I. Climate Change

1. Envisioning and Sustaining Science at Summit Station, Greenland

Summit Station Science Summit; Arlington, Virginia, 28–29 March 2017

https://eos.org/meeting-reports/envisioning-and-sustaining-science-at-summit-station-greenland

2. Environment and Labor Groups Push to Protect EPA Budget

The groups protested funding cuts, reductions in staff, and demoralizing working conditions.

https://eos.org/articles/environment-and-labor-groups-push-to-protect-epa-budget

II. Hazards & Disasters

1. Deepwater Horizon Dispersant Cleared the Air, New Model Shows

A simulation of oil and gas leakage during the Deepwater Horizon disaster finds that the main chemical dispersant used improved air quality for emergency responders.

https://eos.org/articles/deepwater-horizon-dispersant-cleared-the-air-new-model-shows

III. Ocean Sciences

1. World’s Biggest Oxygen Producers Living in Swirling Ocean Waters

Oceanographers probe the impact of deep swirling vortices on phytoplankton.

https://eos.org/research-spotlights/worlds-biggest-oxygen-producers-living-in-swirling-ocean-waters

2. Taking the Pulse of the Planet

How fast is Earth warming? Ocean heat content and sea level rise measurements may provide a more reliable answer than atmospheric measurements.

https://eos.org/opinions/taking-the-pulse-of-the-planet

IV. Geology & Geophysics

1. AGU Revises Its Integrity and Ethics Policy

The updated ethics policy takes a strong stance against harassment in the sciences.

https://eos.org/agu-news/agu-revises-its-integrity-and-ethics-policy

2. AGU Marks Peer Review Week

AGU is committed to assessing and improving the peer review process through various new and recent initiatives.

https://eos.org/editors-vox/agu-marks-peer-review-week

3. Enabling Findable, Accessible, Interoperable and Reusable Data

AGU is convening a partnership in the Earth and space science community to develop the standards to connect researchers, publishers, and data repositories.

https://eos.org/editors-vox/enabling-findable-accessible-interoperable-and-reusable-data

4. Annotation Tool Facilitates Peer Review

AGU journals will incorporate open source software to facilitate dialog among reviewers, editors and authors during peer review.

https://eos.org/editors-vox/annotation-tool-facilitates-peer-review

V. Hydrology, Cryosphere & Earth Surface

1. Hot Water, Cold Ice

Despite careful planning, there can be many uncertainties and unknowns about doing field research in remote locations.

https://eos.org/editors-vox/hot-water-cold-ice

VI. Space & Planets

1. Cassini Plunges into Saturn, Ends a 20-Year Mission

NASA’s Jet Propulsion Laboratory streamed the spacecraft’s final moments live, allowing the public to listen to the mission's end.

https://eos.org/articles/cassini-plunges-into-saturn-ends-a-20-year-mission

2. Diamonds Really Do Rain on Neptune, Experiments Conclude

Researchers subjected hydrocarbon samples in a laboratory to Neptune-like pressures. The samples, reminiscent of molecules found in the ice giant’s atmosphere, compressed into nanodiamonds.

https://eos.org/articles/diamonds-really-do-rain-on-neptune-experiments-conclude

VII. Geophysical Research Letters

1. Mapping subduction interface coupling using magnetotellurics: Hikurangi margin, New Zealand

The observation of slow-slip, seismic tremor, and low-frequency earthquakes at subduction margins has provided new insight into the mechanisms by which stress accumulates between large subduction (megathrust) earthquakes. However, the relationship between the physical properties of the subduction interface and the nature of the controls on interplate seismic coupling is not fully understood. Using magnetotelluric data, we show in situ that an electrically resistive patch on the Hikurangi subduction interface corresponds with an area of increased coupling inferred from geodetic data. This resistive patch must reflect a decrease in the fluid or sediment content of the interface shear zone. Together, the magnetotelluric and geodetic data suggest that the frictional coupling of this part on the Hikurangi margin may be controlled by the interface fluid and sediment content: the resistive patch marking a fluid- and sediment-starved area with an increased density of small, seismogenic-asperities, and therefore a greater likelihood of subduction earthquake nucleation.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074641/full

2. Ancient Continental Lithosphere Dislocated Beneath Ocean Basins Along the Mid-Lithosphere Discontinuity: A Hypothesis

The documented occurrence of ancient continental cratonic roots beneath several oceanic basins remains poorly explained by the plate tectonic paradigm. These roots are found beneath some ocean-continent boundaries, on the trailing sides of some continents, extending for hundreds of kilometers or farther into oceanic basins. We postulate that these cratonic roots were left behind during plate motion, by differential shearing along the seismically imaged mid-lithosphere discontinuity (MLD), and then emplaced beneath the ocean-continent boundary. Here we use numerical models of cratons with realistic crustal rheologies drifting at observed plate velocities to support the idea that the mid-lithosphere weak layer fostered the decoupling and offset of the African continent's buoyant cratonic root, which was left behind during Meso-Cenozoic continental drift and emplaced beneath the Atlantic Ocean. We show that in some cratonic areas, the MLD plays a similar role as the lithosphere-asthenosphere boundary for accommodating lateral plate tectonic displacements.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074686/full

3. Spatial Patterns of Summer Speedup on South Central Alaska Glaciers

Seasonal changes in glacier basal motion are attributable to variations in subglacial hydrology and cause variations in both ice discharge and glacier erosion. We develop a novel workflow based upon Landsat 8 feature tracking to document differences between spatial patterns of summer and winter glacier surface speed, which reflect changes in the distribution of basal motion. We identify and characterize summer speedups on 13 of 19 land-terminating glaciers in Alaska's Wrangell-St Elias Ranges. The speedups are relatively uniform over much of the ablation zones, and the speedup magnitudes vary by only a factor of ~2 between glaciers whose velocities span an order of magnitude. Summer speedups extend up to ~30 km up glacier from termini and often end at the bases of icefalls. These data provide systematic observation of the spatial pattern of enhanced summer glacier basal motion and suggest the possibility of its parameterization in glacier models.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074370/full

4. The Response of the Aegean Sea (Eastern Mediterranean) to the Extreme 2016–2017 Winter

The exceptionally cold December 2016 over the Aegean Sea—one of the most important dense water formation areas of the eastern Mediterranean Sea—resulted in winter heat loss comparable to the peak Eastern Mediterranean Transient winters (1992–1993). Hydrological data sampled in March/April 2017 showed that newly produced dense waters ventilated the North Aegean deep basins up to density horizons of σθ ~ 29.35 kg/m3. The water column ventilation was unable to reach the bottom as the present upper thermohaline circulation of the eastern Mediterranean does not favor the salinity preconditioning of the Aegean Sea. In the southwest Aegean, the Myrtoan basin was ventilated by dense waters traceable farther south to the West Cretan Straits. Export of these masses from the Aegean Sea can potentially have a broader impact on the thermohaline circulation of the eastern Mediterranean.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074761/full

5. Seasonal iron depletion in temperate shelf seas

Our study followed the seasonal cycling of soluble (SFe), colloidal (CFe), dissolved (DFe), total dissolvable (TDFe), labile particulate (LPFe), and total particulate (TPFe) iron in the Celtic Sea (NE Atlantic Ocean). Preferential uptake of SFe occurred during the spring bloom, preceding the removal of CFe. Uptake and export of Fe during the spring bloom, coupled with a reduction in vertical exchange, led to Fe deplete surface waters (<0 .2 nm dfe; 0.11 nm lpfe, 0.45 nm tdfe, and 1.84 nm tpfe) during summer stratification. below the seasonal thermocline, dfe concentrations increased from spring to autumn, mirroring no3− and consistent with supply from remineralized sinking organic material, and cycled independently of particulate fe over seasonal timescales. these results demonstrate that summer fe availability is comparable to the seasonally fe limited ross sea shelf and therefore is likely low enough to affect phytoplankton growth and species composition.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073881/full

VII. AGU Blogs

1. Collecting unique data where the Atlantic Water meets the Arctic Ocean: A-TWAIN2017

A-TWAIN is a long-term project monitoring since 2012 the variability and trends of the Atlantic Water inflow in the Svalbard region of the Arctic, led by the Norwegian Polar Institute, and funded by the Fram Centre ‘Arctic Ocean’ flagship. Every other year, an A-TWAIN cruise takes place in the autumn to gather data and service moorings for the project. Water that flows northward from the Atlantic Ocean into the Arctic Ocean plays a crucial role for environmental conditions there. A-TWAIN collects unique data on the Atlantic Water that enters the Arctic Ocean north of Svalbard, mainly through time series from moorings and high-resolution CTD (conductivity, temperature, and depth) measurements.

http://blogs.agu.org/thefield/2017/09/18/collecting-unique-data-atlantic-water-meets-arctic-ocean-twain2017/

2. Landslides from the Kaikoura Earthquake part 3: the Leader 220 landslide

The Leader 220 landslide, located on the Leader Rover close to Woodchester (the location is -42.585, 173.215 if you want to take a look on Google Earth), is another large valley blocking landslide triggered by the Kaikoura Earthquake in New Zealand. This is one of the most spectacular and photogenic of all of the landslides.

http://blogs.agu.org/landslideblog/2017/09/17/leader-220-landslide/

3. Turning on the aurora switch with HAARP

People travel north from all over for a chance to see the aurora. Soon, Chris Fallen will make his own.

Sometime around the darkness of the September 19 new moon, the space physicist will travel to an antenna field off the Copper River. There, he will pulse transmitters on and off to create radio-induced aurora, also known as airglow. The UAF researcher will use the HAARP facility to attempt to do from below what the sun does from above to create a display of aurora.

http://blogs.agu.org/thefield/2017/09/15/turning-aurora-switch-haarp/