I.Hazards & Disasters

1.Linking Mantle Plumes to Volcanoes and Hot Spot Tracks

Around 80 million years ago, China’s largest continental plate began to creep northeast. As it drifted, it passed over a stationary plume of hot, fluid rock in the mantle. The plume broke through weak parts in the crust and formed a linear anomalous zone. At least, that’s the scenario proposed in a new study, which used multiple lines of evidence to support the existence of the crustal footprint of the Hainan plume and puzzle out how the volcanoes formed.

https://eos.org/research-spotlights/linking-mantle-plumes-to-volcanoes-and-hot-spot-tracks

II. Climate Change

1.An Evolving Framework for Advancing Climate Services in Norway

The Norwegian Centre for Climate Services (NCCS) was established in 2013 to formalize the production of services in support of climate change adaptation and decision-making. Climate service practices are advancing quickly in Norway, but it is important to pause and take stock of what we are learning and where flaws in our current approaches exist.

https://eos.org/meeting-reports/an-evolving-framework-for-advancing-climate-services-in-norway

2.Ocean Gliders Ride the Research Wave in the Agulhas Current

Off the east coast of South Africa, robotic ocean gliders deployed in the Agulhas Current capture new data that help us better understand how energy dissipates in the ocean.

https://eos.org/project-updates/ocean-gliders-ride-the-research-wave-in-the-agulhas-current

III. Biogeosciences

1.Emperor Penguins’ Huddles Change in Response to Weather

How quickly the penguins huddled when weather worsened provided clues about their feeding success and how climate change may alter the Antarctic biosphere, according to scientists.

https://eos.org/articles/emperor-penguins-huddles-change-in-response-to-weather

IV. Ocean Sciences

1.March on Saturday Highlights Threats to the Oceans and Solutions

David Helvarg, lead organizer of the 9 June March for the Ocean, spoke with Eos about the goals for the march and “turning the tide” to protect the oceans.

https://eos.org/articles/march-on-saturday-highlights-threats-to-the-oceans-and-solutions

V. Science Policy

1.Roving Exhibit Highlights Ocean Plastics Problem

The Ocean Plastics Lab, currently on the National Mall in Washington, D. C., illustrates the pollution threat and points to solutions.

https://eos.org/articles/roving-exhibit-highlights-ocean-plastics-problem

VI. Geophysical Research Letters

1.Independent DEM of Antarctica using GNSS‐R data from TechDemoSat‐1

The first Digital Elevation Model (DEM) of the Antarctic Ice Sheet derived from Global Navigation Satellite Systems‐Reflectometry (GNSS‐R) data from the UK TechDemoSat‐1 (TDS‐1) satellite is presented. This is obtained using 32 months of data from the mission. This opportunistic and inexpensive method is shown to produce encouraging results from the technology demonstration platform of TechDemoSat‐1, with median bias under 18 metres and Root Mean Square Difference under 91 metres when compared to the CryoSat‐2 1 km v1.0 Digital Elevation Model. Discrepancies between the two datasets are explored along with possible causes of such differences and potential improvements to further optimise this technique for future GNSS‐Reflectometry missions.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL077429

2.Dependence of present and future European temperature extremes on the location of atmospheric blocking

The impact of atmospheric blocking on European heat waves and cold spells is investigated for present and future conditions. A 50‐member ensemble of CanESM2 is used to quantify the role of internal variability in the response to blocking. We find that the present blocking‐extreme temperature link is well‐represented compared to ERA‐Interim, despite a significant underestimation of blocking frequency in most ensemble members. Our results show a strong correlation of blocking with northern European heat waves in summer, spring, and fall. However, we also find a strong anti‐correlation between blocking and heat wave occurrence in southern Europe in all seasons. Blocking increases the cold spell frequency particularly in southern Europe in fall, winter, and spring but reduces it in summer. For the future we find that blocking will continue to play an important role in the development of both cold spells and heat waves in all seasons.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL077837

3.Time‐dependent compaction as a mechanism for regular stick‐slips

Owing to their destructive potential, earthquakes receive considerable attention from laboratory studies. In friction experiments, stick‐slips are studied as the laboratory equivalent of natural earthquakes, and numerous attempts have been made to simulate stick‐slips numerically using the Discrete Element Method (DEM). However, while laboratory stick‐slips commonly exhibit regular stress drops and recurrence times, stick‐slips generated in DEM simulations are highly irregular. This discrepancy highlights a gap in our understanding of stick‐slip mechanics, which propagates into our understanding of earthquakes. In this work, we show that regular stick‐slips emerge in DEM when time‐dependent compaction by pressure solution is considered. We further show that the stress drop and recurrence time of stick‐slips is directly controlled by the kinetics of pressure solution. Since compaction is known to operate in faults, this mechanism for frictional instabilities directly relates to natural seismicity.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078103

4.Strengthened Indonesian Throughflow drives decadal warming in the Southern Indian Ocean

Remarkable warming of the Southern Indian Ocean during the recent two decades is assessed using a heat budget analysis based on the Estimating the Circulation and Climate of the Ocean version 4 release 3 model results. The annual mean temperature averaged in the upper‐700m Southern Indian Ocean during 1998‐2015 has experienced significant warming at a rate of 1.03×10‐2°C/yr. A heat budget analysis indicates that the increase is mostly driven by decreased cooling from net air‐sea heat flux and increased warming from heat advection. Increased ITF advection is the largest contributor to warming the upper 700m of the Southern Indian Ocean, while the reduction of surface turbulent heat flux is of secondary importance. These results expand our understanding of the decadal heat balance in the Indian Ocean and of Indo‐Pacific decadal climate variability.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078265

VII. AGU Blogs

1.South Napa Earthquake linked to summer groundwater dip

A summertime expansion in the Earth’s crust caused by changes in groundwater may have triggered the magnitude-6.0 earthquake in California’s wine country in 2014, according to a new study.

The August 24, 2014 South Napa quake was the largest earthquake to shake the San Francisco Bay Area since the magnitude-6.9 Loma Prieta quake in 1989. It was also the first earthquake in the region since 1906 to break through to the surface, leaving buckled asphalt and cracked soil in vineyards along the length of the fault.

https://blogs.agu.org/geospace/2018/06/12/south-napa-earthquake-linked-to-summer-groundwater-dip/