/48088-mission-overview/

Goddard Space Flight Center: https://www.nasa.gov/centers/goddard/home/index.html

Journey to Mars: https://www.nasa.gov/topics/journeytomars/index.html

European Space Agency (ESA): http://www.esa.int/ESA

ROSCOSMOS: http://en.roscosmos.ru/

Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Bill Steigerwald.

Greetings, Orbiter.ch

Hubble’s Galaxy Cluster Cornucopia











NASA - Hubble Space Telescope patch.

May 25, 2018


At first glance, this image is dominated by the vibrant glow of the swirling spiral to the lower left of the frame. However, this galaxy is far from the most interesting spectacle here — behind it sits a galaxy cluster.

Galaxies are not randomly distributed in space; they swarm together, gathered up by the unyielding hand of gravity, to form groups and clusters. The Milky Way is a member of the Local Group, which is part of the Virgo Cluster, which in turn is part of the 100,000-galaxy-strong Laniakea Supercluster.

The galaxy cluster seen in this image is known as SDSS J0333+0651. Clusters such as this can help astronomers understand the distant — and therefore early — universe. SDSS J0333+0651 was imaged as part of a study of star formation in far-flung galaxies. Star-forming regions are typically not very large, stretching out for a few hundred light-years at most, so it is difficult for telescopes to resolve them at a distance. Even using its most sensitive and highest-resolution cameras, Hubble can’t resolve very distant star-forming regions, so astronomers use a cosmic trick: they search instead for galaxy clusters, which have a gravitational influence so immense that they warp the space-time around them. This distortion acts like a lens, magnifying the light of galaxies (and their star-forming regions) sitting far behind the cluster and producing elongated arcs like the one seen in the upper left part of this image.

For more information about Hubble, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
http://www.spacetelescope.org/

Image, Text,Credits: ESA/Hubble & NASA/Karl Hille.

Best regards, Orbiter.ch

Take a Virtual Trip to a Strange New World with NASA













Exoplanets - Exobiology logo.

May 25, 2018


Image above: With NASA's interactive Exoplanet Exploration website, you can virtually explore an imagined surface of planets that lie outside our solar system. Shown here, the imagined surface of Kepler-186f, an Earth-size planet orbiting a small red star located 492 light-years from Earth. No real photos of Kepler-186f exist. Image Credits: NASA/JPL-Caltech.

Are you looking for an exotic destination to visit this summer? Why not take a virtual trip to an Earth-size planet beyond our solar system with NASA's interactive Exoplanet Travel Bureau?

We live in a universe teeming with exoplanets, or planets outside our solar system. Unfortunately, even the nearest exoplanets are light-years away, so sending spacecraft and humans to these intriguing worlds remains a distant dream.

But on NASA's Exoplanet Exploration website, you can explore an imagined surface of an alien world via 360-degree, interactive visualizations. As you investigate each planet's surface, you'll discover fascinating features, like the blood-red sky of TRAPPIST-1d, or stand on a hypothetical moon of the massive planet Kepler-16b, which appears larger than either of the planet's two suns. The view from each planet's surface is an artist's impression based on the limited data that is available; no real photos of these planets exist.

The newest planet to feature this 360-degree surface visualization is Kepler-186f, an Earth-size planet orbiting a star much cooler and redder than the Sun. Scientists don't know if Kepler-186f has an atmosphere, but with the NASA visualization tool, you can see how the presence or absence of an atmosphere would change the view of the sky from the planet's surface.


Animation above: The imagined surface of exoplanet Kepler-186f, on NASA's interactive Exoplanet Exploration website. Kepler-186f is an Earth-size planet orbiting a small red star, which may or may not have an atmosphere. No real photos of Kepler-186f exist. Animation Credits: NASA/JPL-Caltech.

Many of the exoplanets featured on the Exoplanet Exploration website were discovered by NASA's Kepler space telescope.

"Because Kepler-186f and the majority of Kepler-discovered planets are so distant, it is currently impossible to detect their atmospheres -- if they exist at all -- or characterize their atmospheric properties," said Martin Still, program scientist for NASA's newest space-based planet-hunting observatory, the Transiting Exoplanet Survey Satellite (TESS).

"Consequently, we have limited knowledge about what these distant worlds are really like, but these surface visualizations allow us to imagine some of the possibilities," Still said. "Current and future NASA missions, including TESS and the James Webb Space Telescope, will find the nearest exoplanets to our solar system and characterize their atmospheres, bridging the gap between speculation and what's really out there."


Image above: Download free travel exoplanet travel posters from NASA's Exoplanet Exploration website (https://exoplanets.nasa.gov/resources/2159/planet-hop-from-trappist-1e/?layout=magic_shell&travel_bureau=true). The posters imagine what it might be like for humans to visit these new worlds; however, even the nearest exoplanets are light-years away, so sending spacecraft and humans to these intriguing worlds remains a distant dream. Image Credits: NASA/JPL-Caltech.

All the 360-degree visualizations are viewable on desktop and mobile devices, or in virtual reality headsets that work with smartphones. You can also peruse travelposters of such distant worlds as Kepler 186f; TRAPPIST-1e, or PSO J318.5-22, where the "nightlife never ends" because the planet doesn't orbit a star, but is instead floating freely through space.

Many exoplanets share characteristics with the planets that orbit our Sun -- some are gaseous like Saturn and Jupiter, while others are rocky like Earth and Mars. But these alien worlds also have unique features that set them apart. NASA is helping scientists discover and learn about these alien worlds with multiple telescopes and observatories, both on the ground and in space. For even more information and visualizations of these alien worlds, check out NASA's Eyes on Exoplanets mobile app.

The Exoplanet Travel Bureau was developed by NASA's Exoplanet Exploration Program communications team and program chief scientists. Based at the agency's Jet Propulsion Laboratory in Pasadena, California, which is a division of Caltech, the program is NASA's search for habitable planets and life beyond our solar system. The program develops technology and mission concepts, maintains exoplanet data archives and conducts ground-based exoplanet science for NASA missions.

Visit NASA's Exoplanet Exploration website:

https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau/

Related links:

TRAPPIST-1d: https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau/explore-trappist-1d/?travel_bureau=true

Kepler-16b: https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau/explore-kepler-16b/?travel_bureau=true

NASA visualization tool: https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau/explore-kepler-186f/

NASA's Kepler space telescope: https://www.jpl.nasa.gov/news/news.php?feature=6874

Transiting Exoplanet Survey Satellite (TESS): https://www.nasa.gov/tess-transiting-exoplanet-survey-satellite

Kepler 186f: https://exoplanets.nasa.gov/resources/2081/where-the-grass-is-always-redder/

TRAPPIST-1e: https://exoplanets.nasa.gov/resources/2159/planet-hop-from-trappist-1e/?layout=magic_shell&travel_bureau=true

PSO J318.5-22: https://exoplanets.nasa.gov/resources/2085/where-the-nightlife-never-ends/?layout=magic_shell&travel_bureau=true

NASA's Eyes on Exoplanets mobile app: https://eyes.nasa.gov/eyes-on-exoplanets.html

Images (mentioned), Animation (mentioned), Text, Credits: NASA/JPL/Calla Cofield.

Best regards, Orbiter.ch

Climate Change May Lead to Bigger Atmospheric Rivers












NASA - EOS Aqua Mission logo.

May 25, 2018

A new NASA-led study shows that climate change is likely to intensify extreme weather events known as atmospheric rivers across most of the globe by the end of this century, while slightly reducing their number.

The new study projects atmospheric rivers will be significantly longer and wider than the ones we observe today, leading to more frequent atmospheric river conditions in affected areas.


Image above: n early 2017, the Western United States experienced rain and flooding from a series of storms flowing to America on multiple streams of moist air, each individually known as an atmospheric river. Image credits: NASA/JPL-Caltech.

"The results project that in a scenario where greenhouse gas emissions continue at the current rate, there will be about 10 percent fewer atmospheric rivers globally by the end of the 21st century," said the study's lead author, Duane Waliser, of NASA's Jet Propulsion Laboratory in Pasadena, California. "However, because the findings project that the atmospheric rivers will be, on average, about 25 percent wider and longer, the global frequency of atmospheric river conditions -- like heavy rain and strong winds -- will actually increase by about 50 percent."

The results also show that the frequency of the most intense atmospheric river storms is projected to nearly double.

Atmospheric rivers are long, narrow jets of air that carry huge amounts of water vapor from the tropics to Earth's continents and polar regions. These "rivers in the sky" typically range from 250 to 375 miles (400 to 600 kilometers) wide and carry as much water -- in the form of water vapor -- as about 25 Mississippi Rivers. When an atmospheric river makes landfall, particularly against mountainous terrain (such as the Sierra Nevada and the Andes), it releases much of that water vapor in the form of rain or snow.

These storm systems are common -- on average, there are about 11 present on Earth at any time. In many areas of the globe, they bring much-needed precipitation and are an important contribution to annual freshwater supplies. However, stronger atmospheric rivers -- especially those that stall at landfall or that produce rain on top of snowpack -- can cause disastrous flooding.

EOS Aqua satellite. Image Credit: NASA

Atmospheric rivers show up on satellite imagery, including in data from a series of actual atmospheric river storms that drenched the U.S. West Coast and caused severe flooding in early 2017.

The Study

Climate change studies on atmospheric rivers to date have been mostly limited to two specific regions, the western United States and Europe. They have typically used different methodologies for identifying atmospheric rivers and different climate projection models -- meaning results from one are not quantitatively comparable to another.

The team sought to provide a more streamlined and global approach to evaluating the effects of climate change on atmospheric river storms.

The study relied on two resources -- a set of commonly used global climate model projections for the 21st century developed for the Intergovernmental Panel on Climate Change's latest assessment report, and a global atmospheric river detection algorithm that can be applied to climate model output. The algorithm, developed earlier by members of the study team, identifies atmospheric river events from every day of the model simulations, quantifying their length, width and how much water vapor they transport.


Animation above: A series of atmospheric rivers that brought drought-relieving rains, heavy snowfall and flooding to California this week is highlighted in a new movie created with satellite data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite. Animation credits: NASA/JPL-Caltech.

The team applied the atmospheric river detection algorithm to both actual observations and model simulations for the late 20th century. Comparing the data showed that the models produced a relatively realistic representation of atmospheric rivers for the late 20th century climate.

They then applied the algorithm to model projections of climate in the late 21st century. In doing this, they were able to compare the frequency and characteristics of atmospheric rivers for the current climate with the projections for future climate.

The team also tested the algorithm with a different climate model scenario that assumed more conservative increases in the rate of greenhouse gas emissions. They found similar, though less drastic changes. Together, the consideration of the two climate scenarios indicates a direct link between the extent of warming and the frequency and severity of atmospheric river conditions.

What does this mean?

The significance of the study is two-fold.

First, "knowing the nature of how these atmospheric river events might change with future climate conditions allows for scientists, water managers, stakeholders and citizens living in atmospheric river-prone regions [e.g. western N. America, western S. America, S. Africa, New Zealand, western Europe] to consider the potential implications that might come with a change to these extreme precipitation events," said Vicky Espinoza, postdoctoral fellow at the University of California-Merced and first author of the study.

And secondly, the study and its approach provide a much-needed, uniform way to research atmospheric rivers on a global level -- illustrating a foundation to analyze and compare them that did not previously exist.

Limitations

Data across the models are generally consistent -- all support the projection that atmospheric river conditions are linked to warming and will increase in the future; however, co-author Marty Ralph of the University of California, San Diego, points out that there is still work to be done.

"While all the models project increases in the frequency of atmospheric river conditions, the results also illustrate uncertainties in the details of the climate projections of this key phenomenon," he said. "This highlights the need to better understand why the models' representations of atmospheric rivers vary."

The study, titled "Global Analysis of Climate Change Projection Effects on Atmospheric Rivers," was recently published in the journal Geophysical Research Letters.

More information about AIRS can be found at: https://www.jpl.nasa.gov/spaceimages/airs.jpl.nasa.gov

Aqua Earth-observing satellite mission: https://aqua.nasa.gov/

Images (mentioned), Animation (mentioned), Text, Credits: NASA/JPL/Alan Buis/Written by Esprit Smith.

Greetings, Orbiter.ch