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AGU Research Spotlight (Nov 02-Nov 08, 2017)

2017-11-10 14:22:51

I.Climate Change

1.Experts Ponder Why Administration Released Tough Climate Report

Scientists and policy experts say the White House released the report, which differs from the administration’s stance, without political tampering to avoid potential further controversy.


2. How Will Climate Change Affect the United States in Decades to Come?

A new U.S. government report shows that climate is changing and that human activities will lead to many more changes. These changes will affect sea levels, drought frequency, severe precipitation, and more.


3. Democrats Push NASA Nominee on Partisanship, Science Integrity

The nominee, Rep. Jim Bridenstine, tried to assure the committee of his support for science and his ability to manage NASA apolitically.


II. Hazards & Disasters

1. What Precursors Foretold Greenland’s Recent 100-Meter Tsunami?

Slippage began hours before a landslide-driven tsunami destroyed a village in northwestern Greenland.


III. Planetary Sciences

1. Imaging the Sun’s Atmosphere

The technique of heliospheric imaging could be valuable for future space weather operations.


IV.Geology & Geophysics

1. Gualtieri Receives 2017 Keiiti Aki Young Scientist Award

Lucia Gualtieri will receive the 2017 Keiiti Aki Young Scientist Award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award recognizes “scientific accomplishments of young scientists in the field of seismology.”


2. Malin Receives 2017 Whipple Award

Michael C. Malin will receive the 2017 Whipple Award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award recognizes “an individual who has made an outstanding contribution in the field of planetary science.”


3. Jacobson Receives 2017 Ronald Greeley Early Career Award in Planetary Science

Seth A. Jacobson will receive the 2017 Ronald Greeley Early Career Award in Planetary Science at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award recognizes “significant early career contributions to planetary science.”


V.Hydrology, Cryosphere & Earth Surface

1. New Greenland Maps Show More Glaciers at Risk

Two to four times as many coastal glaciers are threatened by climate change as previously thought, new research finds.


VI.Geophysical Research Letters

1. Estimation of Seismic Centroid Moment Tensor Using Ocean Bottom Pressure Gauges as Seismometers

We examined the dynamic pressure change at the seafloor to estimate the centroid moment tensor solutions of the largest and second largest foreshocks (Mw 7.2 and 6.5) of the 2011 Tohoku-Oki earthquake. Combination of onshore broadband seismograms and high-frequency (~20–200 s) seafloor pressure records provided the resolution of the horizontal locations of the centroids, consistent with the results of tsunami inversion using the long-period (?10 min) seafloor pressure records although the depth was not constrained well, whereas the source locations were poorly constrained by the onshore seismic data alone. Also, the waveforms synthesized from the estimated CMT solution demonstrated the validity of the theoretical relationship between pressure change and vertical acceleration at the seafloor. The results of this study suggest that offshore pressure records can be utilized as offshore seismograms, which would be greatly useful for revealing the source process of offshore earthquakes.


2. Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

Dynamic topography, the surface deflection induced by sublithosheric mantle flow, is an important prediction made by geodynamic models, but there is an apparent disparity between geodynamic model predictions and estimates of residual topography (total topography minus lithospheric and crustal contributions). We generate synthetic global topography fields with different power spectral slopes and spatial patterns to investigate how well the long-wavelength (spherical degrees 1 to 3) components can be recovered from a discrete set of samples where residual topography has been recently estimated.


3. BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation

Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach. A new 150?m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous data sets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheet is 7.42 ± 0.05 m, which is 7?cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.


4. Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.


5. Quasi-Additivity of the Radiative Effects of Marine Cloud Brightening and Stratospheric Sulfate Aerosol Injection

Stratospheric sulfate aerosol injection (SAI) and marine cloud brightening (MCB) are the two most studied solar radiation management techniques. For the first time we combine them in a climate model to investigate their complementarity in terms of both instantaneous and effective radiative forcings. The effective radiative forcing induced by SAI is significantly stronger than its instantaneous counterpart evaluated at the top of atmosphere. Radiative kernel calculations indicate that this occurs because of a significant stratospheric warming and despite a large increase in stratospheric water vapor that strengthens the greenhouse effect. There is also a large decrease in high-level cloudiness induced by a stratification of the upper tropopause. Our model experiments also show that the radiative effects of SAI and MCB are quasi-additive and have fairly complementary patterns in the Tropics. This results in less spatial and temporal variability in the radiative forcing for combined SAI and MCB as compared to MCB alone.


VII. AGU Blogs

1. New approach to geoengineering simulations is significant step forward

Using a sophisticated computer model, scientists have demonstrated for the first time that a new research approach to geoengineering could potentially be used to limit Earth’s warming to a specific target while reducing some of the risks and concerns identified in past studies, including uneven cooling of the globe.


2.Polluted groundwater eroding Hawaiian coral reefs, study shows

Local land-based pollution makes coral reefs more vulnerable to ocean acidification and could trigger coastal coral reef ecosystem collapses sooner than projected, according to new research.


3. Monday Geology Picture: Inselberg View

Some fantastic geologic scenery in Cape Town, South Africa: an inselberg (left) and the Twelve Apostles section of Table Mountain (right) in the background, a kayak in the middle, and some granitic rocks of the Cape Granite Suite in the foreground.


4. Chaxiqudong Glacier, Tibet Retreat From Lake & Tributary Separation

Chaxiqudong Glacier and Paqu Glacier are located in a sub-range north of the Nepal-China border. Chaxiqudong Glacier is adjacent to Longmiojian Glacier. The glaciers drain into Nepal entering the Bhote Khosi River. The Bothe Khosi had a hydropower project that has been put out of service by a 2015 earthquake and 2016 flood event.




WASHINGTON, DC — Discover the latest in ocean sciences research at the 2018 Ocean Sciences Meeting, where nearly 4,000 attendees are expected to present the latest research findings about the world’s oceans.



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