Interaction of magma with ground or surface water can lead to explosive phreatomagmatic eruptions. Poorly understood questions of this process center on effects of system geometry, length- and time scales, and these necessitate experiments at larger scale than previously conducted in order to investigate the thermohydraulic escalation behavior of rapid heat transfer. Previous experimental work either realized melt-water interaction at similar (meter-) scales, using a thermite-based magma analog in a confining vessel, or on smaller scale using about 0.4kg remelted volcanic rock in an open crucible, with controlled premix and a trigger event created by a low energy air gun pellet (about 5J kinetic energy). The new setup uses 55kg melt for interaction, and the timing and locaiton of the magma-water premix can be controlled on a scale up to 1m. A trigger mechanism is a falling hammer that drives a plunger into the melt (about 28K kinetic energy). Results show intense interaction at relatively low water to magma mass ratio. A video analysis quantifies the rate and amount of melt ejection and compares the results with those using the same melt in the smaller scale setup. Experiments show that on the meter scale intense interaction can start spontaneously without an external trigger if the melt column above the initial mixing location is larger than 0.3m. A dependency of system response on water mass flow rate was not observed.

Surface freshening of the Southern Ocean driven by meltwater discharge from the Antarctic ice sheet has been shown to influence global climate dynamics. However, most climate models fail to account for spatially- and temporally-varying freshwater inputs from ice sheets, introducing significant uncertainty into climate projections. Here, we present the first historically-calibrated projections of Antarctic freshwater fluxes (sub-shelf melting, calving, and surface meltwater runoff) to 2300 that can be used to force climate models lacking interactive ice sheets. Our findings indicate substantial changes in the magnitude and partitioning of Antarctic freshwater discharge over the coming decades and centuries, particularly under very-high warming scenarios, driven by the progressive collapse of the West Antarctic ice shelves. We project a shift in the form and location of Antarctic freshwater sources, as liquid sub-shelf melting increases under all climate scenarios, and surface meltwater runoff could potentially become a dominant contributor under extreme atmospheric warming.

This study explored whether the global temperature had any role in the spread and vulnerability to COVID-19 and how that knowledge can be used to arrest the fast spreading disease. It highlighted that for transmitting the virus, global temperature played an important role and a moderately cool environment was the most favourable state. Whereas, the risk from the virus was reduced significantly for warm places and countries. Based on the temperature of March and April, various degree of vulnerability was identified and countries were specified. The maximum reported case, as well as death, was noted when the temperature was in the range of around 275°K(2°C) to 290°K(17°C). Countries like the USA, UK, Italy and Spain belonged to this category. The vulnerability was moderate when the temperature was less than around 275°K(2°C) e.g., Russia, parts of Canada and a few Scandinavian countries. For temperature 300°K(27°C) and above, a significantly lesser degree of vulnerability was noted. Countries from South Asian Association for Regional Cooperation, South East Asia, the African continent and Australia fell in that category. This work discussed that based on the variability of temperature, countries can switch from one vulnerability state to another. That influence of temperature on the virus and results of previous clinical trials with similar viruses provided a useful insight that regulating the level of temperature can offer remarkable results to arrest and stop the outbreak. Based on that knowledge, some urgent and simple solutions are proposed, which are practically without side effects and very cost-effective too.

The field is not always easy for plant phenotyping using conventional phenotyping platforms due to the limited accessibility and regulated aviation area. Smartphone-triggered ground images were collected on wheat field that has a limited access to monitor growth conditions of four wheat varieties, Shinyoung (SY), Joseong (JS), Taewoo (TW), and Cheongwoo (CW). For field mapping during the growing season, six sets of the raw RGB images were acquired by a smartphone camera in an oblique view angle and processed to transform into nadir view images. A series of algorithms were developed to process the skewed tile images to straighten into the nadir images, align the deskewed images, and stitch them into a field image by detecting crop rows using Hough Transformation. Open-source software, iStitch, was developed to automate the algorithms in a batch process. Plot-level metrics were extracted to analyze plant growth of the wheat varieties using a gridding method for vegetation and leaf area indexes. The processed images resulted in the successful transformation and consistency of algorithms on image alignment and stitching. Plot-level analysis indicated that SY variety performed superior to the other varieties in plant quality and quantity and significantly different from TW variety in canopy coverage. The proposed approach of the stitching and gridding was applied on the skewed images acquired by a smartphone camera but can be directly used for other applications of plant phenotyping on images acquired by a camera on a mobile platform or a grid of stationary cameras in greenhouse or outdoor fields.

The subduction of carbon and recycling to volcanoes affects planetary scale processes that set the composition of Earth’s surface and mantle environments. The largest flux of surficial carbon that subducts at trenches globally is sedimentary. This is paradoxical, as most carbonate dissolves and organic carbon oxidizes in the ocean before reaching the deep seafloor. Nonetheless, different events conspire to deliver variable fluxes of carbon, some of them large, to different trench sectors. Thus, sedimentary carbon subduction is not a global phenomenon – it is a regional one where heterogeneity rules. Here we have calculated the flux and isotopic composition of both incoming sediment and trench fill for organic and inorganic carbon at the world’s trenches. Our calculations are at the scale of kms along the trench, and so make predictions relevant to individual volcanoes as well as entire arc segments. A useful comparative metric is the carbon flux delivered by altered oceanic crust (AOC), which is a less variable input of largely inorganic carbon to all subduction zones. In some regions, subducting sedimentary carbon is much less than in the AOC unit subducts, for example, along the ~ 2000-km Tonga-Kermadec trench. Given the very high convergence rate, this region constitutes a large flux of carbonate with δ13C heavier than the mantle. At the other extreme, downgoing plates with km-thick turbidites deliver terrestrial organic carbon with δ13C lighter than the mantle. Trench segments that subduct >4X AOC carbon in sediments include the Nicobar Fan off Sumatra and the Aleutian and South Chile trenches. Regions with high biological productivity (Central America) and shallow seafloor (Hikurangi) supply large sedimentary carbonate fluxes with δ13C heavier than mantle. In addition to enormous isotopic heterogeneity (spanning from –25 to +1 per mil δ13C), bulk sediments also span a wide range in oxidation capacity, from carbonate to organic carbon. These highly heterogeneous point- and regional-sources of carbon fluxes, isotopes and oxidiation states provide natural laboratories to study recycling efficiencies at subduction zones and the creation of diamonds, carbonated melts and other carbon heterogeneities in the mantle.

Data collected by space probes and Earth-based observations allow to investigate multiple aspects of planetary bodies in the Solar System. Typical spatial data utilized for geological and geophysical global scale investigations include imagery basemaps, digital elevation models, feature density maps, geochemical, magnetic and gravity anomaly maps. Different datasets often present local correlations, and their simultaneous use can help unveil the wide diversity of geological and geophysical processes that contribute to the planetary evolution. A geostatistical approach can be applied to quantify the level of correlation and anticorrelation between the different datasets. We developed a method based on a linear regression analysis of multiple planetary data, producing georeferenced maps that can be imported into a Geographic Information System (GIS) environment. We show how this geostatistical method can be used to quantify the level of correlation between different spatial data, and to investigate the geological and geophysical processes of planetary bodies. We present the results of the geostatistical method for the Mercury science case, using datasets returned by the MESSENGER mission.

The American Geophysical Union (AGU) is pleased to submit this RFI response to 2021-13640 on improving federal scientific integrity policies. AGU is the largest global organization covering the Earth sciences with a mission “to support and inspire a global community of individuals and organizations interested in advancing discovery in Earth and space sciences and its benefit for humanity and the environment.” Fostering integrity is a key part of our new strategic plan and past activities and we are engaged in supporting integrity broadly, including with federal agencies. Although not a focus of these recommendations, AGU has often spoken up through position statements and letters related to scientific integrity. Several examples are listed in the references. With this perspective, we urge OSTP to consider two points that we elaborate below: • Fostering integrity–and in turn public trust in science and science policy–requires a broad, holistic view of practices that extend beyond the typical focus on transparency and ethics to include ensuring deeper public engagement, addressing diversity and inclusivity in science and supporting the backbone infrastructure that enables all of these. • The way science is supported, practiced and conducted is changing significantly, as is its dissemination and communication, and these changes have important implications for fostering integrity in the 21st century. Specifically, parts of the culture and reward system of science need improvement to align with these changes, and OSTP and federal policy can be a strong proactive force in enabling this change. This is particularly the case if these policies and practices provide leading examples and extend to federal grants. Many other organizations would then align.

As part of NASA’s Earth Science Technology Office, the Advanced Information Systems Technology (AIST) Program defines an Earth System Digital Twin (ESDT) as an interactive and integrated multidomain, multiscale, digital replica of the state and temporal evolution of Earth systems that dynamically integrates: Relevant Earth system models and simulations Other relevant models (e.g., related to the world’s infrastructure and human activity); continuous and timely (including near real time and direct readout) observations (e.g., space, air, ground, over/underwater, Internet of Things (IoT), socioeconomic) Long-time records Analytics and artificial intelligence tools. Effective ESDTs will enable users to run hypothetical or “what-if” scenarios to improve the continuous assessment and prediction of Earth system processes, natural phenomena and human activities as well as their many interactions, and to ensure optimal mitigation and response to these phenomena. Toward this goal, the AIST Program is developing individual technologies and a few pilots. Some of the technologies that are being considered include: agile interoperability between measurement acquisition and science investigations; moving from mono-discipline to multi-discipline interconnected models; digital thread developments to provide communication links to all digital twin capabilities and to enable design requirements, records, provenance, and system reconfigurations to be easily coordinated; concepts and technologies for developing “federated ESDTs”; multi-scale simulations, statistics, uncertainty quantification, and causality methodologies; high-end computing and surrogate models to optimize the computational efficiency of “what-if” investigations; and innovative user interfaces and visualization methods capable of visualizing complex systems of systems.

The world surrounding us is more over covered with plastics and we are in a “plastic era”. The bigger plastic materials, as the time moves, disintegrate into micro or nano particles may be as a result of radiations or weathering. These are termed as microplastics and nanoplastics. Technically these microparticles do not create a direct impact, instead they make their way to the food chain or rather a complex food chain. These can be through various steps ranging from filter feeding to adherence. They will start to accumulate, as the trophic level increases their accumulations also get increased. These trophic transfer is mainly through ingestion of smaller to higher organisms. Thus they create various damages and diseases to organisms in successive trophic levels. That can be ranging from respiratory disorders to endocrine or oncogenic issues. Not only in the marine world, the terrestrial world is also prone to these microplastics, either by airborne or through sewage water plants. Moreover in a developing or developed country, exposure to these tiny things are much more. The impacts are showing now and will entangle in the near future, unless this is not dealt as a serious issue to be considered. This article focuses on the classification, sources, exposure to food chain or food web, trophic concentrations, health issues, and remedies of microplastics.

Inverse problems are ubiquitous in hydrological modelling for parameter estimation, system understanding, sustainable water resources management, and the operation of digital twins. While statistical inversion is especially popular, its sampling-based nature often inhibits its application to computationally costly models, which has compromised the use of the Generalized Likelihood Uncertainty Estimation (GLUE) methodology, e.g., for spatially distributed (partial) differential equation based models. In this study we introduce multilevel GLUE (MLGLUE), which alleviates the computational burden of statistical inversion by utilizing a hierarchy of model resolutions. Inspired by multilevel Monte Carlo, most parameter samples are evaluated on lower levels with computationally cheap low-resolution models and only samples associated with a likelihood above a certain threshold are subsequently passed to higher levels with costly high-resolution models for evaluation. Inferences are made at the level of the highest-resolution model but substantial computational savings are achieved by discarding samples with low likelihood already on levels with low resolution and low computational cost. Two example inverse problems, using a rainfall-runoff model and groundwater flow model, demonstrate the substantially increased computational efficiency of MLGLUE compared to GLUE as well as the similarity of inversion results. Findings are furthermore compared to inversion results from Markov-chain Monte Carlo (MCMC) and multilevel delayed acceptance MCMC, a corresponding multilevel variant, to compare the effects of the multilevel extension. All examples demonstrate the wide-range suitability of the approach and include guidelines for practical applications.

Superimposed signatures of grain size effect, lithology and chemical processes on fluvial sediments need to be resolved to answer the profound research questions related to sediment provenance and processes. Hydraulic forces sort the sediments into different grain size classes in the river water column. The finest fraction is transported as the suspended sediments which have different sediment composition than the bed sediments. Thus, suspended sediment may provide additional information about earth surface processes, such as chemical weathering. Hydraulically sorted river bed sediments may or may not provide this information, as bulk sample may be depleted in finer grains by hydraulic processes. Bed sediments that are easily sampled from the sand bars and river banks are often investigated to study the weathering intensity and sediment provenance. It is thus crucial to identify and quantify the specific grain size classes in the bulk sample to be investigated for the research question at hand. End Member Modelling Algorithms (EMMA) for grain size distribution is a useful tool to unmix the grain size population into geological meaningful end members. We applied Hierarchical alternating least squares nonnegative matrix factorization (HALS-NMF) algorithm to unmix the grain size data (62 samples) of river bed sediments collected from the freshly exposed sand bars of the Brahmaputra river over a stretch of 550km. The grain size distribution of the finest end member (mean=18µm) is closely approximated to be of the surface sediment grain size distribution reported previously for the Brahmaputra river. Thus, we were able to quantify the relative contribution of suspended sediment to the bed sediment of the Brahmaputra trunk. Results show that the contribution of the suspended sediments in the bed sediment is higher at the lower reaches of the river near floodplain outlet, possibly due to the reduced flow energy in downstream regions. The findings may also be used to select samples and grain size classes for additional geochemical and mineralogical study in order to interpret signals of weathering, provenance and physical processes in the Brahmaputra’s large dynamic floodplains at a finer spatial scale.

Wind-generated waves strongly interact with sea ice and impact air-sea exchanges, operations at sea, and marine life. Unfortunately, the dissipation of wave energy is not well quantified and its possible effect on upper ocean mixing and ice drift are still mysterious. As the Arctic is opening up and wave energy increases, the limited amount of \emph{in situ} observations is a clear limitation to our scientific understanding. Both radar and optical remote sensing has revealed the frequent presence of waves under the ice, and could be used more systematically to investigate wave-ice interactions. Here we show that, in cloud-free conditions, Sentinel-2 images exhibit brightness modulations in ice-covered water, consistent with the presence of waves measured a few hours later by the ICESat-2 laser altimeter. We also show that a full-focus SAR processing of Sentinel-3 radar altimeter data reveals the presence of waves under the ice and their wavelengths, within minutes of Sentinel-2 imagery. The SWIM instrument on CFOSAT is another source of quantitative evidence for the direction and wavelengths of waves under the ice, when ice conditions are spatially homogeneous. In the presence of sea ice, a quantitative wave height measurement method is not yet available for all-weather near-nadir radar instruments such as altimeters and SWIM. However, their systematic co-location with optical instruments on Sentinel-2 and ICESat-2, which are less frequently able to observe waves in sea ice, may provide the empirical transfer functions needed to interpret and calibrate the radar data, greatly expanding the available data on wave-ice interactions.

The onshore continental margins of western Central Africa have been hosting potentially damaging earthquake events for decades; yet, the links between the seismicity, the contemporary stress field, and pre-existing faults are not well understood. Here, we analyze the regional stress fields along the coastal margin and interior cratonic areas using earthquake focal mechanisms, map and characterize the detailed structure of preexisting fault systems in outcrops, and assess the reactivation potential of the mapped structures. Our results show that the earthquakes originate under a transpressive stress regime with a horizontal maximum principal compressive stress (σ1) that is oriented NNE-SSW. We show that regional stresses acting on offshore oceanic fracture zones are compatible with those acting along with the onshore areas of the continental margin. Field observations reveal the presence of large fault systems that deform both the Precambrian basement and Phanerozoic sedimentary sequences, with widespread hydrothermal alterations of calcite veining, quartz veining, and palygorskite mineralization along the fault zones. Along the margin, the preexisting NNE-, NNW-, and N-S -trending strike-slip faults and normal faults show a high slip tendency (60 – 100 %), ), whereas in the cratonic interior, the NW- and N-S -trending thrust faults are the most likely to reactivate. We argue that favorable orientation of the preexisting faults and potentially, their hydrothermal alteration products, define the susceptibility of the faults to seismic reactivation. We propose that possible stress propagation into the near-shore and onshore tip zones of oceanic fracture zones may be driving stress loading on pre-stressed fault systems onshore.

The prevalence of mixing vs. precipitation processes in biomass burning aerosol (BBA) laden air over the southeast Atlantic is assessed during three intensive observation periods during the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign. Air in the lower free troposphere (FT) and marine boundary layer (MBL) are treated as separate analyses, although connections are made where relevant. The study, centering on aircraft in-situ measurements of total water heavy isotope ratios, has two main objectives. The first is to gauge whether the atmospheric hydrology, and in particular precipitation, can be constrained primarily through visual assessment of the aircraft isotope ratio data plotted against total water concentration, similarly to several previous studies. However, regression of the data onto a simple model of convective detrainment is also used and alludes to the possibility of a precipitation data product derived from isotope ratios. The second objective is to connect variations in aerosol concentrations to the hydrology as diagnosed by the isotope ratio measurements, and determine whether aerosol variations are attributable to wet scavenging. First, joint water concentration (q) and H2O/HDO isotope measurements (δD) in the lower FT are combined with satellite and MERRA-2 data into simple analytical models to constrain hydrologic histories of BBA-laden air originating over Africa and flowing over the southeast Atlantic. We find that even simple models are capable of detecting and constraining the primary processes at play. Further, a strong correlation between isotopic evidence of precipitation in lower FT air masses and an in-situ indicator of wet scavenging of black carbon – the ratio of black carbon to carbon monoxide (BC/CO) – is shown. In comparison, the correlation between BC/CO and the water concentration itself is low. Since wet scavenging is the primary removal mechanism of black carbon, these findings suggest that isotope measurements could support studies constraining the lifetime of black carbon in the FT. Next, the ability of measurements interpreted with simple analytical models in (q, δD) space to distinguish cloud-top entrainment vs. precipitation signals in the MBL is tested. This proves more difficult than the lower FT analysis since signals are smaller. We find that the largest obstacle to this goal is the (q, δD) values of the entrained airmass at cloud-top. We also compare cloud condensation nuclei (CCN) concentrations in the sub-cloud layer to the isotopic measurements. In 2016 and 2018 IOPs, lower CCN concentrations coincide with isotope ratio evidence of precipitation, indicating aerosol scavenging. However, a more complex model simulating water, isotope ratios, and aerosols would be necessary to achieve more definitive conclusions. For the 2017 IOP, with the highest sub-cloud CCN concentrations, there is no connection between precipitation signals and CCN concentrations.

The dynamic topography of the core-mantle boundary (CMB) provides important constraints on dynamic processes in the mantle and core. However, inferences on CMB topography are complicated by the uneven coverage of data with sensitivity to different length scales and strong heterogeneity in the lower mantle. Particularly, a trade-off exists with density variations, which ultimately drive mantle flow and are vital for determining the origin of mantle structures. Here, I review existing models of CMB topography and lower mantle density, focusing on seismological constraints. I develop average models and vote maps with the aim to find model consistencies and discuss what these may teach us about lower mantle structure and dynamics. While most density models image two areas of dense anomalies beneath Africa and the Pacific, their exact location and relationship to seismic velocity structure differs between studies. CMB topography strongly influences the retrieved density structure, which helps to resolve differences between recent studies based on Stoneley modes and tidal measurements. Current CMB topography models vary both in pattern and amplitude and a discrepancy exists between models based on body-wave and normal-mode data. As existing models feature elevated topography below the Large-Low-Velocity Provinces (LLVPs), very dense compositional anomalies may currently be ruled out as possibility. To achieve a similar consistency as observed in lower mantle models of S-wave and P-wave velocity, future studies should combine multiple data sets to break existing trade-offs between CMB topography and density. Important considerations in these studies should be the choice of theoretical approximation and parameterisation. Efforts to develop models of CMB topography consistent with body-wave, normal-mode and geodetic data should be intensified, which will aid in narrowing down possible explanations for the LLVPs and provide additional insights into mantle dynamics.

Stratospheric aerosol geoengineering focused on the Arctic could substantially reduce local and worldwide impacts of anthropogenic global warming. Because the Arctic receives little sunlight during the winter, stratospheric aerosols present in the winter at high latitudes have little impact on the climate, whereas stratospheric aerosols present during the summer achieve larger changes in radiative forcing. Injecting SO2 in the spring leads to peak aerosol optical depth (AOD) in the summer. We demonstrate that spring injection produces approximately twice as much summer AOD as year-round injection and restores approximately twice as much September sea ice, resulting in less increase in stratospheric sulfur burden, stratospheric heating, and stratospheric ozone depletion per unit of sea ice restored. We also find that differences in AOD between different seasonal injection strategies are small compared to the difference between annual and spring injection.

Sea ice production within polynyas, an outcome of the atmosphere - ice - ocean interaction, is a major source of dense water and hence key to the global overturning circulation, but is poorly quantified over open-ocean polynyas. Using the two recent extensive open-ocean polynyas within the wider Maud Rise region of the Weddell Sea in 2016 and 2017, we here explore the surface ice energy budget and estimate their ice production based on satellite retrievals, in-situ hydrographic observations, and the Japanese 55-year Reanalysis (JRA55). We find that the oceanic heat flux amounts to 36.1 and 30.7 W m-2 within the 2016 and 2017 polynyas, respectively. We find that the 2017 open-ocean polynya produced nearly 200 km3 of new sea ice, which is comparable to the production in the largest Antarctic coastal polynyas. Finally, we find that ice production is highly correlated with the 2 m air temperature and wind speed, which affect the turbulent fluxes. It is also highly sensitive to uncertainties in the atmospheric air temperature and mixed layer depth, which urgently need to be better monitored at high latitudes.

Agricultural managed aquifer recharge (AgMAR) is a proposed management strategy whereby surface water flows are used to intentionally flood croplands with the purpose of recharging underlying aquifers. However, legacy nitrate (NO3-) contamination in agriculturally-intensive regions poses a threat to groundwater resources under AgMAR. To address these concerns, we use a reactive transport modeling framework to better understand the effects of AgMAR management strategies (i.e., by varying the frequency, duration between flooding events, and amount of water) on N leaching to groundwater under different stratigraphic configurations and antecedent moisture conditions. In particular, we examine the potential of denitrification and nitrogen retention in deep vadose zone sediments using variable AgMAR application rates on two-dimensional representations of differently textured soils, soils with discontinuous bands/channels, and soils with preferential flow paths characteristic of typical agricultural field sites. Our results indicate that finer textured sediments, such as silt loams, alone or embedded within high flow regions, are important reducing zones providing conditions needed for denitrification. Simulation results further suggest that applying recharge water all-at-once, rather than in increments, increases denitrification within the vadose zone, but transports higher concentrations of NO3- deeper into the profile. This transport into deeper depths can be aggravated by wetter antecedent soil moisture conditions. We conclude that ideal AgMAR management strategies can be designed to enhance denitrification in the subsurface and reduce N leaching to groundwater, while specifically accounting for lithologic heterogeneity, antecedent soil moisture conditions, and depth to the water table.