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Brief Communication: Stay local or go global? On the construction of plausible counterfactual scenarios to assess flash flood hazards
Paul Voit and Maik Heistermann
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-119,2024
Preprint under review for NHESS (discussion: open, 1 comment)
Floods have caused significant damage in the past. To prepare for such events, we rely on historical data, but face issues due to rare rainfall events, lack of data, and climate change. Counterfactuals, or "what if" scenarios, simulate historical rainfall in different locations to estimate flood levels. Our new study refines this by deriving more plausible local scenarios, using the June 2024 Bavaria flood as a case study. This method could improve future flood preparation.

Abstract

A significant increase in the number of anthropogenic objects in Earth orbit has necessitated the development of satellite conjunction assessment and collision avoidance capabilities for new spacecraft. Neutral mass density variability in the thermosphere, driven by enhanced geomagnetic activity and solar EUV absorption, is a major source of satellite propagation error. This work investigates the impacts of space weather driver forecasting uncertainty on satellite drag and collision avoidance maneuver decision-making. Since most operational space weather driver forecasts do not offer an uncertainty assessment, the satellite operator community is left to make dangerous assumptions about the trustworthiness of the forecast models they use to perform satellite state propagation. Climatological persistence-based forecast models are developed for F10.7 and Kp. These models accurately capture the heteroscedastic and, at times, highly non-Gaussian uncertainty distribution on forecasts of the drivers of interest. A set of realistic satellite conjunction scenarios is simulated to demonstrate the contributions of space weather driver forecast uncertainty on the probability of collision and maneuver decisions. Improved driver forecasts, especially forecasts of F10.7, are demonstrated to be very useful for enabling durable maneuver decisions with additional lead time (up to 24 hr for the period examined), though the improvement depends on the specific conjunction scenario of interest.

Abstract

In this study, we revisit the shear-wave velocity structure of the lithosphere and asthenosphere surrounding the Hawaiian hotspot and Hawaiian swell using Rayleigh wave data spanning periods of 20–125 s from the PLUME project. A primary goal of this investigation is to probe the origin of the Hawaiian swell and the mechanism that elevates the topography, providing insights into mantle dynamics beneath hotspot swells. In the shear velocity model, the 30–70 km depth range is largely featureless with weak and local anomalies, indicating that the elevation of the Hawaiian swell cannot be attributed to upper lithospheric reheating or replacement. In contrast, at 80–150 km depth, a pronounced region of anomalously low velocities is well-resolved, with the lowest velocities found beneath the Hawaii-Maui-Molokai part of the island chain. Minimum shear velocities are approximately 4.0 km/s at 100–120 km depth, which is an ∼8%-10% velocity decrease relative to the surrounding velocities away from the swell. This pattern suggests that hot, buoyant mantle from deeper plume sources laterally spread out near the top of the normal oceanic asthenosphere. We find that the low-velocity pattern in the asthenosphere exhibits a strong correlation with the overall shape of the Hawaiian swell topography. Assuming that density anomalies are proportional to shear velocity anomalies, we demonstrate that the anomalous elevation of the swell can be explained by the uplift of a 30-km-thick elastic plate loaded from below by this buoyant, low-seismic-velocity layer in the asthenosphere.

TorchClim v1.0: a deep-learning plugin for climate model physics
David Fuchs, Steven C. Sherwood, Abhnil Prasad, Kirill Trapeznikov, and Jim Gimlett
Geosci. Model Dev., 17, 5459–5475, https://doi.org/10.5194/gmd-17-5459-2024, 2024
Machine learning (ML) of unresolved processes offers many new possibilities for improving weather and climate models, but integrating ML into the models has been an engineering challenge, and there are performance issues. We present a new software plugin for this integration, TorchClim, that is scalable and flexible and thereby allows a new level of experimentation with the ML approach. We also provide guidance on ML training and demonstrate a skillful hybrid ML atmosphere model.

SummaryThis study aims to expand on existing connections between magnetic minerals and hydrocarbons within petroleum systems. Previous studies have focussed on single-source petroleum systems whereas this study, for the first time, analyses a multi-source petroleum system to investigate potential correlations between different kerogen type source rocks and magnetic minerals. To do this, the study investigates the magnetic mineral characteristics of the Inner Moray Firth (IMF), UK North Sea, through room-, low-, and high-temperature techniques, and correlates this to published basin and petroleum systems modelling results that show a three-source hydrocarbon mix. Magnetic mineral analysis identifies extensive evidence for magnetite, goethite, and siderite, alongside more minor lepidocrocite and iron sulphides. Although we find that magnetite is ubiquitous within the IMF, its abundance is relatively low, and, in contrast, the relatively magnetically weak goethite is more likely the most abundant magnetic mineral throughout the IMF. In agreement with previous studies, we find magnetic enhancement at oil-water contacts (OWCs); however, here, we identify two different magnetic enhancement processes at OWCs in wells, which are dependent on the amount of sulphur available in the local environment. Wells with low levels of sulphur have increasing levels of magnetite towards the OWC, with the magnetic enhancement occurring at the top of the water-saturated section. Sulphur-rich environments display an increase in iron sulphides near the OWC at the bottom of the oil-saturated sediments. Additionally, we confirm the presence of siderite as indicator of upward vertical migration. Combining with petroleum system model predictions, we find direct links between iron hydroxide presence and Type I and II-III kerogen source rocks, and iron sulphide presence with Type II kerogen source rocks. This study shows the potential for further utilisation of magnetic mineral analysis within hydrocarbon exploration and petroleum system definition.

SummaryMagnetotelluric data are sometimes accompanied by ‘anomalous’ impedance phases ($\phi $xy and $\phi $yx) in the off-diagonal components deviating from the first (0º < $\phi $xy < 90º) or third (−180º < $\phi $yx < −90º) quadrant, especially in long-period bands. This phenomenon is called the phases out-of-quadrant (POQ). The POQ poses a challenge in Magnetotelluric modeling because simple one- or two-dimensional models cannot explain it. Previous studies have reported that strong inhomogeneity, anisotropy, or particular three-dimensional structures, such as the L-shaped or cross-shaped conductors, could explain the POQ. Aside from these models, we have discovered that a slanted columnar conductor also generates the POQ. Our systematic investigation through the synthetic forward modeling of an inclined conductive column with a varying geometry showed that the inclination angle and the column length may affect the POQ appearance. We investigated herein the behavior of the electric currents around the inclined conductive column embedded in a resistive half space. We found that the induced electric field in the region with the POQ tends to point in the opposite direction to the surrounding vectors. This result can reasonably explain the inverted phase in long-period bands. Furthermore, we confirmed that current is sucked into one end of the column, but discharged from the other end, suggesting that the column works as a current channel. The localized reverse vectors are associated with the current channeling along the inclined conductor, which generates the POQ. A volcanic conduit within a resistive host rock is one of the typical field examples of such an inclined channel. Our study suggests that the POQ is a helpful clue in imaging the geometry of a volcanic magma plumbing system through Magnetotelluric surveys.

SummaryObservations of the seafloor Rayleigh ellipticity contribute to seismic imaging in the ocean. To extract such observables from the arbitrarily oriented ocean-bottom seismometer (OBS) data, we develop an orthogonal-regression based approach to measure the waveform amplitude ratios of the unoriented horizontal and vertical components. The amplitude ratios are then used to calculate the Rayleigh ellipticity (and the sensor orientation angle). The robustness of our method is verified by applications to both the unoriented OBS data and the well oriented on-land seismic data. As we propose to calculate the Rayleigh ellipticity directly from the unoriented three-component data, the measurement process avoids the complexity arising from the surface wave non-great circle effects and uncertainties of the OBS sensor orientation angles. Overall the Rayleigh ellipticity measurements from our method are systematically higher than those by conventional analysis and show less uncertainties. Our analyses suggest that the Rayleigh ellipticity curve (14-60 s), which could be retrieved from the raw broadband OBS data, is effective to constrain the oceanic lithosphere structure, and the accurate measurement of Rayleigh ellipticity curve is important. The potential of seafloor Rayleigh ellipticity for seismic imaging in the ocean is evidenced by a case study of the Japan Basin, the Sea of Japan. Considering the insufficient station coverage in the ocean, the single-station measurement of seafloor Rayleigh ellipticity is of significance for OBS community.

Nature Geoscience, Published online: 22 July 2024; doi:10.1038/s41561-024-01480-8

Oxygen is generated abiotically at the abyssal seafloor in the presence of polymetallic nodules, potentially by seawater electrolysis, according to in situ chamber and ex situ incubation experiments.

А.К. Федоров, Е.О. Киктенко, Н.Н. Колачевский

Значительные успехи в разработке вычислительных устройств, использующих квантовые эффекты, и демонстрация решения с их помощью различных задач стимулировали новую волну интереса к вопросу о природе "квантового вычислительного преимущества" (quantum computational advantage). Хотя различные попытки количественно оценить и охарактеризовать природу квантового вычислительного преимущества предпринимались и раньше, в широком контексте данный вопрос остаётся открытым. В самом деле, не существует универсального подхода, помогающего определить круг задач, решение которых квантовые компьютеры способны ускорить, теоретически и на практике. В настоящей работе мы рассмотрим подход к этому вопросу, основанный на концепции сложности и достижимости квантовых состояний. С одной стороны, класс квантовых состояний, представляющий интерес для квантовых вычислений, должен быть сложным, т.е. не поддающимся моделированию с помощью классических компьютеров с менее чем экспоненциальными ресурсами. С другой стороны, такие квантовые состояния должны быть достижимы на практическом квантовом компьютере. Последнее означает, что унитарная операция, соответствующая преобразованию квантовых состояний от исходного к желаемому, может быть декомпозирована в не более чем полиномиальную по числу кубитов последовательность одно- и двухкубитных вентилей. Формулируя ряд утверждений и гипотез, мы рассматриваем вопрос об описании класса задач, решение которых может быть ускорено с помощью квантового компьютера.

Publication date: Available online 11 July 2024

Source: Advances in Space Research

Author(s): Bruno S. Zossi, Franco D. Medina, Trinidad Duran, Ana G. Elias

Publication date: Available online 10 July 2024

Source: Advances in Space Research

Author(s): Kun Wang, Zheng Chen, Jun Li

Publication date: Available online 9 July 2024

Source: Advances in Space Research

Author(s): Ben Niu, Xuebin Zhuang, Zijian Lin, Linjie Zhang

Abstract

The space weather effects at the Earth's magnetosphere are mostly driven by the solar wind that carries the interplanetary magnetic field (IMF). In this paper, we use 2 years of data in the solar wind from lunar orbiting ARTEMIS and MMS spacecraft upstream of the Earth's bow shock to study the structure of the IMF. We determine the lag times of IMF structures and their dependence on spacecraft positions by conducting an information theory analysis and comparing it with two traditional analysis methods: cross-correlation (CC) analysis and minimum variance of magnetic field analysis (MVAB). For the events with long time intervals (i.e., >4 hr) and with small-spatial separation between the MMS and ARTEMIS along the y GSM -direction (i.e., <40R e , where R e is the Earth's radius), the lag times based on the CC and the mutual information (MI) analyses statistically agree with each other, with p-values of 1.675 × 10−7 and 4.833 × 10−9, with the confidence of 95%. Both the results based on MI and CC have a large deviation from the results from MVAB. For some of the events, such a deviation could be improved by taking the fast mode speed into account; however, p-tests showed that they were not statistically significant to the 95% confidence level.

Abstract

Geoelectric fields produced by time-varying magnetic fields during geomagnetic storms can result in potentially damaging geomagnetically induced currents (GICs) in long conductors at the Earth's surface. GICs can pose a significant risk to the integrity of grounded electrical infrastructure, particularly high-voltage transformers. In this study, an inferred GIC is calculated using an augmented differential magnetometer measurement (DMM) technique on a 500 kV transmission line in central Alberta and is validated using a proximal transformer neutral-to-ground (TNG) current measurement by AltaLink L.P. using a Hall probe at a transformer substation. This research outlines a custom-built and innovative DMM design by which both DMM sensors deployed around a power line measure the background geomagnetic disturbance (GMD) field and the magnetic field generated locally by the GIC. We show how this modified approach provides two independent estimates for GIC derived using only ΔB y or ΔB z , the magnetic field components perpendicular to the line carrying GIC. Results for a geomagnetic storm on 12 Oct 2021 show contemporaneous peaks in the TNG current and the DMM-inferred GIC. The two data sets have similar waveforms and are within the same order of magnitude. The background GMD is reconstructed using DMM and shows excellent correlation to the measured GMD at the permanent Canadian Array for Real-time Investigations of Magnetic Activity magnetic station at Ministik Lake, approximately 48.5 km away. Based on the results presented here, we verify the added utility value of DMM for temporary deployments for assessing GIC risk in electrical power grids.

Abstract

Atmospheric prediction at 2–6 weeks lead time (so-called subseasonal-to-seasonal timescales) entails large forecast uncertainty. Here we investigate the flow-dependence of this uncertainty during Boreal winter. We categorize the large-scale flow using North Atlantic-European weather regimes. First, we show that forecast uncertainty of near-surface geopotential height (Z1000) and temperature (T2m) are strongly sensitive to the prevailing regime. Specifically, forecast uncertainty of Z1000 reduces over northern Europe following Greenland Blocking (enhanced predictability) due to a southward shifting eddy-driven jet. However, due to strong temperature gradients and variable flow patterns, Greenland blocking is linked to increased forecast uncertainty of T2m over Europe (reduced predictability). Second, we show that forecast uncertainty of weather regimes is modulated via the stratospheric polar vortex. Weak polar vortex states tend to reduce regime-uncertainty, for example, due to more frequent predicted occurrence of Greenland blocking. These regime changes are associated with increased T2m uncertainty over Europe.

Abstract

Reconstruction of the seawater carbonate system is essential for an improved understanding of glacial-interglacial oceanic carbon cycling and climate change. However, continuous high-resolution ocean carbonate chemistry data are generally lacking for the Plio-Pleistocene. Here, we present a deep Pacific carbonate ion saturation state (Δ[CO3 2−]) record spanning the last 5.1 Myr, reconstructed from the size-normalized shell weight of planktonic foraminifer in the western tropical Pacific. Deep Pacific Δ[CO3 2−] has been modulated primarily by orbital obliquity since 5.1 Ma, during which it has exhibited in-phase behavior with the 40-Kyr obliquity cycle. Significantly, the amplitude of the 40-Kyr Δ[CO3 2−] cycles has responded linearly to obliquity forcing throughout the Plio-Pleistocene, independent of the late Pliocene intensification of Northern Hemisphere glaciation. We speculate that the obliquity signal in the deep Pacific Δ[CO3 2−] record reflects an ocean-atmosphere circulation feedback mediated by migration of the Southern Hemisphere Westerlies.

Abstract

Using model projections to study the emergence of observable climate signals presumes omniscient knowledge about the climate system. In reality, observational knowledge suffers from data quality and availability issues, for instance data gaps, changes in instrumentation, issues due to gridding and retrieval algorithms. Overlooking such deficiencies leads to misrepresentations of the time of emergence (ToE). We introduce a new definition of ToE that accounts for observational limitations, and show that significant corrections to the ToE may be necessary to achieve the same statistical confidence as would be afforded by omniscient knowledge. We also show how our method can inform future observational needs and observing systems design.

Abstract

Grid- or pixel-based models, used across various scientific disciplines from microscopic to planetary scales, contain an unquantified error that bias our interpretation of the data. The error is produced by projecting 3D data onto a 2D grid. For Digital Terrain Models (DTMs) the projection error affects all slope-dependent topographic metrics, like surface area or slope angle. Due to the proportionality of the error to the cosine of the slope, we can correct for it. We quantify the error and test the correction using synthetic landscapes for which we have analytical solutions of their metrics. Application to real-world landscapes in California, reveal the systematic underestimation of surface area by up to a third, and mean slope angles by up to 10° in steep topography in current DTMs. Correcting projection errors allow for true estimates of surface areas and slope distributions enabling physics-based models of surface processes at any spatial scale.

Abstract

The geopotential height observations from the Aura Microwave Limb Sounder show that the quasi-6-day wave (Q6DW) events with westward zonal wavenumber 1 (W1) in the Northern Hemisphere (NH) mesosphere and lower thermosphere (MLT) during September 2013 and 2014 had a prolonged lifetime of ∼45–50 days and reached their maximum amplitudes after the September equinox, while the climatological Q6DW-W1 is completely dissipated in the background atmosphere before the equinoxes. The Eliassen-Palm flux diagnostic results indicate that Q6DW-W1 during September 2013 and 2014 obtained an additional source at ∼60°-80°S and ∼40–50 km as the September equinox approached, which is related to the baroclinic/barotropic instability in this region. Further investigation on the background atmosphere reveals that several stratospheric minor warming (SMW) events occurred in the Antarctic region during September 2013 and 2014 due to the enhancement of wavenumber 1 activities, accompanied by the increase in the stratospheric temperature, changes in the shape of the polar vortex and the reversal in the zonal mean circulation. The strong planetary wave breaking during the September 2013 and 2014 Antarctic SMW events significantly weakened the strength of the polar night jet (PNJ) and made its peak height descend below ∼35 km, which generated the baroclinic/barotropic instability at the new upper boundary of the PNJ (∼60°-80°S and ∼40–50 km) by an anomalous double-jet configuration in the background winds. This unusual instability provided additional wave source and energy for the trans-equatorial propagation of Q6DW-W1, which finally led to prolonged wave activities in the NH MLT region.

Abstract

Aerosol single-scattering albedo (SSA) is the most critical factor for the accurately calculating of aerosol radiative effects, however, the observation of vertical profiles of SSA is difficult to realize. Current assessments of aerosol radiative effects remain uncertain because of the lack of long-term, high-resolution vertical profiles of SSA observations. High-resolution SSA vertical profiles were observed in a semi-arid region of Northwest China during winter using a tethered balloon. The observed SSA vertical profiles were used to calculate the aerosol direct radiative forcing and radiative heating rates. Significant differences in the calculated radiative forcing were found (e.g., a 48.3% relative difference for the heating effect in the atmosphere at 14:00) between the observed SSA profiles and the constant assumption with SSA = 0.90. Diurnal variations in the vertical distribution of SSA decisively influenced direct radiative forcing of aerosols. Furthermore, high-resolution vertical profiles of absorbing aerosols and meteorological parameters provide robust observational evidence of the heating effect of an elevated absorbing aerosol layer. This study provides a more accurate calculation of aerosol radiative forcing using observed aerosol SSA profiles.