Researchers and end users using climate data face a challenge when they analyze the data they need. Data volumes are increasing very rapidly, and the ability to download all needed data is often no longer possible. Most of the climate analysis tools for research and application needs must use very large datasets, often distributed among several data centres and into a large quantity of files. This is especially true when they are stored in a federated architecture like the ESGF. One of these tools is icclim (https://github.com/cerfacs-globc/icclim ), a flexible python software package to calculate climate indices and indicators. This tool adhere as much as possible to metadata conventions such as CF, implementing also provenance information. It also aims at providing increasing support for all FAIR aspects. It is designed with performance and optimisation in mind, because the goal is to provide on-demand calculations for users. It provides the implementation of most of the international standard climate indices such as ECAD, ETCCDI, ET-SCI, including the correct methodology for calculating percentile indices using the bootstrapping method. It has been validated against R.Climdex as well (https://cran.r-project.org/web/packages/climdex.pcic/index.html ). The new 5.x version of icclim is now based on functions from the xclim python library, which was inspired by earlier versions of icclim, but using xarray and dask for data access and processing. icclim is also a candidate as the software to calculate climate indices for the C3S toolbox (https://cds.climate.copernicus.eu/cdsapp#!/toolbox ). icclim is integrated in the IS-ENES C4I 2.0 platform (https://climate4impact.eu/ ), using a Jupyter notebook collection in a SWIRRL environment (Software for Interactive Reproducible Research Labs https://gitlab.com/KNMI-OSS/swirrl ). Having access to this type of analysis tool is very useful, and seamless integration with front-ends like C4I enable the use of those tools by a larger number of researchers and end users. This project (IS-ENES3) has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement N°824084.

Oceanic slab vertical tearing is prevalently identified in the present Earth. More general background for vertical slab tearing is the transform-fault subduction during horizontally-oblique tectonic convergence. However, its geodynamic mechanisms are poorly understood to date. This work introduces a full numerical 3-D time-dependent Stokes’ thermo-mechanical flow model to investigate the characteristics and mechanism of vertical tearing of active transform-faulted oceanic slab during oblique subduction. We find that (i) transform-fault ages-offset and (ii) subduction horizontal obliqueness have the first-order control, even without the lateral physical-property differences. The overriding plate enforces (surface contact interaction) bending of one slab first, which superimposes the differential sinking driven by slabs-age-thickness differences. For obliqueness angles ≥30° and/or age-ratios of the secondly-bent to the firstly-bent slab being <0.6, well-developed slab vertical tearing is unavoidable inside the mantle. Quantifying the horizontal distance vector between sinking slabs, we find that young overall lithosphere (average <30 Myr, for any age ratio) at high subduction obliqueness angles (>~25°) tends to produce trench-parallel slab tearing. In contrast, combinations of small-intermediate obliqueness angles (0-30°) and age ratios with the slab that bends at the trench first being relatively older-thicker, tend to produce trench-perpendicular tearing, which is related to differential slabs-hinge retreat or rollback. These numerically-predicted scenarios and phenomena are consistent with plate-tear imaging results from subduction zones. Our modeling results also suggest that the continual along-trench variation in subduction dip angle may be related to oblique subduction’s early stages of evolution.

Both in situ measurements and numerical simulations show that the charge exchange collisions between energetic ring current ions (>10keV) and cold ambient neutral atoms of the upper atmosphere and exosphere (<1eV) can be a major loss process of the ring current ions. Owing to the high volume of energetic ion source injected from the ion plasma sheet during storm time under strong convection strength, there can be a significant rate of occurrence of charge exchange collision in the inner magnetosphere, therefore contributing a significant amount of inner magnetospheric cold proton populations. Due to the different charge exchange cross sections among different reactions, cold protons are generated at different rates from different energetic ion species. In this study, both qualitative and quantitative assessments on the production and evolution of charge-exchange byproduct cold protons are performed via numerical simulations, showing that the production and evolution of the cold H+ populations can be primarily driven by the plasma sheet conditions combined with the magnetospheric convection, while having the potential to affect the dynamics of the plasmasphere and facilitate the early-stage local plasmaspheric refilling. Furthermore, the energetic heavy ions composition plays an important role determining the cold H+ contribution structure from the energetic ring current ions.

The OSIRIS-REx mission collected a sample from the surface of the asteroid (101955) Bennu in October 2020. Here we study the impact of the OSIRIS-REx Touch-and-Go Sampling Acquisition Mechanism (TAGSAM) interacting with the surface of an asteroid in the framework of granular physics. Traditional approaches to estimating the penetration depth of a projectile into a granular medium include force laws and scaling relationships formulated from laboratory experiments in terrestrial-gravity conditions. However, it is unclear that these formulations extend to the OSIRIS-REx scenario of a 1300-kg spacecraft interacting with regolith in a microgravity environment. We studied the TAGSAM interaction with Bennu through numerical simulations using two collisional codes, pkdgrav and GDC-i. We validated their accuracy by reproducing the results of laboratory impact experiments in terrestrial gravity. We then performed TAGSAM penetration simulations varying the following geotechnical properties of the regolith: packing fraction (P), bulk density, inter-particle cohesion (σc), and angle of friction (ɸ). We find that the outcome of a spacecraft-regolith impact has a non-linear dependence on packing fraction. Closely packed regolith (P≳0.6) can effectively resist the penetration of TAGSAM if ɸ≳28° and/or σc≳50 Pa. For loosely packed regolith (P≲0.5), the penetration depth is governed by a drag force that scales with impact velocity to the 4/3 power, consistent with energy conservation. We discuss the importance of low-speed impact studies for predicting and interpreting spacecraft-surface interactions. We show that these low-energy events also provide a framework for interpreting the burial depths of large boulders in asteroidal regolith.

We present a novel methodology for exploring 4D seismic data in the context of monitoring subsurface resources. Data-space exploration is a key activity in scientific research, but it has long been overlooked in favour of model-space investigations. Our methodology performs a data-space exploration that aims to define structures in the covariance matrix of the observational errors. It is based on Bayesian inferences, where the posterior probability distribution is reconstructed through trans-dimensional (trans-D) Markov chain Monte Carlo sampling. The trans-D approach applied to data-structures (termed ”partitions’) of the covariance matrix allows the number of partitions to freely vary in a fixed range during the McMC sampling. Due to the trans-D approach, our methodology retrieves data-structures that are fully data-driven and not imposed by the user. We applied our methodology to 4D seismic data, generally used to extract information about the variations in the subsurface. In our study, we make use of real data that we collected in the laboratory, which allows us to simulate different acquisition geometries and different reservoir conditions. Our approach is able to define and discriminate different sources of noise in 4D seismic data, enabling a data-driven evaluation of the quality (so-called ”repeatability’) of the 4D seismic survey. We find that: (1) trans-D sampling can be effective in defining data-driven data-space structures; (2) our methodology can be used to discriminate between different families of data-structures created from different noise sources. Coupling our methodology to standard model-space investigations, we can validate physical hypothesis on the monitored geo-resources.

A document by Sharanya J. Majumdar. Click on the document to view its contents.

We synthesized N2O emissions over North America using 17 bottom-up (BU) estimates from 1980-2016 and five top-down (TD) estimates from 1998-2016. The BU-based total emission shows a slight increase owing to U.S. agriculture, while no consistent trend is shown in TD estimates. During 2007-2016, North American N2O emissions are estimated at 1.7 (1.0-3.0) Tg N yr-1 (BU) and 1.3 (0.9-1.5) Tg N yr-1 (TD). Anthropogenic emissions were twice larger than natural fluxes from soil and water. Direct agricultural and industrial activities accounted for 68% of total anthropogenic emissions, 71% of which was contributed by the U.S. Our estimates of U.S. agricultural emissions are comparable to the EPA greenhouse gas (GHG) inventory, which includes estimates from IPCC tier 1 (emission factor) and tier 3 (process-based modeling) approaches. Conversely, our estimated agricultural emissions for Canada and Mexico are twice as large as the respective national GHG inventories based on tier 1 approaches.

The PRISM Data Library (DL) is designed to optimize the display, analysis, and retrieval of multiple domains datasets. Originally created for climate data, we aggregated data from agriculture and hydrology domains, as well as non-traditional domains for the DL such as ecology, finance, power outage and space weather data. These datasets range from simple geospatial point observations, to spatially gridded data products, to high-resolution satellite measurements, to GIS representation of administrative or domain-specific geographic entities. These datasets are represented in a consistent multi-dimensional (most often spatial and temporal) framework. As a result, dimension-wise comparisons are easily enabled through selection or transformation. Gridded data can be averaged over discrete geometrical entities (e.g. Counties, Bird Conservation Regions). The DL can be used in a browser, by connecting to servers at San Diego Supercomputing Center (SDSC) over the internet. Data selection, processing, and analysis are performed by the SDSC DL servers, and the resulting images or data files are sent back to the client’s desktop. This model optimizes the use of internet bandwidth.

Runoff events play an important role for nitrate export from catchments, but the variability of nutrient export patterns between events and catchments is high and the dominant drivers remain difficult to disentangle. Here, we rigorously asses if detailed knowledge on runoff event characteristics can help to explain this variability. To this end, we conducted a long-term (1955 - 2018) event classification using hydro-meteorological data, including soil moisture, snowmelt and the temporal organization of rainfall, in six neighboring mesoscale catchments with contrasting land use types. We related these event characteristics to nitrate export patterns from high-frequency nitrate concentration monitoring (2013 - 2017) using concentration-discharge relationships. Our results show that small rainfall-induced events with dry antecedent conditions exported lowest nitrate concentrations and loads but exhibited highly variable concentration-discharge relationships. We explain this by a low fraction of active flow paths, revealing the spatial heterogeneity of nitrate sources within the catchments and by an increased impact of biogeochemical retention processes. In contrast, large rainfall or snowmelt-induced events exported highest nitrate concentrations and loads and converged to similar chemostatic export patterns across all catchments, without exhibiting source limitation. We explain these homogenous export patterns by high catchment wetness that activated a high number of flow paths. Long-term hydro-meteorological data indicated an increase of events with dry antecedent conditions in summer and decreased snow-influenced events. These trends will likely continue and lead to an increased nitrate concentration variability during low-flow seasons and to changes in the timing of largest nitrate export peaks during high-flow seasons.

Though thermohaline staircases exist in a large region of the Arctic, the interactions of such staircases with shear and turbulence are still largely unexplored. We perform a series of two- and three-dimensional simulations with and without shear and demonstrate the capacity of shear to both form and disrupt Arctic staircases. Both isotropic shear and unidirectional oscillating shear are considered. Shear is shown to disrupt staircases when the Richardson number falls below 1/4. For isotropic shear, this process works by breaking down layers individually, which leads to the gradual merging of layers, whereas the unidirectional shear tends to break down interfaces more evenly. For weaker shear (Richardson numbers greater than 2), the spontaneous development of layers is observed.

This is a short communication about the inter-annual recurring presence at the coastal site in the Gulf of Naples of density staircases visible below the mixed surface layer of the water-column, from the end of summer to the beginning of winter, each year during nearly two decades of survey (2001 to 2020). We repetitively observe sequences from 1 to 4 small vertical staircases structures (~ 3 m thick) in the density profiles (~ Δ0.2 kg/m³), located between 10 m to 50 m deep below the seasonal mixed layer depth. We interpret these vertical structures as the result of double diffusive processes that could host salt-fingering regime (SF) due to warm salty water parcels overlying on relatively fresher and colder layers. This common feature of the Mediterranean basin (i.e., the thermohaline staircases of the Tyrrhenian sea) may sign here for the lateral intrusions of nearshore water masses. These stably stratified layers are characterized by density ratio Rρ 5.0 to 10.0, slightly higher than the critical range (1.0 - 3.0) generally expected for fully developed salt-fingers. SF mixing, such as parameterized (Zhang et al., 1998), appears to inhibit weakly the effective eddy diffusivity with negative averaged value (~ - 1e-8 m²/s). A quasi 5-year cycle is visible in the inter-annual variability of the eddy diffusivity associated to SF, suggesting a decadal modulation of the parameters regulating the SF regime. Even contributing weakly to the turbulent mixing of the area, we hypothesis that SF could influence the seasonal stratification by intensifying the density of deep layers. Downward transfer of salt could have an impact on the nutrient supply for the biological communities, that remains to be determined.

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The transient climate response (TCR) is 20% higher in the Alfred Wegener Institute Climate Model (AWI-CM) compared to the Max Planck Institute Earth System Model (MPI-ESM) whereas the equilibrium climate sensitivity (ECS) is only by less than 10% higher in AWI-CM. These results are largely independent of the two considered model resolutions for each model. The two coupled CMIP6 models share the same atmosphere-land component ECHAM6.3 developed at the Max Planck Institute for Meteorology (MPI-M). However, ECHAM6.3 is coupled to two different ocean models, namely the MPIOM sea ice-ocean model developed at MPI-M and the FESOM sea ice-ocean model developed at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). A reason for the different TCR is related to ocean heat uptake in response to greenhouse gas forcing. Specifically, AWI-CM simulations show stronger surface heating than MPI-ESM simulations while the latter accumulate more heat in the deeper ocean. The vertically integrated ocean heat content is increasing slower in AWI-CM model configurations compared to MPI-ESM model configurations in the high latitudes. Weaker vertical mixing in AWI-CM model configurations compared to MPI-ESM model configurations seems to be key for these differences. The strongest difference in vertical ocean mixing occurs inside the Weddell Gyre and the northern North Atlantic. Over the North Atlantic, these differences materialize in a lack of a warming hole in AWI-CM model configurations and the presence of a warming hole in MPI-ESM model configurations. All these differences occur largely independent of the considered model resolutions.

We have used the LOw-Frequency ARray (LOFAR) to image a few lightning flashes during a particularly severe thunderstorm. The images show an exceptional amount of VHF activity at altitudes above 10 km. Much of this is in the form of small-scale discharges occurring seemingly randomly around the centers of active storm cells. Because of their small and incidental structure we refer to these as ‘speckles’. A detailed investigation shows strong evidence that these speckles are indicative of positive leader channels and that they are equivalent to the needle activity seen around positive leader tracks at lower altitudes.

Detection of chemical signatures from the core-mantle boundary (CMB) could provide an unprecedented glimpse into our planet’s deep interior and ancient past. Several isotopic and elemental anomalies in ocean island basalts (OIBs) have been proposed as core tracers. However, the process(es) by which particular chemical signatures from the core are conveyed into the mantle remain uncertain. Here we propose a hybrid mechanism that results from a collaborative feedback between dynamic topography, porous infiltration of liquid metal into submerged rock, gravitational collapse of weakened metal-silicate mush, and draw-down of additional rocks from above in the induced small-scale mantle circulation. Using a mantle convection model coupled to gravitational spreading of a thin layer, we show that this mechanism achieves parity with metal-mush interaction alone when the layer is $\sim$10$^5$ times less viscous than overlying mantle.

Pyrogenic dissolved organic matter (pyDOM) is known to be an important biogeochemical constituent of aquatic ecosystems and the carbon cycle. While our knowledge of pyDOM’s production, composition, and photolability has been studied recently, we lack an understanding of potential microbial mineralization and transformation of pyDOM in the biogeosphere. Thus, leachates of oak charred at 400 and 650 °C, as well as their photodegraded counterparts, were incubated with a soil-extracted microbial consortium for up to 96 days. Over the incubation, significantly more carbon was biomineralized from the lower versus higher temperature char leachate (45% versus 37% lost, respectively). Further, the photodegraded leachates were biomineralized to significantly greater extents than their fresh non-photodegraded counterparts. Kinetic modeling identified the mineralizable pyDOC fractions to have half-lives of 9 to 13 days. Proton nuclear magnetic resonance spectroscopy indicated that the majority of this loss could be attributed to low molecular weight constituents of pyDOM (i.e., simple alcohols and acids). Further, quantification of benzenepolycarboxylic acid molecular markers indicated that condensed aromatic compounds in pyDOM were biomineralized to much less extents (4.4 and 10.1% decrease in yields of ΣBPCA-C over 66 days from Oak-400 and Oak-650 pyDOM, respectively), but most of this loss could be attributed to biomineralization of smaller condensed clusters (4 aromatic rings or less). These results highlight the contrasting bioavailability of different portions of pyDOM and the need to examine both to evaluate its role in aquatic heterotrophy and its environmental fate in the hydrogeosphere.

Latin America has emerged as an epicenter of the COVID-19 pandemic. Brazil, Peru, and Ecuador report some of the highest COVID-19 rates. These countries also face dual threats from development challenges and El Niño, which impact local disease ecologies. A country like Peru, e.g., which is highly sensitive to El Niño, already copes with an ecosyndemic burden, i.e., co-occurring multiple infectious diseases, which heighten during climate extreme events. In this commentary, we highlight the importance of El Niño as a major factor that not only may aggravate COVID-19 incidence, but also the broader health problem of ecosyndemics in Latin America.

The ablation of phosphorus from interplanetary dust particles entering the Earth’s atmosphere is a potentially significant source of this key bio-element. In this study, the atmospheric chemistry of phosphorus is explored by developing a reaction network of possible routes from PO, the major ablation product in the upper mesosphere/lower thermosphere region, to the stable reservoirs H3PO3 and H3PO4 that become incorporated into meteoric smoke particles as metal phosphites and phosphates, respectively. The network is constructed with reactions whose kinetics have been measured experimentally, together with reactions where theoretical rate coefficients are estimated using a combination of electronic structure theory calculations and a Rice-Ramsperger-Kassel-Markus master equation treatment. The network is then incorporated into a global chemistry-climate model, together with a phosphorus meteoric input function. The estimated global mean P deposition flux, in the form of sub-micron sized meteoric smoke particles, is 1 × 10-8 g m-2 yr-1, with a maximum of ~5 × 10-8 g m-2 yr-1 over the northern Rockies, Himalayas and southern Andes. The estimated fraction of ablated phosphorus forming bio-available metal phosphites is 11%, which results from the very large concentrations of O and H compared to OH in the upper mesosphere. A layer of OPO is predicted to occur at 90 km with a peak of concentration of ~50 cm-3; this is the counterpart of the well-known layers of meteoric metals such as Na and Fe, and may be observable spectroscopically.