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AGU Research Spotlight (Apr 12-Apr 18, 2018)

2018-04-20 10:41:44

I. Climate Change

1. Tailoring Aerosol Injections to Achieve Desired Climate Effects

Two-dimensional simulations of sulfate aerosol injections suggest that solar geoengineering projects can be customized to maximize solar reflection and help achieve potential climate objectives.


2. Atmospheric Teleconnections: Advanced Tools and Citizen Science

GOTHAM International Summer School on Global Teleconnections in the Earth's Climate System – Processes, Modelling and Advanced Analysis Methods; Potsdam, Germany, 18–22 September 2017


II. Hazards & Disasters

1. Fluid Injection Wells Can Have a Wide Seismic Reach

High-volume fluid injection can cumulatively increase underground pore pressure and induce earthquakes in regions unexpectedly far from injection wells, recent Kansas studies show.


2. Catching the Oncoming Radiation Storm

Improved processing enables satellite-based radiation sensors to match ground-based sensors in providing prompt warnings of the onset of atmospheric radiation storms that can endanger civil aviation.


III. Biogeosciences

1. Radiocarbon in the Oceans

Offsets in radiocarbon concentration within the ocean or between the ocean and the atmosphere are particularly useful proxies for a variety of studies.


2. Australian Algae Aid Understanding of Ecosystem Resilience

Wildfires may have driven a critical ecosystem transition in Tasmania’s Lake Vera more than 800 years ago.


IV. Hydrology, Cryosphere & Earth Surface

1. Testing the Waters: Mobile Apps for Crowdsourced Streamflow Data

Citizen scientists keep a watchful eye on the world's streams, catching intermittent streams in action and filling data gaps to construct a more complete hydrologic picture.


V. Ocean Sciences

1. Scientists Examine Novel Options to Save Coral Reefs

Warming events prompt scientists to look at ecological, genetic, and engineering interventions.


2. Study Proposes Link Between Supercontinents, Ocean Tides

New findings have implications for the formation of our planet, its climate and the evolution of life on Earth.


VI. Geophysical Research Letters

1. Remote Drying in the North Atlantic as a Common Response to Precessional Changes and CO2 Increase Over Land

Here we demonstrate that changes of the North Atlantic subtropical high and its regional rainfall pattern during mid‐Holocene precessional changes and idealized 4xCO2 increase can both be understood as a remote response to increased land heating near North Africa. Despite different sources and patterns of radiative forcing (increase in CO2 concentration versus changes in orbital parameters), we find that the pattern of energy, circulation, and rainfall responses in the Northern Hemisphere summer subtropics are remarkably similar in the two forcing scenarios because both are dominated by the same land‐sea heating contrast in response to the forcing. An increase in energy input over arid land drives a westward displacement of the coupled North Atlantic subtropical high‐monsoon circulation, consistent with increased precipitation in the Afro‐Asia region and decreased precipitation in the America‐Atlantic region. This study underscores the importance of land heating in dictating remote drying through zonal shifts of the subtropical circulation.


2. Dynamics of Internal Tides Over a Shallow Ridge Investigated With a High‐Resolution Downscaling Regional Ocean Model

This study investigates the dynamics of tidally induced internal waves over a shallow ridge, the Izu‐Ogasawara Ridge off the Japanese mainland, using a downscaled high‐resolution regional ocean numerical model. Both the Kuroshio and tides contribute to the field of currents in the study area. The model results show strong internal tidal energy fluxes over the ridge, exceeding 3.5 kW m?1, which are higher than the fluxes along the Japanese mainland. The flux in the upstream side of the Kuroshio is enhanced by an interaction of internal waves and currents. The tidal forcing induces 92% of the total internal wave energy flux, exhibiting the considerable dominance of tides in internal waves. The tidal forcing enhances the kinetic energy, particularly in the northern area of the ridge where the Kuroshio Current is not a direct influence. The tidal forcing contributes to roughly 30% of the total kinetic energy in the study area.


3. A Deep Learning Algorithm of Neural Network for the Parameterization of Typhoon‐Ocean Feedback in Typhoon Forecast Models

Two algorithms based on machine learning neural networks are proposed—the shallow learning (S‐L) and deep learning (D‐L) algorithms—that can potentially be used in atmosphere‐only typhoon forecast models to provide flow‐dependent typhoon‐induced sea surface temperature cooling (SSTC) for improving typhoon predictions. The major challenge of existing SSTC algorithms in forecast models is how to accurately predict SSTC induced by an upcoming typhoon, which requires information not only from historical data but more importantly also from the target typhoon itself. The S‐L algorithm composes of a single layer of neurons with mixed atmospheric and oceanic factors. Such a structure is found to be unable to represent correctly the physical typhoon‐ocean interaction. It tends to produce an unstable SSTC distribution, for which any perturbations may lead to changes in both SSTC pattern and strength. The D‐L algorithm extends the neural network to a 4 × 5 neuron matrix with atmospheric and oceanic factors being separated in different layers of neurons, so that the machine learning can determine the roles of atmospheric and oceanic factors in shaping the SSTC.


4. Investigating Source Contributions of Size‐Aggregated Aerosols Collected in Southern Ocean and Baring Head, New Zealand Using Sulfur Isotopes

Marine sulfate aerosols in the Southern Ocean are critical to the global radiation balance, yet the sources of sulfate and their seasonal variations are unclear. We separately sampled marine and ambient aerosols at Baring Head, New Zealand for 1 year using two collectors and evaluated the sources of sulfate in coarse (1–10 μm) and fine (0.05–1 μm) aerosols using sulfur isotopes (δ34S). In both collectors, sea‐salt sulfate (SO42?SS) mainly existed in coarse aerosols and nonsea‐salt sulfate (SO42?NSS) dominated the sulfate in fine aerosols, although some summer SO42?NSS appeared in coarse particles due to aerosol coagulation. SO42?NSS in the marine aerosols was mainly (88–100%) from marine biogenic dimethylsulfide (DMS) emission, while the SO42?NSS in the ambient aerosols was a combination of DMS (73–79%) and SO2 emissions from shipping activities (~21–27%). The seasonal variations of SO42?NSS concentrations inferred from the δ34S values in both collectors were mainly controlled by the DMS flux.


5. Coral‐Derived Western Pacific Tropical Sea Surface Temperatures During the Last Millennium

Reconstructions of ocean temperatures prior to the industrial era serve to constrain natural climate variability on decadal to centennial timescales, yet relatively few such observations are available from the west Pacific Warm Pool. Here we present multiple coral‐based sea surface temperature reconstructions from Yongle Atoll, in the South China Sea over the last ~1,250 years (762–2013 Common Era [CE]). Reconstructed coral Sr/Ca‐sea surface temperatures indicate that the “Little Ice Age (1711–1817 CE)” period was ~0.7°C cooler than the “Medieval Climate Anomaly (913‐1132 CE)” and that late 20th century warming of the western Pacific is likely unprecedented over the past millennium. Our findings suggest that the Western Pacific Warm Pool may have expanded (contracted) during the Medieval Climate Anomaly (Little Ice Age), leading to a strengthening (weakening) of the Asian summer monsoon, as recorded in Chinese stalagmites.


6. New Mass‐Conserving Bedrock Topography for Pine Island Glacier Impacts Simulated Decadal Rates of Mass Loss

High‐resolution ice flow modeling requires bedrock elevation and ice thickness data, consistent with one another and with modeled physics. Previous studies have shown that gridded ice thickness products that rely on standard interpolation techniques (such as Bedmap2) can be inconsistent with the conservation of mass, given observed velocity, surface elevation change, and surface mass balance, for example, near the grounding line of Pine Island Glacier, West Antarctica. Using the BISICLES ice flow model, we compare results of simulations using both Bedmap2 bedrock and thickness data, and a new interpolation method that respects mass conservation. We find that simulations using the new geometry result in higher sea level contribution than Bedmap2 and reveal decadal‐scale trends in the ice stream dynamics. We test the impact of several sliding laws and find that it is at least as important to accurately represent the bedrock and initial ice thickness as the choice of sliding law.


VII. AGU Blogs

1. Tohoku tsunami impacted home-building habits of eco-engineer heart urchins

In a new study published in the Journal of Geophysical Research: Oceans, a journal of the American Geophysical Union, researchers explore how tsunamis impact shallow marine environments, also known as benthic environments, and the small, burrowing animals that dwell there.


2. Scientists decipher the magma bodies under Yellowstone

Using supercomputer modeling, scientists have unveiled a new explanation for the geology underlying recent seismic imaging of magma bodies below Yellowstone National Park.


3. Castell de Mur: a major, fatal rockslide in Spain on Monday

On Monday a major rockslide occurred at Castell de Mur, in Catalonia, Spain.  Estimates suggest that this rockslope failure had a mass of about 50,000 tonnes, and a volume of about 20,000 cubic metres.  As the image below shows, the landslide came off of a steep scarp and swept across and buried a highway.  Unfortuntaley there was a car on the road at the time, and the two occupants were killed.  This image, tweeted by the local fire and rescue service, provides a good overview of the landslide.


4. Candelaria mine: a large rockslide in October 2017

The Candelaria mine is a large open-cast copper pit located in the Atacama region of northern Chile, and run by the Lundin Mining Corporation.  Back in October 2017 this mine suffered a major rockslide that inhibited operations.  In December 2017 the CEO of the company apologised to investors for the low level of communication around the rockslide.  The share value of the parent company lost 16% of their value when it was revealed that production would be cut by 20%, although that has partially (not completely) recovered since.


5. Sols 2025-2026: From Float Rocks to Suilven Ripple

Over the weekend Curiosity completed a 13 meter drive from some interesting float rocks including some potential breccias to ‘Suilven Ripple’, a sand ripple where it will characterize the grain sizes and ripple morphology.




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