I.Climate Change
1.Heat Waves,More Than Coral Death,May Cause Fish to Flee Reefs
A study over a broad swath of the Great Barrier Reef shows that warming waters directly cause fish and invertebrates to leave the reef, making it harder for coral to recover from bleaching events.
https://eos.org/articles/heat-waves-more-than-coral-death-may-cause-fish-to-flee-reefs
2.Youth Urge Action on Climate Change and Environmental Justice
Marches on Saturday in Washington, D. C., and other cities spring from “a sliver of hope left” to act against climate change.
https://eos.org/articles/youth-urge-action-on-climate-change-and-environmental-justice
3.500 Years of Atmospheric River Landfalls in Southwestern USA
A network of tree-ring chronologies has been used to develop the first reconstruction of atmospheric river landfalls on the US Pacific Coast over the last 500 years.
https://eos.org/editor-highlights/500-years-of-atmospheric-river-landfalls-in-southwestern-usa
4.Developing a Remote Sensing System to Track Marine Debris
Marine debris has become a huge global problem, and neither governments nor scientific communities are prepared to deal with it. Eighty percent of artificial debris is long-living plastic, which is found nearly everywhere, even in the remote Arctic and Southern Oceans and on the deep ocean floor.
https://eos.org/meeting-reports/developing-a-remote-sensing-system-to-track-marine-debris
II.Science Policy
1.Solidarity Among World’s Scientists Needed Now More Than Ever
Challenged by widespread nationalism and xenophobia, scientific societies must stand together to insist that scientific collaboration remain international and interdisciplinary.
https://eos.org/opinions/solidarity-among-worlds-scientists-needed-now-more-than-ever
1.Clean Energy Gains Ground
A new report documents the rise of clean energy despite the Trump administration’s focus on fossil fuels. Several Congress members call renewable energy a bipartisan issue that’s good for the economy.
https://eos.org/articles/clean-energy-gains-ground
IV.Hazards & Disasters
1.Drones Swoop in to Measure Gas Belched from Volcanoes
A team of volcanologists, chemists, physicists, and engineers from around the world test novel techniques at Central America’s two largest degassing volcanoes.
https://eos.org/project-updates/drones-swoop-in-to-measure-gas-belched-from-volcanoes
V.Space & Planets
1.Measurements of Kelvin-Helmholtz Waves in Earth’s Magnetic Field
Simultaneous satellite observations from different distances of Earth’s magnetic tail offer insight into how these instability waves evolve through time and space.
https://eos.org/research-spotlights/measurements-of-kelvin-helmholtz-waves-in-earths-magnetic-field
VI.Education
1.Ten Steps to a Successful Career Launch
How to use your first months on the job strategically to explore your new role and make the connections that will carry you onward and upward.
https://eos.org/features/ten-steps-to-a-successful-career-launch
VII.Geophysical Research Letters
1.Distinct mechanisms of ocean heat transport into the Arctic under internal variability and climate change
Northward ocean heat transport (OHT) plays a key role in Arctic climate variability and change. Unforced climate model simulations suggest that at decadal and longer timescales, strengthened Atlantic Meridional Overturning Circulation (AMOC) is correlated with increased OHT into the Arctic. Yet, greenhouse‐gas (GHG) forced simulations predict increased Arctic OHT while AMOC weakens. Here we partition OHT changes into contributions from ‘dynamic’ circulation changes and ‘thermodynamic’ temperature advection, as well as meridional overturning and gyre changes. We find that under decadal‐scale internal variability, strengthened AMOC converges heat in the subpolar gyre; anomalous heat is advected into the Arctic by both time‐mean circulations and strengthened gyre circulations. Under GHG forcing, weakened AMOC reduces subpolar gyre heat convergence; yet Arctic OHT increases as mean overturning and strengthened gyre circulations advect warmed surface waters. Thus, caution should be exercised when inferring Arctic OHT from AMOC, as the relationship between OHT and AMOC changes depends on whether they are internally generated or externally forced.
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078719
2.Magnetosonic harmonic falling and rising frequency emissions potentially generated by nonlinear wave‐wave interactions in the Van Allen radiation belts
Magnetosonic waves play a potentially important role in the complex evolution of the radiation belt electrons. These waves typically appear as discrete emission lines along the proton gyrofrequency harmonics, consistent with the prediction of the local Bernstein mode instability of hot proton ring distributions. Magnetosonic waves are nearly dispersionless particularly at low harmonics and therefore have the roughly unchanged frequency‐time structures during the propagation. On the basis of Van Allen Probes observations, we here present the first report of magnetosonic harmonic falling and rising frequency emissions. They lasted for up to 2 h and occurred primarily in the dayside plasmatrough following intense substorms. These harmonic emission lines were well spaced by the proton gyrofrequency but exhibited a clear falling (rising) frequency characteristic in a regime with the temporal increase (decrease) of the proton gyrofrequency harmonics. Such unexpected structures might be produced by the nonlinear interactions between the locally generated magnetosonic waves at the proton gyrofrequency harmonics and a constant frequency magnetosonic wave propagating away from the Earth.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079232
3.Groundwater flow and exchange across the land surface explain carbon export patterns in continuous permafrost watersheds
Groundwater flow regimes in the seasonally‐thawed soils in areas of continuous permafrost are relatively unknown despite their potential role in delivering water, carbon, and nutrients to streams. Using numerical groundwater flow models informed by observations from a headwater catchment in arctic Alaska, USA, we identify several mechanisms that result in substantial surface‐subsurface water exchanges across the land surface during downslope movement and create a primary control on dissolved organic carbon (DOC) loading to streams and rivers. The models indicate that surface water flowing downslope has a substantial groundwater component due to rapid surface‐subsurface exchanges across a range of hydrologic states, from unsaturated to flooded. Field‐based measurements corroborate the high groundwater contributions, and river DOC concentrations are similar to that of groundwater across large discharge ranges. The persistence of these groundwater contributions in arctic watersheds will influence carbon export to rivers if thaw depth increases in a warmer climate.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078140
4.Plasma Dynamics Associated with Equatorial Ionospheric Irregularities
The Communication/Navigation Outage Forecasting System (C/NOFS) satellite was operational from 2008, a period of deep solar minimum, to 2015, a period of moderate solar conditions. The behavior of the vertical plasma drift and the distribution of plasma depletions during the deep solar minimum of 2009 deviated substantially from the behavior that was observed during the solar moderate conditions encountered by the C/NOFS satellite in 2014, which are typical of previous observations. Presented here are observations of the vertical drift of plasma depletions and the background plasma in which they are embedded. We find that depletions detected at local times after 2100 h during solar minimum are typically found in background drifts that are weakly downward compared to the strongly downward background drifts observed during moderate solar activity levels. Additionally at solar minimum, the drift within the depletions is upward with respect to the background as compared with observations at the same local times during solar moderate conditions for which the depleted plasma more nearly drifts with the background. We note that weak background plasma drifts observed throughout the night during solar minimum promote the continued growth of depletions that may evolve more slowly or be continuously generated to appear in the topside in the postmidnight hours.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078560
VIII.AGU Blogs
1.Turtles, trees and jackrabbits: Public school students head to the river
Summer at BEMP brings together some of our favorite people, the Horizons Albuquerque community! Horizons is a national summer enrichment program that addresses summer learning loss for public school students. Students return to the program each summer to study and grow together. They continue to get support from their Horizons teachers throughout the school year, at tutoring and monthly events. BEMP has been partnering with Horizons Albuquerque for the last 5 years. In between their reading, math, swimming, music, and art, each class makes time to explore and conduct research in the bosque with BEMP.
https://blogs.agu.org/thefield/2018/07/23/turtles-trees-and-jackrabbits-public-school-students-head-to-the-river/
2.Research provides new clues to origins of mysterious atmospheric waves in Antarctica
Two years after a research team discovered a previously unknown class of waves rippling continuously through the upper Antarctic atmosphere, they’ve uncovered tantalizing clues to the waves’ origins. The interdisciplinary science team’s work to understand the formation of “persistent gravity waves” promises to help researchers better understand connections between the layers of Earth’s atmosphere—helping form a more complete understanding of air circulation around the world.
https://blogs.agu.org/geospace/2018/07/25/research-provides-new-clues-to-origins-of-mysterious-atmospheric-waves-in-antarctica/
