Ganymede is the only Solar System moon that generates a permanent magnetic field. Dynamics inside Ganymede’s magnetosphere is likely driven by energy-transfer interactions on its upstream magnetopause. Previously in Kaweeyanun et al. (2020), we created a steady-state analytical model of Ganymede’s magnetopause and predicted global-scale magnetic reconnection to occur frequently throughout the surface. Using the same model, this paper provides the first assessment of Kelvin-Helmholtz (K-H) instability growth on the magnetopause in isolation from reconnection effects. The linear K-H instability growth rate is calculated at Ganymede’s equatorial magnetopause flank points under the magnetohydrodynamic with finite Larmor radius effect (MHD-FLR) theory, which accounts for inter-flank growth rate asymmetry due to large gyroradii of Jovian plasma ions. The calculation gives growth rates between γ ≈ 0.01-48 /s with notable enhancement at the equatorial flank point closer to Jupiter. Then, the ideal MHD K-H instability onset condition is evaluated across the entire Ganymedean magnetopause. We find the conditions along both magnetopause flanks to be K-H favorable at all latitudes with growth rates similar to those at respective equatorial flank points. Using Mercury’s magnetopause case as a comparison, we determined that nonlinear K-H vortices are viable at Ganymede based on the calculated growth rates, but the vortex growth will likely be suppressed once global reconnection is taken into account.

Numerical mixing, defined here as the physically spurious diffusion of tracers due to the numerical discretization of advection, is known to contribute to biases in ocean circulation models. However, quantifying numerical mixing is non-trivial, with most studies utilizing specifically targeted experiments in idealized settings. Here, we present a precise, online water-mass transformation-based method for quantifying numerical mixing that can be applied to any conserved variable in global general circulation models. Furthermore, the method can be applied within individual fluid columns to provide a spatially-resolved metric. We apply the method to a suite of global ocean-sea ice model simulations with differing grid spacings and sub-grid scale parameterizations. In all configurations numerical mixing drives across-isotherm heat transport of comparable magnitude to that associated with explicitly-parameterized mixing. Numerical mixing is prominent at warm temperatures in the tropical thermocline, where it is sensitive to the vertical diffusivity and resolution. At colder temperatures, numerical mixing is sensitive to the presence of explicit neutral diffusion, suggesting that much of the numerical mixing in these regions acts as a proxy for neutral diffusion when it is explicitly absent. Comparison of equivalent (with respect to vertical resolution and explicit mixing parameters) $1/4^\circ$ and $1/10^\circ$ horizontal resolution configurations shows only a modest enhancement in numerical mixing at $1/4^\circ$. Our results provide a detailed view of numerical mixing in ocean models and pave the way for future improvements in numerical methods.

Isoprene is the dominant non-methane organic compound emitted to the atmosphere, where it drives ozone and aerosol production, modulates atmospheric oxidation, and interacts with the global nitrogen cycle. Isoprene emissions are highly variable and uncertain, as is the non-linear chemistry coupling isoprene and its primary sink, the hydroxyl radical (OH). Space-based isoprene measurements can help close the gap on these uncertainties, and when combined with concurrent formaldehyde data provide a new constraint on atmospheric oxidation regimes. Here we present a next-generation machine-learning isoprene retrieval for the Cross-track Infrared Sounder (CrIS) that provides improved sensitivity, lower noise, and thus higher space-time resolution than earlier approaches. The Retrieval of Organics with CrIS Radiances (ROCR) isoprene measurements compare well with previous space-based retrievals as well as with the first-ever ground-based isoprene column measurements, with 20-50% discrepancies that reflect differing sources of systematic uncertainty. An ensemble of sensitivity tests points to the spectral background and isoprene profile specification as the most relevant uncertainty sources in the ROCR framework. We apply the ROCR isoprene algorithm to the full CrIS record from 2012-2020, showing that it can resolve fine-scale spatial gradients at daily resolution over the world’s isoprene hotspots. Results over North America and Amazonia highlight emergent connections between isoprene abundance and daily-to-interannual variations in temperature, nitrogen oxides, and drought stress.

Engineered multilevel systems (MLS) are one of the few viable options for collecting spatial and temporal datasets in 3-D complex groundwater flow systems. However, these monitoring systems present challenges for hydraulic testing due to small port tubing diameters. In this study, equipment was developed to enable pneumatic slug testing of a G360 MLS, fitted with 1/2-inch ID open tubes that extend from the monitoring ports to the surface. Of the eight ports tested, four exhibited overdamped slug test responses, while underdamped responses were observed in the remaining four ports. It is expected that friction in the small diameter tubing is not negligible, and additional flow constrictions are introduced when installing a transducer in the tubing, effectively changing the open tube geometry to an annulus around the transducer body and around the transducer cable. Steady flow models for annular flow, widely available in the literature, were used to assess tube friction for the overdamped tests. However, for underdamped tests that oscillate quickly, a mathematical solution for unsteady oscillatory flow through an annulus was derived. The results of this study show that it is important to account for frictional and inertial losses to obtain good transmissivity (T) estimates from slug tests conducted in small diameter tubing. Assuming steady flow through small annuli will not introduce appreciable error when calculating the water level; however, if steady flow through the open tube below the transducer is assumed when calculating the formation head, T values can be underestimated as much as an order of magnitude.

MagIC (earthref.org/MagIC (https://www2.earthref.org/MagIC)) is an organization dedicated to improving research capacity in the Earth and Ocean sciences by maintaining an open community digital data archive for rock and paleomagnetic data with portals that allow scientists and others to access to archive, search, visualize, download, and combine versioned datasets. A recent focus of MagIC has been to make our data more accessible, discoverable, and interoperable to further this goal. In collaboration with the GeoCodes/P418 group, we have continued to add more schema.org metadata fields to our data sets which allows for more detailed and deep automated searches. We are involved with the Earth Science Information Partners (ESIP) schema.org cluster which is working on extending the schema.org schema to the sciences. MagIC has been focusing on geo- science issues such as standards for describing deep time. We are also collaborating with the European Plate Observing System (EPOS)’s Thematic Core Service Multi-scale laboratories (TCS MSL). MagIC is sending its contributions’ metadata to TCS MSL via DataCite records for representation in the EPOS system. This collaboration should allow European scientists to use MagIC as an official repository for European rock and paleomagnetic data and help prevent the fragmenting of the global paleomagnetic and rock data into many separate data repositories. By having our data well described by an EarthCube supported standard (schema.org/JSON-LD), we will be able to more easily share data with other EarthCube projects in the future.

Storm-time geomagnetic disturbances induce significant geoelectric fields within the Earth that can adversely affect the operation of electric power grids. The recently completed magnetotelluric survey supported by the NSF EarthScope program (2006-2018) has produced a large public archive of impedance tensors across much of the continental United States (US). In this work, the EarthScope tensors are convolved with long time series of geomagnetic field variation recorded at USGS observatories to obtain estimated time series of historical geoelectric fields. Integrating these geoelectric fields across power transmission lines results in time series of geomagnetically induced voltages on each power line. These voltages are analyzed statistically to construct hazard maps of the maximum voltages that could be realized in transmission lines across the US for an extreme, once in one hundred-year, geomagnetic storm. In combination with grounding resistance data and network topology, these voltage estimates can be utilized by power companies to estimate extreme geomagnetically-induced currents within their networks. These voltage estimates can provide information on which power lines and substations are most vulnerable to geomagnetic storms and can guide power companies in assessments of where to install additional protections within their grid.

A new constellation of radio occultation satellites called COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere and Climate-2) is providing unprecedented dense measurements of the tropical atmosphere, with on average more than 4,000 high quality observations per day over 40o N-S. We use these data to evaluate large- and small-scale thermal variability in the tropical lower stratosphere during October 2019 – April 2020. Space-time spectral analysis of gridded COSMIC-2 data reveals a rich spectrum of traveling planetary-scale waves, including Kelvin waves, mixed Rossby-gravity waves and inertia gravity waves, in addition to propagating diurnal tides. These coherent modes show enhanced amplitudes from the tropical tropopause through the lower stratosphere (~17-25 km). Characteristics of small-scale temperature variances, calculated as deviations from the gridded fields, reveal systematic spatial patterns including time average maxima over Africa and South America overlying persistent deep convection. Small-scale variances also exhibit transient maxima in the equatorial lower stratosphere tied to large-scale Kelvin waves. The new COSMIC-2 observations provide novel details on the rich spectrum of large- and small-scale waves near and above the tropical tropopause.

Developing crops with better root system architecture and nitrogen use efficiency can lead to resilient crops capable of sustaining productivity in both optimum and stress environments. The increase in soybean global demand and its use in biodiesel and new soy-based products calls for new soybean cultivars that have higher yields, better nutritional values or desirable traits for specific use. The soybean germplasm collection at the USDA is a valuable resource in discovering novel allelic variations. This collection has not been screened extensively for the root nodule and root system architecture traits. We have already established root phenotyping platforms in our laboratory and we are proposing to screen a diverse pool of the USDA soybean collection for nodules and root system architecture traits. Availability of SNP data for this collection will let us run genome-wide analysis and identify QTLs responsible for different root traits. We will then use hairy root transformation to knockout/down some of the candidate genes in the loci identified in earlier reports and new QTLs identified in this project. This project will help us in deciphering the phenotypic variation in soybean root traits. Ultimately, better understanding of the regulatory mechanism controlling these traits can help us in developing resilient crops and a sustainable cropping system.

Bedload flux is notoriously challenging to measure and model. The dynamics of bedload therefore remains largely unknown in most fluvial systems worldwide. We present a global scale bedload flux model as part of the WBMsed modeling framework. Our results show that the model can very well predict the distribution of water discharge and suspended sediment and well predict bedload. We analyze the model’s bedload predictions sensitivity to river slope, particle size, discharge, river width and suspended sediment. We found that the model is most responsive to spatial dynamics in river discharge and slope. We analyze the relationship between bedload and total sediment flux globally and in representative longitudinal river profiles (Amazon, Mississippi, and Lena Rivers). We show that while, as expected, the proportion of bedload is decreasing from headwater to the coasts, there is considerable variability between basins and along river corridors. The latter is largely responsive to changes in suspended sediment and river slope due to dams and reservoirs. We provide a new estimate of water and sediment fluxes to global oceans from 2,067 largest river outlets (draining 67% of the global continental mass). Estimated water discharge (30,579 km3/y) corresponds well to past estimates however sediment flux is considerably higher. Of the total 22 Gt/y estimated average sediment flux to global oceans, 19 Gt/y is transported as washload, 1 Gt/y as bedload, and 2 Gt/y as suspended bed material. The largest 25 rivers are predicted to transport over 55% of total sediment flux to global oceans.

Some lipid-biomarker-based sea surface temperature (SST) proxies applied in the modern Mediterranean Sea exhibit large offsets from expected values, generating uncertainties in climate reconstructions. Lateral transport of proxy carriers along ocean currents prior to burial can contribute to this offset between reconstructed and expected SSTs above the burial site and at the particle’s origin in the surface ocean. We perform virtual particle tracking experiments to simulate transport during sinking and derive a quantitative estimate of transport bias for alkenones and glycerol dibiphytanyl glycerol tetraethers (GDGTs), which form the basis of the UK’37 and TEX86 paleothermometers, respectively. We use sinking speeds appropriate for the export of various proxy carriers (6, 12, 25, 50, 100, 250, 500, and 1000 m d-1). For the assessed sinking speeds, lateral transport bias is generally small (always <0.75 °C) within the Mediterranean Sea and does not substantially contribute to the uncertainties in UK’37- or TEX86-based SSTs.

Crop yield is sensitive to climate change and has been projected to be negatively affected by future climate. To reduce yield loss and ensure food security in the context of climate change, it is critical to understand how climate variables interact with crop growth in agroecosystems. One important and widely used tool to study yield responses to climate is process-based modeling. However, using process-based models to simulate the climate impacts on crops is becoming challengeable as the future climate is characterized by more and more frequent extreme events, such as heatwaves, unpredictable rainfall, and droughts. Most existing crop models may not be capable of characterizing the impacts of such extreme events on crops simply because they usually do not simulate some critical processes that climate variables directly affect crop growth such as photosynthesis. Instead, they use a simplified approach–radiation-use efficiency (RUE) which is a coefficient to describe empirical relationships between intercepted radiation and biomass. The usage of RUE has simplified computation but also limited our understanding of interactions between climate variables (e.g., temperature, CO2, rainfall) and crop growth. Thus, we developed a module combining processes of radiative transfer and photosynthesis (RP) within the canopy to account for the impacts of climate variables on crop growth dynamically. Then, we integrated the RP module into a popular agricultural system model—the Environmental Policy Integrated Climate (EPIC) to assess its performance. The results show that its capabilities of predicting crop yield are comparable to the traditional RUE method. The correlation between observed and simulated biomass is 0.77 for the RUE method, while 0.76 for the RP method. But the RP method could show responses of biomass accumulation to changes in climate factors, which is almost overwhelming for RUE. For instance, the RP module could simulate how extremely high temperatures (which usually last several hours during a day) affect crop growth and also allow the EPIC to distinguish elevated CO2 impacts on C3 and C4 crops, while the default RUE method could not. Therefore, the RP module is promising to improve capabilities and extend functionalities of current process-based models, which is not only beneficial to the community of crop modeling but also enhances our ability to evaluate the impacts of climate change on the agroecosystem.

The combination of strontium (87Sr/86Sr) and uranium (234U/238U) isotopes is an especially useful tool to track and quantify mixtures of water sources in arid wetlands, where chemistry and lighter isotopic tracers are strongly influenced by evaporation and transpiration. Those isotopes were used to understand modern water supply to the Pahranagat National Wildlife Refuge (PNWR) in southern Nevada (Paces & Wurster, 2014, J. Hydrol. 517). We investigate the possibility that this isotopic combination might also track paleohydrological changes in such settings. Here, we present Sr and U isotope data for authigenic carbonates in a sediment core spanning 5800 14C cal years from Lower Pahranagat Lake (LPAH), a shallow, alkaline lake within the PNWR. Modern surface waters in the PNWR are comprised of mixtures of discharge from two high volume springs from the regional carbonate aquifer in the northern valley, and smaller amounts of local discharge from the shallow volcanic aquifer in the southern valley. Modern surface water from LPAH has U isotopic values similar to the most recently formed LPAH carbonates; however, Sr isotopic values in LPAH surface water are somewhat lower than values in those same carbonates. Combined Sr and U isotope values in Holocene LPAH carbonates fall within the range defined by the three primary spring sources and reflect varying mixtures of those sources supplying LPAH from mid-Holocene to modern time. Values in the oldest samples (~5800 14C cal yr BP) have distinct 87Sr/86Sr and 234U/238U values that nearly match the local spring end member, suggesting that LPAH water at that time was dominated by proximal volcanic aquifer sources. By ~5300–5200 14C cal yr BP, LPAH water was comprised of a nearly equal mixture of the three spring sources, marking a dramatic shift in hydrologic conditions that allowed contributions of surface flow from distal carbonate springs to the north. Values in samples from ~1,000–3,000 14C cal yr BP indicate decreased contributions from distal carbonate springs during two drought intervals; however, by 730 14C cal yr BP, surface flow from carbonate springs had resumed. Our results indicate that combined Sr and U isotopes preserve evidence of past changes in water sources in arid wetlands useful for interpreting evolving hydrologic conditions.

Climate emergency and exponential population growth threaten urban water security in cities worldwide. In the UK, London aims to build more than half a million households over the next 10 years to cope with a growing demand for housing. These new urban developments will significantly increase the consumer water demand, urban flood risk, and river water pollution levels; therefore, a sustainable approach to development is urgently required. Urban Water Neutrality (WN) has emerged as a concept to frame these concerns about rising water stresses in cities. We adapt the definition of WN as a design process aimed to first minimise the impact of every new development and then offset any remaining stresses with interventions external to the development, so the current overall impact levels are not increased after the project completion. Despite several studies related to WN, little evidence is available on how urban water neutrality might be achieved to tackle predicted pressures at city scale. In this work, we present a novel urban design and evaluation module called CityPlan. It integrates spatial data with an integrated urban water management model, enabling urban design at systems level and delivering a new index that assesses possible future scenarios. Urban form properties and urban water security indicators are improved with design options that deliver different scores of the Water Neutrality Index (WNI). The results from the WNI indicate the potential of a particular urban design scenario to achieve water neutrality and how multiple interventions should be combined at city scale. In London, CityPlan’s results suggest that it will be necessary to retrofit almost the same number of existing homes with WN design options outside the planned development areas to completely offset the forthcoming water stresses. CityPlan provides a clear vision of how water neutrality can be achieved for urban water systems and is a powerful tool for urban planners and other stakeholders to effectively promote new policies and drive sustainable development. Moreover, it provides a framework to contextualise water neutrality and its key role in urban water security.

Geomagnetically induced currents (GICs), a result of solar wind interaction with the Earth’s magnetic field and the resistive ground, are known to flow in power transmission grids, where they can lead to transformer damage and grid operation problems. In this study we present an analysis of five years of continuous GIC measurements in transformer neutral points in Austria. Seven self-designed stand-alone measurement systems are currently installed in the Austrian 220 kV and 380 kV transmission levels, measuring currents up to 25 A. We identify recurrent geomagnetic activity in the measurements, and also find man-made sources of low frequency currents using frequency analysis. In order to support the transmission grid operators, two GIC simulation approaches are used to simulate GICs in the power grid. The first model uses measurements to derive the sensitivity of the location to northward and eastward geoelectric field components (which requires no detailed grid data), and the second model uses the detailed grid model to compute GICs from a geoelectric field. We evaluate two geomagnetic storms from September 2017 and May 2021 to discuss the effects of GICs on the power transmission grid and its assets.

In the Jovian magnetosphere, an electric current system within the ‘current sheet’ generates a magnetic field, which is comparable to or dominating the Jovian intrinsic field in the nightside magnetosphere. However, update of an existing model of the magnetospheric field using newly acquired data by Galileo and Juno have never been conducted since it was first formulated in 1997. Here we used the data by Voyager 1/2, Galileo and Juno to revise the current sheet model as well as the magnetospheric field model based on each spacecraft data. We derived models that reproduced each data well, and revealed long-term variations of both current sheet and magnetospheric field over several decades. The updated models were found useful to detect dynamic events in the magnetosphere such as magnetopause deformation and plasmoid generation. They can also be used as external fields necessary for probing into the Galilean icy moons by electromagnetic induction methods.

As there are strong crustal magnetic fields in some Martian concentrated regions. it has long been a goal of Martian science to understand how crustal magnetic field affects surrounding space environment. In the paper, using the data measured by MAVEN, the ratio of electron/CO2 density ( Ne/NCO2) in region with different levels of Martian ionospheric magnetic fields are studied. It seems that ratio of dayside Ne/NCO2 in region with stronger ionospheric magnetic field is larger while the altitude is more than 260 km. On the other hand, the effect of crustal magnetic field intensity on the nightside ratio of Ne/NCO2 is weak. Since the topological structure of magnetic field is very vulnerable to the solar wind, the correlation between Ne/NCO2 and solar wind parameters are analyzed. We find that there is obvious negative correlation between dayside ratio of Ne/NCO2 and solar wind dynamic pressure in the region with strong ionospheric magnetic field, which may imply that the ionospheric plasmas are significantly escaped in response to enhanced solar wind dynamic pressure pulses in the dayside region. However, the effect of solar wind on nightside ratio of Ne/NCO2 is very little. These results can be useful for understanding the dynamic process in the Martian ionosphere.

Zonal flows in rotating systems have been previously shown to be suppressed by the imposition of a background magnetic field aligned with the direction of rotation. Understanding the physics behind the suppression may be important in systems found in astrophysical fluid dynamics, such as stellar interiors. However, the mechanism of suppression has not yet been explained. In the idealized setting of a magnetized beta plane, we provide a theoretical explanation that shows how magnetic fluctuations directly counteract the growth of weak zonal flows. Two distinct calculations yield consistent conclusions. The first, which is simpler and more physically transparent, extends the Kelvin-Orr shearing wave to include magnetic fields and shows that weak, long-wavelength shear flow organizes magnetic fluctuations to absorb energy from the mean flow. The second calculation, based on the quasilinear, statistical CE2 framework, is valid for arbitrary wavelength zonal flow and predicts a self-consistent growth rate of the zonal flow. We find that a background magnetic field suppresses zonal flow if the bare Alfvén frequency is comparable to or larger than the bare Rossby frequency. However, suppression can occur for even smaller magnetic field if the resistivity is sufficiently small enough to allow sizable magnetic fluctuations. Our calculations reproduce the η/B0^2 = const. scaling that describes the boundary of zonation, as found in previous work, and we explicitly link this scaling to the amplitude of magnetic fluctuations. These results could provide a plausible explanation for why the zonal jets in Jupiter go as deep as Juno has discovered but not any deeper.

In his seminal paper on solution of the infiltration equation, Philip (1957) proposed a gravity time, tgrav, to estimate practical convergence time of his infinite time series expansion, TSE. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity derived from the first two (dominant) terms of the TSE expansion. Evidence that higher order TSE terms describe the infiltration process better for longer times. Since the conceptual definition of tgrav is valid regardless of the infiltration model used, we opted to reformulate tgrav using the analytic approximation proposed by Parlange et al. (1982) valid for all times. In addition to the roles of soil sorptivity (S) and saturated (Ks) and initial (Ki) hydraulic conductivities, we explored effects of a soil specific shape parameter β on the behavior of tgrav. We show that the reformulated tgrav (notably tgrav= F(β) S^2/(Ks - Ki)^2 where F(β) is a β-dependent function) is about 3 times larger than the classical tgrav given by tgrav, Philip= S^2/(Ks - Ki)^2. The differences between original tgrav, Philip and the revised tgrav increase for fine textured soils. Results show that the proposed tgrav is a better indicator for convergence time than tgrav, Philip. For attainment of the steady-state infiltration, both time parameters are suitable for coarse-textured soils, but not for fine-textured soils for which tgrav is too conservative and tgrav, Philip too short. Using tgrav will improve predictions of the soil hydraulic parameters (particularly Ks) from infiltration data as compared to tgrav, Philip.