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.
Previous studies have examined the presence of the bacterium Staphylococcus aureus on marine beaches, but a rigorous study of freshwater beaches was lacking. We investigated S. aureus presence and proximity to wastewater treatment plants on 10 beaches in Northeast Ohio. We found S. aureus in 22.8% of our samples (64/280). Prevalence was higher in summer than fall. Prevalence was also higher in sites with wastewater treatment plants close to the beaches.
Large areas of Earth’s seafloor are traversed by submarine canyons that bear similarities to canyon and gully systems that are known on land. As submarine canyons erode down into the seafloor, they can significantly alter temperature and pressure in the sediments beneath the seafloor. In certain water depths, these environmental changes influence the formation of gas hydrates – ice like compounds of natural gas. In this study, we show how concentrated deposits of gas hydrate can form at depth beneath the seafloor as a result of canyon formation. It is important to understand interactions between submarine canyons and gas hydrate systems because both play key roles in supporting diverse seafloor ecosystems. Additionally, natural gas from concentrated gas hydrate deposits represents a possible future energy resource in the transition to cleaner energy alternatives.
The solar wind that flows out from the Sun and pervades our solar system is largely deflected around Mars by its interaction with the upper atmosphere. However, this interaction also transfers energy to planetary ions, giving some of them sufficient velocity to escape from Mars. Therefore, the Mars-solar wind interaction has implications for the long-term evolution of the Martian atmosphere and its habitability. In this work, we study the structure and variability of the interaction and the macroscopic forces responsible for decelerating and deflecting the solar wind around Mars as well as those that accelerate planetary ions. We also investigate the asymmetries in this interaction and how they change in response to variations in the incoming solar wind flow and the magnetic field carried with the flow.
In this report, we show the first high-quality, and wide-field-of-view (FOV) image of Earth’s hydrogen corona of 100 Earth radii (RE) obtained by the first interplanetary microspacecraft. Because hydrogen geocorona has not been observed since Apollo 16 in 1972, which observed only up to 10 RE of FOV. The field of view of our observation is ~10 times wider than that in past. Furthermore, since the advancement in deep UV detection technology in the last four decades is very large, the improvement in data quality is very large. In fact, our newly obtained data strongly supports a different picture for geocorona distribution. More specifically, we found that the observed ecliptic north-south symmetrical distribution can be reproduced by a simple analytic model and is not consistent with past results. Our result strongly suggests a combination between a compact science instrument and a flexible interplanetary microspacecraft allows us to measure important scientific observables not readily accessible with conventional large-scale spacecraft missions.
In the North Atlantic Ocean, immense amounts of hot material rises up beneath Iceland from deep within Earth’s mantle, forming a gigantic pancake-shaped upwelling. This upwelling, known as the Iceland mantle plume, is the largest on Earth and plays a key role in determining the depth and shape of the North Atlantic Ocean over thousands of kilometers. A pattern of distinctive V-shaped ridges and troughs that are hundreds of kilometers long and tens of kilometers wide occur on the seabed south of Iceland. These V-shaped ridges are thought to have been generated by waxing and waning of the plume, but their precise origin is hotly debated. Here we use an acoustic (i.e., seismic) survey, spanning the North Atlantic Ocean to image these features. We assess competing hypotheses for their formation and argue that they are indeed an indirect record of plume activity through time. Pulses of hot material appear to be generated every 3 to 8 Ma. As they spread beneath adjacent tectonic plates, these pulses cause vertical movements that trigger changes in ancient oceanic circulation.
Ceres is the largest body in the asteroid belt. Unlike most of the objects in that region of the solar system, Ceres has a round shape due to its sufficient gravity. Little was known about Ceres before the Dawn mission. The measurements by the Dawn spacecraft allowed precise determination of Ceres’ shape and gravity field. We use these two data sets to understand its internal structure. It was predicted in the past that Ceres topography would quickly viscously relax if Ceres had an icy crust. We find only a modest evidence of viscous relaxation, which implies that Ceres’ crust is much stronger than water ice. We also find that Ceres topography is isostatically compensated. That is, much like with a floating iceberg, the weight of mountains is compensated by a displaced volume of the underlying mantle. Such a simple model explains most of Ceres’ gravity anomalies. However, some gravity anomalies remain unaccounted for. For example, we find evidence for a mass concentration analogous to those in lunar maria in the two biggest impact basins. A strong negative anomaly is observed around Occator—the famous bright spot crater. A strong positive anomaly is centered at Ahuna Mons—a unique pyramid-shaped mountain. The globally averaged crustal density that we find is rather low. Remarkably, Ceres crust is made out of a strong, rock-like material that, however, has a density much lower than that of rocks. This implies that Ceres’ crust contains a lot of salts and clathrates, which are strong and light materials.
A picture being worth a thousand words is not always a good thing. When a satellite picture of a complex environmental scene contains too much information, it can be hard to make sense of it all. Simple attempts to distill the information into colorful displays to ‘enhance’ a certain feature can be helpful, but sometimes they can do more harm than good. Problems arise when parts of the image share properties with the feature of interest, masquerading as false alarms and confusing our interpretation. This work attempts to reduce the chances of false alarms happening by accounting for them ahead of time. The Dynamic Enhancement Background Reduction Algorithm (DEBRA), applied in this paper to satellite-detected dust storms, accounts for land surfaces that ‘look like dust’ under non-dusty conditions, and then adjusts the sensitivity of the detection tests accordingly. The result is a numerical measure of our confidence in there being dust present. DEBRA can be communicated as simple, visually intuitive imagery where the only colors involved pertain to the feature of interest—the rest is portrayed as gray scale. The resulting picture may no longer be worth a thousand words, but its added utility to forecasters speaks volumes.
We measured the Moon’s temperature cycles with the Lunar Reconnaissance Orbiter’s Diviner instrument to make the first global maps of important physical properties of the dusty surface layer. These maps reveal a rich new view of the last billion years of impact processes and volcanism on the Moon. Impacts by meteorites cause the breakdown of rocks and accumulation of regolith – the granular surface materials. Our results show that regolith formation is a rapid process, which homogenizes and redistributes fine particles over large distances. These new observations provide a wealth of data for future study, and also suggest a new technique for determining the ages of craters on the Moon and other planetary surfaces, using temperatures to infer the depth of accumulated regolith.
One of the best ways we have of knowing how the upper atmosphere is moving is by making measurements from the ground. These measurements are of naturally occurring light in the upper atmosphere known as airglow. The Doppler shift of this light tells us the movement. We can similarly measure the temperature. The problem is that the atmosphere is in between our instruments and the airglow, and a previous study revealed that the way it scatters light during active times can confuse us into thinking that the upper atmosphere is moving vertically, much too fast to agree with theory. In this study, we look at the horizontal artifacts, especially during quiet times, and develop a theory that lets us correct our measurements. We also show some actual measurements that are able to independently validate this correction, at least for temperature.
Solar radio bursts are radio emissions from the Sun that can interfere with communication, radar and navigation systems (for example GPS). This paper examines the Radio Solar Telescope Network (RSTN)data archive of solar radio burst events at the National Centers for Environmental Information for the period 1966 to 2010. We show that the archive is missing substantial events. We also show that different sites within RSTN show statistically different burst rates at the frequency of 245 MHz. We also show that different sunspot cycles can have different radio burst distributions at 245 MHz. That is to say the sunspot cycles can vary and that they should not be considered identical. Prediction of future solar events will be an underestimate of the true burst rate due to the deficiencies in the data archives.
When a tornado touches down, its winds and air pressure shake the ground, creating small, but measurable, seismic waves. We look at these waves created by the Joplin tornado in Missouri (2011), which happened to pass close to a seismometer. We modeled these waves to find out how large of a force the tornado is exerting on the ground. We found that the force is largest during the time when the tornado was reported to be strongest (EF 4–5 on the Enhanced Fujita Scale) and smallest when the tornado was weak (EF 0–2). Further understanding this relationship could open a new way to study the strength of tornadoes by seismic waves.
The amount of carbon dioxide seeping out of the Earth’s surface is poorly understood. Magma carries dissolved carbon dioxide from the deep earth towards the surface, where it is released and travels along fractures in the crust. This study attempts to quantify this phenomenon in central Ethiopia, where a continental rift is splitting one tectonic plate in two. In Kenya and Tanzania, a similar study suggested that the flow of carbon dioxide through the East African Rift was much larger than previously thought. We undertook new surveys and found that it varies greatly, which makes estimating a total flow through the rift very difficult. The distribution of hot springs and volcanic vents provides clues concerning where heat and carbon dioxide come to the surface – by compiling the locations of these features we were able to extrapolate from our surveys for a new estimate. Our results suggest that the East African Rift releases less carbon dioxide than was thought from Kenya and Tanzania, but still a substantial amount. If the rift does emit as much carbon dioxide as suggested, either more carbon is below the crust in East Africa than we thought or more magma is involved.
Since most Antarctic meteorological observations start around 1957, very little is known about atmospheric pressure variability across Antarctica throughout the entire twentieth century. Yet changes in the atmospheric circulation around Antarctica have been linked to warming across West Antarctica, the lack of warming in East Antarctica, and changes in the sea ice surrounding Antarctica. To better understand the significance of these changes in a historical context, a new spatially complete summer pressure reconstruction is generated and evaluated in this paper. Through the high quality of this reconstruction, we determine that only across East Antarctica are pressure changes significant when in context of the full twentieth century; over portions of the South Atlantic coastal sector of Antarctica, the early twentieth century was marked with pressure increases. Using a suite of climate model simulations, we determine that other factors, including tropical sea surface temperatures, are needed in order to fully replicate the recent negative summer pressure trends that have occurred across the entire continent. This work therefore highlights the role of natural variability in Antarctic pressure during the twentieth century, and the need to consider multiple mechanisms beyond ozone depletion to understand recent Antarctic pressure changes.
Clear-air turbulence is potentially hospitalizing in-flight bumpiness experienced by aircraft. Often, pilots cannot avoid it, because it is invisible to the naked eye and undetectable by onboard sensors. Previous research suggests that climate change will increase instabilities in the North Atlantic jet stream in winter, generating more clear-air turbulence. This study analyzes changes to clear-air turbulence over the entire globe by the second half of this century. We consider eight geographic regions, two flight levels, five turbulence strength categories, and all four seasons. We find strong increases in clear-air turbulence over the entire globe and in particular the midlatitudes, which is where the busiest flight routes are. We also find that the strongest turbulence will increase the most, highlighting the importance of improving turbulence forecasts and flight planning to limit discomfort and injuries to passengers and crew.
Viewed from a satellite above Earth, the Yakima folds are west-trending, mountain-scale ridges that protrude out of an otherwise flat landscape in central Washington, USA. The problem we address is understanding how the Yakima folds originated. What processes account for their character? Over what time period did the folds form? Are the folds associated with faults that produce earthquakes? To address these questions, we did geologic mapping, we used seismic and gravity surveys and we investigated high resolution images. Our results indicate that the folds are underlain by faults, and the faults have been active for the last 15 million years. The faults are still active and have generated earthquakes within the last 100,00 years. We also propose a framework to understand how the faults and folds in central Washington define the overall tectonic setting of the eastern portion of the Cascadia subduction zone. Our work is important because first, we corroborate the findings of earlier investigators that the Yakima fault-cored folds are seismically active, and second, we put the folding and faulting of the Yakima folds province within a general tectonic model. The model helps inform geologists how Earth’s crust is deforming in the Pacific northwest.
Aerosols are small particles in the atmosphere like desert dust, volcanic ash, smoke, industrial haze, and sea spray. Understanding them is important for applications such as hazard avoidance, air quality and human health, and climate studies. Satellite instruments provide an important tool to study aerosol loadings over the world. This paper evaluates a new satellite-based data set of aerosol loading, from a set of instruments called the Advanced Very High Resolution Radiometers (AVHRRs), using ground-based observations and by comparing to other satellite data products.
The ocean and atmosphere conditions of a extraordinarily abrupt termination of one of the most intense El Niño event ever recorded are replicated in unprecedented detail by using our newly developed global high-resolution atmosphere-ocean numerical model on one of the top-tier super-computers. Results show that a huge envelope of stormy activity centered over the Indonesian archipelago remotely enhanced easterly winds over the eastern Pacific ocean, which drove upward motion of cold water to the surface to suddenly end the El Niño condition. The newly developed model may improve predictions of weather tendencies and tropical cyclone probabilities at the sub-seasonal to seasonal time-range.
Lightning results from strong storms lifting cloud drops up to high altitudes where freezing occurs and collisions between drops, graupel, and ice crystals lead to electrification. Thus, lightning is an indicator of storm intensity and sensitive to the microphysics of cloud drop formation, interactions, and freezing. We find that lightning is nearly twice as frequent directly over two of the world’s busiest shipping lanes in the Indian Ocean and the South China Sea. The lightning enhancement maximizes along the same angular paths ships take along these routes and cannot be explained by meteorological factors, such as winds or the temperature structure of the atmosphere. We conclude that the lightning enhancement stems from aerosol particles emitted in the engine exhaust of ships traveling along these routes. These particles act as the nuclei on which cloud drops form and can change the vertical development of storms, allowing more cloud water to be transported to high altitudes, where electrification of the storm occurs to produce lightning. These shipping lanes are thus an ongoing experiment on how human activities that lead to airborne particulate matter pollution can perturb storm intensity and lightning.
The solar wind consists of a continual stream of plasma and magnetic field emitted from the Sun in all directions, permeating the heliosphere. The density and magnetic field strength in the solar wind decrease with distance from the Sun, so Mercury, located in the inner heliosphere (0.3-0.45 AU) experiences a very strong interaction with the solar wind. The surface of Mercury is protected from this powerful solar wind by the planetary magnetic field, which carves out a cavity in the solar wind called the magnetosphere. The primary means by which the solar wind drives global dynamics in the Mercury’s system is via a mechanism known as magnetic reconnection, in which energy and momentum are transferred to the planetary magnetosphere. Energy builds up in the magnetosphere until it cannot be sustained and is explosively released, accelerating particles towards the planetary surface. At Earth, this energy release may be observed in the brightening of the aurora, and its lower latitudes. This loading and unloading of energy into the terrestrial system is known as a substorm. This research paper characterises the properties of analogous loading and unloading of energy in Mercury’s magnetosphere, using data from the MESSENGER spacecraft.
In several regions worldwide, in particular in the Western world and Asia, large-scale livestock farms are located in densely populated areas. The presence of large numbers of farm animals raises questions about health risks for neighboring residents who are not farmers themselves. Large-scale livestock farms expanded rapidly in the last few decades, but their potential impact on neighboring residents’ health has hardly been accompanied by any research. In our commentary, we argue that the current situation in densely populated livestock farming areas could be regarded as a “natural experiment”, with residents being exposed to potentially harmful bacteria, viruses, and air pollutants. We discuss studies in people living near farms, with examples of infectious diseases that can be transmitted from animals to humans, and transmission of bacteria that are resistant to antibiotics. It is less well known that people living close to livestock farms are also exposed to air pollutants that may affect the airways, such as fine dust and ammonia. Recent studies have shown that air pollution from livestock farms is associated with a worsening in lung function.