Jessie Creamean, a postdoctoral associate at NOAA's Earth System Research Laboratory in Boulder, Colo., co-authored the paper appearing in the journal Science with Kaitlyn Suski, a graduate student in the laboratory of Distinguished Chair in Atmospheric Chemistry Prof. Kimberly Prather, who holds appointments at Scripps Institution of Oceanography and the Department of Chemistry and Biochemistry at UCSD.
Study leader UCSD Distinguished Chair in Atmospheric Chemistry Prof. Kimberly Prather
Researchers have long known that winds can carry aerosols such as dust at altitudes above 5,000 meters (16,400 feet) from continent to continent. An unrelated 2009 study found that in one instance, Asian dust made a complete circuit around the planet in 13 days.
These dust particles can act as ice nuclei within clouds at warmer temperatures than would occur in their absence. They initiate the freezing of water vapor and water droplets, then precipitate as rain, snow, or hail depending on whether meteorological conditions enable them to attain sufficient mass to fall from the sky before evaporating. Without ice nuclei, ice would likely not form in clouds with temperatures above -38 degrees C (-36.4 degrees F).
Besides dust, aerosols can be composed of sea salt, bits of soot and other pollution, or biological material. Bacteria, viruses, pollen, and plants, of both terrestrial and marine origin, also add to the mix of aerosols making the transcontinental voyage.The researchers' analysis of winter storms in 2011 found that dust and biological aerosols tend to enhance precipitation-forming processes in the Sierra Nevada. In previous studies, researchers have found that pollution particles have the opposite effect, suppressing precipitation in the Sierra Nevada.
Ryan Sullivan of Carnegie Mellon University (seated) and Paul DeMott of Colorado State University aboard a Department of Energy G-1 aircraft during CalWater. Photo: Carnegie Mellon University
The bulk of the data collected during CalWater came from instruments known as aerosol time-of-flight mass spectrometers (ATOFMS), co-developed by Prather, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, which tracked the transport of aerosols through the atmosphere from continent to continent. Measurements in and around clouds utilized the Department of Energy's G-1 research aircraft, which carried other vital instruments, such as a specialized detector for the presence of dust ice nuclei feeding clouds and their presence in the collected residue of ice crystals. That portion of the study was led by co-author Paul DeMott, a senior research scientist at Colorado State University.Using these tools, the researchers were able to determine that at least some of the dust and bioparticles detected by an aircraft-mounted ATOFMS unit during February 2011 flights through Sierra Nevada storm clouds were in the skies over Oman 10 days earlier, having likely originated in the Sahara a few days earlier. Along the journey, the Saharan dust and microbes mixed with other aerosols from deserts in China and Mongolia before wafting over the Pacific Ocean. Upon arrival in California, the aerosols effectively seeded the storm clouds and contributed to the efficiency of clouds in producing precipitation. Two other transportable ATOFMS units housed in trailers at Sugar Pine Dam just south of Interstate 80 in the Tahoe National Forest and other instruments made further measurements. They determined the chemical composition of aerosols at the end of their journey by looking at the particles present in precipitation samples that were collected during storms.
Robert Monroe | EurekAlert!
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy