AGU 期刊一周Research Spotlights (Oct 13~Oct 19, 2016)

发布时间:2016-10-21 8:25:46 点击次数:626


I. Natural Hazards

1. Mapping Geoelectric Hazards Across the United States

Variations in Earth’s magnetic field can induce electric fields in the ground, driving damaging currents through our power grids.

II. Geology & Geophysics

1. Porporato Receives 2016 Hydrologic Sciences Award

Amilcare Porporato will receive the 2016 Hydrologic Sciences Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award is for outstanding contributions to the science of hydrology.

2. Harman Receives 2016 Early Career Hydrologic Science Award

Ciaran Harman will receive the 2016 Early Career Hydrologic Science Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award is for significant early-career contributions to hydrologic science.

3. Celebrating the 2016 Class of Fellows

The new class of American Geophysical Union Fellows has been selected and will be recognized at the upcoming Fall Meeting in San Francisco, Calif.

4. Anderegg Receives 2016 Global Environmental Change Early Career Award

William Anderegg is the first recipient of the Global Environmental Change Early Career Award. He will receive the award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes an early-career scientist "for outstanding contributions in research, educational, or societal impacts on the area of global environmental change, especially through interdisciplinary approach."

5. Betts Receives 2016 Bert Bolin Global Environmental Focus Group Award

Alan K. Betts is the first recipient of the Bert Bolin Award/Lecture of the American Geophysical Union's Global Environmental Change focus group. He will receive the award and present this lecture at the 2016 AGU Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes an Earth scientist "for his/her ground-breaking research or/and leadership in global environmental change through cross-disciplinary, interdisciplinary, and transdisciplinary research in the past 10 years."

6. Shaar Receives 2016 William Gilbert Award

Ron Shaar will receive the 2016 William Gilbert Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes outstanding and unselfish work in magnetism of Earth materials and of the Earth and planets.

7. Fielding Receives 2016 Ivan I. Mueller Award for Distinguished Service and Leadership

Eric Jameson Fielding will receive the 2016 Ivan I. Mueller Award for Distinguished Service and Leadership at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes "major achievements in service and/or leadership to the geodesy community."

8. Hill Receives 2016 Geodesy Section Award

Emma M. Hill will receive the 2016 Geodesy Section Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award is given in recognition of major advances in geodesy.

III.Hazards & Disasters

1. Flood Response Using Earth Observation Data and Products

NASA Flood Response Workshop; Greenbelt, Maryland, 14–16 June 2016

IV. Climate Change

1. Scientists, Activists Call for Climate Topic in Wednesday’s Debate

As environmentalists petition for climate questions in the final presidential debate, some scientists are urging—and others taking polls about—climate as a topic for politicians to address.

2. Can We Predict the Future of Ocean Carbon Dioxide Uptake?

A new understanding of uncertainties in climate change models allows scientists to decide which source to tackle first in order to better forecast our planet's changing climate.

V. Hydrology, Cryosphere & Earth Surface

1. Map Reveals Hot Spots for Arctic Greenhouse Gas Emissions

By bringing together data on permafrost stability, soils, and other Arctic conditions, scientists have plotted where permafrost is vulnerable to collapse, which could release long-stored carbon.

VI. Earth and Space Science

1.Soil moisture, snowpack data could help predict ‘flash droughts’

New research suggests “flash droughts” — like the one that unexpectedly gripped the Southern Rockies and Midwest in the summer of 2012 — could be predicted months in advance using soil moisture and snowpack data. Researchers analyzed the conditions leading up to the 2012 drought, which ultimately caused $30 billion in economic losses, looking for any warning signs that a drought was on the way.

2. Fires fueled by grass, crops can produce dangerous air pollutants

Grass and crop fires can emit more of certain types of hazardous fumes than wood fires, a new study finds. Results from the study could help scientists better understand the dangers from fire emissions, allowing firefighters or individuals close to a fire to react more appropriately, according to the study’s authors.

VII. Geophysical Research Letters

1. An advective mechanism for deep chlorophyll maxima formation in southern Drake Passage

We observe surface and subsurface fluorescence-derived chlorophyll maxima in southern Drake Passage during austral summer. Backscatter measurements indicate that the deep chlorophyll maxima (DCMs) are also deep biomass maxima, and euphotic depth estimates show that they lie below the euphotic layer. Subsurface, offshore and near-surface, onshore features lie along the same isopycnal, suggesting advective generation of DCMs. Temperature measurements indicate a warming of surface waters throughout austral summer, capping the winter water (WW) layer and increasing off-shelf stratification in this isopycnal layer. The outcrop position of the WW isopycnal layer shifts onshore, into a surface phytoplankton bloom. A lateral potential vorticity (PV) gradient develops, such that a down-gradient PV flux is consistent with offshore, along-isopycnal tracer transport. Model results are consistent with this mechanism. Subduction of chlorophyll and biomass along isopycnals represents a biological term not observed by surface satellite measurements which may contribute significantly to the strength of the biological pump in this region.

2. Magnitude-based discrimination of man-made seismic events from naturally occurring earthquakes in Utah, USA

We investigate using the difference between local (ML) and coda/duration (MC) magnitude to discriminate man-made seismic events from naturally occurring tectonic earthquakes in and around Utah. For 6846 well-located earthquakes in the Utah region, we find that ML-MC is on average 0.44 magnitude units smaller for mining-induced seismicity (MIS) than for tectonic seismicity (TS). Our interpretation of this observation is that MIS occurs within near-surface low-velocity layers that act as a waveguide and preferentially increase coda duration relative to peak amplitude, while the vast majority of TS occurs beneath the near-surface waveguide. A second data set of 3723 confirmed or probable explosions in the Utah region also has significantly lower ML-MC values than TS, likely for the same reason as the MIS. These observations suggest that ML-MC is useful as a depth indicator and could discriminate small explosions and mining-induced earthquakes from deeper, naturally occurring earthquakes at local-to-regional distances.

3. Water mass transformation by cabbeling and thermobaricity

Water mass transformation is an important process for the global ocean circulation. Nonlinearities in the equation of state of seawater lead to water mass transformation due to cabbeling and thermobaricity. Here the contribution of cabbeling and thermobaricity to water mass transformation is calculated in a Neutral Density framework, using temperature gradients derived from observationally based gridded climatologies and observationally based estimates of the spatially varying eddy diffusivities. It is shown that cabbeling and thermobaricity play a significant role in the water mass transformation budget, with cabbeling having a particularly important role in the formation of Antarctic Intermediate Water and Antarctic Bottom Water. A physical hypothesis is presented which explains why cabbeling is important for Antarctic Intermediate Water formation. It is shown that spatially varying estimates of eddy diffusivities are essential to correctly quantify the role of cabbeling to the formation of Antarctic Intermediate Water.

4. Under ice habitats for Antarctic krill larvae: Could less mean more under climate warming?

Overwintering of larvae underneath Antarctic pack ice is a critical stage in the life cycle of Antarctic krill. However, there are no circumpolar assessments of available habitat for larval krill, making it difficult to evaluate how climate change may impact this life stage. We use outputs from a circumpolar sea ice model, together with a set of simple assumptions regarding key habitat features, to identify possible regions of larval krill habitat around Antarctica during winter. We assume that the location and suitability of habitat is determined by both food availability and three-dimensional complexity of the sea ice. A comparison of the combined area of these regions under current conditions with a warm climate scenario indicates that while total areal sea ice extent decreases, there is a consistently larger area of potential larval krill habitat under warm conditions. These findings suggest that decreases in sea ice extent may not necessarily be detrimental for krill populations.

5. Evolution of the upper-level thermal structure in tropical cyclones

Tropical cyclones (TCs) are associated with tropopause-level cooling above tropospheric warming. We collect temperature retrievals from 2007 to 2014 near worldwide hurricane-strength TCs using three remote sensing platforms: the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), the Advanced Microwave Sounding Unit-A (AMSU-A), and geostationary infrared (IR) imagery. These retrievals are composited about the lifetime maximum intensity (LMI) to examine the evolution of the fine-scale temperature structure within TCs. The convective structure evolves highly asymmetrically about LMI, while intensity evolution shows a much weaker degree of asymmetry. Relative to the far-field structure, tropopause-level cooling occurs before a tropospheric warm core is established. We speculate that the associated convective destabilization exerts a positive feedback on TC development by increasing the depth of existing convection. Tropopause-level cold anomalies move away from the storm after LMI, potentially increasing the near-surface horizontal pressure gradient toward the storm center and increasing the maximum winds.

6. The complex nature of storm-time ion dynamics: Transport and local acceleration

Data from the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) spectrometers reveal hitherto unresolved spatial structure and dynamics in ion populations. Complex regions of O+ dominance, at energies from a few eV to >10 keV, are observed throughout the magnetosphere. Isolated regions on the dayside that are rich in energetic O+ might easily be interpreted as strong energization of ionospheric plasma. We demonstrate, however, that both the energy spectrum and the limited magnetic local time extent of these features can be explained by energy-dependent drift of particles injected on the nightside 24 h earlier. Particle tracing simulations show that the energetic O+ can originate in the magnetotail, not in the ionosphere. Enhanced wave activity is colocated with the heavy ion-rich plasma, and we further conclude that the waves were not a source of free energy for accelerating ionospheric plasma but rather the consequence of the arrival of substorm-injected plasma.

7. Impact of ocean resolution on coupled air-sea fluxes and large-scale climate

Air-sea fluxes are a crucial component in the energetics of the global climate system. The largest air-sea fluxes occur in regions of high sea surface temperature variability, such as ocean boundary, frontal currents and eddies. In this paper we explore the importance of ocean model resolution to resolve air-sea flux relationships in these areas. We examine the sea surface temperature-wind stress relationship in high-pass filtered observations and two versions of the Met Office climate model with eddy-permitting and eddy-resolving ocean resolutions. Eddy-resolving resolution shows marginal improvement in the relationship over eddy-permitting resolution. However, by focussing on the North Atlantic we show that the eddy-resolving model has significant enhancement of latent heat loss over the North Atlantic Current region, a long-standing model bias. While eddy-resolving resolution does not change the air-sea flux relationship at small scale, the impact on the mean state has important implications for the reliability of future climate projections.



WASHINGTON, DC — Discover the latest Earth and space science news at the 49th annual AGU Fall Meeting this December, when about 24,000 attendees from around the globe are expected to assemble for the largest worldwide conference in the Earth and space sciences. This year, the meeting runs from Monday through Friday, Dec. 12-16, 2016 at the Moscone Center, 747 Howard St., San Francisco, California.