The Enriquillo-Plantain Garden Fault (EPGF), one of two left-lateral transforms that define the Caribbean-North American plate boundary in Haiti, plunges beneath Lake Azuei in the eastern part of the country. In 2017, we acquired 220 km of sub-bottom and multichannel seismic reflection profiles (CHIRP and MCS) in a 1.2 km grid pattern across the lake. The two seismic methods achieved subbottom penetration of up to 15 m and 200 m, respectively. CHIRP and MCS data reveal folded turbidites across the expected extension of the EPGF fault zone at the south end of the lake, although direct evidence for faulting is lacking. Along the west side of the lake, however, MCS data image a broad NW-SE monoclinal fold whose geometry is compatible with an underlying SW-dipping blind thrust fault. CHIRP profiles image patches of soft- sediment deformations above the monoclinal fold; they also image a distinctive 11 m-deep paleoshoreline all around the lake that is uplifted by 1-2 m above that fold. These results are compatible with a scenario where some large slip event(s) on the presumed blind thrust occurred after formation of the paleoshoreline, locally uplifting the lakebed and causing liquefaction. Two short sediment cores sampled a layer correlatable to a reflection in the CHIRP profiles. That reflection extends laterally below the 11m shoreline, and thus predates its formation. On-going 14C dating of material from the two cores are expected to provide a maximum age for the shoreline, and thus for some hypothetical slip event(s) on the presumed blind thrust fault. The prominent character of the paleoshoreline suggests that it was stable, something best achieved if the lake level was controlled by the sill depth of an outlet. Presently, no such outlet exists and the lake level fluctuates. Pending results from radiometric dating, we propose that, earlier in the Holocene, the lake overflowed eastward into adjacent Lake Enriquillo along the narrow valley marking the extension of the EPGF fault zone - a valley that is presently blocked by an alluvial fan. Regardless of the relevance of that model, the uplifted shoreline implies a significant uplift rate on a structure extending up to 10 km north of the EPGF fault zone and striking oblique to it, confirming that transpressional tectonics is partitioned over an area at least as broad as Lake Azuei.

Physical habitat losses for Pacific salmonids in California’s Central Valley motivate stream restoration. Considerable river morphodynamics affect the sustainability of habitat enhancing interventions. In addition, the presence of large dams in many river catchments causes low sediment supply. This study revises existing stream restoration techniques for their ecologically efficient and physically stable embedding in a 36-km testbed river. Ecological efficiency is evaluated in terms of a commonly used hydraulic habitat suitability index. Physical stability results from 2D hydrodynamic modelling of bed shear stress during steady flows of different flood frequencies. We differentiate between terraforming, stabilizing and maintaining stream restoration techniques, which constitute three feature layers. The first layer, terraforming, includes artificial terrain modifications such as grading or backwater creation to generate new habitat. These features require stabilization, which is provided by the second feature layer. The stabilization (layer two) is achieved by bioengineering such as placement of streamwood, angular boulders and vegetation plantings. The third feature layer has the purpose to maintain newly created habitat, e.g., through artificial gravel injections. We illustrate the application of the three-layer-approach at one major restoration site of the lower Yuba River using a self-written Python package. Ecohydraulic 2D modeling was applied to designs with incremental layer additions to evaluate newly created spawning habitat and feature sustainability. This procedure represents a pertinent way for stream restoration planning, which avoids non-sustainable habitat enhancement features and implements ecologically as well as physically sustainable features only.

Global environmental science challenges in the limnological research and applications communities can only be advanced when harnessing the collective expertise and capabilities of the satellite remote sensing community and well-established in situ communities such as the Global Lake Ecological Observatory Network (GLEON). At first glance, the groups seem wildly divergent: GLEON is a grass-roots effort which has been active since 2005 and connects researchers and practitioners from around the world to ask and answer questions about lake ecosystems. Earth observing missions can take a decade to plan, build, and launch. NASA and ESA have different missions as space agencies: one primarily focused on exploration and basic research with a year-to-year appropriations cycle, while the other presents a long-term commitment to address societal needs through the Copernicus program Sentinel satellite series. The Surface Biology and Geology (SBG) mission is a future NASA satellite that will launch toward the end of this decade as part of the Earth Systems Observatory. Working together to advance the science of lake ecosystem response to climate change, each group brings different complementary strengths and assets to this societal challenge. Increasing access through open science and cloud computing are creating opportunities for better collaboration. We describe our strategy for international engagement between these groups – cultural and methodological differences aside – to derive new information, learn new insights, and expand the body of knowledge around these unique natural resources.

Farmland mulching can maintain soil temperature and moisture, increase crop yields, which plays a positive role in agricultural planting in the arid area. However, the composition of the soil microbial community and the carbon cycle involved is not well understood under the ground cover scenario. Based on the Changwu Agro-Ecological Experiment Station, this study set up a long-term positioning Experiment to explore the impact of long-term land cover pattern on soil bacterial community structure and carbon metabolism capacity. In this study, we include five treatments: control uncovered (CK), plastic film mulching (F), high amount of straw mulching is carried out in July, August and September every year (St90), low amount of straw mulch throughout the growth period (S45), high amount of straw cover throughout the growth period (S90). We combined Illumina MiSeq sequencing and Biolog-ECO technology to analyze the functional characterization of soil bacterial community composition in terms of carbon source metabolism. The results indicated that the soil bacteria showed high degree of epistatic clustering after mulching treatments, and the operational taxonomic units (OTU) numbers of soil bacteria under different treatments decrease as St90, S45, F, CK, S90. Redundancy analysis (RDA) showed that AP, NH4+-N, MC were the main environmental factors affecting bacterial community composition. Proteobacteria, Acidobacteria and Actinobacteria are the main dominant flora in this area. Long-term surface cover resulted in significant differences in soil bacterial carbon metabolism, which was highest in the F treatment. Structural equation modeling (SEM) shows that surface cover has direct and indirect effects on bacterial carbon metabolism capacity and diversity through soil physicochemical properties. Reasonable mulching patterns can greatly change the community structure and carbon metabolism of soil bacteria, and play a positive role in the sustainable development of agro-ecosystems in arid area.

Place-based field education is the foundation of Lamont-Doherty Earth Observatory’s Hudson River Field Station. The most effective method of engaging and connecting people with their local environment is through memorable and hands-on field investigations, with the Hudson River itself as the best educational tool. Our ‘Next Generation of Hudson River Educators’ is a six week summer internship program specifically designed to more effectively engage underrepresented minority (URM) students and communities with the Hudson River using a tiered mentoring structure. The high school interns first take a deep dive into the Hudson River to develop a better understanding of the historic to present human connection to the estuary, the dynamism of its biology, physics, chemistry, geology, and topography, and the challenges the Hudson faces, along with potential community solutions. These field investigations build an appreciation for the estuary that they can pass on to their communities. Unfortunately, the coronavirus introduced a unique challenge on place-based education making it impossible to run an in-person program. Through an innovative approach to place-based learning, we decided ‘if we couldn’t bring the students to the river, we would bring the river to the students’. The interns dedicated the first weeks to learning about the Hudson through “Virtual River” videos, games, interactive web activities, and live river demonstrations hosted down by the water. While the content is virtual, it simulates a place-based education that effectively engages students in the geosciences and increases science literacy. The interns then work in teams to create their own communication tools to share Hudson information that is captivating to a multigenerational and diverse audience. In order to offer information that is interesting and relevant to their communities, interns performed interviews to learn directly from their friends, family, and neighbors about their perceptions and existing knowledge of the Hudson. Involving the community in place-based education is crucial because residents provide key information that would be otherwise unknown to a visiting scientist or educator. They then use this information to build their communication outputs that are intended to better connect URM to their local waterways.

We conducted two 10-day observational campaigns in 2019 targeting turbulence in the troposphere and lower stratosphere by adopting a frequency domain radar interferometric imaging technique using Program of the Antarctic Syowa (PANSY) radar and radiosonde observations obtained at Syowa Station in the Antarctic. Overall, 73 cases of Kelvin-Helmholtz (K-H) billows were detected, and 2 characteristic cases were examined in detail. In the first case with the longest duration of ~6.5 h, the K-H billows had thickness of ~800 m and horizontal wavelength of ~2500 m. According to a numerical simulation of the environmental conditions, continuously existing orographic gravity waves maintained strong vertical shear of the horizontal winds sufficient to cause the K-H instability. In the second case with the deepest thickness of ~1600m, the K-H billows had duration of ~1.5 h and horizontal wavelength of ~4320m. Numerical simulation suggested that an enhanced upper-tropospheric jet associated with a well-developed synoptic-scale cyclone caused the K-H instability. Such background conditions, frequently observed in the Antarctic coastal region, are typical mechanisms for K-H excitation. Linear stability analysis also indicated that the characteristics of the observed K-H billows were consistent with the most unstable modes. Furthermore, statical analysis was performed using data of all 73 observed cases. The characteristics of K-H billows observed at Syowa Station are similar to those observed over Japan. However, the weaker vertical shear and longer wave period of the K-H billows over Syowa Station reflect that the tropospheric jet over the Antarctica is not as strong as that over Japan.

In the field of Astrobiology, a quantitative approach has not been made to predict the number of extraterrestrial intelligent civilizations that may have existed on a habitable exoplanet as well their corresponding properties, such as intelligence, lifespan, and recovery time. Prior research indicates that numerous planetary systems within the Milky Way Galaxy are of over six billion years in age, implying many exoplanets, if sustainable to life, may have had several cycles of civilizations emergence and self-destruction, suggesting the ruins of advanced civilizations should be commonplace within the galaxy. We investigate this problem by utilizing statistical algorithmic simulations to predict and estimate the number of civilizations (both future and extinct) that may arise within an exoplanetary continuum, further generating the accompanying characteristics of said civilizations. Within the model, factors such as self-induced extinction/destruction, natural civilization decay, planetary disasters, and civilization rediscovery have been incorporated to examine the pathways a civilization can encounter. Our results corroborate the notion that on many of the older exoplanets in our galaxy, civilizations may have existed, however most have ultimately died out within a short period, further limiting the search for current extraterrestrial intelligence, but strengthening the approach of interstellar archeology.

Mesozooplankton biomass plays a key parameter in the recruitment processes of fish and biogeochemical processes. Four decadal observations in the coastal Sea of Japan, the marginal sea of the North Pacific, indicate that wet weight-based mesozooplankton biomass is controlled by both environment-induced bottom-up and predatory-induced top-down processes. Interannual variations in mesozooplankton biomass using a generalized linear model approach showed a decrease in biomass during the 1980s, followed by a rapid increase in the early 1990s, and a gradual decrease in the 2010s. These interannual variations were the mirror image of the small pelagic planktivorous fish biomass. The difference in zooplankton biomass from the previous year was negatively correlated with the difference in small pelagic planktivorous fish biomass, which was supported by a Granger causality analysis. Therefore, the results of this study indicate that top-down control is one of the main causes of long-term variations of zooplankton biomass in the ocean.

Fluid stratification is a common phenomena in magmatic systems. To address this, we conducted a series of analogue experiments and numerical simulations. We present three sets of experiments modelling the behavior of instability that develops between two stably stratified magmas and the degree of mixing that follows. The first set of analogue experiments examines the instability at the interface between two stably stratified fluids of similar composition with a low viscosity ratio wherein the upper fluid is less viscous than the lower fluid. The successive set experiments examine the interface instability between fluids of different compositions with high viscosity ratios wherein the upper fluid is initially more viscous and less dense than the lower fluid. The instability in all three experiments forms through the growth of a chaotic mixing region by the development of Rayleigh-Taylor instabilities through viscous fingering and buoyant ascent of plumes. The three experiments exhibit different degrees of mixing at significantly different timescales which are contingent upon the size of the mixing region relative to the bulk volume of the two fluids. Diffusive processes and small viscosity ratios enhance the growth of the mixing region in the first set of experiments. The growth timescale of the interface instability is characterized by a transient stage and a subsequent rapid stage. Our three-dimensional simulations, based upon the second and third sets of experiments, examine increased viscosity ratios to 3 orders of magnitude above those of our experiments. We discuss the implications for different configurations of stably stratified magma chambers.

Interferometric Synthetic Aperture Radar (InSAR) is used to measure deformation rates over whole continents to constrain tectonic processes. The resulting velocity measurements are only relative, due to unknown integer ambiguities introduced during propagation of the signal through the atmosphere. However, these ambiguities mostly cancel when using spectral diversity to estimate along-track motion, allowing measurements to be made with respect to a global reference frame. Here, we calculate along-track velocities for a partial global dataset of Sentinel-1 acquisitions and find good agreement with ITRF2014 model values. We include corrections for solid-earth tides and gradients of ionospheric total electron content. By combining data from ascending and descending orbits we are able to estimate north and east velocities with average precision of 4 and 20 mm/year, respectively. Although we have calculated these over large 250x250 km areas, such measurements can also be made at much higher resolution, albeit with lower accuracy. These “absolute” measurements can be particularly useful for global velocity and strain rate estimation, where GNSS measurements are sparse.

A precise and accurate timescale is critical for calibrating major events in Earth history and testing their spatiotemporal relationships for putative causes. The Newark-Hartford astrochronostratigraphic polarity timescale (APTS) was developed in cyclical lacustrine continental deposits spanning 27 million years of Late Triassic and earliest Jurassic time using the theoretically constant 405 kyr eccentricity cycle linked to gravitational interactions with Jupiter-Venus as a tuning target and provides a major calibration for the early Mesozoic. While this cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth’s climate in numerical solutions, there has been no empirical confirmation of that behavior, given the potential chaotic behavior of the Solar System. An additional criticism of the Newark-Hartford APTS is that it is anchored only at its younger end by U-Pb zircon dates at 201.6 Ma. To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence providing an unambiguous correlation to the APTS in the volcaniclastic-bearing Chinle Formation in drill core PFNP-1A from Petrified Forest National Park (Arizona, US). New U-Pb CA-TIMS detrital zircon dates from the core are indistinguishable from ages predicted by the APTS back to 215 Ma. The APTS is evidently continuous to a small fraction of a remarkably constant 405 kyr orbital eccentricity cycle, thus extending the empirical evidence well beyond theoretical solutions regarded as reliable back to only 50 Ma. The Newark-Hartford APTS becomes the longest directly calibrated polarity sequence and can be used to resolve various Earth history problems, for example, to differentiate provinciality from global temporal patterns in the ecological rise of early dinosaurs.

A Helium Lidar system, which is being developed for measurements of metastable helium density in the thermosphere and exosphere, employs a CW 1083nm laser with power of 60W, a telescope array consisting of six 1m-diameter telescope and an area-array ICCD. To realize range-resolved remote sensing, the laser is located separately from the location of telescope with a distance of D and the laser beamed is leaned towards the Field-of-view (FOV) of the telescope array with an zenith angle of θ. The signal in a specific height is finally imaged onto a corresponding pixel of the ICCD. Before the retrieval of metastable helium density, the first procedure is to decide the relation between the pixels and corresponding heights. Based on the FOV of the telescope, the divergence angle of the laser beam, the geometry of the laser and telescope, and the size of the pixels, every pixel corresponds to a specific height range, as shown in Fig. 1. The darkest shade corresponds to one pixel of the ICCD. Therefore, the second procedure is to correct the height range overlap of the signal from adjacent pixels to decrease the smoothness of the signal profile caused by the height overlap of adjacent pixels. The signal received by the ICCD is simulated based on a metastable helium density model developed by Waldrop et. al. The results show that these two signal correcting procedures can improve the precision of each pixel’s signal by 5% in average.

In global climate models, CO2-driven warming causes strong and very widespread mean drying trends in climatic wetness indices like the Palmer Drought Severity Index, Aridity Index and Standardized Precipitation-Evapotranspiration Index. Yet, these same simulations also predict that runoff will not decline over most of Earth’s surface, that root-zone soil moisture and evaporative fraction will decline only regionally, and that vegetation will become broadly greener. Thus, actual drought impacts of warming in these models are far less broad and severe than implied by the drought indices. Here, I probe why this “index-impact gap” occurs, and whether it is a feature of reality as well as models. In particular, I show that the discrepancies are not just limited to simulations which assume a substantial direct CO2 effect on vegetation, but are also large in greenhouse-only simulations, implying that they occur for fundamental climatic reasons rather than via CO2-physiological pathways. I also review key observational evidence that the index-impact gap has also been large over the historical era and was very evident for the last glacial-to-interglacial warming, lending much additional credence to the model output.

We present in-situ ion composition and velocity measurements from the Enhanced Polar Outflow Probe during the August 2017 solar eclipse, which crossed the path of totality at ~640 km altitude within 10 minutes of totality passing. These measurements reveal two distinct H+ ion populations, and show a ~40% decrease in topside plasma density, a similar drop in upward but not downward H+ ion flux, and a downward O+ ion velocity of ~100 m/s. These features are directly linked to changes in the H+/O+ composition and field-aligned or interhemispheric light ion flow, and reduction in the negative spacecraft potential. These observed features were absent on the preceding, non-eclipse days, and corroborate the reduction in F-region plasma density and topside Total Electron Content (TEC) observed by the Global Position System (GPS) receivers onboard. They are attributed to the temporary reduction of photoionization in the eclipsed F-region.

Biosphere-atmosphere interactions in forest settings have a large impact on the budget and fate of nitrogen oxides (NOx) and ozone, as forests cover over 30% of Earth’s land surface area, where major sources and sinks of these key trace gases are located. Owing to their structure and biological activity, forests affect trace gas transport and chemistry both within and above the canopy. Factors such as turbulence, surface deposition, soil emission, and gas-phase oxidation chemistry must be considered when evaluating canopy-scale NOx and ozone fluxes. Interactions involving these processes result in canopy-scale bi-directional exchange of NOx. This might be further affected by leaf-level bi-directional NOx exchange characterized by the compensation point, the ambient NOx mixing ratio above which NOx is taken up by leaves and below which NOx is emitted by leaves. During the summer 2016 Program for Research on Oxidants: PHotochemistry, Emissions, and Transport campaign at the University of Michigan Biological Station, we conducted leaf-level gas exchange experiments on white pine (Pinus strobus), bigtooth aspen (Populus grandidentata), red maple (Acer rubrum), and red oak (Quercus rubra), all dominant tree species of the forest surrounding the campaign site. Known amounts of NO, NO2, or ozone were added to a pair of branch and blank enclosures. Measurements of these gases were made continuously in a sequence of inlet and outlet air from the branch enclosure followed by the blank enclosure. We also measured PAR, ambient and enclosure temperatures and moisture, leaf temperatures and wetness, and CO2 within the enclosure. Initial analyses show that the NOx mixing ratio differences before and after the enclosure have a small but clear correlation to the input NOx mixing ratio. Further analysis is required to examine the dependence of these differences on the micro-environment of the enclosures before conclusions can be made on the existence and magnitude of compensation points for each tree type. These results, combined with the concurrently observed NOx and ozone vertical gradients, will be further analyzed using a Multi-Layer Canopy Chemistry Exchange Model for assessing the effect of leaf-level exchange on the NOx and ozone dynamics at this forest site.

During the last few years, the debate over the changes in the global average temperature has been one of the most important political issues. A better understanding of the effects of the temperature increase on other variables is one of the main challenges in climate. In the last IPCC report, due in part to the limited rainfall data in the tropics, there is no reliable conclusion about the observed and expected long-term precipitation changes in association with the global temperature increase. Since water resources are essential for energy generation and food production in the Department of Antioquia, Colombia, a better understanding of changes in rainfall in the long term becomes a vital tool for decision making. This research presents an assessment of rain variability at different temporal and spatial scales over Colombia, and more specifically over Antioquia. The data used was corresponds to long-term records of 86 rain gauges, in addition to 9 temperature stations, and TRMM precipitation products. The use of in-situ rain gauge information allows focusing on a spatial scale useful not only for a general understanding of precipitation changes but also for engineering and other practical applications. Analyses reveal that while there are no long-term trends in precipitation at the monthly or longer timescales, relatively short-lived extreme events show long-term changes in intensity and frequency. Results show that the shorter the duration of the intense events, the higher the magnitude of the increasing intensity trend. Similarly, for more intense events, the trends are also larger and more significant from a statistical point of view. Analysis of temperatures shows a clear relationship with extreme precipitation events with scaling features explained via the Clausius-Clapeyron relation, controlling the intensification of precipitation. The long-term rainfall trends are compared with modeling results from the different scenarios of a small set of CMIP runs given that most models do not adequately represent Colombia´s precipitation climatology. The results indicate a substantial reduction of return period of extreme events with implications in engineering: the current hydraulic designs would be obsolete in less than 50 years if the increment in the frequency of intense events is not considered in the design.

WBSCAT is a new terrestrial microwave scatterometer supporting polarimetric observations over 1 to 40 GHz. This instrument is being developed for the European Space Agency (ESA) to conduct microwave studies of a wide range of ground covers including snow and ice. This instrument is built upon the heritage of SnowScat , operating over the range of 9.2 to 17.8 GHz, that has been used for generating tomographic time-series of snow pack and is part of the ongoing ESA SnowLab project [2]. WBSCAT, like its predecessor, acquires coherent data and can measure polarimetric scattering matrices, interferometric phase, and coherence. Both instruments will be operated in Winter 2018/2019 in Davos Laret, Switzerland mounted on a 10- meter tower and performing multiple daily observations of the snow pack. Either instrument can be attached to a 2.2-meter linear scanner inclined at 45-degrees permitting tomographic snow profiling [1]. The WBSCAT instrument uses radial-scan aperture synthesis to acquire independent observations of the scattering volume and also to restrict the field of view to the undisturbed test site, despite wide antenna beamwidths at low frequencies. The 6 horn antennas, with overlapping frequency ranges of 1 to 6, 2 to 18, and 10 to 40 GHz, are mounted approximately 60 cm radially from the rotation axis of the pan/tilt scanner. The antennas can be scanned between +35 and -45 degrees in elevation and +/- 90 degrees in azimuth, creating a synthetic aperture. The aperture dimensions are mostly determined by the antenna pattern, but at low frequencies, the antenna beamwidth exceeds 90 degrees. Aperture synthesis substantially increases the number of looks for improved radiometric resolution and is a novel approach for ground-based microwave scatterometry. Combining ranging information along with WBSCAT aperture synthesis perpendicular to the line of sight, has the potential for direct 3D imaging of the snow pack.

Summer ice in the Arctic is diminishing at an alarming rate. Increase in radiative forcing due to the loss of sea ice is contributing to global warming. Artificially enhancing the sea ice albedo could be a possible lever to restoring and rebuilding the Arctic sea ice. Using reflective hollow glass spheres with low environmental impact, Field et al (2018) reported that such a technology could be promising towards restoring Arctic Sea Ice. Here we present the preliminary climate modeling and impact assessment of such a technology both regionally and globally. We seek to answer the scientific question of whether an enhanced sea ice albedo over the whole of Arctic sea ice provides a large enough perturbation to the climate in the Arctic and if so what is its likely impact over the rest of the globe. The study shows that the climate impact of such a method results in more than 1.5°C cooler temperatures over a large part of the Arctic and about 3°C reduction over regions north of Barents and Kara Seas. We also see notable increases in sea ice thickness (20–50 cm Arctic wide) and (>15–20%) increases in sea ice concentration across large parts of the central Arctic. These preliminary results suggest that such a technology may be a viable instrument for restoring Arctic ice. However, practicality dictates that a localized targeted deployment of the technology may be more desirable. We are extending this work to evaluate targeted deployment of materials in key areas and will present the climate modeling results on efficiency of targeted deployment for at least one such targeted area. Reference: Field, L., Ivanova, D., Bhattacharyya, S., Mlaker, V., Sholtz, A., Decca, R., et al.(2018). Increasing Arctic sea ice albedo using localized reversible geoengineering. Earth’s Future, 6. https://doi.org/10.1029/2018EF000820