AGU 期刊一周Research Spotlights (Oct 27~Nov 3, 2016)

发布时间:2016-11-3 16:36:26 点击次数:699

I. Natural Hazards

1. AGU's TEX Program to Lead Climate Effort Launched by White House

The Resilience Dialogues program unveiled today fosters discussion, networking, and problem solving among communities with climate-related challenges, scientists, and other experts.

II. Geology & Geophysics

1. Reilinger Receives 2016 Paul G. Silver Award for Outstanding Scientific Service

Robert Reilinger will receive the 2016 Paul G. Silver Award for Outstanding Scientific Service at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes outstanding contributions to the fields of geodesy, seismology, or tectonophysics through mentoring of junior colleagues, leadership of community research initiatives, or other forms of unselfish collaboration in research.

2. Behr Receives 2016 Jason Morgan Early Career Award

Whitney Behr will receive the 2016 Jason Morgan Early Career 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 in Tectonophysics.

3. Lau and O'Rourke Receive 2016 Study of the Earth's Deep Interior Focus Group Graduate Research Award

Harriet Lau and Joseph O'Rourke will receive the 2016 Study of the Earth's Deep Interior Focus Group Graduate Research Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. This award is given annually for advances that contribute to the understanding of the deep interior of the Earth or other planetary bodies using a broad range of observational, experimental, and/or theoretical approaches.

4. Komar Receives 2016 Basu United States Early Career Award for Research Excellence in Sun-Earth Systems Science

Colin Komar will receive the 2016 Basu United States Early Career Award for Research Excellence in Sun-Earth Systems Science at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. This award is given annually to one early-career scientist (no more than 3 years post-degree) from the United States in recognition of significant work that shows the focus and promise of making outstanding contributions to research in Sun-Earth systems science that further the understanding of both plasma physical processes and their applications for the benefit of society.

5. Lopez Receives 2016 Space Physics and Aeronomy Richard Carrington Award

Ramon E. Lopez will receive the 2016 Space Physics and Aeronomy Richard Carrington 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 significant and outstanding impact on students' and the public's understanding of our science through education and/or outreach activities.

6. Yeo Receives 2016 Fred L. Scarf Award

Kok Leng Yeo will receive the Fred L. Scarf Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. This award is given annually to one honoree in recognition of an outstanding dissertation that contributes directly to solar-planetary science.

7. Olwendo Receives 2016 Basu Early Career Award in Sun-Earth Systems Science

Joseph Olwendo will receive the Sunanda and Santimay Basu Early Career Award in Sun-Earth Systems Science. He will present a talk and will be formally presented with the award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif.

III.Hazards & Disasters

1. Anthropogenic Drought: How Humans Affect the Global Ecosystem

Amir AghaKouchak discusses how human activity affects water supply and the environment.

2. Space Weather from a Southern Point of View

A recently completed instrument array in Antarctica provides a more complete understanding of the near-Earth space environment.

IV. Climate Change

1. Ancient Ocean Floor Seashells Improve Model of Past Glaciers

More accurate reconstruction of ice sheets over the past 150,000 years could help scientists predict future climate change.

2. Administration Official Sees Alaska Offshore Drilling Ahead

At a recent forum, leaders laid out some interdependent energy, environmental, infrastructure, and military issues coming into play in a more navigable Arctic region.

3. High-Resolution Ocean Model Captures Large-Scale Heat Transport

A lower-resolution model is sufficient to capture air-sea interactions, but a high-resolution model better simulates average sea surface temperatures in the North Atlantic.

4. Clouds in Climate Models of a Simulated Water-Covered Earth

Researchers use aquaplanet experiments to zero in on the effects of small-scale processes in the tropics that cause discrepancies between climate models.

5. Corals Reveal Ancient Ocean Temperatures in Great Barrier Reef

Old coral colonies suggest that a prehistoric warming event called the mid-Holocene Thermal Maximum may have occurred earlier than previously thought.

V. Planetary Sciences

1. Cracking Comet: A Window to the Past

An unusual feature on comet 67P/Churyumov-Gerasimenko offers insights into cometary origins.

VI. Geophysical Research Letters

1. Direct space-based observations of anthropogenic CO2 emission areas from OCO-2

Anthropogenic CO2 emissions from fossil fuel combustion have large impacts on climate. In order to monitor the increasing CO2 concentrations in the atmosphere, accurate spaceborne observations—as available from the Orbiting Carbon Observatory-2 (OCO-2)—are needed. This work provides the first direct observation of anthropogenic CO2 from OCO-2 over the main pollution regions: eastern USA, central Europe, and East Asia. This is achieved by deseasonalizing and detrending OCO-2 CO2 observations to derive CO2 anomalies. Several small isolated emission areas (such as large cities) are detectable from the anomaly maps. The spatial distribution of the CO2 anomaly matches the features observed in the maps of the Ozone Monitoring Instrument NO2 tropospheric columns, used as an indicator of atmospheric pollution. The results of a cluster analysis confirm the spatial correlation between CO2 and NO2 data over areas with different amounts of pollution. We found positive correlation between CO2 anomalies and emission inventories. The results demonstrate the power of spaceborne data for monitoring anthropogenic CO2emissions.

2. Perspectives on the causes of exceptionally low 2015 snowpack in the western United States

Augmenting previous papers about the exceptional 2011–2015 California drought, we offer new perspectives on the “snow drought” that extended into Oregon in 2014 and Washington in 2015. Over 80% of measurement sites west of 115°W experienced record low snowpack in 2015, and we estimate a return period of 400–1000 years for California's snowpack under the questionable assumption of stationarity. Hydrologic modeling supports the conclusion that 2015 was the most severe on record by a wide margin. Using a crowd-sourced superensemble of regional climate model simulations, we show that both human influence and sea surface temperature (SST) anomalies contributed strongly to the risk of snow drought in Oregon and Washington: the contribution of SST anomalies was about twice that of human influence. By contrast, SSTs and humans appear to have played a smaller role in creating California's snow drought. In all three states, the anthropogenic effect on temperature exacerbated the snow drought.

3. A new soil mechanics approach to quantify and predict land subsidence by peat compression

Land subsidence threatens many coastal areas. Quantifying current and predicting future subsidence are essential to sustain the viability of these areas with respect to rising sea levels. Despite its scale and severity, methods to quantify subsidence are scarce. In peat-rich subsidence hot spots, subsidence is often caused by peat compression. We introduce the standard Cone Penetration Test (CPT) as a technique to quantify subsidence due to compression of peat. In a test in the Holland coastal plain, the Netherlands, we found a strong relationship between thickness reduction of peat and cone resistance, due to an increase in peat stiffness after compression. We use these results to quantify subsidence of peat in subsiding areas of Sacramento-San Joaquin delta and Kalimantan, and found values corresponding with previously made observations. These results open the door for CPT as a new method to document past and predict future subsidence due to peat compression over large areas.

4. Can reducing the incoming energy flux over the Southern Ocean in a CGCM improve its simulation of tropical climate?

Atmosphere-ocean general circulation models (CGCMs) show important systematic errors. Simulated precipitation in the tropics is generally overestimated over the oceans south of the equator, and stratocumulus (SCu) clouds are underestimated above too warm sea surface temperatures (SSTs). In the extratropics, SSTs are also too warm over the Southern Ocean. We argue that ameliorating these extratropical errors in a CGCM can result in an improved model's performance in the tropics depending upon the success in simulating the sensitivity of SCu to underlying SST. Our arguments are supported by the very different response obtained with two CGCMs to an idealized reduction of solar radiation flux incident at the top of the atmosphere over the Southern Ocean. It is shown that local perturbation impacts are very similar in the two models but that SST reductions in the SCu regions of the southern subtropics are stronger in the model with the stronger SCu-SST feedbacks.

5. Distinct persistence barriers in two types of ENSO

El Niño–Southern Oscillation (ENSO) is usually subject to a persistence barrier (PB) in boreal spring. This study quantifies the PB and then reveals its distinct features in the two types of ENSO, the eastern Pacific (EP) and central Pacific (CP) types. We suggest that the PB of ENSO can be measured by the maximum rate of autocorrelation decline of Niño sea surface temperature anomaly (SSTA) indices. Results show that the PB of ENSO generally occurs in boreal late spring to early summer in terms of Niño3.4 index, and the EP ENSO has the PB in late spring, while the CP type has the PB in summer. By defining an index to quantify PB intensity of ENSO, we find that the CP ENSO type features a much weaker PB, compared to the EP type, and the PB intensity of equatorial SSTAs is larger over the EP than the western Pacific and the far EP.

6. An unexpected restructuring of combustion soot aggregates by subnanometer coatings of polycyclic aromatic hydrocarbons

We investigated the effect of thin polycyclic aromatic hydrocarbon (PAH) coatings on the structure of soot aggregates. Soot aerosol from an inverted diffusion burner was size classified, thermally denuded, coated with six different PAHs, and then characterized using scanning electron microscopy, light scattering, and mass-mobility measurements. Contrary to our expectation, significant restructuring was observed in the presence of subnanometer layers of pyrene, fluoranthene, and phenanthrene. These PAHs remained in subcooled liquid state in thin films, whereby the liquid layer acted as a lubricant, reducing the force required to initiate the restructuring. Thin layers of PAH of higher melting temperatures (perylene, anthracene, and triphenylene) presumably remained solid because these chemicals induced lesser structural changes. Our results suggest that some of the intrinsic PAH generated during incomplete combustion may induce significant restructuring of soot aggregates, even when present in small quantities, altering the properties and atmospheric impacts of combustion aerosols.

7. Sensitivity of pine island glacier to observed ocean forcing

We present subannual observations (2009–2014) of a major West Antarctic glacier (Pine Island Glacier) and the neighboring ocean. Ongoing glacier retreat and accelerated ice flow were likely triggered a few decades ago by increased ocean-induced thinning, which may have initiated marine ice sheet instability. Following a subsequent 60% drop in ocean heat content from early 2012 to late 2013, ice flow slowed, but by < 4%, with flow recovering as the ocean warmed to prior temperatures. During this cold-ocean period, the evolving glacier-bed/ice shelf system was also in a geometry favorable to stabilization. However, despite a minor, temporary decrease in ice discharge, the basin-wide thinning signal did not change. Thus, as predicted by theory, once marine ice sheet instability is underway, a single transient high-amplitude ocean cooling has only a relatively minor effect on ice flow. The long-term effects of ocean temperature variability on ice flow, however, are not yet known.

8. Correlating laser-generated melts with impact-generated melts: An integrated thermodynamic-petrologic approach

Planetary collisions in the solar system typically induce melting and vaporization of the impactor and a certain volume of the target. To study the dynamics of quasi-instantaneous melting and subsequent quenching under postshock P-T conditions of impact melting, we used continuous-wave laser irradiation to melt and vaporize sandstone, iron meteorite, and basalt. Using high-speed imaging, temperature measurements, and petrologic investigations of the irradiation targets, we show that laser-generated melts exhibit typical characteristics of impact melts (particularly ballistic ejecta). We then calculate the entropy gains of the laser-generated melts and compare them with the entropy gains associated with the thermodynamic states produced in hypervelocity impacts at various velocities. In conclusion, our experiments extend currently attainable postshock temperatures in impact experiments to ranges commensurate with impacts in the velocity range of 4–20 km s–1 and allow to study timescales and magnitudes of petrogenetic processes in impact melts.

9.Interpolation of 2-D vector data using constraints from elasticity

We present a method for interpolation of sparse two-dimensional vector data. The method is based on the Green's functions of an elastic body subjected to in-plane forces. This approach ensures elastic coupling between the two components of the interpolation. Users may adjust the coupling by varying Poisson's ratio. Smoothing can be achieved by ignoring the smallest eigenvalues in the matrix solution for the strengths of the unknown body forces. We demonstrate the method using irregularly distributed GPS velocities from southern California. Our technique has been implemented in both the Generic Mapping Tools and MATLAB®.



WASHINGTON, DC – The American Geophysical Union (AGU) today announced thelaunch of the Resilience Dialogues, a collaborative effort between federal agencies, non-profit organizations, and private partners, to help local communities address climate-related vulnerabilities. The program will initially focus on historically underserved communities by prioritizing urban, tribal, and small rural communities.


WASHINGTON, DC – The western-most region of the continental United States set records for low snowpack levels in 2015. In a new study, scientists point the finger at high temperatures, not the low precipitation characteristic of past “snow drought” years.