Advective Component Research Articles

An Update for Predicting Left-Moving Supercell Motion

Abstract A sample of 889 left-moving (LM) supercells of varying rotational strength across the United States was examined to determine if improvements could be made in predicting their motion using an existing hodograph-based technique. This technique was previously applied to a sample of only 30 LM supercells, and it was assumed that the same off-hodograph deviation from the mean wind for right-moving (RM) supercells was appropriate for LM supercells. However, our larger sample herein reveals the average deviation for LM supercells is less than the assumed 7.5 m s−1 based on a subset of 207 observed proximity soundings. At the same time, the 0–6-km mean-wind layer is still optimal for the advective component of storm motion (consistent with that for RM supercells). Applying the same methods to a subset of 678 model-derived RUC/RAP proximity soundings generally confirms these results, but with slightly smaller deviations. These findings support decreasing the deviation parameter to 5.0 m s−1 for predicting LM supercell motion (at least for the United States). The sample of LM supercells additionally was subdivided based on strength and duration, and then reevaluated using the observed proximity soundings. The predicted motion of moderate-strength mesoanticyclones had the least error, whereas the strong category had the largest errors by about 1 m s−1. Similarly, mesoanticyclones lasting 60–120 min had the least error in predicted motion. These two findings also are consistent with the results when using the RUC/RAP proximity soundings.

A discretization-free deep neural network-based approach for advection-dispersion-reaction mechanisms

This study aims to provide insights into new areas of artificial intelligence approaches by examining how these techniques can be applied to predict behaviours for difficult physical processes represented by partial differential equations, particularly equations involving nonlinear dispersive behaviours. The current advection-dispersion-reaction equation is one of the key formulas used to depict natural processes with distinct characteristics. It is composed of a first-order advection component, a third-order dispersion term, and a nonlinear response term. Using the deep neural network approach and accounting for physics-informed neural network awareness, the problem has been elaborately discussed. Initial and boundary conditions are added as constraints when the neural networks are trained by minimizing the loss function. In comparison to the existing results, the approach has produced qualitatively correct kink and anti-kink solutions, with losses often remaining around 0.01%. It has also outperformed several traditional discretization-based methods.

Assessment of cooling effect of sea breeze under future climate based on analysis of heat balance mechanism of urban space

In this study, a scheme was developed to quantitatively assess the effectiveness of measures against hot outdoor environments under future climate conditions. In this scheme, each component of heat balance (i.e. advection, turbulent diffusion, anthropogenic heat release) were analyzed based on mesoscale simulations. By comparing the current and future values of the component of the heat balance corresponding to the measure being targeted, it is possible to clarify how the effectiveness of the measure changes. To illustrate the application of the scheme, it was applied to a coastal city (Sendai, Japan) and the advection component was analyzed to assess the effectiveness of introducing a sea breeze into a coastal city as a measure against hot outdoor environments under future climate conditions. Mesoscale simulations were conducted using WRF (Weather Research and Forecasting model) and pseudo global warming method was adopted to create boundary conditions. The increase in air temperature and humidity from the 2000s to the 2050s was more significant in the coastal area than in the inland areas, resulting in increased incoming sensible and latent heat fluxes generated by advection. It was quantitatively demonstrated that while it is currently effective to introduce the sea breeze as a measure against the hot outdoor environment in coastal cities, the effectiveness will not be as significant in the future.

Quantifying the impact of assimilating sensitive observations on heavy precipitation forecast with ensemble-based forecast sensitivity to observations technique

In this study, the Ensemble-based Forecast Sensitivity to Observations (EFSO) technique was used to examine the impact of assimilated sensitive observations on the forecast of heavy rainfall through three data assimilation strategies, i.e., running without observation assimilation (CNTL); with assimilation of all observations (CNTL_DA); with assimilation of sensitive observations (SEN_DA). The Infrared Atmospheric Sounder Interferometer presented the largest positive impact on the forecast, followed by the Advanced Microwave Sounding Unit A and surface land reports. The top 10% of observations contributing the largest positive impact on the forecast were located in the upstream ocean of the low-level winds associated with precipitation maximum. Compared to ensemble CNTL and CNTL_DA experiments, ensemble SEN_DA exhibited better precipitation probability, in which the representative member in ensemble SEN_DA successfully predicted the precipitation magnitude and location. Based upon the representative experiments of the ensemble CNTL, CNTL_DA, and SEN_DA, synoptic conditions were examined to understand how the SEN_DA improves the forecast of heavy precipitation. The three representative experiments exhibited similar characteristics and variations in large-scale circulation, horizontal water vapor transport, and wind fields. However, compared to the representative experiments of CNTL and CNTL_DA, the advection and barotropic components of potential divergence contributed to the increase and persistence of convective instability throughout heavy rainfall in SEN_DA. Heavy precipitation was closely associated with the intensity, duration, and location of the maximum convective instability. Furthermore, the release of convective instability depended on the mesoscale ascent, which determined the maximum and location of the precipitation. These results help to understand the optimization of observational design and assimilation strategy.

Topographic Response to Horizontal Advection in Normal Fault‐Bound Mountain Ranges

AbstractTectonic displacements consist of vertical uplift or subsidence, and horizontal advection. We consider the effects of tectonic advection on mountain range topography, surface drainage patterns and drainage divides. Through numerically modeling a normal fault and uplifted footwall, we find that advection promotes the elongation of catchments and reduction in outlet spacing at mountain fronts. We demonstrate an erosional disequilibrium associated with the advection‐induced transfer of mass from the proximal mountain front toward the distal mountain front. Our modeling also demonstrates the development of an erosion rate disequilibrium around fixed geomorphic features such as drainage divides, that we deem characteristic of advection. In our model, steady‐state is achieved when the divide migration occurs at the same rate as advection; advection moves topography away from the fault, meaning drainage migration becomes a mechanism for balancing advection. Topographic observations in a mountain range bound by a low angle normal fault, the Sierra la Laguna (Mexico), are consistent with our modeling results when advection is included. These observations reveal a strong influence of advection on the development of the Sierra la Laguna's topography and suggest the main drainage divide is migrating toward the fault to counterbalance advection. Tectonic advection exerts a significant control on erosion rate distribution, topographic and drainage patterns and the stability of drainage divides. This work also highlights that the Gilbert metrics and across‐divide χ disequilibrium cannot always be interpreted in terms of growing or shrinking catchments in settings with a large advection component of tectonic displacement.

Ensemble of CMIP6 derived reference and potential evapotranspiration with radiative and advective components

Assessing changes in future aridity requires an understanding of variations in the atmospheric demand for water. Such assessments are often driven by estimations of potential evapotranspiration (ETP) and/or reference evapotranspiration (ET0), yet no comprehensive and validated estimate of these climate metrics exists to date from the Coupled Model Intercomparison Project 6 (CMIP6). Here we describe the development and validation of a published dataset of global monthly estimates of the Penman-Monteith derived ET0, its advective and radiation components, Priestley-Taylor derived ETP, and vapor pressure deficit from 16 CMIP6 projections and four emissions scenarios. Historical validation of the ensemble of CMIP6 evaporative demand shows general agreement with observationally-derived baselines of ET0 and ETP from the Climate Research Unit (CRU) and ERA5-Land reanalysis products, with GCM biases driven primarily by regional differences in modeled humidity and advective contributions to ET0. Overall, evaporative demand is projected to increase across all emissions scenarios, with the largest increases over polar regions, and with a larger contribution from advection particularly for regions with higher baseline ET0.

Handily measuring sensible and latent heat exchanges at a bargain: A test of the variance-Bowen ratio approach

Eddy covariance has been the gold standard used to quantify on-farm crop water use and validate evapotranspiration and remote sensing models, but it comes with a high cost. Development of surface renewal allowed cheaper implementations, but it still requires complex data processing. Additionally, the thermocouple used in this method is vulnerable to breakage. With the depleting water resources in the western U.S., there needs to be a method that is cost-effective and simple to quantify water use across wide range of crops. Here, we employed the variance-Bowen ratio approach at an alfalfa site to measure sensible and latent heat flux (λE) using 1) a sonic anemometer and 2) an air temperature and relative humidity sensor (T-RH). The variance-based sensible heat flux, using a sonic anemometer and a T-RH sensor, agreed strongly (slope = 0.98, R2 = 0.96, n = 3726) with eddy covariance. The modified-Bowen-based latent heat flux (λEβ) also showed very good results (slope = 0.89, R2 = 0.91, n = 3773) with some uncertainty. We then assessed cases where λEβ performed lesser based on heat advection measurements and remote sensing observations from ECOSTRESS. The problematic λEβ was attributed as a product of the advection of heat and moisture from upwind fields because the assumed equal diffusion of heat and water no longer stands under advection. Overall, our results suggest that the variance-Bowen ratio is a robust, inexpensive, yet user-friendly approach to measure sensible and latent heat flux. Given its reduced cost, this approach also has the potential for measuring horizontal heat advection and validating remote sensing models across many different crop types and ecosystems. Furthermore, the inclusion of advection measurement could be crucial in addressing certain remote sensing models (i.e. DisALEXI and PT-JPL) as they systematically omit any advection components.

Contrast of fine sediment dynamics between shoals and channels in a microtidal estuary with mixed semi-diurnal tides

Estuaries usually feature complex bathymetries, where shoals and channels are co-existent. Due to the differences in water depth, current, density gradient and therefore stratification, sediment dynamics on the shoal and in the channel demonstrate significant variations. In this study, field measurements were carried out during spring and neap tides in both wet and dry seasons in the Huangmaohai Estuary, a microtidal estuary located in the southwest of the Pearl River Delta. Harmonic analysis was conducted for the timeseries data of current and suspended sediment concentration (SSC) for each deployment. Sediment transport flux was decomposed into an advective component, and tidal pumping fluxes by different tidal constituents. During the neap tides, sediment transport is primarily controlled by the advective flux, whereas during the spring tides, tidal pumping fluxes become comparable to, sometimes even exceeding, the advective one. For a 25-hr period, the M1 component of SSC usually denotes the maximum SSC associated with the highest bottom stress, while the M2 component signifies the two highs of the SSC. The M4 component is generally insignificant. The M1 and M2 components can be induced by both the advection and bottom resuspension. For the resuspension part, the M1 component is mostly induced by tidal velocity asymmetry, while the M2 component is generated by tidal straining effect. Sediment transport at the shoal is mostly controlled by the advective flux and the tidal pumping due to tidal velocity asymmetry, while that in the channel is dictated by advective transport and the tidal pumping due to tidal mixing asymmetry.

Advective Components Determination of Mass, Heat and Substances Exchange According to Natural Data at the Mouth of the Black River (Sevastopol Region)

Physical and mathematical modeling of nonstationary exchange processes in the zone of interaction of heterogeneous waters at the mouths of rivers remains problematic. Therefore, the paper proposes and tests a method for estimating multidirectional water, heat and salts consumption in this zone based on field data. For this purpose, a program of long-term expeditionary research was developed, full-scale measurements were carried out in 2017–2021, an algorithm and a calculation program were developed and methods for quantifying the components of metabolic processes were tested according to full-scale studies in 2019 at the mouth of the Black river, in the zone of interaction of river water and desalinated water of the Sevastopol Bay. The article provides a methodology and an example of the assessment of water, salt and heat exchange for a representative expedition carried out under average hydrometeorological conditions during the low-water periods. Calculations are made by the analytical method, using standard programs, and by the graphical method, by graphical interpolation and planimetry of areas. The discrepancies between the results obtained by different methods were 2–7 %, which indicates the possibility of using this technique to process long-term data with sufficient accuracy. The proposed method for quantifying the components of exchange processes based on natural data can be used in any formation of different types of river mouths for balance calculations, forecasting possible changes in their state and adjacent parts of the sea under the influence of natural and anthropogenic factors, as well as for calibration and verification of models.

Mechanistic spatial models for heavy metal pollution

AbstractMining operations can contribute substantial amounts of pollution in the form of atmospheric dust. Statistical models predicting the spread of pollutants from these sources are useful for evaluating the environmental impacts of mines. Our study develops a mechanistic spatial model for heavy metal concentrations in Cape Krusenstern National Monument (CAKR), Alaska, USA. We characterize the spatial structure in our statistical model using a spatio‐temporal process for atmospheric dispersion. Mathematically, this is modeled using an advection‐diffusion partial differential equation that incorporates information about pollutant sources, diffusion, duration of spread, and advection (i.e., prevailing winds). Our approach improves upon previous statistical methods by including a temporally varying advection component and linking indirect concentration measurements to the spatio‐temporal dynamics in the model. We estimated concentrations of three heavy metals jointly using a Bayesian hierarchical model to account for the similarity in processes across chemicals. Our mechanistic statistical model is beneficial because it can predict chemical concentrations for scenarios where mining activities change. Additionally, our analysis provides an example of how using spatio‐temporal processes in statistical models for spatial data can incorporate understanding of mechanisms governing the spread of pollution and provide inferences for parameters associated with these processes.

Phase Separation in Systems of Interacting Active Brownian Particles

The aim of this paper is to discuss the mathematical modeling of Brownian active particle systems, a recently popular paradigmatic system for self-propelled particles. We present four microscopic models with different types of repulsive interactions between particles and their associated macroscopic models, which are formally obtained using different coarse-graining methods. The macroscopic limits are integro-differential equations for the density in phase space (positions and orientations) of the particles and may include nonlinearities in both the diffusive and advective components. In contrast to passive particles, systems of active particles can undergo phase separation without any attractive interactions, a mechanism known as motility-induced phase separation (MIPS). We explore the onset of such a transition for each model in the parameter space of occupied volume fraction and P\'eclet number via a linear stability analysis and numerical simulations at both the microscopic and macroscopic levels. We establish that one of the models, namely the mean-field model which assumes long-range repulsive interactions, cannot explain the emergence of MIPS. In contrast, MIPS is observed for the remaining three models that assume short-range interactions that localize the interaction terms in space.

Transitional model for rarefaction-driven Rayleigh−Taylor mixing on the diffuse interface

Large eddy simulations are performed to explore transitional characteristics with parametric variations under initial conditions for rarefaction-driven Rayleigh–Taylor mixing flows and to develop a transitional model for the prediction of transition onset. Three-dimensional, multi-mode perturbations imposed on the diffuse interface are excited by a rarefaction wave, resulting in a large but non-constant acceleration. Initial conditions investigated here profoundly impact characteristic transition times through the variation in the net contributions between the advection and pressure components dominated in the laminar regimes, making the spatial transition criteria sensitive and questionable as well as the temporal transition criteria insensitive and feasible. Therefore, a new transition model originating from empirical correlations and ignoring physical details is calibrated and tested in a series of numerical realizations, and it is certified that the modeling framework is sufficiently flexible, accurate, and robust and can be a promising strategy for handling complex transitional phenomena.

Quantifying the Contribution of Each Driving Force to the Lagrangian Residual Velocity in Xiangshan Bay

A three-dimensional numerical model is used to quantitatively evaluate the contribution of each driving force to the Lagrangian residual velocity (LRV) in Xiangshan Bay under conditions of constant buoyancy gradient in time and multi-frequency tide. Each component of the LRV from various processes is derived by tracking each driving force in a tidal period along the particle trajectory. For a comparison of the results, the driving force in the momentum equations is averaged at the fixed points to obtain six components of the Eulerian residual velocity (ERV). A quantitative evaluation of the contribution of each component to the total ERV and total LRV is performed. The sum of the acceleration component, nonlinear advection component, and barotropic pressure gradient component of ERV determines the structure of the total ERV. The LRV is influenced by different dynamic mechanisms. The barotropic pressure gradient component of LRV determines the outflow pattern of the total longitudinal LRV at the surface of the inner Xiangshan Bay, and the density gradient component of LRV is the main determinant of the structure of the total longitudinal LRV at the bottom of the inner Xiangshan Bay. The eddy viscosity component causes the total longitudinal LRV to flow seaward in the Niubi Channel. The sum of the acceleration component and nonlinear advection component of LRV is the main contributor to the inward total longitudinal LRV in the Fodu Channel. The barotropic pressure gradient component leads to total lateral flow in the outer Xiangshan Bay. The collective effect of the components induced by all of the forces determines the structure of the lateral LRV in the inner Xiangshan Bay.

A novel analytical model of solute transport in a layered aquifer system with mixing processes in the reservoirs.

Analytical models of solute transport have been widely used to aid the understanding of the physical and chemical processes undergone by substances introduced in a layered aquifer system. However, in previous studies, the advection component of transport was assumed to be one dimensional, while also ignoring the mixing processes that occur in the inlet and the outlet reservoirs. In this study, new sets of models describing those mixing processes are presented. Beyond that, these models were integrated into already existing models and the result is a novel analytical model of solute transport in aquifer-aquitard systems. The novel analytical solution was derived by the Laplace transform method and the finite-cosine Fourier transform method under the mobile-immobile (MIM) framework. The calculations take into account: the longitudinal and vertical dispersion, the molecular diffusion and the horizonal and vertical advection components of solute transport, as well as first-order chemical reaction, in both the aquifer and the aquitard. A finite-difference solution of the model is tested against experimental data in order to critique its reliability. Results indicate that the numerical and analytical solutions of the new model match well with experimental data. This new model outperforms the previous models in terms of interpreting experimental data. The mixing old and new water in the reservoirs during solute transport in aquifer-aquitard systems is important. Global sensitivity analysis demonstrates that the output concentration of solute in the aquifer-aquitard system is most sensitive to the volume of water in the inlet reservoir. The contribution of the molecular diffusion effect to the total mass flux of the tracer cross the aquifer-aquitard interface is much smaller than the contribution of the dispersive and advective effects.

Numerically consistent budgets of potential temperature, momentum, and moisture in Cartesian coordinates: application to the WRF model

Abstract. Numerically accurate budgeting of the forcing terms in the governing equations of a numerical weather prediction model is hard to achieve. Because individual budget terms are generally 2 to 3 orders of magnitude larger than the resulting tendency, exact closure of the budget can only be achieved if the contributing terms are calculated consistently with the model numerics. We present WRFlux, an open-source software that allows precise budget evaluation for the WRF model and, in comparison to existing similar tools, incorporates new capabilities. WRFlux transforms the budget equations from the terrain-following grid of the model to the Cartesian coordinate system, permitting a simplified interpretation of budgets obtained from simulations over non-uniform orography. WRFlux also decomposes the resolved advection into mean advective and resolved turbulence components, which is useful in the analysis of large-eddy simulation output. The theoretical framework of the numerically consistent coordinate transformation is also applicable to other models. We demonstrate the performance and a possible application of WRFlux with an idealized simulation of convective boundary layer growth over a mountain range. We illustrate the effect of inconsistent approximations by comparing the results of WRFlux with budget calculations using a lower-order advection operator and two alternative formulations of the coordinate transformation. With WRFlux, the sum of all forcing terms for potential temperature, water vapor mixing ratio, and momentum agrees with the respective model tendencies to high precision. In contrast, the approximations lead to large residuals: the root mean square error between the sum of the diagnosed forcing terms and the actual tendency is 1 to 3 orders of magnitude larger than with WRFlux.

The transition to turbulence in rarefaction-driven Rayleigh–Taylor mixing: Effects of diffuse interface

Effects of interface diffusion on the transition to turbulence in rarefaction-driven flows are numerically investigated via Implicit Large-Eddy simulation. Three-dimensional, multimode perturbations are imposed on the diffuse interface between Air and SF6, with various diffusion layer thicknesses. A non-constant acceleration ranging from 103g0 to 104g0, where g0 is the acceleration due to gravity, is generated by the interaction between the interface and a rarefaction wave. Evolution of first- and second-order statistics, instantaneous flow structures, and the power spectrum of turbulent kinetic energy as well as spatial distributions of energy budget are evaluated, in order to confirm the accuracy and robustness of the mixed mass transition criterion proposed here. Meanwhile, it turns out that transitional behaviors are mainly governed by Reynolds normal stresses in the plane perpendicular to the streamwise direction. Furthermore, as interface diffuses, the decrease in peak values of pressure and advection components dominated in the laminar regimes, particularly at the bubble tips, eventually leads to transition delay.

Upscaled modeling of complex DNAPL dissolution

A straightforward, upscaled DNAPL mass dissolution model is developed using relatively simple input consisting of characteristic dimensions and saturations of a DNAPL accumulation. Multiple accumulations are aggregated into a single source zone volume. Physically, the dissolution process is a combination of flow through the mass (advective component) and flow around the mass (dispersive component). The contribution of each component is based on initial characteristic length scales and the average initial saturation. Changes over time with the depletion of mass are captured with a changing relative permeability and a power law relationship for the fraction of initial mass remaining. The utility of the upscaled process model is demonstrated with data from three studies: numerical simulation of multiple pools, two-dimensional test cell experiments with mixed architecture and with heterogeneous soil, and a controlled field study of multicomponent DNAPL release and depletion. Use of the model successfully reproduced the observed multistage mass discharge in each study and illuminated the governing processes. The power law exponent was relatively constant for the various conditions and relative permeability changes were integral to the success. The numerical and experimental studies were run to complete mass depletion which the upscaled model matched. The input parameters are minimal and are found in typical DNAPL source zone characterization data.

Mixed Mesh Finite Volume Method for 1D Hyperbolic Systems with Application to Plug-Flow Heat Exchangers

We present a finite volume method formulated on a mixed Eulerian-Lagrangian mesh for highly advective 1D hyperbolic systems altogether with its application to plug-flow heat exchanger modeling/simulation. Advection of sharp moving fronts is an important problem in fluid dynamics, and even a simple transport equation cannot be solved precisely by having a finite number of nodes/elements/volumes. Finite volume methods are known to introduce numerical diffusion, and there exist a wide variety of schemes to minimize its occurrence; the most recent being adaptive grid methods such as moving mesh methods or adaptive mesh refinement methods. We present a solution method for a class of hyperbolic systems with one nonzero time-dependent characteristic velocity. This property allows us to rigorously define a finite volume method on a grid that is continuously moving by the characteristic velocity (Lagrangian grid) along a static Eulerian grid. The advective flux of the flowing field is, by this approach, removed from cell-to-cell interactions, and the ability to advect sharp fronts is therefore enhanced. The price to pay is a fixed velocity-dependent time sampling and a time delay in the solution. For these reasons, the method is best suited for systems with a dominating advection component. We illustrate the method’s properties on an illustrative advection-decay equation example and a 1D plug flow heat exchanger. Such heat exchanger model can then serve as a convection-accurate dynamic model in estimation and control algorithms for which it was developed.

Numerical dispersion of solute transport in an integrated surface–subsurface hydrological model

Integrated surface–subsurface hydrological models (ISSHMs) are increasingly being used for the assessment of contaminant transport in the environment, in addition to their more common use in water flow applications. However, the subsurface solute transport solvers in these models are prone to numerical dispersion errors. Numerical dispersion is a well-known issue in groundwater modeling, but its impacts on the results of ISSHM simulations are still poorly understood. In this study, the CATchment HYdrology (CATHY) model is used to assess the potential impacts of numerical dispersion on the simulation of coupled surface–subsurface solute transport. We first simulate the subsurface transport of a nonreactive tracer in two soil column test cases (1D and 3D) with known analytical solutions. The subsurface solute transport solver in CATHY adopts a computationally efficient time-splitting technique whereby the advection component of the governing equation is solved on elements and the hydrodynamic dispersion component is solved on nodes. Comparison between simulation results and analytical solutions with different mesh discretizations and different values for the hydrodynamic dispersion coefficients allows for accurate quantification of the numerical dispersion error and yields insights into the parameters and other factors that control it. It is shown that, taken alone, the advection and dispersion solvers are very robust, but their combination can result in significant numerical dispersion, stemming from the exchange of concentration information from elements to nodes and vice versa in the time-splitting procedure. The tests also show that these errors can be kept under control by ensuring that the grid Péclet number is in the range 0.5-1.0 or smaller. We then apply CATHY in a third test case involving two synthetic hillslopes (concave and convex) in fully coupled surface–subsurface mode, in order to examine the impact of this subsurface numerical dispersion on simulated streamflow hydrographs, in particular with reference to pre-event water contributions to runoff. Here as well the results show that the effect of numerical dispersion can be controlled by keeping the grid Péclet number sufficiently small. This work provides a new set of benchmark test cases for integrated surface–subsurface hydrological models, extending to solute transport the flow-only suite of benchmarks recently published in two intercomparison studies.

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.