As coastal areas become more vulnerable to climatic impacts, the need for understanding estuarine carbon budgets with sufficient spatiotemporal resolution arises. A mass balance model has been constructed for carbon fluxes in four estuaries along the northwestern Gulf of Mexico (nwGOM) coast from 2014 to 2018. The annual lateral carbon exports from tidal marsh-mangrove to estuaries account for 97.9% and 84.4% of total organic carbon (TOC) and dissolved inorganic carbon (DIC) inputs, respectively. This sustains a relatively high air-water CO2 flux (16.8 ± 3.0 mol·C·m-2·yr-1) compared with most estuaries on the North American Atlantic coast. In addition, annual air-water CO2 flux reaches as high as oceanic DIC export coastwide. The majority of imported riverine TOC has been exported to the coastal ocean (62.2%), leaving 22.3% of TOC for sediment deposition and 15.5% for remineralization. These fluxes are highly variable because of hydrologic variability. For example, episodic flooding can elevate estuarine CO2 efflux by 2 – 10 times in short periods of time. Flood following a drought state also increases lateral exchanges of TOC (from 90.7 ± 65.7 to 200.5 ± 160.2 mmol·C·m-2·d-1) and DIC (from 49.1 ± 39.8 to 166.9 ± 236.1 mmol·C·m-2·d-1). The contribution of nwGOM estuaries increases the overall North American estuarine CO2 flux by 220%, impacting coastal carbon budget. Hydrologic control explains temporal variability in these estimates.

A substantial amount of dust aerosol was transported to the central Himalayas during the multiple dust storm event that occurred from 12 to 15 June 2018 in the Thar desert, northwestern India. In this study, we implemented a cloud-resolving Weather Research and Forecasting model coupled with chemistry (WRF-Chem) to assess the impact of transported Thar-related dust aerosols on precipitation processes over the central Himalayas. We isolated the effect of the transported dust on the precipitation distribution by zeroing out dust aerosols from lateral boundary condition and keeping other species of aerosols. Results show the noticeable impacts of transported dust aerosols on regional precipitation and cloud properties over the central Himalayas. When transported dust is included, spatially averaged (25°N-31°N and 78°E-89°E) AOD increases by 0.36. Over the Himalayas foothills with the dust, precipitation is enhanced by 7.5% (0.63mm), while surface temperature is reduced. The presence of mineral dust aerosols increased the cloud droplets and ice crystal number concentration, which is further facilitated by the mountainous terrain by orographic lifting, leading to enhanced precipitation. We diagnosed the role of cloud microphysics and that of the cloud dynamics in the simulated precipitation sensitivity. This study highlights the effect of remote dust aerosol on the perturbation of cloud microphysical properties, which can significantly influence precipitation over the Himalayas and impact the regional hydrology.

Stable isotope analysis has been widely used to aid the source identification of methane. However, the isotopic (13C/12C and D/H) and isotopologue (13CH3D and 12CH2D2) signatures of microbial methane in natural environments are often different from those in laboratory cultures in which methanogens are typically grown under optimal conditions. Growth phase and hydrogen (H2) concentration have been proposed as factors controlling the isotopic compositions of methane, but their effects on the relationship among carbon, hydrogen and doubly-substituted “clumped” isotopologue systems have not been assessed in a quantitative framework. Here we experimentally investigate the bulk (δ13C and δD) and clumped (∆13CH3D) isotopologue compositions of methane produced by hyperthermophilic hydrogenotrophic (CO2-reducing) methanogens using batch and fed-batch systems at different growth phases and H2 mixing ratios (Methanocaldococcus bathoardescens at 82 or 60 °C and on 80 or 25% H2; Methanothermobacter thermautotrophicus ∆H at 65 °C and on 20, 5 or 1.6% H2). We observed a large range (18 to 63‰) of carbon isotope fractionations, with larger values observed during later growth phase, consistent with previous observations. In contrast, hydrogen isotope fractionations remained relatively constant at –317 ± 25‰. Linear growth was observed for experiments with M. bathoardescens, suggesting that dissolution of gaseous H2 into liquid media became the rate limit as cell density increased. Accordingly, the low (and undersaturated) dissolved H2 concentrations can explain the increased carbon isotope fractionations during the later growth phase. The δD and Δ13CH3D values indicated departure from equilibrium throughout experiments. As the cell density increased and dissolved H2 decreased, Δ13CH3D decreased (further departure from equilibrium), contrary to expectations from previous models. Our isotopologue flow network model reproduced the observed trends when the last H-addition step is less reversible relative to the first three H-addition steps (up to CH3-CoM). In this differential reversibility model, carbon, hydrogen and clumped isotopologue fractionations are largely controlled by the reversibility of the first three H-addition steps under high H2 concentrations; the last H-addition step becomes important under low H2. The magnitude of depletion and decreasing trend in Δ13CH3D values were reproduced when a large (≥6‰) secondary clumped kinetic isotope effect was considered in the model. This study highlights the advantage of combined bulk and clumped isotope analyses and the importance of physiological factors (growth phase) and energy availability (dissolved H2 concentration) when using isotope analyses to aid the source identification of methane.

Fault zone usually presents a granular gouge, coming from the wear material of previous slips. Considering a mature fault gouge with mineral cementation between particles, we aim to understand the influence of these cohesive links on slip mechanisms. As cohesion is difficult to follow and to quantify with Lab or in-situ experiments, we choose to use Discrete Element Method that has already shown its ability to represent granular gouges with relevant kinematics and rheology. In this work, we consider a dry cohesive contact model in 2D (2x20mm²) involving two rough surfaces representing the rock walls separated by the granular gouge (5000 particles, grain size 27- 260 μm). A step forward compared to literature is to add cohesion on real angular and faceted grains that modifies contact between particles. Focusing on physics of contacts inside the granular gouge, we explore contact interactions and friction coefficient between the different bodies. To represent the cementation we set up a Bonded Mohr-Coulomb law, considering that inter-particular bridges and particles are made with the same material. This numerical model is displacement-driven and is implemented to study the peak of static friction (shape, slope, duration) under a confined pressure of 40 MPa. Depending on the compacity and on the cohesion level of each model, the peak strength may be sharp, short, and intense for dense and highly cohesive cases or smooth, delayed with moderate amplitude for mid-dense and moderately cohesive cases. Three main behaviors are observed: a non-cohesive regime where the added cohesion is too small to truly disturb the global slip mechanism (Couette flow), an intermediate cohesive regime with clusters of cohesive grains, changing the granular flow and acting on slip weakening mechanisms (Riedel shear band R1) and an ultra-cohesive regime where gouge behaves as a brittle material with several Riedel shear bands emergence. We also investigate the role of cohesive bonds in energy budget, focusing on fracture energy term. Three mechanisms are playing a role in fracture energy evolution: the rupture of cohesive bonds, the dilatancy of the gouge and Coulomb dissipations due to friction. These factors are linked to the initial percentage of cohesion inside the sample and help characterize the mechanisms at stake in the initiation of sliding.

International Observe the Moon Night is an annual worldwide public event that encourages observation, appreciation, and understanding of our Moon and its connection to NASA planetary science and exploration. Everyone on Earth is invited to join the celebration by hosting a public or private event or attending an International Observe the Moon event – and uniting on one day each year to look at and learn about the Moon together. October 5, 2019 marks the 10th annual worldwide celebration of the Moon. Since 2010, an estimated 1.4 million people from across the globe have participated in International Observe the Moon Night events at museums/science centers, libraries, planetaria, observatories, K-12 schools, universities, public parks, community centers, private residences and businesses. Event hosts along with their partners help support and achieve global participation in International Observe the Moon Night. Between 2010 and 2018, a total of 5,551 events were registered worldwide. Over the last nine years, International Observe the Moon Night events have taken place in 107 different countries. Results of the evaluation of International Observe the Moon Night shows that the events continue to be successful in raising visitors’ awareness of lunar science and exploration, providing audiences with information about lunar science and exploration – along with access to lunar mission data and science results, inspiring visitors to want to learn more about the Moon, and providing connections to opportunities to do so. Each year, formative evaluation is used to make recommendations to the International Observe the Moon Night coordinating committee to make iterative changes for the next year. Worldwide evaluation data collection has included registration data, host surveys, visitor surveys, and social media data. The evaluation has been revised over the past ten years based on evolving program goals and resources available. Data collection has also included visitor interviews, observations, and alternative data collection strategies. We will discuss the challenges and successes of different evaluation strategies in evaluating the success of this program. Additionally, we will discuss the challenges and lessons learned in evaluating a large science outreach program that spans across so many countries and sites.

Nitrate aerosol plays an important role in affecting regional air quality as well as Earth’s climate. However, it is not well represented or even neglected in many global climate models. In this study, we couple the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) module with the four-mode version of the Modal Aerosol Module (MAM4) in DOE’s Energy Exascale Earth System Model version 2 (E3SMv2) to treat nitrate aerosol and its radiative effects. We find that nitrate aerosol simulated by E3SMv2-MAM4-MOSAIC is sensitive to the treatment of gaseous HNO3 transfer to/from interstitial particles related to accommodation coefficients of HNO3 (αHNO3) on dust and non-dust particles. We compare three different treatments of HNO3 transfer: 1) a treatment (MTC_SLOW) that uses a low αHNO3 in the mass transfer coefficient (MTC) calculation; 2) a dust-weighted MTC treatment (MTC_WGT) that uses a high αHNO3 on non-dust particles; and 3) a dust-weighted MTC treatment that also splits coarse mode aerosols into the coarse dust and sea salt sub-modes in MOSAIC (MTC_SPLC). MTC_WGT and MTC_SPLC increase the global annual mean (2005-2014) nitrate burden from 0.096 (MTC_SLOW) to 0.237 and 0.185 Tg N, respectively, mostly in the coarse mode. They also produce stronger nitrate direct radiative forcing (–0.048 and –0.051 W m–2, respectively) and indirect forcing (–0.33 and –0.35 W m–2, respectively) than MTC_SLOW (–0.021 and –0.24 W m–2). All three treatments overestimate nitrate surface concentrations compared with ground-based observations. MTC_WGT and MTC_SPLC improve the vertical profiles of nitrate concentrations against aircraft measurements below 400 hPa.

Stochastic hydrology produces ensembles of time series that represent plausible future streamflow to simulate and test the operation of water resource systems. A premise of stochastic hydrology is that ensembles should be statistically representative of what may occur in the future. In the past, the application of this premise has involved producing ensembles that are statistically equivalent to the observed or historical streamflow sequence. This requires a number of metrics or statistics that can be used to test statistical similarity. However, with climate change, the past may no longer be representative of the future. Ensembles to test future systems operations should recognize non-stationarity, and include time series representing expected changes. This poses challenges for their testing and validation. In this paper, we suggest an evidence-based analysis in which streamflow ensembles, whether statistically similar to and representative of the past or a changing future, should be characterized and assessed using an extensive set of statistical metrics. We have assembled a broad set of metrics and applied them to annual streamflow in the Colorado River at Lees Ferry to illustrate the approach. We have also developed a tree-based classification approach to categorize both ensembles and metrics. This approach provides a way to visualize and interpret differences between streamflow ensembles. The metrics presented and their classification provide an analytical framework for characterizing and assessing the suitability of future streamflow ensembles, recognizing the presence of non-stationarity. This contributes to better planning in large river basins, such as the Colorado, facing water supply shortages.

Pulsating aurora (PsA) is characterized by quasi-periodic intensity modulations with a period of a few to a few tens of seconds. It is caused by precipitation of energetic electrons of a few to several tens of kilo electronvolts produced by chorus waves in the magnetosphere. Precipitating electron energies of PsA have been identified in the past by sounding rocket and satellite observations, but the spatial distributions of precipitating electron energies of PsA have never been estimated. In this study, using the data from ground-based all-sky cameras at two wavelengths of 427.8 nm and 844.6 nm, we estimated the temporal and spatial variations in the precipitating electron energy of PsA. The results showed that the spatial distribution of precipitating electron energies was not uniform in the PsA patch, suggesting that the coherent spatial scale of the wave-particle interactions is smaller than each PsA patch size.

An unusual devastating tsunami occurred on 28 September 2018 after a strike-slip faulting earthquake in Sulawesi, Indonesia. The induced tsunami struck Palu city with 4-m wave height and flow depth. We performed a two-step analysis to investigate the source of the tsunami. We first conducted the teleseismic source inversion and obtained the slip distribution of the strike-slip fault. Our tsunami simulation from the coseismic deformation of the seismically-estimated strike-slip faulting produced a tsunami comparable to the leading part of the observation at Pantoloan. We then jointly utilized the tsunami waveform and Synthetic Aperture Radar (SAR) data to reconstruct the detailed slip distribution on the fault plane. Because of the lack of SAR data in the bay, the tsunami data is necessary to constrain the offshore slip distribution, which directly induces the tsunami. The inverted source model shows a strike-slip fault which consists of three segments extending from the epicenter to the south of 1.4°S with two bends and two asperities around Palu city. The joint inversion model accurately reconstructs the observed surface displacements and the leading part of the tsunami waveform. Our result exhibits the significant contribution of the strike-slip faulting to the tsunami, but it also suggests additional tsunami sources, such as landslides, for the high inundations near Palu bay. The result also indicates that regional devastating tsunamis can result from an onshore strike-slip fault with localized large dip slip.

Growin is a module that calculates the flux-tube-integrated linear Rayleigh-Taylor instability (grow)th rate of (i)o(n)ospheric irregularities is often used in the study of equatorial spread F(ESF). The Rayleigh-Taylor instability is often the prevailing explanation for the growth of plasma irregularities in the bottomside into plumes of depleted plasma, therefore a computation of its growth rate is valuable. This package includes many common approximations used in the computation of the Rayleigh-Taylor growth rate. Although not the focus of this discussion, Kelvin-Helmholtz instabilitiesfrom neutral wind shear below the bottomside F region are another source of plasma instability in the bottomside F region intended to be included in this package eventually.

Coral reefs are widely recognised for providing a natural breakwater effect that modulates erosion and flooding hazards on low-lying sedimentary reef islands. Increased water depth across reef platforms due sea-level rise (SLR) can compromise this breakwater effect and enhance island exposure to these hazards, but reef accretion in response to SLR may positively contribute to island resilience. Morphodynamic studies suggest that reef islands can adjust to SLR by maintaining freeboard through overwash deposition and island accretion, but the impact of different future reef accretion trajectories on the morphological response of islands remain unknown. Here we show, using a process-based morphodynamic model, that, although reef growth significantly affects wave transformation processes and island morphology, it does not lead to decreased coastal flooding and island inundation. According to the model, reef islands evolve during SLR by attuning their elevation to the maximum wave runup and islands fronted by a growing reef platform attain lower elevations than those without reef growth, but have similar overwash regimes. The mean overwash discharge across the island crest plays a key role in the ability of islands to keep up with SLR and maintain freeboard, with a value of (10 l m s) separating island construction from destruction. Islands, therefore, can grow vertically to keep up with SLR via flooding and overwash if specific forcing and sediment supply conditions are met, offering hope for uninhabited and sparely populated islands. However, this physical island response will negatively impact infrastructure and assets on developed islands.

Thunderstorms are often described as consisting of three charge layers: upper positive, central negative, and lower positive. This simple charge structure is inferred from balloon-borne electric field measurements, however, they typically only provide information from a single moving point. Realistic charge structures in thunderclouds are expected to be more complicated than this tripole description for a variety of reasons, including non-trivial updraft geometry, turbulence, and charge deposition by lightning. In order to more fully measure such charge structures, we herein describe the development of an experiment composed of multiple low-cost electric field dropsondes. Each dropsonde consists of two pairs of electrodes where each pair has the electrodes on opposing sides of the device and connected to a differential charge amplifier. The enclosures for the dropsondes are designed so that they spin as they fall which induces charge motion and allows us to measure electric field strength. This electric field data will be transmitted to a ground station in real time along with GPS coordinates. By keeping instrument and recovery costs low, we aim to launch a single balloon payload carrying several of these instruments to drop at intervals to provide a multi-point map of electric field and infer associated charge structures inside a thunderstorm.

“Pressure and time.” A momentous quote in a compelling movie from a few decades ago interestingly pointed at some of the ingredients that contributed to shaping the Earth. The movie set off from how to seep through masses that appeared just too vast to be shakable or vulnerable – if not by deciphering their inner core. The planetary size and time frame of the Earth may have elicited a perception of a durable, unbuckling living environment – just because “pressure and time” to really affect it would have been out of human reach – supposedly. However, the Earth and environmental sciences have long striven to alert contemporary societies that this is just not the case, as humans have been well exerting scattered yet ubiquitous, planetary-scale pressure over a relatively brief time – with consequential, durable effects. Rising global population, long-term migration shifts of continental extents – due to risks, climate, resources – and unpredicted factors – from vulnerabilities to instabilities – pressure on the environment (natural and built) in unprecedented scale throughout human history. The Earth sciences were born out of deciphering ancient life forms teeming in an aboriginal environment, unfolding on a planet that could be explained only by looking at the Solar system – and at the inception of the Universe.Cross-disciplinary by nature, the Earth and environmental sciences offer crucial tools to gauge location, economic turnout, and societal costs of those very resources and fragilities. They also are pivotal co-actors of intellectual stewardship bridging the gulf with sister disciplines well beyond the remits of the physical sciences. From economics to philosophy, and from history to literature, multiple, diverse and concurring threats call for resourceful, multi-faceted mind- and skill-sets where no single hazard may be really treated apart – not on societal terms.Adapting a famous statement from the 20th century, evolution in a time of poly-crises, multiple hazards, and accrued vulnerabilities is not going to be a dinner party for contemporary societies – especially as they dwell a world perceived as increasingly richer in risks and poorer in resources, with a growing population and across instabilities. Human Earth sciences offer a bridge towards our collective future – as societies, continents, planets.Earth-prints @ INGV  

Under the impact of global warming and climate change, the frequency of extreme precipitation and drought events have been increasing. In Taiwan, the government usually guides agricultural fallows to meet the needs of domestic, public, and industrial water during droughts. However, this situation causes that the cultivation rights of farmers are not guaranteed even though the priority of agricultural water is higher than that of industrial water. To this end, a framework of virtual water trading market is proposed in this study to protect the cultivation right. The water supply system and field water balance models that use the historical drought event during 2003 to 2004 as the hydrological scenario have been completed to support the gaming water-trading auction. Through the gaming simulation process, agricultural or industrial stakeholders are invited to carry on the round-designed water trading. Based on the results of player's decisions, we discuss the feasibility of water market in this region and investigate the possibility of adopting the water market as a solution of the water reallocation during times of drought. An application with the principle of user charge in the Taoyuan region of Taiwan is successfully implemented. The results show that industrial stakeholders are willing to pay more costs of water purchase to prevent severe loss of production line shutdown caused by water shortage. After several times of the gaming auction, stakeholders may learn the trading information in terms of evaluating the price of water and estimating the possible amount of water. This study can further provide a potential substitute solution to the government and policy makers when the water reallocation is considered during drought periods.

Many indigenous peoples are working to maintain cultural survival through integration of indigenous knowledge (e.g., phenological observations, wild cultivation expertise, and ecosystem management expertise) with climate change research and climate based ecological restoration/adaptation. Even though local, place-based climate knowledge maintained through story and knowledge of sacred sites, ancestral gathering, hunting, camping and fishing areas are incredibly valuable for climate change adaptation planning, this information is not readily transferable to the scientific literature, and in most cases, it would be inappropriate or offensive to publish. This presents a challenge for those working to blend traditional knowledge and western science during the development of climate change adaptation programs and collaborative relationships with scientific and educational institutions. The Nez Perce Tribe is working to overcome these barriers through meaningful community participation, surveys and elder interviews, hiring in-house social and natural science professionals, climate smart conservation projects that include cultural values without revealing sacred information, and the leadership and grace of the Tribal Community, Government, and Staff. We present a case study on collaborations with Point Blue Conservation Science and the University of Idaho to include cultural traditions and values in a restoration toolkit for ecological and cultural resilience, and a climate-smart agricultural program. We discuss the steps taken by the Tribe to overcome barriers, lessons learned, suggestions for methodologies, and measures to honor the resilience, wisdom, and wishes of the Nez Perce People during this process. Our collective future depends upon collaborations amongst human beings with a checkered collective past, and bold and courageous leadership. Tribal communities are demonstrating a model of leadership and grace by working with each other and with western scientists in visionary ways on climate change resilience planning. This has allowed for collaborative relationships that are expanding the capacity of the Nez Perce Tribe to address climate change and integrate cultural values and perspectives into the process.

Modern investigations have shown that oxygen and carbon isotopes of land snail shells are useful indicators of climate and vegetation in monsoonal region. However, stable isotope study on snail fossil shells in strata has been seldom done, and the reliability of those indicators needs further verification. Moreover, intra-shell stable isotope analysis of individual snail is rather scarce, and seasonal variation of the glacial-interglacial monsoonal climate remains unclear. In this context, we performed δ18O and δ13C analyses on fossil shells of cold-aridiphilous Cathaica pulveratrix and sub-humidiphilous Metodontia yantaiensis from the loess section over the last two glacial cycles at Beiyao site in southern Chinese Loess Plateau. The δ18O of fossil shells reflected monsoonal rainfall amount and more rainfall during MIS3 and MIS7. Meanwhile, the δ13C of fossil shells indicated relative abundance of C3/C4 plants and more C4 biomass during MIS3 and MIS7. The δ18O and δ13C of the two species from the same horizon are significantly different, reflecting differences in their growing season and/or physiological habits. Intra-shell variations of stable isotopes showed that climatic seasonality was relatively strong during the glacial periods whereas seasonality became weakened during the interglacials. Our findings provide an environmental background for explaining past human activities at the Beiyao site. The investigation of stone artifacts showed that ancient human activities were relatively strong during MIS3 and MIS7. During these stages, the warm and humid climate with smaller seasonal contrast was favorable for the regional expansion of human activities.

Tropical ecosystems strongly influence Earth’s climate and weather patterns. Most tropical ecosystems remain warm year-round; nonetheless, their plants undergo seasonal cycles of carbon and water exchange. Previous research has shown the importance of water and light as drivers of the seasonality of photosynthetic activity in the tropics. Although data are scarce, field-based studies have found that seasonal cycles at a handful of tropical forest sites do not match those in land surface model simulations. A comprehensive understanding and model comparison of how seasonal variations in tropical photosynthetic activity relate to climate is lacking. In this study, we identify the seasonal relationships of precipitation and light availability with satellite-based photosynthetic activity. Three dominant and spatially distinct seasonal relationships emerge between photosynthetic activity and these two environmental drivers: photosynthetic activity that is positively correlated with both drivers (36% of tropical pixels), activity that increases following rain but decreases with light (28%), and activity that increases following bright seasons but decreases with rain (14%). We compare distributions of these observed relationships with those simulated by land surface models. In general, model simulations of gross primary productivity (GPP) overestimate the extent of positive correlations of photosynthetic activity with water and underestimate positive correlations with light. The largest discrepancies between simulations and observations are in the representation of the regions where photosynthetic activity increases with light and decreases with rain. Our clear scheme for representing the relationship between climate and photosynthetic activity can be used to benchmark tropical seasonality of GPP in land models.

The Indian Ocean (IO) is witnessing acidification as a direct consequence of the continuous rising of atmospheric CO2 concentration and indirectly due to the rapid ocean warming, which disrupts the pH of the surface waters. This study investigates the pH seasonality and trends over various bio-provinces of the IO and regionally assesses the contribution of each of its controlling factors. Simulations from a global and a regional ocean model coupled with biogeochemical modules were validated with pH measurements over the basin, and used to discern the regional response of pH seasonality (1990-2010) and trend (1961-2010) in response to changes in Sea Surface Temperature (SST), Dissolved Inorganic Carbon (DIC), Total Alkalinity (ALK) and Salinity (S). DIC and SST are significant contributors to the seasonal variability of pH in almost all bio-provinces. Total acidification in the IO basin was 0.0675 units from 1961 to 2010, with 69.3% contribution from DIC followed by 13.8% contribution from SST. For most of the bio-provinces, DIC remains a dominant contributor to changing trends in pH except for the Northern Bay of Bengal and Around India (NBoB-AI) region, wherein the pH trend is dominated by ALK (55.6%) and SST (16.8%). Interdependence of SST and S over ALK is significant in modifying the carbonate chemistry and biogeochemical dynamics of NBoB-AI and a part of tropical, subtropical IO bio-provinces. A strong correlation between SST and pH trends infers an increasing risk of acidification in the bio-provinces with rising SST and points out the need for sustained monitoring of IO pH in such hotspots.