Vertical Scale Research Articles

Internal Solitary Waves Observed on the Continental Shelf in the Northern South China Sea From Acoustic Backscatter Data

Internal solitary waves (ISWs) are investigated offshore of Guangdong in the northern South China Sea (SCS) using high-frequency acoustic backscatter data of 100 kHz acquired in July 2020. Simultaneous XBT profiles and satellite images are incorporated to understand their propagation, evolution, and dissipation processes in shallow water at depths less than 50 m. The water column structures revealed by acoustic backscatter data and XBT profiles are consistent with a small difference of less than 3 m. A soliton train with apparent vertical and horizontal scales of ∼7 and 100 m, respectively, is captured three times in 20 h in the repeated acoustic sections, which provides spatiotemporal constraints to the solitons. The characteristics of ISW phase speeds are estimated from acoustic backscatter data and satellite data and using theoretical two-layer Korteweg-de Vries (KdV) and extended KdV (eKdV) models. The acoustically observed phase speed of ISWs is approximately 0.4–0.5 m/s, in agreement with the estimates from both satellite data and model results. The shallow solar-heated water in summer (∼10–20 m) lying on the bottom cold water is responsible for the extensive occurrence of ISWs in the study region. ISWs are dissipated at the transition zone between the heated surface water and the upwelled water, forming a wide ISW dissipation zone in the coastal area, as observed from satellites. The acoustic backscatter method could be an effective way to observe ISWs with high resolution in shallow water and thus a potential compensatory technique for imaging the shallow blind zone of so-called seismic oceanography.

Soft-bottom exploration of assemblage patterns of the Red Sea amphipods at multiple spatial and vertical scales

We described here the assemblage patterns accompanying the soft-bottom amphipods on both spatial and vertical scales. During winter 2020, 6820 individuals were collected from Hurghada and Shalateen, the Red Sea coast from five different depths ranging from 0.5 to 35 m. Twenty two amphipod species were recorded of which 18 (82 %) and 9 (41%) species were from Hurghada and Shalateen, respectively. Perioculodes aequimanus was the most abundant sand amphipod amounting to 17% and 39% in Hurghada and Shalateen, respectively, followed byCeradocus rubromaculatus (27%) in Shalateen, and Metaphoxus sp. and Bemlos sp. (15%) in Hurghada. Depth influenced the total amphipod abundance in Hurghada, while, in Shalateen it showed an opposite assemblage pattern. The multivariate approach based on Non-Metric Multi-Dimensional Scaling (MDS) was helpful to detect differences between the study sites against depths.Sandy bottom composition, temperature, and depth variations were the main factors that influenced the amphipod assemblages according to the PCA and ANOSIM outputs. The SIMPER analysis showed that the amphipod Lysianassa ceratina and Lembos sp. were the most contributing species to the dissimilarity between the two study sites, whileGuernea petalocera was the most contributing species to the similarity between Hurghada and Shalateen.

A large deformation finite element analysis of uplift behaviour for helical anchor in spatially variable clay

Helical anchors are emerging as an innovative foundation design option for offshore applications to resist uplift loading. Numerous studies have been conducted to investigate the uplift behaviour of helical anchor under different helical bearing plate configurations in clay, using field or model tests and numerical analyses. However, almost all of them are limited to deterministic analyses, ignoring the influence of inherent spatial variability of soil. This work conducts a 3D large deformation random finite element analysis to examine the uplift behaviour of helical anchor in spatially variable clay. Both the stochastic and deterministic trends are reflected in the 3D non-stationary random field adopted. It is found that the spatial variability of soil strength significantly influences the failure mechanism of helical anchor. Parametric studies indicate that the coefficient of variation and vertical scales of fluctuation of soil strength can much influence on the uplift capacity, while the effect of horizontal scales of fluctuation is trivial. The goodness-of-fit test of probability distribution suggests that random uplift capacities follow log-normal distribution, whereby the relationship between factor of safety and probability of failure is established. The findings of this paper might facilitate the safety design of helical anchor.

Airborne and Spaceborne Lidar Reveal Trends and Patterns of Functional Diversity in a Semi-Arid Ecosystem

Assessing functional diversity and its abiotic controls at continuous spatial scales are crucial to understanding changes in ecosystem processes and services. Semi-arid ecosystems cover large portions of the global terrestrial surface and provide carbon cycling, habitat, and biodiversity, among other important ecosystem processes and services. Yet, the spatial trends and patterns of functional diversity in semi-arid ecosystems and their abiotic controls are unclear. The objectives of this study are two-fold. We evaluated the spatial pattern of functional diversity as estimated from small footprint airborne lidar (ALS) with respect to abiotic controls and fire in a semi-arid ecosystem. Secondly, we used our results to understand the capabilities of large footprint spaceborne lidar (GEDI) for future applications to semi-arid ecosystems. Overall, our findings revealed that functional diversity in this ecosystem is mainly governed by elevation, soil, and water availability. In burned areas, the ALS data show a trend of functional recovery with time since fire. With 16 months of data (April 2019-August 2020), GEDI predicted functional traits showed a moderate correlation (r = 41–61%) with the ALS predicted traits except for the plant area index (PAI) (r = 11%) of low height vegetation (<5 m). We found that the number of GEDI footprints relative to the size of the fire-disturbed areas (=< 2 km2) limited the ability to estimate the full effects of fire disturbance. However, the consistency of diversity trends between ALS and GEDI across our study area demonstrates GEDI’s potential of capturing functional diversity in similar semi-arid ecosystems. The capability of spaceborne lidar to map trends and patterns of functional diversity in this semi-arid ecosystem demonstrates its exciting potential to identify critical biophysical and ecological shifts. Furthermore, opportunities to fuse GEDI with complementary spaceborne data such as ICESat-2 or the upcoming NASA-ISRO Synthetic Aperture Radar (NISAR), and fine scale airborne data will allow us to fill gaps across space and time. For the first time, we have the potential to monitor carbon cycle dynamics, habitats and biodiversity across the globe in semi-arid ecosystems at fine vertical scales.

Numerical investigation of pile responses induced by adjacent tunnel excavation in spatially variable clays

The pile responses induced by adjacent tunnel excavation have been a hot research topic in geotechnical engineering. Tunnel excavation may exert disturbance to the surrounding soil mass and then influence the adjacent pile foundations. In this paper, the random finite difference analysis considering the spatial variations of soil properties is conducted to explore the effect of tunnel excavation on the adjacent pile response by varying the distance of pile away from the tunnel centerline (D), the pile length (L), the pile diameter (dp), the tunnel depth (h), and the anisotropic ratio between the horizontal and the vertical scales of fluctuation (δx/δy). A set of pile response curves are developed to assess the influence of tunnel excavation on the adjacent passive pile foundations in spatially variable clays and provide guidelines for the tunnel excavation in the complex constructed environment.

Martian nonmigrating atmospheric tides in the thermosphere and ionosphere at solar minimum

The response of Martian nonmigrating tidal perturbations in the thermospheric and ionospheric densities to solar minimum, as contrasted with their behavior in the solar declining phase, is investigated using five years of data collected by the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite. We find that the average tidal amplitudes, expressed as the percent variation of the neutral and electron densities from their respective average background values, are larger (by a factor of ~1.3 above 170 km) during solar minimum compared to the declining phase of the solar cycle. These larger amplitudes, on the dayside, may be due to a decrease in the atmospheric scale height, which for neutral argon averaged over a Martian year, goes from 12.5 km during declining phase, to 10.5 km for solar minimum. An additional controlling factor is that the average vertical dissipation length scale becomes shorter, going from ~34 km during the declining phase to ~29 km at solar minimum. On the nightside, the amplitude of the neutral atmospheric tides is similar between the declining phase and solar minimum. There are changes in the length scales, with the average night side scale height becoming somewhat greater during solar minimum, as well as an increase in the dissipation length scale. Dayside tidal perturbations in the ionosphere at ~145 km to ~170 km exhibit the expected amplitude relation predicted by simplified photochemistry for the observed neutral perturbation amplitudes as well as strong correlation with the longitudinal neutral density perturbations. Interpretation of the data are faced with the complication of limited coverage between season, latitude, and local times together with long temporal baselines that may mix different tidal modes; discussion on the possible role of the latitude effect on amplitude are discussed. The results of the study are put into context of a hypothesis on how tidal amplitudes might be expected to change in response to solar minimum.

Turbulence: Vertical Shear of the Horizontal Wind, Jet Streams, Symmetry Breaking, Scale Invariance and Gibbs Free Energy

The increase of the vertical scaling exponent of the horizontal wind Hv(s) with altitude from the surface of the Pacific Ocean to 13 km altitude, as observed by GPS dropsondes, is investigated. An explanation is offered in terms of the decrease of gravitational force and decrease of quenching efficiency of excited photofragments from ozone photodissociation with increasing altitude (decreasing pressure). Turbulent scaling is examined in both the vertical from dropsondes and horizontal from aircraft observations; the scaling exponents H for both wind speed and temperature in both coordinates are positively correlated with traditional measures of jet stream strength. Interpretation of the results indicates that persistence of molecular velocity after collision induces symmetry breaking emergence of hydrodynamic flow via the mechanism first modelled by Alder and Wainwright, enabled by the Gibbs free energy carried by the highest speed molecules. It is suggested that the combined effects have the potential to address the cold bias in numerical models of the global atmosphere.

Environmental gradients and physical barriers drive the basin‐wide spatial structuring of Mediterranean Sea and adjacent eastern Atlantic Ocean prokaryotic communities

AbstractThe Mediterranean Sea is a miniature ocean divided by the Sicily Strait into two basins with a marked west to east trophic gradient and separated of the nearby eastern Atlantic Ocean by the Strait of Gibraltar. Here, we test the hypothesis that these physical and environmental barriers favor the development of specific prokaryotic assemblages, leading to changes in community structure both in the vertical and horizontal spatial scales. By analyzing taxonomic and phylogenetic diversity using amplicon sequence variants (ASVs) of the 16S rRNA gene, we show that there is indeed marked vertical segregation of prokaryotic groups, similar to that found in other areas of the ocean, but also a clear horizontal structuring among the two Mediterranean basins and the adjacent Atlantic waters. Prokaryotic diversity increased with depth and toward the Atlantic, whereas the easternmost stations displayed more phylogenetically diverse phylotypes, despite harboring globally less diverse communities. Basin‐indicator taxa (ASVs) accounted for a large fraction of the community (between 50% and 80%) in each of the basins at the surface and bathypelagic layers, being associated with different environmental variables. The existence of biogeographic and environmental barriers in the Mediterranean Sea is likely related to the trophic gradient at the surface and the isolation of water bodies in depth due to the Gibraltar and Sicily straits. Our work highlights the importance of studying microbial regional biogeography and provides the basis for future studies on the impact of this regionalization in the function of Mediterranean Sea prokaryotic communities.

Mammatus‐Like Echo Structures Along the Base of Upper‐Tropospheric Outflow‐Layer Clouds of Typhoons Observed by Cloud Radar

AbstractUpper‐tropospheric clouds in the outflow layer of typhoons can affect the track of typhoons (tropical cyclones) through radiation effects. In this study, the microstructure of the outflow‐layer clouds of several typhoons was examined. Cloud radar observations of three typhoons around Japan revealed numerous protuberances in echoes along the base of the upper‐level clouds, which are referred to as mammatus‐like echoes. The horizontal and vertical scales of these mammatus‐like echoes were 0.5–3.0 and 0.3–1.5 km, respectively. Vertical observations revealed downward (upward) Doppler velocities in (between) the hanging echo regions. Upward and downward velocity maxima were estimated at 3 m s−1 around the mammatus‐like echoes. Neutral stratification developed in the dry layer beneath the cloud base in which the mammatus‐like echoes formed. These mammatus‐like structures may promote mixing along the cloud base that contributes to dissipation of the outflow‐layer clouds.

Satellite‐Based Estimate of Intrinsic Predictability Limits at Convective Scales Over Northeast India

AbstractSpheroscale estimates are essential not only for incorporating the seemingly incompatible phenomenon of atmospheric convection within the framework of wide‐range horizontal and vertical scaling in the atmosphere, but also to make semi‐empirical estimates of the storm‐scale atmospheric predictability limits. Since spheroscales are extremely variable, this study computes yearly spheroscales during convective weather events over a selected part of northeast India for 5 different years using the ensemble‐averaged fluctuations of radar reflectivity from the CloudSat geometric profile data set. All these spheroscale estimates are consistently less than 100 m and are directly proportional to the maximum reflectivity observed during the corresponding year. This is in agreement with the fact that spheroscales for unstable atmospheric fields are larger than that of stable atmospheric fields. The semi‐empirical angle‐averaged predictability limits estimated using these spheroscale estimates illustrate that atmospheric fields with larger spheroscales are weakly stable and have smaller intrinsic predictability limits thereby making them less predictable.

Maximizing Throughput of Delay-Sensitive NFV-Enabled Request Admissions via Virtualized Network Function Placement

Network Function Virtualization (NFV) has attracted significant attention from both industry and academia as an important paradigm change in network service provisioning. Most existing studies on admissions of NFV-enabled requests focused on deploying dedicated Virtualized Network Function (VNF) instances to serve each individual request without exploring the sharing of VNF instances among multiple user requests. However, with ever-growing demands of user services, exclusive usages of VNF instances in most networks drastically degrade the network performance and largely under-utilize the VNF instance resources. In this paper, we jointly explore two different VNF instance scaling techniques, horizontal scaling and vertical scaling techniques, to improve the network throughput while minimizing the operational cost of the network, where horizontal scaling that migrates some existing VNF instances from their current locations to new locations to allow the VNF instances to be shared by multiple requests to reduce the resource consumption and operational cost of the network, and vertical scaling that instantiates new VNF instances to meet the demands of new request admissions if existing VNF instances sharing becomes more expensive or the end-to-end delay requirements of currently executing requests will be violated. We first propose a unified framework of maximizing the network throughput, by admitting as many as NFV-enabled requests while meeting the end-to-end delay requirements of the admitted requests. We then provide an Integer Linear Programming (ILP) solution for the problem when the problem size is small. Otherwise, we devise an efficient algorithm through a non-trivial reduction that reduces the problem to the minimum-weight feedback arc set problem and the generalized assignment problem (GAP). We finally conduct experiments to evaluate the performance of the proposed algorithm. Experimental results demonstrate that the proposed algorithm outperforms a baseline algorithm and achieves a performance on a par with its optimal ILP solution.

A remarkable fact for the box dimensions of fractal interpolation curves of R3

In this paper, we give the fractal interpolation curves generated on the Koch curve by Hölder continuous functions and function vertical scaling factors, and at the same time, we present the estimation method of box dimensions of curves of R3 through the estimation of lower and upper box dimensions of obtained curves, where a remarkable fact is that the box dimensions are dependent not only on function vertical scaling factors but also on Hölder exponent of harmonic functions on the Koch curve.

Thorpe Turbulence Scaling in Nighttime Convective Surface Layers in the North Indian Ocean

AbstractWe use profiles from a Lagrangian float in the north Indian Ocean to explore the usefulness of Thorpe analysis methods to measure vertical scales and dissipation rates in the ocean surface boundary layer. An rms Thorpe length scale LT and an energy dissipation rate εT were computed by resorting the measured density profiles. These are compared to the mixed layer depth (MLD) computed with different density thresholds, the Monin–Obukhov (MO) length LMO computed from the ERA5 reanalysis values of wind stress, and buoyancy flux B0 and dissipation rates ε from historical microstructure data. The Thorpe length scale LT is found to accurately match MLD for small (<0.005 kg m−3) density thresholds, but not for larger thresholds, because these do not detect the warm diurnal layers. We use ξ = LT/|LMO| to classify the boundary layer turbulence during nighttime convection. In our data, 90% of points from the Bay of Bengal (Arabian Sea) satisfy ξ < 1 (1 < ξ <10), indicating that wind forcing is (both wind forcing and convection are) driving the turbulence. Over the measured range of ξ, εT decreases with decreasing ξ, i.e., more wind forcing, while ε increases, clearly showing that ε/εT decreases with increasing ξ. This is explained by a new scaling for ξ ≪ 1, εT = 1.15B0ξ0.5 compared to the historical scaling ε = 0.64B0 + 1.76ξ−1. For ξ ≪ 1 we expect ε = εT. Similar calculations may be possible using routine Argo float and ship data, allowing more detailed global measurements of εT, thereby providing large-scale tests of turbulence scaling in boundary layers.

Analyses of Differences in Properties of Vertical Scales by the Hieronymus Scaling Method with Different Linking Methods and Sample Sizes

본 연구는 다분형 문항으로 구성된 검사에서 Hieronymus 방법으로 수직 척도를 개발할 때, 점수 연계 방법과 표집 크기에 따른 수직 척도의 속성(평균, 표준편차, 효과크기)에서의 차이를 밝히는데 있다. 점수 연계 방법으로 Tucker(TK) 방법, Levine 진점수(LT) 방법, Braun-Holland(BH) 방법, 명목 가중 평균동등화(NW) 방법을 고려하고, 표집 크기는 500명, 1,000명, 3,000명을 조건에 포함했다. 공통문항 비동등 집단 설계에서 각 표집 크기 조건별로 이요인 등급반응 모형으로 모의 자료를 생성했다. 각 점수 연계 방법으로 6개 학년의 점수를 연계한 후 Hieronymus 방법으로 수직 척도를 개발하였다. 연구 결과 첫째, LT 방법과 NW 방법이 TK 방법 및 BH 방법에 비해 Hieronymus 방법에 의한 수직 척도를 위한 점수 연계 방법으로 더 적절했다. 둘째, 각 점수 연계 방법 내에서 표집의 크기에 따른 수직 척도 속성 차이는 크지 않았고, 또한 점수 연계 방법에 의한 차이에 비해 표집 크기에 따른 수직 척도 속성 차이는 상대적으로 매우 작았다.

Experimental and Numerical Study of the Effect of Model Geometric Distortion on Laboratory Modeling of Urban Flooding

AbstractLaboratory studies of urban flooding often use geometrically distorted scale models due to the multi‐scale nature of these specific flows. The possible bias induced by geometric distortion has never been thoroughly investigated with dedicated laboratory experiments. In this study, we combine experimental and computational modeling to systematically assess the influence of the distortion ratio, that is, the ratio of horizontal to vertical scale factors, on upscaled flow depths and discharge partition between streets. Three flow configurations were considered: a street junction, a street bifurcation, and a small synthetic urban district. When the distortion ratio is varied up to a value of about 5, the upscaled flow depths at the model inlets decrease monotonously and the flow discharge in the branch that conveys the largest portion of the flow is greatly enhanced. For equal flow depths at the model outlets and depending on the configuration, the distortion effect induces a variation of the upstream flow depth approximately from ∼4% to ∼17% and a change in outlet discharge partition up to 24 percentage points. For a distortion ratio above 5, both upscaled upstream flow depths and outlet discharge partition tend to stabilize asymptotically. Our study indicates the direction and magnitude of the bias induced by geometric distortion for a broad range of flow cases, which is valuable for offsetting these effects in practical laboratory studies of urban flooding.

Size and Shape of (11351) Leucus from Five Occultations

Abstract We present observations of five stellar occultations for (11351) Leucus and reports from two efforts on (21900) Orus. Both objects are prime mission candidate targets for the Lucy Discovery mission. Combined results for Leucus indicate a very dark surface with p V = 0.037 ± 0.001, which is derived from the average of the multichord occultations. Our estimate of the triaxial ellipsoidal shape is for axial diameters of 63.8 × 36.6 × 29.6 km assuming that the spin pole is normal to the line of sight. The actual shape of the object is only roughly elliptical in profile at each epoch. Significant topography is seen with horizontal scales up to 30 km and vertical scales up to 5 km. The most significant feature is a large depression on the southern end of the object as seen from a terrestrial viewpoint. For this work we developed a method to correct for differential refraction, accounting for the difference in color between the target object and the reference stars for astrometry derived from ground-based images.

A Computational Intelligence Approach to Predict Energy Demand Using Random Forest in a Cloudera Cluster

Society’s energy consumption has shot up in recent years, making the prediction of its demand a current challenge to ensure an efficient and responsible use. Artificial intelligence techniques have proven to be potential tools in handling tedious tasks and making sense of large-scale data to make better business decisions in different areas of knowledge. In this article, the use of random forests algorithms in a Big Data environment is proposed for household energy demand forecasting. The predictions are based on the use of information from different sources, confirming a fundamental role of socioeconomic data in consumer’s behaviours. On the other hand, the use of Big Data architectures is proposed to perform horizontal and vertical scaling of the solution to be used in real environments. Finally, a tool for high-resolution predictions with great efficiency is introduced, which enables energy management in a very accurate way.

Experimental Investigation of the Partial Vegetation Effect on the Flood Wave Propagation Resulted from Dam Failure in Urkmez Residential Area by means of Distorted Physical Model

The purpose of this study is to investigate the effect of partial vegetation on the wave propagation resulted from sudden dam failure in a residential area. Temporal variations of water depths and flood wave propagation velocities were determined and compared with those obtained from the experiments performed without vegetation. The experiments were performed on the distorted physical model of Urkmez Dam and its downstream region. The distorted physical model with horizontal scale of 1/150 and vertical scale of 1/30 contains the dam reservoir, the dam body, the residential area of Urkmez coastal town until the sea and the partial vegetation. In the model, the reservoir has an active volume of 11.222 m3, the dam body has a length of 2.84 m and a height of 1.07 m, and the downstream area is nearly 200 m2. Water depths were measured by e+ WATER L level sensors placed at various locations of the downstream region. Velocities were measured by ultrasonic velocity profilers (UVP) located near the level sensors. Flood wave propagation was recorded by the high definition digital camera. Experimental findings obtained from the physical model were converted to the prototype values, in nature. The changes in water depths and elapsed times, also the changes in velocities and their occurrence times were determined for different zones of the downstream area in the presence of vegetation. The experimental results revealed that in such a dam failure, the flood arrives at the sea in 6 s in the absence of vegetation, while in 10 s in the presence of vegetation. These values correspond to 2.74 min and 4.57 min, respectively in the prototype. The existence of vegetation resulted in decrease in flood propagation velocities mainly in the dense residential area, as expected. It was observed that the maximum water depths were increased at the left bank and decreased at the right bank, except at level sensor S6 which is very close to the creek. It was observed that the maximum depth averaged velocities were decreased in the sparse and dense residential areas. The existence of the vegetation changed considerably the local velocities during rising and recession stages of the water depth. It was found that the order of magnitude of the prototype velocities was high and such velocities can cause serious damage mainly in the buildings close to the dam body. Because the presence of vegetation caused a decrease in flood propagation velocities in the sparse and dense residential areas, it would reduce the damages on the buildings in these areas.

Formation of ring-like structures in flared α-discs with X-ray/FUV photoevaporation

ABSTRACT Protoplanetary discs are complex dynamical systems where several processes may lead to the formation of ring-like structures and planets. These discs are flared following a profile where the vertical scale height increases with radius. In this work, we investigate the role of this disc flaring geometry on the formation of rings and holes. We combine a flattening law change with X-ray and FUV photoevaporative winds. We have used a semi-analytical 1D viscous α approach, presenting the evolution of the disc mass and mass rate in a grid of representative systems. Our results show that changing the profile of the flared disc may favour the formation of ring-like features resembling those observed in real systems at the proper evolutionary times, with proper disc masses and accretion rate values. However, these features seem to be short-lived and further enhancements are still needed for better matching all the features seen in real systems.

Determining the role of diffusion and basement flux in controlling 4He distribution in sedimentary basin fluids

The transport of helium from the crystalline continental basement and overlying Phanerozoic sedimentary formations to the near surface can be controlled by both diffusive and advective processes. The relative role of each is vital to helium resource prediction, and important in quantifying the residence times of fluids relevant to groundwater resources, hydrocarbon systems, geologic repositories for nuclear waste and carbon sequestration. The Williston Basin, North America, is a prominent sedimentary basin, providing an excellent natural laboratory to assess these processes. Here, we report noble gas isotopic and composition data for 28 gas samples from natural gas wells that sample different stratigraphic horizons down to the basement (Cretaceous to the Cambrian). Helium isotope ratios show a resolvable mantle 3He component (up to 4.7%) in most samples. Neon isotopic compositions of the Cambrian samples are consistent with a crystalline basement gas contribution. Both helium and neon isotopic observations provide evidence for the contribution of conservative noble gases from the crystalline basement or deeper into the overlying sedimentary basin. 4He groundwater concentrations in the sedimentary formations, calculated from 4He/20Ne values in gas samples, are in excess of in situ U+Th 4He production in some shallow units and depleted in others, providing further evidence of cross formation gas contributions.The highest 4He groundwater concentrations can be compared with the results obtained from a fully-coupled vertical scale transport model characterising diffusive-dominated transport through a static groundwater column. The model includes the 4He flux into the basin from the Precambrian basement and quantifies the apparent basement 4He flux to be between 0.8 - 1.6 × 10−6 mol 4He/m2 yr, comparable to the steady-state flux estimated for the average continental crust (1.47 × 10−6 mol 4He/m2 yr) (Torgersen, 2010). The lithologies in which 4He concentrations are significantly lower than the reference model predictions are consistent with a history of water flooding and produced water disposal in those formations over decades of hydrocarbon production. While an advective component cannot be ruled out, this work demonstrates the importance of both diffusion and the basin architecture development in controlling 4He flux into and out of different lithologies. The assumption of negligible 4He loss from the top surface of a lithology is often made when determining the 4He age of its groundwater. In the Williston Basin, this study shows that deeper lithologies may reach steady state at different stages of basin development, with shallower lithologies sometimes also showing significant 4He loss from their top surface. In the Williston Basin, 4He diffusive loss from the target lithology must be considered to accurately interpret 4He groundwater residence times and accumulation potential.