Idealized Test Cases Research Articles

Physics–dynamics–chemistry coupling across different meshes in LFRic‐Atmosphere: Formulation and idealised tests

AbstractThe main components of an atmospheric model for numerical weather prediction are the “dynamical core,” which describes the resolved flow, and the “physical parametrisation,” which capture the effects of non‐fluid and non‐resolved fluid processes. Additionally, models used for air quality or climate applications may include a component that represents the evolution of chemicals and aerosols within the atmosphere. Though, traditionally, all these components use the same mesh with the same grid spacing, we present a formulation for the different components to use a series of nested meshes, with different horizontal grid spacings. This gives the model greater flexibility in the allocation of computational resources, so that resolution can be targeted to those parts that provide the greatest benefits in accuracy. The formulation presented here concerns the methods for mapping fields between meshes and is designed for the compatible finite‐element discretisation used by LFRic‐Atmosphere, the Met Office's next‐generation atmosphere model. Key properties of the formulation include the consistent and conservative transport of tracers on a mesh that is coarser than the dynamical core, and the handling of moisture to ensure mass conservation without generation of unphysical negative values. Having presented the formulation, it is then demonstrated through a series of idealised test cases that show the feasibility of this approach.

Optimizing regression testing with AHP-TOPSIS metric system for effective technical debt evaluation

Regression testing is essential to ensure that the actual software product confirms the expected requirements following modification. However, it can be costly and time-consuming. To address this issue, various approaches have been proposed for selecting test cases that provide adequate coverage of the modified software. Nonetheless, problems related to omitting and/or rerunning unnecessary test cases continue to pose challenges, particularly with regard to technical debt (TD) resulting from code coverage shortcomings and/or overtesting. In the case of testing-related shortcomings, incurring TD may result in cost and time savings in the short run, but it can lead to future maintenance and testing expenses. Most prior studies have treated test case selection as a single-objective or two-objective optimization problem. This study introduces a multi-objective decision-making approach to quantify and evaluate TD in regression testing. The proposed approach combines the analytic-hierarchy-process (AHP) method and the technique of order preference by similarity to an ideal solution (TOPSIS) to select the most ideal test cases in terms of objective values defined by the test cost, code coverage, and test risk. This approach effectively manages the software regression testing problems. The AHP method was used to eliminate subjective bias when optimizing objective weights, while the TOPSIS method was employed to evaluate and select test-case alternatives based on TD. The effectiveness of this approach was compared to that of a specific multi-objective optimization method and a standard coverage methodology. Unlike other approaches, our proposed approach always accepts solutions based on balanced decisions by considering modifications and using risk analysis and testing costs against potential technical debt. The results demonstrate that our proposed approach reduces both TD and regression testing efforts.

Regional and fine-scale local adaptation in salinity tolerance in Daphnia inhabiting contrasting clusters of inland saline waters.

Understanding the spatial scales at which organisms can adapt to strong natural and human-induced environmental gradients is important. Salinization is a key threat to biodiversity, ecosystem functioning and the provision of ecosystem services of freshwater systems. Clusters of naturally saline habitats represent ideal test cases to study the extent and scale of local adaptation to salinization. We studied local adaptation of the water flea Daphnia magna, a key component of pond food webs, to salinity in two contrasting landscapes-a dense cluster of sodic bomb crater ponds and a larger-scale cluster of soda pans. We show regional differentiation in salinity tolerance reflecting the higher salinity levels of soda pans versus bomb crater ponds. We found local adaptation to differences in salinity levels at the scale of tens of metres among bomb crater pond populations but not among geographically more distant soda pan populations. More saline bomb crater ponds showed an upward shift of the minimum salt tolerance observed across clones and a consequent gradual loss of less tolerant clones in a nested pattern. Our results show evolutionary adaptation to salinity gradients at different spatial scales, including fine-tuned local adaptation in neighbouring habitat patches in a natural landscape.

A Moving-Wave Implementation in WRF to Study the Impact of Surface Water Waves on the Atmospheric Boundary Layer

Abstract While numerous modeling studies have focused on the interaction of ocean surface waves with the atmospheric boundary layer, most employ idealized waves that are either monochromatic or synthetically generated from a theoretical wave spectrum, and the atmospheric solvers are typically incompressible. To study wind–wave coupling in real-world scenarios, a model that can simulate both realistic meteorological and wave conditions is necessary. In this paper we describe the implementation of a moving bottom boundary condition into the Weather Research and Forecasting Model for large-eddy simulation applications. We first describe the moving bottom boundary conditions within WRF’s pressure-based vertical coordinate system. We then validate our code with idealized test cases that have analytical solutions, including flow over a monochromatic wave with and without viscosity. Finally, we present results from turbulent flows over a moving monochromatic wave with different wave ages, and demonstrate satisfactory agreement of the wave growth rate with results from the literature. We also compare atmospheric stress and wind parameters from two physically equivalent cases. The first specifies a wind moving in the same direction as a propagating wave, while the second involves a stationary wave with the wind adjusted such that the wind relative to the wave is the same as in the first case. Results indicate that the velocity and Reynolds stress profiles for the two cases match, further validating the moving bottom implementation.

Observing gravitational redshift with X-ray emission in galaxy clusters withAthenaX-IFU

Context.The Doppler shift predicted by general relativity for light escaping a gravitational potential has been observed on Earth as well as in the direction of various stars and galaxy clusters at optical wavelengths.Aims.Observing the gravitational redshift in the X-ray band within galaxy clusters could provide information on their properties and, in particular, their gravitational potential. We present a feasibility study of such a measurement, using the capabilities of the next-generation European X-ray observatoryAthena.Methods.We used a simple generalized Navarro–Frenk–White potential model along with aβ-model for the density of baryonic matter, which sets the emission to provide an estimation of the observed redshift in the simplest of cases. We generated mock observations with theAthenaX-ray Integral Field Unit (X-IFU) for a nearby massive cluster, while seeking to recover the gravitational redshift along with other properties of the toy model cluster.Results.We investigated the observability of the gravitational redshift in an idealized test case of a nearby massive cluster with theAthenaX-IFU instrument, as well as its use in probing the properties of the potential well. We were also able to constrain the mass to a ∼20% level of precision and the cosmological redshift to less than ∼1%, within a simplified and idealized observational framework. More refined simulations accounting for further effects such as the internal gas motions and the actual shape of the potential well are required to fully investigate the feasibility of measuring the gravitational redshift for a single target or statistically over a sample of galaxy clusters.

Wave Excitation Tests on a Fixed Sphere

Wave excitation tests on a fixed sphere with the center at the still water level were carried out with three different physical wave basin setups. The tests were completed as a continued effort of the working group OES Wave Energy Converters Modelling Verification and Validation to increase confidence in numerical models of wave energy converters by generation of accurate benchmarks datasets for numerical model validation. An idealized testcase with wave excitation of a fixed sphere to be used with the benchmarks was formulated. The three investigated physical wave basin setups included: 1) a six degree-of-freedom load cell mounted to the top of the sphere, 2) a bending beam force transducer mounted to the top of the sphere, and 3) a system of six pretensioned wires mounted to the top and bottom of the sphere with force transducers attached to each wire. The aim of the present paper is to identify the best representation of the idealized testcase. To this end, the three experimental setups are inter-compared in terms of dynamic properties, sensitivity, and disturbances of the water phase from the presence of measurement equipment. Low inter-experiment variability was disclosed, i.e., 5-8% depending on wave-nonlinearity, indicating accurate representations of the idealized testcase across all setups. Setup 3 was found to be the more accurate representation and further work with this setup to release a public benchmark dataset was planned.

Development and Application of an Infragravity Wave (InWave) Driver to Simulate Nearshore Processes

AbstractInfragravity waves are key components of the hydro‐sedimentary processes in coastal areas, especially during extreme storms. Accurate modeling of coastal erosion and breaching requires consideration of the effects of infragravity waves. Here, we present InWave, a new infragravity wave driver of the Coupled Ocean‐Atmopshere‐Waves‐Sediment Transport (COAWST) modeling system. InWave computes the spatial and temporal variation of wave energy at the wave group scale and the associated incoming bound infragravity wave. Wave group‐varying forces drive free infragravity wave growth and propagation within the hydrodynamic model of the coupled modeling system, which is the Regional Ocean Modeling System (ROMS) in this work. Since ROMS is a three‐dimensional model, this coupling allows for the combined formation of undertow currents and infragravity waves. We verified the coupled InWave‐ROMS with one idealized test case, one laboratory experiment, and one field experiment. The coupled modeling system correctly reproduced the propagation of gravity wave energy with acceptable numerical dissipation. It also captured the transfer of energy from the gravity band to the infragravity band, and within the different infragravity bands in the surf zone, the measured three‐dimensional flow structure, and dune morphological evolution satisfactorily. The idealized case demonstrated that the infragravity wave variance depends on the directional resolution and horizontal grid resolution, which are known challenges with the approach taken here. The addition of InWave to COAWST enables novel investigation of nearshore hydro‐sedimentary dynamics driven by infragravity waves using the strengths of the other modeling components, namely the three‐dimensional nature of ROMS and the sediment transport routines.

Verification of a Modified Nonhydrostatic Global Spectral Dynamical Core Based on the Dry-Mass Vertical Coordinate: Three-Dimensional Idealized Test Cases

Verification of a Modified Nonhydrostatic Global Spectral Dynamical Core Based on the Dry-Mass Vertical Coordinate: Three-Dimensional Idealized Test Cases

Stability of Constant and Variable Coefficient Semi-Implicit Schemes for the Fully Elastic System of Euler Equations in the Case of Steep Slopes

Abstract Crank–Nicolson temporal schemes are usually employed in most semi-implicit models commonly applied in numerical weather prediction. These schemes are approached by fixed points methods like the iterative centered implicit scheme, where a linear operator is introduced to invert the implicit problem. When this operator is spatially dependent the scheme is a variable coefficient one, and a constant coefficient one otherwise. Constant and variable coefficient temporal schemes are analyzed and tested on idealized test cases to improve numerical stability on the steepest slopes of the orography encountered at hectometric scales. These analyses and experiments are conducted for the fully elastic system of Euler equations for different slopes and different thermal residuals. Because of their low computational cost, several strategies can be easily tested. None of the strategies considered for constant coefficient schemes significantly improves numerical stability without worsening efficiency or accuracy. Hence, constant coefficient schemes are probably not the most suitable schemes for high-resolution computing. A successful strategy consists in using the same features of constant coefficient schemes except for the orographic terms that are implicitly treated, resulting in a variable coefficient scheme. In this case, slopes up to 70° can be easily reached, even in the case of a moderate thermal residual. Since estimates on the condition number of the implicit problem containing orographic terms remains low even in case of steep slopes, the implicit problem should be easily inverted by an iterative solver.

The simulation of ice jam profiles in multi-channel systems using a one-dimensional network model

This paper presents a new modelling method for simulating ice jam profiles in channel networks, implemented in the University of Alberta's public-domain hydrodynamic and river ice process model, River1D. The method includes provisions for handling junctions when solving the ice jam stability equation within a channel network. At junction elements, the solution of the ice jam stability equation is calculated as a function of the junction water discharge ratio. The model was first compared to a series of idealized test cases from a previous study that sought to investigation the impact of islands on ice jam profiles. Seventeen tests were performed in rectangular channels with islands of different length. The results from River1D agreed well with the results from the previous study, showing the same stage reduction along the length of the island and minimum depth at the upstream end of the island. The model was then applied to the Hay River Delta in the Northwest Territories of Canada. The model was first validated for open water scenarios (with surveyed data and 2D modelling results) and was then used to simulate a series of ice jam profiles and validated using data collected within the Hay River Delta during the 2009 breakup. Using just a single value of 0.055 for the under ice jam roughness, the modelled ice jam profiles agreed favourably with the surveyed levels. However, the model did have a tendency to under predict levels in the East Channel for the profile that was collected after an upstream ice jam release wave had passed through the delta. When jam consolidation was considered in the simulation, the model was able to more accurately simulate the surveyed levels. The model results suggest that ice jamming conditions during the 2009 breakup reduced the percentage of flow entering the East Channel compared to open water conditions.

Development and Validation of Accumulation Term (Distributed and/or Point Source) in a Finite Element Hydrodynamic Model

During tropical storms, precipitation and associated rainfall-runoff can lead to significant flooding, in both the upland and coastal areas. Flooding in coastal areas is compounded by the storm surge. Several hurricanes in recent history have exhibited the destructive force of compound flooding due to precipitation, rainfall-runoff, storm surge and waves. In previous work, various coupled modeling systems have been developed to model total water levels (defined as tides, waves, surge, and rainfall-runoff) for tropical storms. The existing coupled system utilizes a hydrologic model in the upland areas of the domain to capture the precipitation and rainfall-runoff associated with the storms; however, in the coastal areas the precipitation and rainfall-runoff is not captured. Herein a source/sink term is incorporated within the hydrodynamic model itself to capture precipitation and rainfall-runoff over the already inundated coastal areas. The new algorithm is verified for several idealized test cases, and then it is applied to Hurricane Irene. Validation indicates that the new methodology is comparable to the existing river flux forcing under most conditions and allows for the addition of streamflows due to overland runoff, as well as the actual precipitation itself.

Improving tidal turbine array performance through the optimisation of layout and yaw angles

Tidal stream currents change in magnitude and direction during flood and ebb tides. Setting the most appropriate yaw angles for a tidal turbine is not only important to account for the performance of a single turbine, but can also be significant for the interactions between the turbines within an array. In this paper, a partial differentiation equation (PDE) constrained optimisation approach is established based on the Thetis coastal ocean modelling framework. The PDE constraint takes the form here of the two-dimensional, depth-averaged shallow water equations which are used to simulate tidal elevations and currents in the presence of tidal stream turbine arrays. The Sequential Least Squares Programming (SLSQP) algorithm is applied with a gradient obtained via the adjoint method in order to perform array design optimisation. An idealised rectangular channel test case is studied to demonstrate this optimisation framework. Located in the centre of the computational domain, arrays comprised of 12 turbines are tested in aligned and staggered layouts. The setups are initially optimised based on their yaw angles alone. In turn, turbine coordinates and yaw angles are also optimized simultaneously. Results indicate that for an aligned turbine array case under steady state conditions, the energy output can be increased by approximately 80\% when considering yaw angle optimisation alone. For the staggered turbine array, the increase is approximately 30\%. The yaw optimised staggered array is able to outperform the yaw optimised aligned array by approximately 8\%. If both layout and the yaw angles of the turbines are considered within the optimisation then the increase is more significant compared with optimising yaw angle alone.

Skill assessment of different quadruplet wave-wave interaction formulations in the WAVEWATCH-III model with application to the Gulf of Mexico

In this study, the Gaussian Quadrature Method (GQM) method was implemented in the WAVEWATCH-III model and used along with embedded formulations for estimating the nonlinear wave interactions. The results of DIA, GMD, GQM and WRT methods were compared for ideal test cases. The GQM was in good agreement with the exact WRT method while its medium resolution conjuration was ∼10 times faster than WRT. The GMD was more than 50 times faster than GQM but it could not reproduce WRT results for slanting fetch condition. Two different packages named ST3 and ST6, were employed for calculating the wind input and energy dissipation formulations over the Gulf of Mexico. The high quality ERA5 wind data from August to September in 2017 blended with Holland parametric model were used to run the wave model. The simulation period includes both fair weather condition and extreme events of Hurricanes Harvey and Irma. The performance of wave model using different nonlinear wave interaction terms was assessed against bulk wave parameters measured by in-situ buoys as well as altimeter-derived data by introducing a new error index. The general features of in-situ directional wave spectra were well captured by all DIA, GMD, GQM and WRT methods; however, the spectra produced by GMD and GQM were closer to the results by WRT method. Interestingly, the DIA method with calibrated whitecap dissipation term outperformed other methods in reproducing in-situ data (i.e. wave bulk parameters and wave spectra) during both fair weather and extreme events; indicating overfitting in the white capping or/and wind input terms in the wave model.

Realistic operation of two residential cordwood-fired outdoor hydronic heater appliances—Part 2: Particle number and size

ABSTRACT The use of wood as a fuel for home heating is a concern from an environmental health and safety perspective as biomass combustion appliances emit high concentrations of particulate matter. Wood burning significantly contributes to wintertime particulate matter concentrations in many states in the northern United States. Of particular concern are outdoor wood-fired hydronic heaters. These devices are concerning as they tend to have very large combustion chambers and typical use patterns can result in long periods of low output, which result in an increased particulate matter emission rate relative to high heat output operating conditions. In this study, the performance of two hydronic heaters operating under different combustion conditions, including four different heat output categories approximately corresponding to categories I–IV denoted in Environmental Protection Agency Method 28 Outdoor Wood-fired Hydronic Heaters, and during start-up and reloading events were investigated. Measurements of flue gas particulate number concentration and size for particles with aerodynamic diameters between 0.006 and 10 µm were made using a dilution sampling system. The measured particle number concentration in the flue gas was between 0.71 and 420 million particles per cubic centimeter and was dependent on fuel loading and heat output. For each hydronic heater tested, the highest average particle concentration was found at the beginning of each test during the cold-start condition. Additionally, the majority of the particles had aerodynamic diameters less than 0.100 µm (particles of this size made up between 64% and 97% of all particles) and less than 1% of all particles had aerodynamic diameters greater than 1 µm for all phases. For particles in the accumulation mode, between 0.100 and 1 µm, the mean particle diameter was dependent on fuel loading and heat output. Implications: In this work, we provide information on the particle number concentration and particle size of emissions from outdoor cord- wood-fired hydronic heaters. Wood-fired hydronic heater data is sparsely available compared to wood stove data. Thus, additionaldata from this source help to inform the work of modelers and policy makers interested in hydronic heaters. The test method used in this work is also novel, as it is more inclusive of real-world use cases than the current certification method. Our data helps to validate the test method and allows for comparisons between real-world use case scenarios, and idealized test cases.

MPAS-Seaice (v1.0.0): sea-ice dynamics on unstructured Voronoi meshes

Abstract. We present MPAS-Seaice, a sea-ice model which uses the Model for Prediction Across Scales (MPAS) framework and spherical centroidal Voronoi tessellation (SCVT) unstructured meshes. As well as SCVT meshes, MPAS-Seaice can run on the traditional quadrilateral grids used by sea-ice models such as CICE. The MPAS-Seaice velocity solver uses the elastic–viscous–plastic (EVP) rheology and the variational discretization of the internal stress divergence operator used by CICE, but adapted for the polygonal cells of MPAS meshes, or alternatively an integral (“finite-volume”) formulation of the stress divergence operator. An incremental remapping advection scheme is used for mass and tracer transport. We validate these formulations with idealized test cases, both planar and on the sphere. The variational scheme displays lower errors than the finite-volume formulation for the strain rate operator but higher errors for the stress divergence operator. The variational stress divergence operator displays increased errors around the pentagonal cells of a quasi-uniform mesh, which is ameliorated with an alternate formulation for the operator. MPAS-Seaice shares the sophisticated column physics and biogeochemistry of CICE and when used with quadrilateral meshes can reproduce the results of CICE. We have used global simulations with realistic forcing to validate MPAS-Seaice against similar simulations with CICE and against observations. We find very similar results compared to CICE, with differences explained by minor differences in implementation such as with interpolation between the primary and dual meshes at coastlines. We have assessed the computational performance of the model, which, because it is unstructured, runs with 70 % of the throughput of CICE for a comparison quadrilateral simulation. The SCVT meshes used by MPAS-Seaice allow removal of equatorial model cells and flexibility in domain decomposition, improving model performance. MPAS-Seaice is the current sea-ice component of the Energy Exascale Earth System Model (E3SM).

Reinterpreting the Bruun Rule in the Context of Equilibrium Shoreline Models

Long-term (>decades) coastal recession due to sea-level rise (SLR) has been estimated using the Bruun Rule for nearly six decades. Equilibrium-based shoreline models have been shown to skillfully predict short-term wave-driven shoreline change on time scales of hours to decades. Both the Bruun Rule and equilibrium shoreline models rely on the equilibrium beach theory, which states that the beach profile shape equilibrates with its local wave and sea-level conditions. Integrating these two models into a unified framework can improve our understanding and predictive skill of future shoreline behavior. However, given that both models account for wave action, but over different time scales, a critical re-examination of the SLR-driven recession process is needed. We present a novel physical interpretation of the beach response to sea-level rise, identifying two main contributing processes: passive flooding and increased wave-driven erosion efficiency. Using this new concept, we analyze the integration of SLR-driven recession into equilibrium shoreline models and, with an idealized test case, show that the physical mechanisms underpinning the Bruun Rule are explicitly described within our integrated model. Finally, we discuss the possible advantages of integrating SLR-driven recession models within equilibrium-based models with dynamic feedbacks and the broader implications for coupling with hybrid shoreline models.

Idealised 3D simulations of diabatically forced Ledoux convection

Aims.We investigate the impact of dimensionality, resolution, and long timescales on convective numerical simulations forced by thermo-compositional diabatic processes. We focus our study on simulations that are stable to the Schwarzschild criterion but unstable to the Ledoux one (i.e. simulations with a stabilising temperature gradient and a destabilising mean-molecular-weight gradient). We aim to establish the possibility of a reduced temperature gradient in such setups.Methods.A suite of 3D simulations incorporating both time series and convergence studies were conducted using a high-performance numerical hydrodynamic code. We used, as a simplified and idealised test case, a sample region of the secondary atmosphere of a hot rocky exoplanet, of the order of the scale height of the system, within which the chemical transition CO + O ↔ CO2could occur. Newtonian cooling was employed to force an equilibrium temperature, and a chemical source term was used to maintain a negative mean-molecular-weight gradient in the vertical direction.Results.Our results demonstrate that a mean-molecular-weight gradient and a chemical source term can reduce the atmosphere temperature gradient, a result that does not converge away with resolution and is stable when exploring long timescales. Simulations in two dimensions are prone to the development of shear modes, as already seen in the literature for double-diffusive convection. The 3D convective steady state is not impacted by these shear modes, suggesting that this phenomenon is linked to the dimensionality of the problem. We also show that the presence of the reduced temperature gradient is a function of the forcing timescales, disappearing if the chemical forcing is too slow. We find that the above transition leads to a bifurcation of the atmosphere’s temperature profile when the chemical forcing is fast. Such a bifurcation is reminiscent of the bifurcation seen in the boiling crisis for steam or liquid convection.Conclusions.With the reduced temperature gradient in these idealised setups, there exists the possibility of an analogy of the reddening (currently observed in the spectra of brown dwarfs) in the spectra of rocky exoplanet atmospheres. This possibility needs, however, to be checked with detailed 1D models in order to precisely characterise the equilibrium thermal and compositional gradients, the thermal and compositional forcing timescales, and the impact of a realistic equation of state to, in turn, assess if the regime identified here will develop in realistic situations. However, the possibility of this reddening cannot be excluded a priori. This prediction is new for terrestrial atmospheres and represents strong motivation for the use of diabatic models when analysing the atmospheric spectra of rocky exoplanets that will be observed with, for example, theJames WebbSpace Telescope.

Adapting the MPAS Dynamical Core for Applications Extending Into the Thermosphere

AbstractTo extend the nonhydrostatic global Model for Prediction Across Scales (MPAS) for deep‐atmosphere (geospace) applications, we have modified the model equations and numerics to include variable atmospheric composition and (potentially large) molecular viscosity and thermal conductivity. The split‐explicit numerical integration techniques in MPAS remain stable in idealized test cases for atmospheric domains extending into the upper thermosphere and continue to provide an efficient numerical framework for nonhydrostatic simulations. Variations in the atmospheric constituents influence the dynamical equations by altering the heat capacity and ideal gas constants. These feedbacks require little alteration of the dynamical equations although our testing reveals that the amplitude of disturbances may be sensitive to even small variations in the thermodynamic coefficients. Although the potential temperature is no longer formally conserved for adiabatic flow, it remains effective as a prognostic thermodynamic variable in the model equations. Molecular viscosity and thermal conductivity are dominant influences in the upper thermosphere and are represented implicitly in the model numerics. Because of the large magnitude of these terms, their treatment, though stable, may significantly under represent the true magnitude of their damping effects. Further consideration of these deep‐atmosphere extensions to MPAS will be explored in more realistic simulations of thermospheric dynamics.

Drivers of productivity differences between Douglas-fir planted within its native range in Oregon and on exotic sites in New Zealand

Forest species planted outside their native range sometimes exhibit growth rates that far exceed those in their native range. In species grown for timber production, the improved growth in certain exotic environments has led to the widescale propagation of some outstanding species, but the proposed mechanistic drivers behind this improved growth are little studied. Given the increasing importance of understanding growth response to climate changes, many of these species present ideal test cases, including coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), a widely planted timber species native to the Pacific Coast of North America. We identified a set of seven sites in the Oregon Cascades Range and the South Island of New Zealand that were planted with Douglas-fir seedlings originating from a shared seed source in 2004, presenting an opportunity to examine drivers of productivity while reducing the confounding effect of genetics. We sampled plots at each of these sites during the 2019 dormant season by measuring standing trees, collecting increment cores, assessing soil conditions, and installing meteorological instruments. Using these data, we constructed an environmentally sensitive model of annual radial growth of the stem at breast height, accounting for between- and within-location variation controlled by environmental factors. Trees at New Zealand locations had increased diameter growth compared to those in Oregon. Lower vapor pressure deficit during the growing season was the primary cause of this improved productivity in New Zealand through presumed effects on higher stomatal conductance and net photosynthesis. In contrast, other environmental factors were identified as driving productivity differences between sites within Oregon and within New Zealand.

Computations of soliton impact onto a vertical wall: Comparing incompressible and compressible assumption with experimental validation

This paper present numerical computations of solitary wave impact on a vertical wall. Different wave breaking cases were studied such as the high-aerated (air-pocket) or low-aerated (flip-through) in order to test the software ability to accurately reproduce the generated wall pressure loads. The numerical toolbox OpenFOAM was used here under the incompressible and compressible assumptions, together with 2D and 3D configurations. First, an idealised test case was used to validate the numerical convergence on an analytical value of the pressure impulse. Pressure impulse convergence was always numerically obtained but the pressure levels never converged under the incompressible assumption. Switching to the compressible assumption, pressure impulse and pressure time series converged both on the idealised test case and on the experimental configuration used. A large variety of spatial and temporal pressure variations were highlighted in this study that enable some physical interpretation of the impact mechanism.