Plain Language Summaries Collection

Plain Language Summaries are published alongside a paper’s scientific abstract, and are a great way to communicate your work to a broader audience. Submitting a Plain Language Summary is now an option across all AGU Journals. We showcase some good examples here. Find out more about how to write a good Plain Language Summary.


Exploring the Utility of IASI for Monitoring Volcanic SO2 Emissions by Isabelle A. Taylor, et al in JGR: Atmospheres

Gas emissions at volcanoes are dangerous to health and can alter the environment and climate. Monitoring the gases emitted is therefore important, and it gives volcanologists some insight into volcanic behavior. Ground‐based monitoring can be dangerous and is limited in remote regions, and so satellite imagery is used to detect and measure volcanic gas emissions (usually sulfur dioxide [SO2]) across the globe. This study focused on the Infrared Atmospheric Sounding Interferometer, which is an infrared sensor onboard two meteorological satellites. First, a fast tool was used to detect emissions of SO2 across the globe: including from explosive volcanic activity, smaller eruptions, and human pollution sources. Following this, a second method was applied to calculate the amount of SO2emitted from volcanoes in Ecuador and Kamchatka (Eastern Russia)—two regions with regular volcanic activity. This technique was shown to capture changing levels of volcanic activity in both areas. At Tungurahua, a volcano in Ecuador, comparisons could be made to another satellite and to measurements made on the ground. The three methods compared well suggesting that the technique developed for Infrared Atmospheric Sounding Interferometer can capture changing activity at this volcano and could be valuable for tracking and quantifying emissions.

Long‐lasting response of the global thermosphere and ionosphere to the 21 August 2017 solar eclipse by Jiuhou Lei, et al in JGR: Space Physics

The thermosphere is the layer of the Earth’s atmosphere above the mesosphere between about 60 and 1000 km, and the ionosphere is the ionized part of the atmosphere. In this region, the neutral gas and the ionized plasma have significant impact on low Earth orbiting determination and satellite radio communications. This work is the first to use a stateofart, firstprinciples model of the coupled thermosphere and ionosphere, with selfconsistent electrodynamics, to systematically investigate the dynamics and electrodynamic behavior of the global ionosphere and thermosphere after an eclipse. Although the solar eclipse is a transient local event, its impact on the ionosphere and thermosphere can persist for a long time over the entire globe, rather than just being an impulse event with a localized response as was previously expected. This effort paves the way for improving the understanding of the upper atmospheric variability.

Quantifying Debris Thickness of Debris‐Covered Glaciers in the Everest Region of Nepal Through Inversion of a Subdebris Melt Model by David R. Rounce, et al in JGR: Earth Surface

Debris‐covered glaciers are ubiquitous in the Himalaya and this debris significantly alters the evolution of these glaciers. Estimating the thickness of debris on these glaciers, however, remains a challenge. This study develops a novel method for estimating the debris thickness on three glaciers in the Everest region of Nepal based on digital elevation models, surface velocity data, ice thickness estimates, and a debris‐covered glacier energy balance model. The method was calibrated and validated on Ngozumpa Glacier, one of the largest debris‐covered glaciers in Nepal, and was found to accurately estimate debris thickness. Specifically, this method was able to estimate thick debris (> 0.5 m), which has been a major limitation of previous studies. This is important because thick debris significantly reduces glacier melt rates by insulating the underlying ice. This study creates a step‐change in our ability to model the past, present, and future evolution of debris‐covered glaciers. 

Episodes of aqueous flooding and effusive volcanism associated with Hrad Vallis, Mars by Christopher W. Hamilton, et al in JGR: Planets

The Elysium Volcanic Province of Mars includes major outflow channels that are interpreted to have been carved by either catastrophic aqueous floods or turbulent lava flows. Determining the origin of these channels is therefore important for determining the hydrological and volcanic history of the planet. This study focuses on Hrad Vallis, which is a geologically recent outflow channel within the Elysium Volcanic Province. Through a combination of mapping and modeling, we find evidence for both aqueous flooding and effusive volcanism associated with this channel, indicating a complex hydrologic and geologic history. However, lava flows are interpreted to be the products of pāhoehoe‐like lava flow emplacement, similar to terrestrial lava flows on Earth in New Mexico and Hawaii, and not highly turbulent flows as previously suggested. The identification of ~50 m thick pāhoehoe‐like lava flows near Hrad Vallis implies a gradual formation process over the course of decades and heat from these lava flows may have interacted with ground ice in the region to generate meltwater and steam. Associated lava‐water interactions are important because they could have developed habitable environments for microbial organisms adapted for survival within hydrothermal systems. 

Browning‐related decreases in water transparency lead to long‐term increases in surface water temperature and thermal stratification in two small lakes by Rachel M. Pilla, et al in JGR: Biogeosciences

Lakes provide key services to society ranging from drinking water and food to recreation and increased property value. But lakes are vulnerable to many environmental threats, including climate change. Two study lakes in Pennsylvania have experienced decreases in water clarity as the water has become more brown over the past three decades. As a result, sunlight and heat are more completely absorbed near the surface of the lake, with less light and heat reaching deeper waters. This leads to warmer surface waters and cooler deep waters. We attribute the reduced water clarity and changes in lake temperature to recovery from acid rain following the Clean Air Act amendments in the 1990s, combined with climate change‐induced increases in precipitation and storm events in the northeastern United States that increase runoff of organic matter into lakes. These changes are influencing other aspects of the lake ecosystem by accelerating oxygen depletion and altering the abundance of and habitat availability for algae, zooplankton, and fish. 

A Field Guide to Finding Fossils on Mars by S. McMahon, et al in JGR: Planets

This paper reviews the rocks and minerals on Mars that could potentially host fossils or other signs of ancient life preserved since Mars was warmer and wetter billions of years ago. We apply recent results from the study of Earth’s fossil record and fossilization processes, and from the geological exploration of Mars by rovers and orbiters, in order to select the most favored targets for astrobiological missions to Mars. We conclude that mudstones rich in silica and iron‐bearing clays currently offer the best hope of finding fossils on Mars and should be prioritized, but that several other options warrant further research. We also recommend further experimental work on how fossilization processes operate under conditions analogous to early Mars. 

Seasonal non‐tectonic loading inferred from cGPS as a potential trigger for the M6.0 South Napa Earthquake by Meredith L. Kraner, et al in JGR: Solid Earth

It is well established that earthquakes occur on fault systems where stress has accumulated over periods of centuries to millennia. The specific factors that trigger individual earthquakes are typically unknown, but researchers have recently found links between seasonal variations in earthquake occurrence and local changes in water storage and temperature. Using data from high‐precision continuous GPS stations in Northern California, we observed a small 3 mm horizontal expansion of the Earth’s crust prior to and in the vicinity of the August 2014 M6.0 South Napa earthquake. By analyzing the previous eight years of GPS data, we additionally found that a similar pattern of crustal motion repeats every summer. We have determined that this crustal expansion releases pressure on nearby faults, including those in the South Napa fault system, making them more likely to slip during the summer months. Large seasonal variability in the amount of groundwater in the Napa Valley and Sonoma subbasins may contribute to the observed changes. 

Understanding the Twist Distribution Inside Magnetic Flux Ropes by Anatomizing an Interplanetary Magnetic Cloud by Yuming Wang, et al in JGR: Space Physics

Magnetic Flux rope (MFR) is a fundamental structure in the universe filled with plasmas, and related to various eruptive phenomena, e.g., mass ejections, jets, etc. How the magnetic twist distributes in a MFR is key information in understanding many puzzles: e.g., (1) why a very-long (thousands of light-years long) and high-twist astrophysical jet can exist, (2) whether or not a seed MFR exists prior to coronal mass ejections, which is a long debate in the solar physics, and (3) when a MFR gets kink-unstable. Here, we try to address these puzzles by presenting a rare observed MFR, namely magnetic cloud, in interplanetary space. Four spacecraft near Mercury, Venus, Earth and Mars, respectively, observed the magnetic cloud sequentially in time and space. By analyzing the in-situ measurements of the magnetic cloud, we find that the axial flux and helicity decreased with the heliocentric distance but the twist increased. The ‘pancaking’ effect and ‘erosion’ effect may jointly cause such variations. The erosion effect suggests that the magnetic cloud might consist of a strong-twist core and a less-twisted outer shell, posing a great challenge to the current understanding on the solar eruptions as well as the formation and instability of MFRs. 

In situ microphysical observations of the 29‐30 May 2012 Kingfisher, OK supercell with a balloon‐borne video disdrometer by Sean M. Waugh, et al in JGR: Atmospheres

A microphysics instrument capable of measuring the number, size, shape, and composition of particles inside thunderstorms has been developed that flies on a weather balloon. The observations collected are compared to radar observations and some aspects of computer models that validate what these other tools are seeing and shows room for improvements. These observations are providing a unique and unprecedented look at the details of in situ particle concentrations. Understanding of the processes responsible for the formation and maintenance of these particles can lead to advances in forecasting ability and real time decision making. 

The impacts of Chinese wind farms on climate by Hongwei Sun, et al in JGR: Atmospheres

With the rapid development of wind energy, the impacts of wind farms on environment have attracted increasing attention. A new wind farm fleet scenario is designed in the study to analyze the climatic impacts of wind farms in China. The results show the local and regional climatic impacts of wind farms in China (e.g., changes within {plus minus}0.5 K for 2-m temperature and {plus minus}30 m2/s2 for 500-hPa geopotential height), which are much smaller than the natural climate variability. This research can provide China, as well as other countries and regions, with useful scientific advice for the environment-friendly development of wind energy. 

Interfacial Form Stress in the Southern Ocean State Estimate by Jessica Masich, et al in JGR: Oceans

Winds over the Southern Ocean blow towards the east, continuously inputting eastward momentum into the ocean. This eastward momentum is balanced by the landmasses and undersea ridges that block the Antarctic Circumpolar Current (ACC)’s eastward path around Antarctica. We analyze a high-resolution model of the Southern Ocean to map interfacial form stress (IFS), the mechanism by which momentum travels from wind source to topographic sink. We conduct this analysis in a new, unique way, by calculating the pressure exerted from one ocean layer to another for every day in the six-year model run; this analysis shows where lighter layers are ‘leaning’ against denser layers and thus transferring eastward momentum downward from lighter to denser ocean layers. We find that IFS mostly concentrates where there are large-scale meanders in the ACC, and to a lesser degree in regions where the Southern Ocean is mixed by eddies. 

Observations of Surface Wave Dispersion in the Marginal Ice Zone by Clarence Collins, et al in JGR: Oceans

The relationship between wavelength and wave period is known as the dispersion relation. The dispersion relation is well known for waves on the open ocean. The relationship is altered by shallow water and by changing currents at the surface, but we do not know if it is altered by ice cover. In this study we present measurements of the dispersion relation in the marginal ice zone, the transition zone between open areas of ocean and areas dominated by ice cover. The measurements were tricky, so there is a good deal of uncertainty involved. We found that dispersion of long period waves was not affected by ice in this zone, but under certain circumstances, the short period waves were slightly reduced in wavelength. This reduction in wavelength was consistent with a theory which adjust dispersion for the added weight of the ice.

Denali ice core methanesulfonic acid records north Pacific marine primary production by David J. Polashenski, et al in JGR: Atmospheres

The base of the marine food web is composed of single-celled photosynthetic organisms that are collectively termed primary producers. Because these microscopic organisms support all marine life, changes in their biomass can impact the entire food web. Over the past three decades, satellite data has shown that primary producers are declining around the world with some of the greatest declines occurring in the north Pacific Ocean. The reasons for these declines may include changes in ocean temperatures, nutrient availability, and wind-driven ocean mixing, all of which are related to climate. To place these changes within a longer-term context, we wanted to develop a proxy tool by measuring a chemical produced by phytoplankton, called methanesulfonic acid (MSA). MSA is transported through the atmosphere by storms, which deposit it on mountain glaciers in the north Pacific region. We measured MSA in a new ice core from Denali National Park, Alaska. We describe how we found strong, statistically significant correlations between ice core MSA concentrations and chlorophyll concentrations in the western Gulf of Alaska. We suggest that the ice core MSA proxy record can help us understand how primary production in this region has changed through time and put contemporary changes in context. 

Buoyancy Waves in Earth's Magnetosphere: Calculations for a 2D Wedge Magnetosphere by R. A. Wolf, et al in JGR: Space Physics

Plasma in the near‐Earth region of space exhibits many kinds of ultra‐low‐frequency (ULF) waves. The present paper deals with a specific class of space‐plasma ULF waves that have unique properties and have not been much studied. They can be called “buoyancy waves”, because they are mathematically equivalent to buoyancy waves in a neutral atmosphere, but the buoyancy force in near‐Earth space plasmas is due to magnetic tension rather than gravity. 

This paper develops a theory of near‐Earth‐space buoyancy waves, by considering a simplified geometry for which the wave equations can be solved analytically. The frequency and propagation characteristics of the waves are determined mainly by a parameter called the “buoyancy frequency”, which can be calculated from a mathematical model of near‐Earth space. 

Transient bursts of very rapid flow in Earth’s magnetotail cause buoyancy waves in near‐Earth space. When one of these bursts encounters the strong magnetic field near the Earth, the flow brakes and oscillates a few times before coming to rest. That process generates buoyancy waves that spread out through a region of space, like a raindrop generates ripples in a pond. However, the magnetosphere is highly non‐uniform, causing refraction and reflection. 

The Origin of the Moon Within a Terrestrial Synestia by Simon J. Lock, et al in JGR: Planets

The favored theory for lunar origin is that a Mars‐sized body hit the proto‐Earth and injected a disk of material into orbit, out of which the Moon formed. In the traditional Giant Impact Model the Moon forms primarily from the body that hit Earth and is chemically different from Earth. However, Earth and the Moon are observed to be very similar, bringing the traditional model into question. We present a new model that explains the isotopic and chemical compositions of the Moon. In this model, a giant impact, that is more energetic than in the traditional model, drives the Earth into a fast‐spinning, vaporized state that extends for tens of thousands of kilometers. Such planetary states are called synestias. As the synestia cools, material condenses and forms the Moon. Here we present physical and chemical models of the cooling synestia and predict the pressure and temperature history of the material that forms the Moon. We find that the Moon forms within the synestia, surrounded by Earth‐composition vapor at pressures of tens of bars. The Moon orbits within the synestia long enough to chemically equilibrate with the vaporized Earth. Our calculations predict the chemical similarities between Earth and the Moon. 

Predicting Hydrologic Function With Aquatic Gene Fragments by S. P. Good, et al in WRR

An important task in water resources is prediction of the discharge in rivers and streams at locations where there are no direct measurements. In this study, we show that the flow in a river can be predicted based only on the bacteria that are present in the river. Because different flow conditions create environments in which different groups of bacteria grow, measurements of the diversity of the bacteria community can be used for hydrologic purposes. We call this approach ‘genohydrology‘ and explore different discharge predictions based on streamwater bacteria composition. 

Sea Level Rise Impacts on Wastewater Treatment Systems along the U.S. Coasts by Michelle A. Hummel, et al in Earth's Future

Wastewater treatment plants are susceptible to flooding resulting from sea level rise. Previous estimates of wastewater exposure have only considered the impacts of marine flooding at the local or regional scale. In this analysis, we quantify the exposure to marine flooding across the coastal U.S. and then consider the relative impacts of marine and groundwater flooding at the regional scale in the San Francisco Bay Area. We also estimate the number of people who may lose access to wastewater services if no actions are taken to prevent flooding at wastewater treatment plants. We find that the number of people impacted by sea level rise due to loss of wastewater services could be five times as high as previous predictions of the number of people who experience direct flooding of their homes or property. We also find that groundwater flooding poses a significant threat to wastewater plants in the San Francisco Bay region.

lant Osmoregulation as an Emergent Water‐Saving Adaptation by Saverio Perri, et al in WRR

Soil salinization represents a major threat for the food security and sustainable development of drylands, with salt affected soils – presently covering more than 9 billion ha worldwide – expected to further increase due to climate change, land use modifications and erroneous irrigation/groundwater abstraction practices. Despite this fact, the effects of salinity on the rate at which plants transpire and grow in salt affected soils are rarely considered in ecological and ecohydrological models, and the different processes leading to salt tolerance are yet poorly understood. Here, we introduce a simple model of how salt tolerant species adapt to elevated salt concentrations in the soil, and of how such adaptations substantially lead to plant osmoregulation, as an emergent water-saving behavior similar to the strategies that aridity-tolerant species (xerophytes) use to cope with extreme water scarcity. The bottom line is that salt-tolerant plants experience salt-stress as an alternative form of water-limitation and developed both short- and long-term adaptations accordingly. Our findings are instrumental to a better comprehension of the interplay between soil salinization, salt tolerance and efficient water use that is, in turn, the key to understand the potential of salt-tolerant crops and contrast soil salinization. 

Discovery of a Powerful, Transient, Explosive Thermal Event at Marduk Fluctus, Io, in Galileo NIMS data by A. G. Davies, et al in GRL


A very brief but powerful volcanic explosion has been identified on Io, the highly-volcanic moon of Jupiter, in data collected by the imaging spectrometer on NASA’s Galileo spacecraft in 1997. This event is likely driven by a build-up of gas, resulting in explosive activity, perhaps similar to that regularly seen at Stromboli volcano on Earth. The huge explosion in the Marduk region of Io likely created a myriad of tiny lava fragments that cooled very rapidly, which explains the speed at which the resulting thermal anomaly decayed back to background, pre-explosion levels. Similar events, ideally observed from close to Io by instruments on some future mission to this volcanic wonder, could help answer one of the biggest questions remaining in the wake of the Galileo mission, that of the dominant composition of Io’s highly-voluminous lavas. This determination would be accomplished by measuring the temperature of the lava as it erupts. Such a measurement would strongly constrain Io’s interior composition and current state, which is important for understanding the evolution of the large Galilean satellites (including the ice-covered Europa). 

A 400‐year ice core melt layer record of summertime warming in the Alaska Range by Dominic Winski, et al in JGR: Atmospheres

Warming in mountainous areas affects glacier melt, water resources, and fragile ecosystems, yet we know relatively little about climate change in alpine areas, especially at high latitudes. We use ice cores drilled on Mt. Hunter, in Denali National Park, to develop a record of summer temperatures in Alaska that extends 400 years into the past; farther than any other mountain record in the North Pacific region.  The ice core record shows that 60 times more snowmelt occurs today than 150 years ago.  This corresponds to roughly a 2{degree sign}C increase in summer temperature, which is faster than summertime warming in Alaska near sea level.  We suggest that warming of the tropical Pacific Ocean has contributed to the rapid warming on Mt. Hunter by enhancing high-pressure systems over Alaska.  Our ice core record indicates that alpine regions surrounding the North Pacific may continue to experience accelerated warming with climate change, threatening the already imperiled glaciers in this area.