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This study investigates the effects of sea spray on extreme precipitation forecast in Beijing of China between 28 July and 2 August 2023 as a case test. In this case, fully coupled model increased upward moisture in the Bohai and Yellow Seas and increased accumulated rainfall by 21% in North China. For the extreme precipitation events with the 5‐day accumulated precipitation exceeding 500 mm, the atmosphere‐only model did not forecast the events; the coupled model without sea spray performed well with the 0.29 threat score (TS) and 88 mm root mean square error (RMSE); in the fully coupled model, the effects of sea spray increased atmospheric instability, which increased the precipitation around Beijing and yielded a more accurate forecast with the 0.37 TS and 65 mm RMSE. This paper suggests a scientific clue to improve numerical simulation for extreme rainfall events, however, more cases are still needed for statistical evaluation. Plain Language Summary Although meteorological forecasting ability has been improved considerably during the past decades, precipitation during extreme events remains typically underestimated. Improving model accuracy for heavy rainfall events is, indeed, a ground challenge. In this study, we conducted three numerical experiments under different conditions to evaluate the effects of sea spray on extreme precipitation forecasts for the Beijing extreme rainfall event between 28 July and 2 August 2023. Our results indicated that for this 5‐day forecasting case, including sea spray in the simulations enhanced precipitation in North China by transporting more moisture from the Bohai and Yellow Seas upward into the atmosphere. The moister and warmer air caused by sea spray effects was transported to Beijing through northwestward wind and lifted by the local terrain, then caused a more unstable atmosphere and higher intensity of precipitation around Beijing. By using statistical indicators and setting different precipitation thresholds for this extreme rainfall case, we determined that in this case, the fully coupled model including sea spray yielded more accurate forecast. To statistically evaluate the effects of sea spray in extreme precipitation forecasts, more cases are still needed. Key Points Fully coupled model led more upward moisture in the Bohai and Yellow Seas and increased 5‐day accumulated rainfall by 21% in North China Fully coupled model improved the forecasting threat score from 0 to 0.37 with the 5‐day accumulated precipitation exceeding 500 mm Sea spray led to more unstable atmosphere for the Beijing extreme rainfall event, yielding a more accurate forecast

With the aim of developing a fully coupled atmosphere‐hydrology model system, the Weather Research and Forecasting (WRF) model was enhanced by integrating a new set of hydrologic physics parameterizations accounting for lateral water flow occurring at the land surface. The WRF‐Hydro modeling system was applied for a 3 year long simulation in the Crati River Basin (Southern Italy), where output from the fully coupled WRF/WRF‐Hydro was compared to that provided by original WRF model. Prior to performing coupled land‐atmosphere simulations, the stand‐alone hydrological model (“uncoupled” WRF‐Hydro) was calibrated through an automated procedure and validated using observed meteorological forcing and streamflow data, achieving a Nash‐Sutcliffe Efficiency value of 0.80 for 1 year of simulation. Precipitation, runoff, soil moisture, deep drainage, and land surface heat fluxes were compared between WRF‐only and WRF/WRF‐Hydro simulations and validated additionally with ground‐based observations, a FLUXNET site, and MODIS‐derived LST. Since the main rain events in the study area are mostly dependent on the interactions between the atmosphere and the surrounding Mediterranean Sea, changes in precipitation between modeling experiments were modest. However, redistribution and reinfiltration of local infiltration excess produced higher soil moisture content, lower overall surface runoff, and higher drainage in the fully coupled model. Higher soil moisture values in WRF/WRF‐Hydro slightly influenced precipitation and also increased latent heat fluxes. Overall, the fully coupled model tended to show better performance with respect to observed precipitation while allowing more water to circulate in the modeled regional water cycle thus, ultimately, modifying long‐term hydrological processes at the land surface. Key Points: Fully coupled model includes lateral surface and subsurface water fluxes Lateral redistribution increases soil moisture content compared to control run Precipitation and long‐term land surface hydrological processes are influenced

For decades, Arctic temperatures have increased twice as fast as average global temperatures. As a first step toward quantifying parametric uncertainty in Arctic climate, we performed a variance‐based global sensitivity analysis (GSA) using a fully coupled, ultra‐low resolution (ULR) configuration of version 1 of the U.S. Department of Energy's Energy Exascale Earth System Model (E3SMv1). Specifically, we quantified the sensitivity of six quantities of interests (QOIs), which characterize changes in Arctic climate over a 75 year period, to uncertainties in nine model parameters spanning the sea ice, atmosphere, and ocean components of E3SMv1. Sensitivity indices for each QOI were computed with a Gaussian process emulator using 139 random realizations of the random parameters and fixed preindustrial forcing. Uncertainties in the atmospheric parameters in the Cloud Layers Unified by Binormals (CLUBB) scheme were found to have the most impact on sea ice status and the larger Arctic climate. Our results demonstrate the importance of conducting sensitivity analyses with fully coupled climate models. The ULR configuration makes such studies computationally feasible today due to its low computational cost. When advances in computational power and modeling algorithms enable the tractable use of higher‐resolution models, our results will provide a baseline that can quantify the impact of model resolution on the accuracy of sensitivity indices. Moreover, the confidence intervals provided by our study, which we used to quantify the impact of the number of model evaluations on the accuracy of sensitivity estimates, have the potential to inform the computational resources needed for future sensitivity studies. Plain Language Summary Feedbacks associated with Arctic warming are consequential for both the region and the strongly coupled global climate system. To assess the variability of the impacts of global warming and associated feedbacks in model‐based predictions, we quantified the sensitivity of the Arctic climate state to nine uncertain variables parameterizing the U.S. Department of Energy's global climate model known as the Energy Exascale Earth System Model (E3SM). Because the computational cost of repeatedly running high‐resolution configurations of E3SM was prohibitive, we used an ultra‐low resolution (ULR) configuration as a physics‐based surrogate for sensitivity analysis. Our first ever global sensitivity study of version 1 of the E3SM identified that the atmospheric parameters in E3SM's cloud physics model had the most impact on the atmosphere, sea ice, and ocean quantities of interest. This result demonstrates the importance of fully coupled climate analyses, which are necessary to identify such cross‐component influences. While we constructed confidence intervals that quantify the error in our estimates of parameter sensitivity introduced by using a limited number of ULR E3SM model runs, future investigation is needed to quantify the impact of resolution on error. Key Points We perform the first global sensitivity analysis using the fully coupled ultra‐low resolution Energy Exascale Earth System Model Uncertainty in cloud physics parameters is found to most greatly impact Arctic climate predictions Our inferred quantity of interest parameter correlations uncover key physical feedbacks and can guide model tuning

To explore the effects of air‐sea interaction on the eyewall replacement cycle (ERC) of tropical cyclones (TCs), an ERC of Typhoon Sinlaku (2008) was reproduced using the high‐resolution coupled ocean‐atmosphere‐wave‐sediment transport (COAWST) model. The numerical simulations were evaluated with a wide range of observational datasets. Moreover, the importance of the ocean to ERC is discussed by comparing six sensitive experiments, that is, three uncoupled experiments with different time‐invariant sea surface temperatures, an ocean‐atmosphere coupled experiment, an ocean‐wave coupled experiment, and an ocean‐atmosphere‐wave fully coupled experiment. The results show that Sinlaku simulated by the fully coupled experiment was highly consistent with the observations, and the evolution of ERC varies from those only simulated by the atmospheric models in previous studies. When the ocean and waves were both considered, the lifetime of the ERC was significantly prolonged, even though the simulated Sinlaku was weakened by the cooling of the sea; the asymmetric distribution of the concentric eyewalls (CEs) which caused by the non‐uniform energy exchanges was also prominent. By contrast, without ocean coupling, the simulated secondary eyewall, composed of axisymmetric convections, exhibited false enhancement and fake inward contraction, and the duration of the ERC was also shorter than that actually observed. In conclusion, the results highlight the significance of ocean coupling for the numerical simulation of the ERC of a TC, including survival time and asymmetric structure. Plain Language Summary A tropical cyclone (TC) is a severe weather system that is generated on warm tropical ocean and brings strong wind, heavy rainfall, and drastic storm surge. The eyewall of a TC is the most disaster‐prone area. In an intense TC, there are often two concentric eyewalls (CEs) over a period of time due to an eyewall replacement cycle (ERC), which is an important process that affects TC intensity and rainfall forecast. However, little work has been done to accurately forecast a real case of an ERC under the real atmospheric and ocean conditions. Therefore, our study aims to reproduce an ERC of Typhoon Sinlaku (2008) by the fully coupled ocean‐atmosphere‐wave model and validate the accuracy of simulations against the observations. The results show that the duration of the ERC and CEs structure are very sensitive to the underlying ocean, and air‐sea interaction is requisite for accurate simulation of CEs. On the basis of successful simulation under air‐sea interaction, the subsequent theoretical research for CEs can be more reliable and convincing. Key Points The eyewall replacement cycle can be successfully simulated by the air‐sea coupled model at a high resolution The ocean plays a significant role in the formation and duration of the eyewall replacement cycle A long survival time and asymmetric structure of the secondary eyewall were reproduced when the ocean was considered

High-speed passenger car requires a lighter weight for improving power performance and reducing fuel consumption; a car with higher-speed and lighter weight will lead to the passenger car more sensitive to the crosswind, which will affect the stability and drivability of the passenger car. This study employs the fully-coupled method to investigate a passenger car subjected “1-cos” crosswind with consideration of the vehicle motion. Large eddy simulation (LES) and dynamic mesh is adopted to investigate the unsteady aerodynamic, and the vehicle is treated as a three-freedom-system and driver’s control is considered to investigate the vehicle dynamic. The one-way simulation and quasi-steady simulation are also conducted to compare with the fully-coupled simulation. The results of the three simulation methods show large difference. The peak value of the lateral displacement in fully-coupled simulation is the smallest between the three simulation approaches. While the change of aerodynamic loads and vehicle motion in fully-coupled simulation is more complicated than in one-way and quasi-steady simulation. These results clearly indicate the significance of including of the unsteady aerodynamic loads in passenger car moving analysis.

Converting and harvesting the unwanted sounds produced by noise, especially in busy cities, can solve the issue of sound pollution and provide renewable power sources for low-power electronics. Although sound energy is freely available, it is hard to harvest due to its relatively low energy density compared to other sources. To enhance the efficiency of acoustic energy harvesting, particularly in the low-frequency range. The intgration of an optimised resonator is essential. This research study explores the performance of a vibroacoustic energy harvester incorporating a straight tube quarter-wavelength resonator coupled with a piezoelectric patch mounted on a flexible backplate. A fully coupled finite element model (FEM) was developed to capture the interaction between acoustic field, structural dynamic and piezoelectric transduction, and its predictions were validated against experimental results. The numerical model yielded a maximum output voltage of 1.41 V/Pa at 112 Hz, closely matching experiment findings of 1.44 V/Pa at 106 Hz under an incident sound pressure level of 90 dB. The proposed modelling framework demonstrates strong predictive capability and provides a robust basis for the design and optimisation of low-frequency acoustic energy harvester based on quarter-wavelength resonator configuration. 

In groundwater numerical simulations, the interactions between surface and groundwater have received great attention due to difficulties related to their validation and calibration due to the dynamic exchange occurring at the soil–water interface. The interaction is complex at small scales. However, at larger scales, the interaction is even more complicated, and has never been fully addressed. A clear understanding of the coupling strategies between the surface and groundwater is essential in order to develop numerical models for successful simulations. In the present review, two of the most commonly used coupling strategies in detailed domain models—namely, fully-coupled and loosely-coupled techniques—are reviewed and compared. The advantages and limitations of each modelling scheme are discussed. This review highlights the strategies to be considered in the development of groundwater flow models that are representative of real-world conditions between surface and groundwater interactions at regional scales.

The growing interest in renewable energy solutions for sustainable development has significantly advanced the design and analysis of floating offshore wind turbines (FOWTs). Modeling FOWTs presents challenges due to the considerable coupling between the turbine’s aerodynamics and the floating platform’s hydrodynamics. This review paper highlights the critical role of computational fluid dynamics (CFD) in enhancing the design and performance evaluation of FOWTs. It thoroughly evaluates various CFD approaches, including uncoupled, partially coupled, and fully coupled models, to address the intricate interactions between aerodynamics, hydrodynamics, and structural dynamics within FOWTs. Additionally, this paper reviews a range of software tools for FOWT numerical analysis. The research emphasizes the need to focus on the coupled aero-hydro-elastic models of FOWTs, especially in response to expanding rotor diameters. Further research should focus on developing nonlinear eddy viscosity models, refining grid techniques, and enhancing simulations for realistic sea states and wake interactions in floating wind farms. The research aims to familiarize new researchers with essential aspects of CFD simulations for FOWTs and to provide recommendations for addressing challenges.

The modern Yellow River Delta (YRD) has witnessed frequent channel avulsions followed by the morphological processes of “wandering‐ short‐lived braiding ‐merging” in history. However, process‐based investigation and relevant physics behind these processes remain poorly constrained. The present study complements the understanding for this evolution through numerical experiments. This is achieved by applying a two‐dimensional (2‐D) depth‐averaged fully coupled morphodynamic model that considers the feedbacks of sediment‐laden flow and bed deformation to a schematized fan‐shaped YRD. Under an uneven bed of uniform sediment, the avulsed processes of “wandering‐ short‐lived braiding ‐merging” during new channel routing on the YRD are satisfactorily reproduced by the present modelling in terms of the time evolution of planar channel pattern and channel length. Moreover, the mechanisms of the avulsed evolution have been elucidated through factor analysis on delta slope, incoming flow‐sediment conditions and artificial trenching, etc. It is suggested that morphological stability could be reached when a single meandering channel is finally sustained, of which the time scale is 4–8 years echoing the documented data of abandoned channels on the YRD. In addition, quantitative criteria have been advocated to help distinguishing the sub‐stages of the avulsed evolution together with the characteristic pattern judgement. Based on the above, implications for the YRD management are discussed. Key Points The avulsed processes of “wandering‐ short‐lived braiding ‐merging” on the Yellow River Delta are numerically reproduced Physics of the avulsed evolution is elucidated by factor analysis of delta slope, boundary conditions and artificial trenching, etc Morphological stability could be reached in numerical modeling, of which the time scale (4–8 years) echoes documented data in history

Direct flexoelectricity is a size-dependent phenomenon, very prominent at smaller scales, that connects the strain gradients and the electric field. The very existence of strain gradients enhances noncentrosymmetry and heightens the interaction between piezoelectricity and flexoelectricity, demanding fully coupled higher-order electromechanical formulations. The numerical instability of the existing finite elements used to model flexoelectricity alone is revealed due to their reliance on the stabilization parameter. Thus, two new finite elements Qu2s2p2l0 (QL0-4) and Qu2s2p2l1 (QL1-16) are proposed for mixed FEM that are numerically robust without any need of such stabilization parameters. Additionally, the existing finite element Qu2s1p2l0 [Q47 in (Deng et al. in J Appl Mech 84:081004, 2017)], is implemented from scratch to replicate known results and benchmark the performance of newly proposed finite elements. To verify the robustness of these elements, various benchmark problems for flexoelectricity in dielectric solids, such as a thick cylinder and truncated pyramid are simulated. The great agreement of the numerical results with the existing ones reflects the foundational nature of the proposed elements. Furthermore, the proposed mixed finite elements were used to successfully analyze cantilever beam and truncated pyramid problems where piezoelectric effects were taken into account for the first time. Current results are intrumental in simulating flexoelectricity and piezoelectricity together to highlight their interactions using newly proposed numerically robust finite elements.