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AGU Research Spotlight (Oct 20-Oct 26, 2016)

2016-10-27 10:56:53

I. Natural Hazards

1.Hong Kong, Macau at Greater Tsunami Risk Than We Thought

Researchers assess tsunami risk in the South China Sea based on models of seismic slip along the Manila megathrust.


II. Geology & Geophysics

1.Zhan Receives 2016 Keiiti Aki Young Scientist Award

Zhongwen Zhan will receive the 2016 Keiiti Aki Young Scientist Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes the scientific accomplishments of a young scientist who makes outstanding contributions to the advancement of seismology.


2.Spencer Receives 2016 Whipple Award

John Spencer will receive the 2016 Whipple Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes an individual who has made an outstanding contribution in the field of planetary science.


3.Kite Receives 2016 Ronald Greeley Early Career Award in Planetary Science

Edwin Kite will receive the 2016 Ronald Greeley Early Career Award in Planetary Science at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes significant early-career contributions to planetary science.


4.McManus Receives 2016 Paleoceanography and Paleoclimatology Dansgaard Award

Jerry McManus will receive the inaugural Dansgaard Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif., as selected by a Dansgaard Award selection committee. The award is given in recognition of the awardee's research impact, innovative interdisciplinary work, educational accomplishments (mentoring), societal impact, and other relevant contributions and to acknowledge that the awardee shows exceptional promise for continued leadership in paleoceanography or paleoclimatology.


5.Bopp Receives 2016 Ocean Sciences Voyager Award

Laurent Bopp will receive the 2016 Ocean Sciences Voyager Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award is given to mid-career scientists for significant contributions and expanding leadership in ocean sciences.


6.Kamer Receives 2016 Donald L. Turcotte Award

Yavor Kamer will receive the 2016 Donald L. Turcotte Award, given annually to recent Ph.D. recipients for outstanding dissertation research that contributes directly to the field of nonlinear geophysics.


III.Hazards & Disasters

1.Developing a Remote Sensing System to Track Marine Debris

Workshop on Mission Concepts for Marine Debris Sensing; Honolulu, Hawaii, 19–21 January 2016


2.Volcanic Ash Contributes to Climate Cooling

A new study shows that atmospheric ash reflects solar radiation months after volcanic eruptions.


IV. Climate Change

1.AGU Should Sever Its Ties with ExxonMobil

AGU and its funders should be held to the same standards of evidence-based scrutiny that it expects of the scientists who publish in its own journals.


2.Reconstructing Ocean Climate History

Scientists recreate ocean climate data to explore historical warming—and cooling—trends in Earth's seas.


3.Climate Change Omitted from Presidential Debate Questions

Climate advocates and scientists express dismay that none of the moderators of the three debates brought up the issue of climate change.


4.Upscaling Peatland Science Through Collaborative Big Data

PeatDataHub launch meeting; Leeds, United Kingdom, 23–24 May 2016


V. Hydrology, Cryosphere & Earth Surface

1.U.S. Winter Outlook Sees No Drought Relief

A weak La Ni?a is expected to further dry out southwestern and Gulf Coast states.


VI. Geophysical Research Letters

1. Excavating Stickney crater at Phobos

Stickney crater, at 9?km across, dominates the morphology of ~22?km Phobos, the larger of the two moons of Mars. The Stickney impact event had global repercussions for Phobos, including extensive resurfacing and fracturing of the moon. Understanding the initial conditions and dynamical consequences of the collision is necessary to test competing hypotheses for the origin of peculiar grooved terrain that striates much of the surface. Previous modeling of the impact event was unable to replicate Stickney without globally fragmenting the satellite. Here we describe high-resolution numerical simulations that successfully generate Stickney crater while maintaining the large-scale structure of Phobos. Target porosity, which is estimated to be significant, aids in keeping the moon intact. Damage follows patterns centered on Stickney that are inconsistent with the observed alignment of grooved terrain on Phobos. Low-velocity boulders are ejected at shallow angles in sufficient numbers to support a rolling-boulder origin for grooved terrain.


2. Persistent artifacts in the NSIDC ice motion data set and their implications for analysis

In this study we evaluate weekly Equal-Area Scalable Earth Grid (EASE-Grid) sea ice velocities released by the National Snow and Ice Data Centre (NSIDC). We identify persistent Eulerian and Lagrangian features that arise solely as an artifact of the method used in the incorporation of buoy data. This, in turn, significantly impacts calculation of sea ice motion gradients, including divergence, convergence, and shear. Our numerical experiments and comparison with observations further demonstrate the impact of these artificial features on climatological assessments, including age-of-ice studies. In particular, we find that age-of-ice studies using this data set significantly underestimate multiyear ice extent by an average of 0.8 × 106 km2 in the month of March.


3. Closing the sea level budget on a regional scale: Trends and variability on the Northwestern European continental shelf

Long-term trends and decadal variability of sea level in the North Sea and along the Norwegian coast have been studied over the period 1958–2014. We model the spatially nonuniform sea level and solid earth response to large-scale ice melt and terrestrial water storage changes. GPS observations, corrected for the solid earth deformation, are used to estimate vertical land motion. We find a clear correlation between sea level in the North Sea and along the Norwegian coast and open ocean steric variability in the Bay of Biscay and west of Portugal, which is consistent with the presence of wind-driven coastally trapped waves. The observed nodal cycle is consistent with tidal equilibrium. We are able to explain the observed sea level trend over the period 1958–2014 well within the standard error of the sum of all contributing processes, as well as the large majority of the observed decadal sea level variability.


4. A cold and fresh ocean surface in the Nordic Seas during MIS 11: Significance for the future ocean

Paleoceanographical studies of Marine Isotope Stage (MIS) 11 have revealed higher-than-present sea surface temperatures (SSTs) in the North Atlantic and in parts of the Arctic but lower-than-present SSTs in the Nordic Seas, the main throughflow area of warm water into the Arctic Ocean. We resolve this contradiction by complementing SST data based on planktic foraminiferal abundances with surface salinity changes using hydrogen isotopic compositions of alkenones in a core from the central Nordic Seas. The data indicate the prevalence of a relatively cold, low-salinity, surface water layer in the Nordic Seas during most of MIS 11. In spite of the low-density surface layer, which was kept buoyant by continuous melting of surrounding glaciers, warmer Atlantic water was still propagating northward at the subsurface thus maintaining meridional overturning circulation. This study can help to better constrain the impact of continuous melting of Greenland and Arctic ice on high-latitude ocean circulation and climate.


5. Identification of rocket-induced acoustic waves in the ionosphere

Acoustic waves can create plasma disturbances in the ionosphere, but the number of observations is limited. Large-amplitude acoustic waves generated by energetic sources like large earthquakes and tsunamis are more readily observed than acoustic waves generated by weaker sources. New observations of plasma displacements caused by rocket-generated acoustic waves were made using the Vertically Incident Pulsed Ionospheric Radar (VIPIR), an advanced high-frequency radar. Rocket-induced acoustic waves which are characterized by low amplitudes relative to those induced by more energetic sources can be detected in the ionosphere using the phase data from fixed frequency radar observations of a plasma layer. This work is important for increasing the number and quality of observations of acoustic waves in the ionosphere and could help improve the understanding of energy transport from the lower atmosphere to the thermosphere.


6. Global linkages originating from decadal oceanic variability in the subpolar North Atlantic

The anomalous decadal warming of the subpolar North Atlantic Ocean (SPNA), and the northward spreading of this warm water, has been linked to rapid Arctic sea ice loss and more frequent cold European winters. Recently, variations in this heat transport have also been reported to covary with global warming slowdown/acceleration periods via a Pacific climate response. We here examine the role of SPNA temperature variability in this Atlantic-Pacific climate connectivity. We find that the evolution of ocean heat content anomalies from the subtropics to the subpolar region, likely due to ocean circulation changes, coincides with a basin-wide Atlantic warming/cooling. This induces an Atlantic-Pacific sea surface temperature seesaw, which in turn, strengthens/weakens the Walker circulation and amplifies the Pacific decadal variability that triggers pronounced global-scale atmospheric circulation anomalies. We conclude that the decadal oceanic variability in the SPNA is an essential component of the tropical interactions between the Atlantic and Pacific Oceans.


7. Isolated regions of remote triggering in South/Southeast Asia following the 2012Mw 8.6 Indian Ocean earthquake

Large earthquakes are capable of triggering either shallow earthquakes or deep tectonic tremors at long-range distances. So far, most of remotely triggered tremors were found along major plate boundary faults around the Pacific Rim. Here we conduct a systematic search for remotely triggered earthquakes and tremors in South/Southeast Asia following the 11 April 2012 Mw 8.6 Indian Ocean earthquake. We find additional evidence of triggered tectonic tremors beneath the Java Island and the Sulabes Island in Eastern Indonesia and triggered earthquakes in Vietnam. Tremors mostly occurred during the large-amplitude Rayleigh waves of the Indian Ocean main shock and were also triggered by several other large distant earthquakes. Although we are unable to locate them, they were recorded at stations close to major tectonic faults, suggesting that they are likely of tectonic origin. However, we find no evidence of triggered tremor/earthquakes along the Sumatra subduction zone and eastern portion of Himalaya frontal thrusts, indicating that remote triggering was not as widespread as previously thought.




WASHINGTON, DC — Low-frequency vibrations of the Ross Ice Shelf are likely causing ripples and undulations in the air above Antarctica, a new study finds. Using mathematical models of the ice shelf, the study’s authors show how vibrations in the ice match those seen in the atmosphere, and are likely causing these mysterious atmospheric waves.



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