On 15 January 2022, the Hunga Tonga-Hunga Ha’apai submarine volcano erupted violently and triggered a giant atmospheric shock wave and tsunami. The exact mechanism of this extraordinary eruptive event, its size and magnitude are not well understood yet. In this work, we analyze data from the nearest ground-based receivers of Global Navigation Satellite System (GNSS) to explore the ionospheric total electron content (TEC) response to this event. We show that the ionospheric response consists of a giant TEC increase followed by a strong long-lasting depletion. We observe that the explosive event of 15 January 2022 began at 04:05:54UT and consisted of at least 5 explosions. Based on the ionospheric TEC data, we estimate the energy released during the main major explosion to be between 9 and 37 Megatons in TNT equivalent. This is the first detailed analysis of the eruption sequence scenario and the timeline from ionospheric TEC observations.

The Arctic climate is changing dramatically, especially in terms of sea ice loss, with potentially large downstream impacts on the Nordic Seas and the North Atlantic Ocean. The East Greenland Current (EGC) transports substantial amounts of freshwater (in liquid and solid states) southward along the east Greenland continental slope. To increase our understanding of the drivers of surface salinity changes in the interior Nordic Seas, we investigate the diversion of freshwater from the EGC into the Nordic Seas. To this end, we analyse the outcomes of an ocean model hindcast for the period 1973-2004 with a horizontal resolution of 0.25 degree. We find that sea ice contributes large amounts of freshwater to the interior Nordic Seas. On an interannual time scale, this sea ice diversion has a high and significant correlation with surface salinity in the Greenland and Iceland Seas (correlation < -0.7). On a seasonal time scale, the model hindcast and observations demonstrate a clear signal in surface salinity: a lateral migration of the Polar Front position occurring along all of east Greenland. In the model hindcast, these lateral shifts in the front are consistent with seasonal changes in the westward wind-driven Ekman transport. Thus, this climate model study indicates that there are two main causes of seasonal and interannual surface salinity changes; wind-driven Ekman transport and sea ice diversion from the EGC, respectively.

The mid-Proterozoic (~1.8–0.8 Ga) is characterized by low atmospheric oxygen and pervasive oceanic anoxia, with transient oxygenations. One of the prominent oxygenation events happened at ~1.57 Ga, during which atmospheric O2 may have reached ≥4% present atmospheric level (PAL) and thus promoted the evolution of multi-cellular eukaryotes. The causes for this oxygenation event, however, remained unknown. Here, we report the result of δ202Hg and ∆199Hg, P concentration, Rb/Al, and eNd(t) across this oxygenation interval in the Gaoyuzhuang Formation of North China. The positive δ202Hg, eNd(t), and negative Δ199Hg shifts, and the accompanied peaks in Rb/Al, P and I/(Ca+Mg) suggest that this oxygenation was likely resulted from enhanced weathering of intermediate to mafic rocks, which may have promoted primary production via increasing P influx to the ocean and led to the rise in oxygen levels. The data indicate that enhanced weathering input can trigger transient oxygenation events during the mid-Proterozoic.

The 13 km SHiELD (System for High-resolution prediction on Earth-to-Local Domains) global model that is under development at the Geophysical Fluid Dynamics Laboratory (GFDL) and runs in near real time, produced outstanding tropical cyclone track forecasts during the 2021 Atlantic hurricane season, compared to both the upgraded National Weather Service Global Forecast System (GFSv16), the Hurricane Weather Research and Forecasting (HWRF) model and the European Centre for Medium-Range Weather Forecast Integrated Forecasting System (IFS). SHiELD’s average track forecast errors were 10% and 15% less than the GFSv16 and HWRF, respectively, for the 3-5 day forecast lead times. SHiELD’s track forecast skill was comparable to the National Hurricane Center’s official forecast at several forecast lead times, and approached 70% skill relative to the Climatology and Persistence Model (CLIPER) at 3 and 4 days. Similar improvements were found in the western Pacific basin in 2021, with improvements also seen in the eastern Pacific at days 4 and 5. Improved performance was also found in the 2019 Atlantic hurricane season, with neutral performance in 2020, when SHiELD was run retrospectively from the GFSv16 initial conditions. Distribution of the spatial errors and biases showed that in both the 2021 Atlantic hurricane season and the previous two years, the largest track forecast errors from both SHiELD and GFSv16 occurred in the subtropical eastern Atlantic, associated with a distinct northeast bias. Analysis indicated that some of the excessive north bias in the GFSv16 is associated with lower geopotential height fields compared to those in SHiELD.

The climate of the southwestern North America has experienced profound changes between wet and dry phases over the past 200 kyr. To better constrain the timing, magnitude and paleoenvironmental impacts of these changes in hydroclimate, we conducted a multiproxy biomarker study from samples collected from a new 76 m sediment core (SLAPP-SRLS17) drilled in Searles Lake, California. Here, we use biomarkers and pollen to reconstruct vegetation, lake conditions and climate. We find that δD values of long chain n-alkanes are dominated by glacial to interglacial changes that match nearby Devils Hole calcite δ18O variability, suggesting both archives predominantly reflect precipitation isotopes. However, precipitation isotopes do not simply covary with evidence for wet-dry changes in vegetation and lake conditions, indicating a partial disconnect between large scale atmospheric circulation tracked by precipitation isotopes and landscape moisture availability. Increased crenarchaeol production and decreased evidence for methane cycling reveal a 10 kyr interval of a fresh, productive and well-mixed lake during Termination II, corroborating evidence for a paleolake highstand from shorelines and spillover deposits in downstream Panamint Basin during the end of the penultimate (Tahoe) glacial (140–130 ka). At the same time brGDGTs yield the lowest temperature estimates (mean months above freezing = 9 ± 3°C) of the 200 kyr record. These limnological conditions are not replicated elsewhere in the 200 kyr record, suggesting that the Heinrich stadial 11 highstand was wetter than that during the last glacial maximum and Heinrich 1 (18–15 ka).

Green Bay is a large freshwater estuarine system that drains one-third of the Lake Michigan basin. The International Joint Commission designated southern Green Bay as an area of concern (AOC) in the 1980s due to ecosystem degradation including eutrophication, harmful algal blooms (HABs), hypoxia, lost or altered habitat, and reduced water quality. Restoration studies have found excessive nutrient loading and release of toxic materials, primarily produced in farmlands and industrial units, to be major drivers of Green Bay environmental/ecological issues. The Green Bay geomorphology and restricted mixing is a barrier to the efficient transport of sediments (as well as the accompanying nutrients and contaminants), acting as a retention basin for Lake Michigan. The purposes of this research were to: a) use the existing database of hydrodynamic, wave, and sediment field data to develop a three-dimensional (3D) predictive model of sediment transport in Lake Michigan, with an emphasis in Green Bay; b) use the sediment transport model to contribute to understanding ecological and environmental problems in the bay, and to recommend long-term solutions to those problems; and c) analyze summer patterns of circulation, wave action, current and wave-induced bottom shear stress, thermal structure, and sediment transport in Lake Michigan, with special attention to Green Bay.

The effects of precipitation (Pr) and evapotranspiration (ET) on soil moisture play an essential role in the land-atmosphere system. Here we evaluate multimodel differences of these effects within the Coupled Model Intercomparison Project Phase 5 (CMIP5) compared to Soil Moisture Active Passive (SMAP) products in the frequency domain. The variability of surface soil moisture (SSM), Pr, and ET within three frequency bands (7 ~ 30 days, 30 ~ 90 days, and 90 ~ 365 days) after normalization is quantified using Fourier transform. We then analyze the impact of ET and Pr on SSM variability based on a transfer function assuming these variables with a linear time-invariant (LTI) system. For the simulated effects of ET and Pr on SSM variability, models underestimate them in the two higher frequency bands and overestimate them in the lowest frequency band but show better estimates in transitional zones between dry and wet climates. Besides, the effects on SSM by Pr and ET are found to be different across the three frequency bands, and models underestimate the one of Pr and ET as the dominant factor controlling SSM variability in each frequency band. This study identifies the spatiotemporal distribution of the CMIP5 model deficiencies in simulating ET and Pr effects on SSM. Overcoming these deficiencies could improve the interpretability and predictability of Earth system models in simulating interactions among the three variables.

At the international level, the term “water security” (WS) has gained increasing attention in recent decades. At the operational level, WS is assessed using tools that define the concept using a variety of dimensions and sub-dimensions, with qualitative and quantitative indicators and parameters. The breadth of tools and concepts is an obstacle to the operationalization of the concept of water security (WS). Clearly we need a range of diverse data to evaluate water security (WS). However, there are several barriers to designing an optimal Data Gathering Strategy (DGS). Such a strategy must strike a balance between a wide range of competing and overlapping data requirements and characteristics including: resources, information, and impact. The conceptual aim of the framework can be summarised as shifting the focus of the DGS from a “data to information approach” to a “data to action approach”. The specific aims of this paper are to: identify the key issues that should be addressed in designing a Data Gathering Strategy for Water Security (DGSxWS); communicate the key issues with a clear conceptual framework; and suggest approaches and activities that could help water practitioners in dealing with the issues identified.

Mapping modern and paleo-grounding lines around the Antarctic Ice Sheet elucidates processes occurring at the grounded ice-ocean interface. Positional differences across individual grounding lines manifest as longitudinal (plan-view) grounding line sinuosity. We explore the causes and significance of such sinuosity by coupling observations of contemporary Antarctic grounding lines and paleo-grounding lines expressed as ice-marginal landforms, specifically focusing on the role that bed topography may play in influencing grounding-line sinuosity. For equal-length grounding-line segments, modern and paleo-grounding lines have remarkably similar sinuosity distributions, with the vast majority of grounding lines being near linear. Surprisingly, grounding line sinuosity is highest on low sloping beds and lower on rougher beds, even for grounding lines that are clearly pinned on topographic highs. For contemporary grounding lines, sinuosity is higher and more variable for grounding lines near floatation with shallow height-above-buoyancy gradients. We argue that grounding line sinuosity is a product of the combined influence of height-above-buoyancy gradient, bed slope, and bed roughness and, perhaps counterintuitively, that this relationship does not appear to be sensitive to the presence of pinning points, ice-flow speed, or the presence/absence of an ice shelf.

While meteorology and aerosols are identified as key drivers of snow cover variability in High Mountain Asia (HMA), complex non-linear interactions between them are not adequately quantified. Here, we attempt to unravel these interactions through a simple relative importance (RI) analysis of meteorological and aerosol variables from ERA5/CAMS-EAC4 reanalysis against satellite-derived snow cover from MODIS across 2003-2018. Our results show a statistically significant 7% rise in the RI of aerosol-meteorology interactions (AMI) in modulating snow cover during late snowmelt season (June-July), notably over low snow-covered (LSC) regions. Sensitivity tests further reveal that the importance of meteorological interactions with individual aerosol species are more prominent than total aerosols over LSC regions. We find that the RI of AMI for LSC regions is clearly dominated by carbonaceous aerosols, on top of the expected importance of dynamic meteorology. These findings clearly highlight the need to consider AMI in hydrometeorological monitoring, modeling, and reanalyses.

The ability of global climate models to reproduce recurrent regional atmospheric circulation types is introduced as an overarching concept to explore potential dependencies between these models. If this approach is applied on a sufficiently large spatial domain, the similarity of the resulting error pattern can be compared from one model to another. By computing a pattern correlation matrix for a large multi-model ensemble from the Coupled Model Intercomparison Project, groups of comparatively strong correlation coefficients are obtained for those models working with similar atmospheric components. Thereby, frequent shared error patterns are found within in the ensemble, which also occur for nominally different atmospheric component models.

In gravel-bed rivers, deterministic approaches to predicting bedload transport use the mean bed shear stress (termed one-dimensional or ‘1D’ equations) or integrate across the frequency distribution of shear stress (2D equations). At low flows, incorporating a range of shear stress values increases prediction accuracy, but at relatively high flows the 1D and 2D approaches are similarly accurate. We contribute to an understanding of the stage-dependent relationship between morphology and bedload transport, and specifically why the mean shear stress characterises transport capacity at formative discharges. We performed physical modelling using a generic Froude-scaled model of a steep laterally-constrained gravel-bed river and captured digital elevation models to perform 2D hydraulic modelling. Both 1D and 2D Meyer-Peter Müller equations were highly accurate across two distinct channel morphologies. In alternate bar channels, transport capacity was controlled by negative feedbacks between flow depth and local bed slope that resulted in a relatively homogeneous distribution of bed shear stress. In plane-bed channels, which lacked the degrees-of-freedom available for large-scale morphologic adjustment, transport capacity was controlled by a spatially variable migrating surface texture. The contrasting spatial patterns of morphology, hydraulics, and surface texture between the two channel morphologies highlight the potential for the same correlation between mean shear stress and transport capacity to emerge through different mechanisms. We suggest that nonlinear feedbacks explain why simple bedload transport equations can be highly effective above a certain flow stage across a range of channel morphologies, and further work should examine whether lateral adjustment confounds this result.

The monthly time series of carbonyl sulfide (OCS) atmospheric mole fractions measured at NOAA network stations (2000 to 2020) have been analyzed, and the long-term behaviour has been assessed based on the Empirical Mode Decomposition (EMD). EMD is a fully non-parametric analysis of frequency modes and trends in a given series and is based on the data alone. We have found that the OCS atmospheric mole fraction, after an increasing phase up to ~2015, with a temporary decline around 2009, is now decreasing at all stations, reflecting a recent imbalance in its total sources and losses. Our analysis has revealed a characteristic time scale for variation of 8-10 years. The variance associated with this long-term behaviour ranges from 15 to 40% of the total strength of the signal, depending on location. To our knowledge, this low-frequency mode is a novel result not assessed in previous studies. Apart from this complex long-term behaviour, the OCS time series show a strong annual cycle, which primarily results from summertime OCS uptake by vegetation. In addition, we have also found one more frequency of minor variance intensity in the measured mole fraction time-history, which corresponds to periods in the range of 2 to 3 years. This inter-annual variability of OCS may be linked to the Quasi-Biennial Oscillation or QBO.

Unlike embankments, earth dams, and other man-made structures, most landslide dams are formed by rapid accumulation of rock or debris rather than mechanical compaction; thus, they are loose and pose a great risk of seepage failure. Landslide materials usually have complex pore structures with randomly distributed pores of various sizes, making the flow and transport processes very complex. Aiming at these challenges, we have studied the influences of pore structure on the micro-and macro-scale flow characteristics of landslide materials. First, landslide materials are simplified as spherical granular packings with wide grain size distributions. Then, we use finite difference method (FDM) and lattice Boltzmann method (LBM) to simulate the fluid flow through granular packings and calculate their permeability. We find that both the correlation between pore-scale velocity and throat diameters and the correlation between macroscopic permeability and average throat diameters follow a power-law scaling with an exponent close to 2, in agreement with the Hagen–Poiseuille equation for laminar flow in pipes, suggesting that the relationships in complex pore structures are conformed with the simple theory. Moreover, we propose a new method by combining pore networks and complex networks to characterize the pore structure. The network analysis illustrates that granular packings with different permeability display distinctive distributions of pore throat size and pore connectivity and their correlations. Compared with disassortative pore networks, assortative ones generally have higher permeability. Furthermore, pores with larger closeness centrality have higher flow efficiency that results in higher macroscopic permeability.

Material samples are vital across multiple scientific disciplines with samples collected for one project often proving valuable for additional studies. The Internet of Samples (iSamples) project aims to integrate large, diverse, cross-discipline sample repositories and enable access and discovery of material samples as FAIR data (Findable, Accessible, Interoperable, and Reusable). Here we report our recent progress in controlled vocabulary development and mapping. In addition to a core metadata schema to integrate SESAR, GEOME, Open Context, and Smithsonian natural history collections, three small but important controlled vocabularies (CVs) describing specimen type, material type, and sampled feature were created. The new CVs provide consistent semantics for high-level integration of existing vocabularies used in the source collections. Two methods were used to map source record properties to terms in the new CVs: Keyword-based heuristic rules were manually created where existing terminologies were similar to the new CVs, such as in records from SESAR, GEOME, and Open Context and some aspects of Smithsonian Darwin Core records. For example specimen type =liquid>aqueous in SESAR records mapped to specimen type = liquid or gas sample and material type = liquid water. A machine learning approach was applied to Smithsonian Darwin Core records to infer sampled feature terms from record text describing habitat, locality, higher geography, and higher classification fields. Applying fastText with a 600-billion-token corpus in the general domain, we provided the machine a level of “understanding” of English words. With 200 and 995-record training sets, 87%, 94% precision and 85%, 92% recall were obtained respectively, yielding performance sufficient for production use. Applying these approaches, more than 3x106 records of the four large collections have been mapped successfully to a common core data model facilitating cross-domain discovery and retrieval of the sample records.

Conventional engineering measures, such as surge barriers and mobile floodgates, are being adopted in many coastal cities worldwide, threatened by the increasing flooding hazard due to rising sea levels. Famous examples include London, the Netherlands, New Orleans, St. Petersburg and Venice. However, the question of how flood regulation affects the morphodynamic evolution of shallow tidal embayments still lingers. Storm-surge barriers may importantly modify the propagation of tides, surges and wind waves, changing sediment transport and, thus, the morphological evolution of regulated tidal environments, in particular in sediment-starved systems. Combining field data and numerical modelling, we investigate the effect of the Mo.S.E. storm-surge barriers, designed to protect Venice from flooding, on the morphodynamic evolution of the Venice lagoon. Artificial reduction of water levels within the lagoon affects the interaction between tide propagation and wind waves, increasing sediment resuspension on tidal flats. Resuspended sediment hardly accumulates on salt marshes, contributing to their vertical accretion and offsetting the negative effect of relative sea-level rise, owing to the reduction of marsh flooding determined by reduced water levels. Although barrier closures temporarily reduce the sediment export toward the open sea, this does not point to preserve the characteristic lagoonal morphology, hindering salt-marsh accumulation and promoting tidal-flat deepening and channel infilling. We conclude that the operations of flood barriers can promote a significant loss of geomorphological diversity, which will critically impact the ecosystem services provided by the shallow tidal environments they are meant to protect, thus increasing the costs related to their conservation and restoration.

The Malalak Tephra (sourced from Tandikat volcano) is considered one of the youngest and most voluminous tephra deposits (VEI-5) in West Sumatra, Indonesia. However, several constraints such as deposit characteristics and eruption dynamics, remain poorly understood. Therefore, this study focuses on the linkage between temporal variation (stratigraphy) with componentry, bulk density, and juvenile textures such as vesicles and phenocrysts of the Malalak Tephra deposit. This deposit mainly consists of five pumice fall layers (F-1, F-2, F-3, F-4, and F-5) with gradational contact between each layer (repetitions of normal and reverse grading). White and grey pumices occur as the main juvenile phase. White pumice has a higher crystallinity (avg. of 44 %) and more evolved chemical composition of glass (73–78 wt. % SiO2) compared to grey pumice (average crystallinity 37 % with 71–77 wt. % SiO2), suggesting that both pumices originated from different magma chambers and mingled just before and during the eruption. Grey pumice is typically denser than white pumice, with varying bulk density of 0.65–1.78 g/cm3 and 0.48–1.09 g/cm3 for grey pumice and white pumice, respectively. Bulk density was observed to increase (for white and grey pumices) from the main stage (F-1 and F-2) to the closing stage (F-3, F-4, and F-5). Because bulk density is strongly dependent on bulk vesicularity, and bulk vesicularity is controlled by vesicle number density (which is a function of decompression rate), it can be inferred that the main stage was relatively more explosive compared to the closing stage.

A dynamic response of the ocean to surface pressure loading by the well-known 5-day Rossby-Haurwitz mode in the atmosphere has been inferred from limited in situ tide gauge and bottom pressure data, but a global characterization of such response, including details at mid and high latitudes, has been lacking. Here we explore two daily data products from the Gravity Recovery and Climate Experiment (GRACE) mission to obtain a first quasi-global look at the associated ocean bottom pressure (OBP) signals at 5-day period. The previously reported in-phase behavior over the Atlantic basin, seesaw between the Atlantic and Pacific, and westward propagation in the Pacific are all seen in the GRACE solutions. Other previously unknown features include relatively strong responses in the Southern Ocean and also some shallow coastal regions (e.g., North Sea, East Siberian shelf, Patagonian shelf). Correlation analysis points to the Rossby-Haurwitz surface pressure wave as the main forcing for the observed large-scale OBP anomalies, while wind-driven signals are more spatially confined. The GRACE observations are found to be consistent with in situ OBP data and also with model simulations of the 5-day ocean variability where no in situ data is available. Inferences on energetics based on data and model results point to decay time scales shorter than the oscillation period, with substantial kinetic energy and dissipation located over a few topographic features in the Southern Ocean. Results illustrate the potential of space gravity measurements for examining large-scale oceanic variability at sub-weekly periods.