Simulated Dust Research Articles

Analysis the Principle and Realization for Cosmic Dust Simulation

Astrophysics simulations are becoming crucial to the understanding of how the universe came to be the way it is today. Cosmic dusts are quite important in these astrophysics’ simulations, although they have only recently been introduced to the simulations. This study offers analysis on the different parts of current cosmic dust simulations. Astrophysics simulations and cosmic dusts’ role in this simulation was first discussed. Simulation requirements on cosmic dusts were then evaluated, both in the software and the hardware. The realization of cosmic dusts simulations was then discussed, focusing on the creation, growth, and destruction of cosmic dusts and briefly discussing the algorithmic process of incorporating calculations and presenting data. At last, limitations on current cosmic dusts simulations and some future prospects were proposed. These results provide an organization of the different prospects of current progresses in cosmic dust simulations, which could be beneficial as an overview of the topic and a base for which directions for future researches could be suggested.

Polar alignment of a dusty circumbinary disc–II. Application to 99 Herculis

ABSTRACT We investigate the formation of dust traffic jams in polar-aligning circumbinary discs. In our first paper, we found as the circumbinary disc evolves towards a polar configuration perpendicular to the binary orbital plane, the differential precession between the gas and dust components leads to multiple dust traffic jams. These dust traffic jams evolve to form a coherent dust ring. In part two, we use 3D smoothed particle hydrodynamical simulations of gas and dust to model an initially highly misaligned circumbinary disc around the 99 Herculis (99 Her) binary system. Our results reveal that the formation of these dust rings is observed across various disc parameters, including the disc aspect ratio, viscosity, surface density power-law index, and temperature power-law index. The dust traffic jams are long-lived and persist even when the disc is fully aligned polar. The midplane dust-to-gas ratio within the rings can surpass unity, which may be a favourable environment for planetesimal formation. Using 2D inviscid shearing box calculations with parameters from our 3D simulations, we find streaming instability modes with significant growth rates. The streaming instability growth time-scale is less than the tilt oscillation time-scale during the alignment process. Therefore, the dust ring will survive once the gas disc aligns polar, suggesting that the streaming instability may aid in forming polar planets around 99 Her.

Intertwined formation of H2, dust, and stars in cosmological simulations

Intertwined formation of H2, dust, and stars in cosmological simulations

Simulating air pollution at the province level: A case of Ba Ria – Vung Tau province, Vietnam

Abstract This study aimed to simulate air pollution in Ba Ria - Vung Tau province (BR-VT), a significant transportation hub in Vietnam and Southeast Asia. The FVM-TAPOM model system was employed to create a spatial distribution map of air pollution concentration including PM2.5, PM10, NO2, SO2, and CO. The model had sufficient capability for simulating air pollutant distribution (R2>0.6). For PM2.5, the average simulated 1-hour PM2.5 concentration is highest during the dry and rainy seasons, reaching 68 μg/m3 and 46 μg/m3, respectively. For PM10, the average 1-hour simulated PM10 dust concentration is highest during the dry and rainy seasons, reaching 90 μg/m3 and 62 μg/m3, respectively. For NO2, the average 1-hour simulated NO2 concentration is highest during the dry and rainy seasons, reaching 56 (μg/m3) and 46 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 200 μg/m3). For SO2, the average 1-hour simulated SO2 concentration is highest during the dry and rainy seasons, reaching 140 μg/m3 and 88 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 350 μg/m3). For CO, the average 1-hour simulated CO concentration is highest during the dry and rainy seasons, reaching 2.950 μg/m3 and 2.280 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 30.000 μg/m3).

Synoptic Analysis and WRF‐Chem Model Simulation of Dust Events in the Southwestern United States

AbstractDust transported from rangelands of the Southwestern United States (US) to mountain snowpack in the Upper Colorado River Basin during spring (March‐May) forces earlier and faster snowmelt, which creates problems for water resources and agriculture. To better understand the drivers of dust events, we investigated large‐scale meteorology responsible for organizing two Southwest US dust events from two different dominant geographic locations: (a) the Colorado Plateau and (b) the northern Chihuahuan Desert. High‐resolution Weather Research and Forecasting coupled with Chemistry model (WRF‐Chem) simulations with the Air Force Weather Agency dust emission scheme incorporating a MODIS albedo‐based drag‐partition was used to explore land surface‐atmosphere interactions driving two dust events. We identified commonalities in their meteorological setups. The meteorological analyses revealed that Polar and Sub‐tropical jet stream interaction was a common upper‐level meteorological feature before each of the two dust events. When the two jet streams merged, a strong northeast‐directed pressure gradient upstream and over the source areas resulted in strong near‐surface winds, which lifted available dust into the atmosphere. Concurrently, a strong mid‐tropospheric flow developed over the dust source areas, which transported dust to the San Juan Mountains and southern Colorado snowpack. The WRF‐Chem simulations reproduced both dust events, indicating that the simulations represented the dust sources that contributed to dust‐on‐snow events reasonably well. The representativeness of the simulated dust emission and transport in different geographic and meteorological conditions with our use of albedo‐based drag partition provides a basis for additional dust‐on‐snow simulations to assess the hydrologic impact in the Southwest US.

Numerical simulation of plume–surface interaction and lunar dust dispersion during lunar landing using four engines

As the lander approaches the lunar surface, the engine plumes impinge on the lunar regolith and entrain lunar dust from the surface. This plume–surface interaction and the resulting dispersion of lunar dust form a multi-physics, multi-scale problem, which becomes even more complex under multi-engine conditions. This study employed the direct simulation Monte Carlo method to simulate the plume–surface interaction flow field of a four-engine lunar lander at various landing altitudes and lunar surface angles. Flow characteristics were analyzed, and the impact of the plume and backflow on the lander was assessed. Subsequently, lunar dust simulation was conducted using the plume field as a basis. The study determined the spatial distribution of particles with different diameters at various landing altitudes and surface angles, as well as their impact velocities on the lander. Furthermore, taking into account the variations in the lander's altitude and attitude, a dynamic simulation of lunar dust during the landing process was conducted. This process resulted in the dynamic distribution of lunar dust during landing, laying the groundwork for real-time simulation of lunar dust distribution and reliable visualization during landing simulations. These findings are valuable for assessing and mitigating the hazards posed by lunar dust.

Novel design of multi-point injection system for laboratory simulation of Martian low-pressure dust devils

The Martian surface is frequently traversed by dust devils, presenting formidable challenges to exploration missions and posing significant safety risks. Establishing a ground-based simulation device for low-pressure Martian dust devils is essential for conducting reliability testing and research on extreme environments relevant to Mars rovers. This study introduces a Martian dust devil simulator comprising a simulation cabin and multi-point injectors. This apparatus facilitates the investigation of velocity and pressure distribution patterns within the flow field under varying operational conditions by adjusting injector positions, inlet pressure, and internal pressure. The simulator's design allows it to replicate Martian dust devil velocity fluctuations from 0 to 50 m/s and pressure variations spanning 100–1500 Pa, thereby meeting crucial criteria for simulating Martian atmospheric conditions. Through computational fluid dynamics (CFD) simulation, we analyzed the characteristics of dust devils generated by the simulation device and scrutinized the flow field properties following the coupling of sand-dust particles with airflow. The observed dust devil flow field closely resembles the Vastitas Borealis vortex. Additionally, experimental research was conducted. Comparing experimental, simulated, and theoretical models revealed a high degree of consistency in the internal flow field characteristics of the simulated dust devils. The apparatus's versatility extends to simulating various dust devil morphologies, offering significant potential for conducting model experiments pertinent to Martian probes and facilitating future crewed Mars exploration endeavors.

Polar alignment of a dusty circumbinary disc – I. Dust ring formation

ABSTRACT We investigate the formation of dust traffic jams in polar-aligning circumbinary discs. We use 3D smoothed particle hydrodynamical simulations of both gas and dust to model an initially highly misaligned circumbinary disc around an eccentric binary. As the circumbinary disc evolves to a polar configuration (perpendicular to the binary orbital plane), the difference in the precession between the gas and dust produces dust traffic jams, which become dense dust rings. We find the formation of dust rings exists for different Stokes number, binary eccentricity, and initial disc tilt. Dust rings are only produced while the circumbinary disc is misaligned to the binary orbital plane. When the disc becomes polar aligned, the dust rings are still present and long-lived. Once these dust rings are formed, they drift inward. The drift time-scale depends on the Stokes number. The lower the Stokes number, the faster the dust ring drifts near the inner edge of the disc. The dust rings will have an increased mid-plane dust-to-go ratio, which may be a favourable environment for the steaming instability to operate.

Preparation and performance study of environmentally friendly and durable kaolin/PDMS/cotton fabrics superhydrophobic surface

In this research work, a fluorine-free, durable, and excellent self-cleaning and oil-water separation performance kaolin/polydimethylsiloxane/cotton fabrics (Kaolin/PDMS/cotton) superhydrophobic surface was successfully prepared. The morphology, wettability, and phase composition of the coating were characterized and tested using scanning electron microscopy (SEM), dynamic contact angle measuring instrument, and X-ray diffraction (XRD). The experimental results showed that the organic composite of hydrophobic modified kaolin particles and cotton fabrics was successfully achieved through the bridging effect of PDMS. A dense superhydrophobic micro-nano structure coating was constructed on the surface of cotton fibers, and the tested performance was excellent. Has good local anti-pollution performance for common coffee, Coca-Cola, dyeing water, and simulated dust; After being worn for a distance of 1200 centimeters under a load of 10KPa, the contact angle with water remained above 150°, indicating excellent durability of the coating; In addition, kaolin/PDMS/cotton also exhibited good oil/water separation performance. After 15 cycles of oil-water separation tests, the separation efficiency for gasoline and dichloromethane both exceeded 96%.

One-third of Southern Ocean productivity is supported by dust deposition.

Natural iron fertilization of the Southern Ocean by windblown dust has been suggested to enhance biological productivity and modulate the climate1-3. Yet, this process has never been quantified across the Southern Ocean and at annual timescales4,5. Here we combined 11 years of nitrate observations from autonomous biogeochemical ocean profiling floats with a Southern Hemisphere dust simulation to empirically derive the relationship between dust-iron deposition and annual net community production (ANCP) in the iron-limited Southern Ocean. Using this relationship, we determined the biological response to dust-iron in the pelagic perennially ice-free Southern Ocean at present and during the last glacial maximum (LGM). We estimate that dust-iron now supports 33% ± 15% of Southern Ocean ANCP. During the LGM, when dust deposition was 5-40-fold higher than today, the contribution of dust to Southern Ocean ANCP was much greater, estimated at 64% ± 13%. We provide quantitative evidence of basin-wide dust-iron fertilization of the Southern Ocean and the potential magnitude of its impact on glacial-interglacial timescales, supporting the idea of the important role of dust in the global carbon cycle and climate6-8.

Simulation and synoptic investigation of a severe dust storm originated from the Urmia Lake in the Middle East

Dried lake beds are one of the largest sources of dust in the world, causing environmental problems in the surrounding areas. In this study, the desiccated Urmia Lake was the primary source of dust for all nearby synoptic stations during the April 24-25, 2017 dust episode. Synoptic analysis revealed that the heavy dust storm was triggered by a strong Black Sea cyclone and a low-pressure system over central Iraq in conjunction with a vast high-pressure system. HYSPLIT-based trajectory analysis showed that high PM10 recorded over the Urmia Lake region on April 23-26, 2017, influenced western Azerbaijan, the south of the Caspian Sea, southwestern Kazakhstan, northwestern Uzbekistan, and western Turkmenistan. The dustiest air masses (PM10 > 400 µg m–3) affected the south of the Caspian Sea and western Azerbaijan. Furthermore, the WRF-Chem model was run to evaluate the spatial distribution of dust particles in the study region. The vertical profile revealed that the simulated dust concentration ascended to 5 km from the lake. The WRF-Chem dust schemes accurately simulated dust propagation and the vertical dust profile over Urmia Lake; however, the AFWA and GOCART dust schemes showed that PM10 fluctuating changes were earlier than the measured surface PM10 at five stations around Urmia Lake on April 23-26, 2017. Furthermore, the maximum amount anticipated by the model simulation was 12 h earlier than the maximum surface mass concentration of measured PM10 at the stations throughout the period.

Polymer composite coatings subjected to sliding wear under simulated lunar temperature and dust conditions

Due to the detrimental effect of lunar dust on tribological components, it is imperative to develop bearing materials and surfaces which can survive and mitigate dust at the interface while operating under lunar environmental conditions. This issue is poised to become more significant in the near future, with lunar exploration evolving beyond the short probing missions of the Apollo era. Therefore, this study aims to investigate the combined effect of temperature and lunar dust on the tribological performance of aromatic thermosetting copolyester (ATSP) and polyether ether ketone (PEEK) -based polymer composite coatings from −150 to 110 °C. The experiments were conducted using a flat pin-on-disk configuration under dry sliding conditions, sliding speed of 0.25 m/s, 17.5 MPa contact pressure, and nitrogen gas environment. It was found that metal-on-polymer coating sliding results in dust embedment and accumulation on the softer material, which yields high friction and two-body abrasive wear. The chemical analysis of transfer film on the metal pin surface indicated a mixture of dust and polymer phases, which increased with increasing temperature, and thus resulted in deteriorated tribological performance. Self-mating polymer coatings yielded lower friction coefficient and wear due to a better dust mitigation resulting in three-body wear at the interface. The ATSP-based coatings showed higher wear resistance at all temperatures, particularly under self-mating sliding condition.

Validation of a Mid-Fidelity Numerical Approach for Wind Turbine Aerodynamics Characterization

This work is aimed at investigating the capabilities and limits of the mid-fidelity numerical solver DUST for the evaluation of wind turbines aerodynamic performance. In particular, this study was conducted by analysing the benchmarks NREL-5 MW and Phase VI wind turbines, widely investigated in the literature via experimental and numerical activities. The work was started by simulating a simpler configuration of the NREL-5 MW turbine to progressively integrate complexities such as shaft tilt, cone effects and yawed inflow conditions, offering a detailed portrayal of their collective impact on turbine performance. A particular focus was then given to the evaluation of aerodynamic responses from the tower and nacelle, as well as aerodynamic behavior in yawed inflow condition, crucial for optimizing farm layouts. In the second phase, the work was focused on the NREL Phase VI turbine due to the availability of experimental data on this benchmark case. A comparison of DUST simulation results with both experimental data and high-fidelity CFD tools shows the robustness and adaptability of this mid-fidelity solver for these applications, thus opening a new scenario for the use of such mid-fidelity tools for the preliminary design of novel wind turbine configurations or complex environments as wind farms, characterised by robust interactional aerodynamics.

High-fidelity 3D simulation of dust-loading behavior and clogging process of coarse nonwoven filter media considering collision effect

The filter lifetime of fibrous media is important for the energy-saving application of air filters and efficient delivery of clean air. The clogging process significantly affects the dust-loading behavior of fibrous filter media. Therefore, an effective methodology for determining the deposition of dust particles inside filter structures is necessary. This study conducted numerical dust loading simulations on a three-dimensional (3D) X-ray tomographic structure of coarse nonwoven filter media. Spherical particles with a density of 1808 kg/m3 were used in the simulations instead of plate-like dust particles with a higher silica density. A high-fidelity simulation model was successfully developed by considering collision effects. Key factors were determined, including the Hamaker constant for the adhesion energy, restitution coefficient for the particle kinetic energy, and sliding motion. Remarkably, the deviation between the simulated and experimental dust holding capacity was less than 1 %. The developed simulation model enabled a quantitative evaluation of the clogging process and 3D in-situ evolution of particle deposition and pore structures. It was observed that 95.6 % of the maximum deposited dust mass within the fibrous structure was captured at the clogging point. Several computational methods yielded accurate pore size evaluations and clear 3D pore structure visualizations. The developed methodology for high-fidelity simulation and 3D analysis can be further applied to other two-phase filtration and separation fields, including aerosol filtration, coalescence filtration, membrane fouling, micro/nanoplastic capture, and oil/water separation.

A hygroscopic dual-porous road dust suppressant with good dust suppression prepared by the freeze-thawing method

Based on the problem of dust rapidly resuspending after settling by water on the road, a road dust suppressant PVA&GG@IA-F with excellent solubility and hygroscopicity for the effective suppression of dust-raising was developed in this study by a freeze-thawing method. The freeze-thawing method endowed PVA&GG@IA-F with characteristics including water retention (after 9 h at 50 °C, the sand that was sprayed with 1.5 wt% PVA&GG@IA-F solution had 6.5 ± 0.09 % water content), hygroscopicity, and dual-porous microstructure. PVA&GG@IA-F possessed an ordered three-dimensional structure with interconnected smaller pores (1.4–3.2 μm) and bigger pores (8.4–15 μm) similar to spider nets. The viscosity of PV&GG@IA-F was only 3.9 mPa s−1, while PV&GG@IA-F had a strong consolidation capacity for sand, indicating that the polymer chain of dust inhibitor firmly entwined particles. Simulated dust suppression experiments demonstrated that without surfactant, the dust suppressant had a slightly lower dust deposition rate than the surfactant-added dust suppressant, but showed stable inhibition of dust resuspension (the dust suppressant prevented over 70% of PM10 and TSP from rising after five days). As revealed by the results of bonding tests, PVA&GG@IA-F was superior to suppressants reported in existing studies not because of its viscosity and wettability, but based on the suppression of dust resuspension by the double pore size structure, the stable water retention and hygroscopicity, which improved the aggregation of particles at night and thus enhanced the ability to inhibit the resuspension of dust. Therefore, the properties including water retention, hygroscopicity, and the dual-porous can provide novel ideas for preparing road dust suppressants.

Investigation of observed dust trends over the Middle East region in NASA Goddard Earth Observing System (GEOS) model simulations

Abstract. Satellite observations and ground-based measurements have indicated a high variability in the aerosol optical depth (AOD) in the Middle East region in recent decades. In the period that extends from 2003 to 2012, observations show a positive AOD trend of 0.01–0.04 per year or a total increase of 0.1–0.4 per decade. This study aimed to investigate if the observed trend was also captured by the NASA Goddard Earth Observing System (GEOS) model. To this end, we examined changes in the simulated dust emissions and dust AOD during this period. To understand the factors driving the increase in AOD in this region we also examined meteorological and surface parameters important for dust emissions, such as wind fields and soil moisture. Two GEOS model simulations were used in this study: the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis (with meteorological and aerosol AOD data assimilated) and MERRA-2 Global Modeling Initiative (GMI) Replay (with meteorology constrained by the MERRA-2 reanalysis but without aerosol assimilation). We did not find notable changes in the modeled 10 m wind speed and soil moisture. However, analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data did show an average decrease of 8 % per year in the region encompassing Syria and Iraq, which prompted us to quantify the effects of vegetation on dust emissions and AOD in the Middle East region. This was done by performing a sensitivity experiment in which we enhanced dust emissions in grid cells where the NDVI decreased. The simulation results supported our hypothesis that the loss of vegetation cover and the associated increase in dust emissions over Syria and Iraq can partially explain the increase in AOD downwind. The model simulations indicated dust emissions need to be 10-fold larger in those grid cells in order to reproduce the observed AOD and trend in the model.

A new process-based and scale-aware desert dust emission scheme for global climate models – Part II: Evaluation in the Community Earth System Model version 2 (CESM2)

Abstract. Desert dust is an important atmospheric aerosol that affects the Earth's climate, biogeochemistry, and air quality. However, current Earth system models (ESMs) struggle to accurately capture the impact of dust on the Earth's climate and ecosystems, in part because these models lack several essential aeolian processes that couple dust with climate and land surface processes. In this study, we address this issue by implementing several new parameterizations of aeolian processes detailed in our companion paper in the Community Earth System Model version 2 (CESM2). These processes include (1) incorporating a simplified soil particle size representation to calculate the dust emission threshold friction velocity, (2) accounting for the drag partition effect of rocks and vegetation in reducing wind stress on erodible soils, (3) accounting for the intermittency of dust emissions due to unresolved turbulent wind fluctuations, and (4) correcting the spatial variability of simulated dust emissions from native to higher spatial resolutions on spatiotemporal dust variability. Our results show that the modified dust emission scheme significantly reduces the model bias against observations compared with the default scheme and improves the correlation against observations of multiple key dust variables such as dust aerosol optical depth (DAOD), surface particulate matter (PM) concentration, and deposition flux. Our scheme's dust also correlates strongly with various meteorological and land surface variables, implying higher sensitivity of dust to future climate change than other schemes' dust. These findings highlight the importance of including additional aeolian processes for improving the performance of ESM aerosol simulations and potentially enhancing model assessments of how dust impacts climate and ecosystem changes.

Paleo±Dust: quantifying uncertainty in paleo-dust deposition across archive types

Abstract. Mineral dust aerosol concentrations in the atmosphere varied greatly on glacial–interglacial timescales. The greatest changes in global dust activity occurred in response to changes in orbital parameters (which affect dust emission intensity through glacial activity) and the lifetime of dust in the atmosphere (caused by changes in the global hydrological cycle). Long-term changes in the surface dust deposition rate are registered in geological archives such as loess, peats, lakes, marine sediments, and ice. Data provided by these archives are crucial for guiding simulations of dust and for better understanding the natural global dust cycle. However, the methods employed to derive paleo-dust deposition rates differ markedly between archives and are subject to different sources of uncertainty. Here, we present Paleo±Dust, an updated compilation of bulk and <10 µm paleo-dust deposition rates with quantitative 1σ uncertainties that are inter-comparable among archive types. Paleo±Dust incorporates a total of 285 pre-industrial Holocene (pi-HOL) and 209 Last Glacial Maximum (LGM) dust flux constraints from studies published until December 2022, including, for the first time, peat records. We also recalculate previously published dust fluxes to exclude data from the last deglaciation and thus obtain more representative constraints for the last pre-industrial interglacial and glacial end-member climate states. Based on Paleo±Dust, the global LGM:pi-HOL ratio of <10 µm dust deposition rates is 3.1 ± 0.7 (1σ). We expect Paleo±Dust to be of use for future paleoclimate dust studies and simulations using Earth system models of high to intermediate complexity. Paleo±Dust is publicly accessible at https://doi.org/10.1594/PANGAEA.962969 (Cosentino et al., 2024).

Numerical coupling of aerosol emissions, dry removal, and turbulent mixing in the E3SM Atmosphere Model version 1 (EAMv1) – Part 1: Dust budget analyses and the impacts of a revised coupling scheme

Abstract. An earlier study evaluating dust life cycle in the Energy Exascale Earth System Model (E3SM) Atmosphere Model version 1 (EAMv1) has revealed that the simulated global mean dust lifetime is substantially shorter when higher vertical resolution is used, primarily due to significant strengthening of dust dry removal in source regions. This paper demonstrates that the sequential splitting of aerosol emissions, dry removal, and turbulent mixing in the model's time integration loop, especially the calculation of dry removal after surface emissions and before turbulent mixing, is the primary reason for the vertical resolution sensitivity reported in that earlier study. Based on this reasoning, we propose a revised numerical process coupling scheme that requires the least amount of code changes, in which the surface emissions are applied before turbulent mixing instead of before dry removal. The revised scheme allows newly emitted particles to be transported aloft by turbulence before being removed from the atmosphere, and hence better resembles the dust life cycle in the real world. Sensitivity experiments show that the revised process coupling substantially weakens dry removal and strengthens vertical mixing in dust source regions. It also strengthens the large-scale transport from source to non-source regions, strengthens dry removal outside the source regions, and strengthens wet removal and activation globally. In transient simulations of the years 2000–2009 conducted using 1∘ horizontal grid spacing, 72 vertical layers, and unchanged tuning parameters of emission strength, the revised process coupling leads to a 40 % increase in the global total dust burden and an increase of dust lifetime from 1.8 to 2.5 d in terms of 10-year averages. Weakened dry removal and increased mixing ratios are also seen for other aerosol species that have substantial surface emissions, although the changes in mixing ratio are considerably smaller for the submicron species than for dust and sea salt. Numerical experiments confirm that the revised coupling scheme significantly reduces the strong and non-physical sensitivities of model results to vertical resolution in the original EAMv1. This provides a motivation for adopting the revised scheme in EAM as well as for further improvements on the simple revision presented in this paper.

Numerical coupling of aerosol emissions, dry removal, and turbulent mixing in the E3SM Atmosphere Model version 1 (EAMv1) – Part 2: A semi-discrete error analysis framework for assessing coupling schemes

Abstract. Part 1 (Wan et al., 2024) of this study discusses the motivation and empirical evaluation of a revision to the aerosol-related numerical process coupling in the atmosphere component of the Energy Exascale Earth System Model version 1 (EAMv1) to address the previously reported issue of strong sensitivity of the simulated dust aerosol lifetime and dry removal rate to the model's vertical resolution. This paper complements that empirical justification of the revised scheme with a mathematical justification leveraging a semi-discrete analysis framework for assessing the splitting error of process coupling methods. The framework distinguishes the error due to numerical splitting from the error due to the time integration method(s) used for each individual process. Such a distinction results in a framework that provides an intuitive understanding of the causes of the splitting error. The application of this framework to the dust life cycle in EAMv1 confirms (i) that the original EAMv1 scheme artificially strengthens the effect of dry removal processes and (ii) that the revised splitting reduces that artificial strengthening. While the error analysis framework is presented in the context of the dust life cycle in EAMv1, the framework can be broadly leveraged to evaluate process coupling schemes, both in other physical problems and for any number of processes. This framework will be particularly powerful when the various process implementations support a variety of time integration approaches. Whereas traditional local truncation error approaches require separate consideration of each combination of time integration methods, this framework enables evaluation of coupling schemes independent of particular time integration approaches for each process while still allowing for the incorporation of these specific time integration errors if so desired. The framework also explains how the splitting error terms result from (i) the integration of individual processes in isolation from other processes and (ii) the choices of input state and time step size for the isolated integration of processes. Such a perspective has the potential for the rapid development of alternative coupling approaches that utilize knowledge both about the desired accuracy and about the computational costs of individual processes.