AGU 期刊一周Research Spotlights (July 07~July 12, 2016)

发布时间:2016-7-14 21:43:26 点击次数:667

I. Atmospheric Sciences

1. Closing the Air Quality Data Gap in the Developing World

How a husband-and-wife team created the world's first open access, open source international air quality data hub—a global resource for health organizations, policy makers, and others.


II. Geology & Geophysics

1. Tougher Guidelines Issued for Alaska Offshore Drilling

The regulations will reinforce safety mechanisms and provide stronger planning efforts and enhanced regulatory certainty, according to the Department of the Interior.


III.Hydrology, Cryosphere & Earth Surface

1. Closing the Pacific Rainfall Data Void

A new climatology tool uses satellite data to map precipitation in a data-sparse region of the Pacific Ocean.


IV. Planetary Sciences

1. Carbon Dioxide Frost May Keep Martian Soil Dusty

Temperature readings acquired from orbit show that Mars's surface gets cold enough at night to allow layers of solid carbon dioxide frost up to several hundred micrometers thick to build up near the equator.

2. Saturn's Magnetosphere: A Dozen Years of Discovery

Twelve years of studying Saturn's magnetosphere has produced many compelling breakthroughs. Even more exciting, however, is what's left to learn.


V.Ocean Sciences

1. How Do the Deep Waters of the Antarctic Form?

Researchers uncover new insights into the life cycle of water in the Antarctic region by measuring noble gas concentrations.


VI.Earth and Space Science

1. Climate tipping points: What do they mean for society?

The phrase “tipping point” passed its own tipping point and caught fire after author Malcolm Gladwell’s so-named 2000 book. It’s now frequently used in discussions about climate change, but what are “climate tipping points”? And what do they mean for society and the economy?

2. Dormant volcano near Rome is waking up

Scientists previously assumed Colli Albani, a 15-kilometer (9-mile) semicircle of hills outside Rome, was an extinct volcano since there was no record of it having erupted in human history. But in recent years, scientists have observed new steam vents, earthquakes and a rise in ground level in the hills and surrounding area.


VII. Geophysical Research Letters

1. Microfluidic observation of the onset of reactive-infitration instability in an analog fracture

 

Reactive-infiltration instability plays an important role in many geophysical problems yet theoretical models have rarely been validated experimentally. We study the dissolution of an analog fracture in a simple microfluidic setup, with a gypsum block inserted in between two polycarbonate plates. By changing the flow rate and the distance between the plates, we are able to scan a relatively wide range of Péclet and Damkhöhler numbers, characterizing the relative magnitude of advection, diffusion, and reaction in the system. We quantify the characteristic initial wavelengths of the perturbed fronts during the onset of instability. The results agree well with theoretical predictions based on linear stability analysis, thus experimentally validating current reactive-infiltration instability theory and opening new opportunities for experimental assessment of mineral reactivity.

2. The sensitivity of water availability to changes in the aridity index and other factors—A probabilistic analysis in the Budyko space

One of the pending questions in the context of global change is whether climatic drivers or other factors have stronger influences on water availability. Here we present an approach that allows to estimate the probability that changes in the aridity index have a larger effect on water availability than equal relative changes in other factors. The analysis builds upon a probabilistic extension of the Budyko framework, which is subject to an analytical sensitivity assessment. The results show that changes in water availability are only dominated by changes in the aridity index in very humid climates. This implies that projected intensifications of aridity in drylands may have less influence on water availability than commonly assumed. Instead, other climatic or nonclimatic factors are dominating. The analysis does hence allow to map regions in which water availability is more sensitive to equal relative changes in either the aridity index or all other factors.

3. Can slip heterogeneity be linked to earthquake recurrence?

The rupture process of two M4 repeating earthquake sequences in eastern Taiwan with contrasting recurrence behavior is investigated to demonstrate a link between slip heterogeneity and earthquake recurrence. The M3.6–3.8 quasiperiodic repeating earthquakes characterized by 3 years recurrence interval reveal overlapped slip concentrations. Inferred slip distribution for each event illustrates two asperities with peak slip of 47.7 cm and peak stress drop of 151.1 MPa. Under the influence of nearbyM6.9 event, the M4.3–4.8 repeating earthquakes separated only by 6–87 min, however, reveal an aperiodic manner. There is a distinct rupture characteristic without overlap in the slip areas, suggesting that shortening of the recurrence interval by the nearby large earthquake may change the slip heterogeneity in a repeatedly ruptured asperity. We conclude that the inherent heterogeneity of stress and strength could influence the distribution of coseismic slip, which is strongly tied to the recurrence behavior.

4. ARTEMIS observations of terrestrial ionospheric molecular ion outflow at the Moon

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft observes outflowing molecular ionospheric ions at lunar distances in the terrestrial magnetotail. The heavy ion fluxes are observed during geomagnetically disturbed times and consist of mainly molecular species ( N2+, NO+, and O2+, approximately masses 28–32 amu) on the order of 105–106 cm−2 s−1 at nearly identical velocities as concurrently present protons. By performing backward particle tracing in time-dependent electromagnetic fields from the magnetohydrodynamic Open Global Geospace Circulation Model of the terrestrial magnetosphere, we show that the ions escape the inner magnetosphere through magnetopause shadowing near noon and are subsequently accelerated to common velocities down the low-latitude boundary layer to lunar distances. At the Moon, the observed molecular ion outflow can sputter significant fluxes of neutral species into the lunar exosphere while also delivering nitrogen and oxygen to the lunar volatile inventory.

5. The response of high-impact blocking weather systems to climate change

Midlatitude weather and climate are dominated by the jet streams and associated eastward moving storm systems. Occasionally, however, these are blocked by persistent anticyclonic regimes known as blocking. Climate models generally predict a small decline in blocking frequency under anthropogenic climate change. However, confidence in these predictions is undermined by, among other things, a lack of understanding of the physical mechanisms underlying the change. Here we analyze blocking (mostly in the Euro-Atlantic sector) in a set of sensitivity experiments to determine the effect of different parts of the surface global warming pattern. We also analyze projected changes in the impacts of blocking such as temperature extremes. The results show that enhanced warming both in the tropics and over the Arctic act to strengthen the projected decline in blocking. The tropical changes are more important for the uncertainty in projected blocking changes, though the Arctic also affects the temperature anomalies during blocking.


VIII. AUG Newsroom

1. DAWN MAPS CERES CRATERS WHERE ICE CAN ACCUMULATE

WASHINGTON, DC — Scientists with NASA’s Dawn mission have identified permanently shadowed regions on the dwarf planet Ceres. Most of these areas likely have been cold enough to trap water ice for a billion years, suggesting that ice deposits could exist there now. The findings were published this week in Geop