Mixing Strength Research Articles

Discovery prospects with the Dark-photons & Axion-Like particles Interferometer

We discuss the discovery potential of the Dark-photons & Axion-Like particles Interferometer in this paper. The apparatus, currently in a design and prototyping phase, will probe axion dark matter from the Teide Observatory, an environment protected from terrestrial microwave sources, reaching Dine-Fischler-Srednicki-Zhitnitsky-like axion sensitivity in the range 25–250 μeV of mass. The experimental approach shows a potential to probe dark sector photons of kinetic mixing strength in excess of several 10−16 and to establish new constraints to a stochastic gravitational wave background in its band. We identify different branches, including cosmology, stellar, and particle physics, where this next-generation halo-telescope may play a role in coming years. Published by the American Physical Society 2024

On the influence of vertical mixing, boundary layer schemes, and temporal emission profiles on tropospheric NO2 in WRF-Chem – comparisons to in situ, satellite, and MAX-DOAS observations

Abstract. We present WRF-Chem simulations over central Europe with a spatial resolution of 3 km × 3 km and focus on nitrogen dioxide (NO2). A regional emission inventory issued by the German Environmental Agency, with a spatial resolution of 1 km × 1 km, is used as input. We demonstrate by comparison of five different model setups that significant improvements in model accuracy can be achieved by choosing the appropriate boundary layer scheme, increasing vertical mixing strength, and/or tuning the temporal modulation of the emission data (“temporal profiles”) driving the model. The model setup with improved vertical mixing is shown to produce the best results. Simulated NO2 surface concentrations are compared to measurements from a total of 275 in situ measurement stations in Germany, where the model was able to reproduce average noontime NO2 concentrations with a bias of ca. −3 % and R=0.74. The best agreement is achieved when correcting for the presumed NOy cross sensitivity of the molybdenum-based in situ measurements by computing an NOy correction factor from modelled peroxyacetyl nitrate (PAN) and nitric acid (HNO3) mixing ratios. A comparison between modelled NO2 vertical column densities (VCDs) and satellite observations from TROPOMI (TROPOspheric Monitoring Instrument) is conducted with averaging kernels taken into account. Simulations and satellite observations are shown to agree with a bias of +5.5 % and R=0.87 for monthly means. Lastly, simulated NO2 concentration profiles are compared to noontime NO2 profiles obtained from multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements at five locations in Europe. For stations within Germany, average biases of −25.3 % to +12.0 % were obtained. Outside of Germany, where lower-resolution emission data were used, biases of up to +50.7 % were observed. Overall, the study demonstrates the high sensitivity of modelled NO2 to the mixing processes in the boundary layer and the diurnal distribution of emissions.

The Emergence of the Normal Distribution in Deterministic Chaotic Maps.

The central limit theorem states that, in the limits of a large number of terms, an appropriately scaled sum of independent random variables yields another random variable whose probability distribution tends to attain a stable distribution. The condition of independence, however, only holds in real systems as an approximation. To extend the theorem to more general situations, previous studies have derived a version of the central limit theorem that also holds for variables that are not independent. Here, we present numerical results that characterize how convergence is attained when the variables being summed are deterministically related to one another through the recurrent application of an ergodic mapping. In all the explored cases, the convergence to the limit distribution is slower than for random sampling. Yet, the speed at which convergence is attained varies substantially from system to system, and these variations imply differences in the way information about the deterministic nature of the dynamics is progressively lost as the number of summands increases. Some of the identified factors in shaping the convergence process are the strength of mixing induced by the mapping and the shape of the marginal distribution of each variable, most particularly, the presence of divergences or fat tails.

Mixing of North Pacific water masses in the Bali Sea

As part of the Indonesian Throughflow (ITF) from western route, water masses in the Bali Sea are fed by North Pacific water masses. We examined the mixing strength in the Bali Sea which contributes to reducing the core layer S-max of the North Pacific Subtropical Water (NPSW) from 34. 8 – 35 psu in the source region to 34.5 psu in the Bali Sea. Using Thorpe method, we found the mixing strength in the Bali Sea is relatively low. The turbulent kinetic energy dissipation rate (ɛ) of O( 10-11 - 10-6 ) WKg-1 and density turbulent diffusivity (Kρ) are O (10-5 10-3) m-2s-1 were similar to typical open ocean values. However, mixing in the eastern region of the Bali Sea is relatively stronger than in the western region. Based on the critical Ri #, we found the Thorpe scale (LT) under Ri# < 0.25 in the eastern region, which is contrary to other parts. It indicated the turbulent mixing was dominantly caused by shear instability. Shear from the strong outflow of ITF towards the Lombok Strait and the reversal northward current in the lower layer forces a strong turbulent layer.

Optimized Proportioning Model and Efficacy Analysis of High Performance Concrete in Bridge Construction

Abstract As an important part of the raw materials for building construction, high performance concrete is well known for its many properties. This paper analyzes the prerequisites for high-performance concrete proportioning from the technical point of view and processes involved in designing high-performance concrete proportioning. A particle swarm algorithm combined with a neural network is used to establish the relationship model between concrete strength and proportion, and the constructed PSO-BP model is used for the prediction of concrete mixing ratio strength to get the best material proportion. The prediction ability of the BP neural network model, GP model, and PSO-BP model is compared. In order to test the applicability and reliability of the high-performance concrete formulated by the PSO-BP model in members, static load tests were carried out in this paper on a 20m test single girder to test the strain and deflection of concrete in the control section. The results show that the relative error of the high-performance concrete strength predictions predicted by the PSO-BP model is within 2%. It shows that the optimum high-performance concrete can be formulated using the PSO-BP model. The test beams can meet design and practical engineering requirements in terms of strength and stiffness and can be applied to real bridges. Based on the research and analysis, suggestions have been made for the application of high-performance concrete in bridge construction from four aspects.

Estimating Ejecta Masses of Stripped-envelope Supernovae Using Late-time Light Curves

Stripped-envelope supernovae (SESNe) are a subclass of core-collapse supernovae that are deficient in hydrogen (SN IIb, SN Ib) and possibly helium (SN Ic) in their spectra. Their progenitors are likely stripped of this material through a combination of stellar winds and interactions with a close binary companion, but the exact ejecta mass range covered by each subtype and how it relates to the zero-age main-sequence progenitor mass is still unclear. Using a combination of semianalytic modeling and numerical simulations, we discuss how the properties of SESN progenitors can be constrained through different phases of the bolometric light curve. We find that the light-curve rise time is strongly impacted by the strength of radioactive nickel mixing and treatment of helium recombination. These can vary between events and are often not accounted for in simpler modeling approaches, leading to large uncertainties in ejecta masses inferred from the rise. Motivated by this, we focus on the late-time slope, which is determined by gamma-ray leakage. We calibrate the relationship between ejecta mass, explosion energy, and gamma-ray escape time T 0 using a suite of numerical models. Application of the fitting function we provide to bolometric light curves of SESNe should result in ejecta masses with approximately 20% uncertainty. With large samples of SESNe coming from current and upcoming surveys, our methods can be utilized to better understand the diversity and origin of the progenitor stars.

Impact of Oil Viscosity on Dispersion in the Aqueous Phase of an Immiscible Two‐Phase Flow in Porous Media: An X‐Ray Tomography Study

AbstractIn this study, dispersion and mixing were studied in a steady two‐phase flow generated using a co‐injection method. The impact of oil viscosity was investigated over a large range of fluid viscosity ratios. The results indicate that highly heterogeneous flow fields are generated by a wide distribution of oil clusters with varied volumes. Variation in the velocity distribution enhanced the deformation and spreading of a tracer plume, resulting in large dispersion scales and accelerated spreading rates. The dispersion coefficients vary with time and exhibit a non‐Fickian dispersion during co‐injection. Consequently, anomalous mixing behaviors can be observed when the viscosity ratio exceeds 10. The mixing strength, characterized by the scalar dissipation rate, is first enhanced by distortion on the surface of the solute. Therefore, diffusion contributes to mixing, resulting in a faster decrease in the mixing strength in the late time regime. These results can be attributed to the fact that the non‐wetting fluid becomes disconnected, and the size of each cluster decreases as the oil viscosity increases. The formation of an oil film narrows pore spaces, and a lubrication effect of the oil film may contribute to the enhanced dispersion and mixing state, even with the low relative permeability of the wetting phase. This study provides insights into dispersion in partially saturated porous media with varied oil viscosities at both the macro and pore scales, which can further improve CO2 storage capacity and safety.

Intercomparison of Atmospheric Carbonyl Sulfide (TransCom‐COS): 2. Evaluation of Optimized Fluxes Using Ground‐Based and Aircraft Observations

AbstractWe present a comparison of atmospheric transport models that simulate carbonyl sulfide (COS). This is part II of the ongoing Atmospheric Transport Model Inter‐comparison Project (TransCom–COS). Differently from part I, we focus on seven model intercomparison by transporting two recent COS inversions of NOAA surface data within TM5‐4DVAR and LMDz models. The main goals of TransCom‐COS part II are (a) to compare the COS simulations using the two sets of optimized fluxes with simulations that use a control scenario (part I) and (b) to evaluate the simulated tropospheric COS abundance with aircraft‐based observations from various sources. The output of the seven transport models are grouped in terms of their vertical mixing strength: strong and weak mixing. The results indicate that all transport models capture the meridional distribution of COS at the surface well. Model simulations generally match the aircraft campaigns HIAPER Pole‐To‐Pole Observations (HIPPO) and Atmospheric Tomography Mission (ATom). Comparisons to HIPPO and ATom demonstrate a gap between observed and modeled COS over the Pacific Ocean at 0–40°N, indicating a potential missing source in the free troposphere. The effects of seasonal continental COS uptake by the biosphere, observed on HIPPO and ATom over oceans, is well reproduced by the simulations. We found that the strength of the vertical mixing within the column as represented in the various atmospheric transport models explains much of the model to model differences. We also found that weak‐mixing models transporting the optimized flux derived from the strong‐mixing TM5 model show a too strong seasonal cycle at high latitudes.

Robotic friction stir welding in lightweight battery assembly of extrusion-cast aluminium alloys

The present study focuses on developing lightweight assembly of two different aluminium alloys extruded and high pressure die cast (HPDC) for battery frame assembly in BEV. The goal is to produce defect-free welds in lap configuration with smooth surface finish. Stationary shoulder friction stir welding (SSFSW) was employed with welding speeds of 3–15 mm/s. EBSD analysis revealed two groups of grains in the stir zone (SZ) due to dynamic recrystallization. Moreover, the grain size of the SZ significantly decreased compared to both alloys. The cast alloy contains large iron particles, and that were broken by the rotating probe, and the stirred material consisted of fine dispersed precipitates. Tensile-shear test found the fracture location at the hook area near to cast, and a model representing fracture behavior is also discussed. With increasing welding speed from 3 to 5 mm/s, the tensile strength found ∼95 and ∼100 MPa, respectively without any significance difference in the fracture behavior and location. Overall, this study provides valuable insights such as materials mixing, grain refinement, and joint strength in dissimilar joining using SSFSW. The findings could be useful in developing optimized welding parameters and improving the overall quality and productivity of the SSFSW process for battery pack assembly in BEV.

Reaction characteristics of non-Newtonian species in a microreactor: The role of electroosmotic vortices

With a focus on biochemical applications and utilizing relevant physical properties, the current study numerically analyzes the impact of electroosmotic vortex and fluid rheology on the chemical reaction characteristics of species. This is achieved by installing integrated positively charged patches on the extended region of the microreactor with three inlets for injecting the reactants and generating the electroosmotic vortex. In order to produce species “C” in the extended region of the microreactor, it is presumed that reactant species “A” is injected through the upper and lower inlets and reactant species “B” is injected via the intermediate inlet. To solve the associated transport equations with appropriate boundary conditions, a thorough theoretical framework is developed. The results show that the ability of the reactant species to react is boosted when vortices form in the microreactor, increasing the convective mixing strength for reactant species. Furthermore, the fluid rheology significantly affects the reaction characteristics, which is a noteworthy finding. For fluids exhibiting a higher shear-thinning nature, the average concentration of the produced species follows an increasing–decreasing trend with the Carreau number. Additionally, it becomes apparent that the influence of the Damkohler number on the average generated species concentration is negligible at lower Carreau numbers, but it increases with the Damkohler number at higher Carreau numbers. The study also reveals that both rheological and chemical parameters have a substantial impact on the flow rate of product species. Overall, the findings of this investigation provide valuable insights for the development of technologically advanced electroosmotic microreactor capable of effectively generating the intended product species.

Evaluation of WRF Model Boundary Layer Schemes in Simulating Temperature and Heat Extremes over the Middle East–North Africa (MENA) Region

Abstract We assess the sensitivity of the Weather Research and Forecasting (WRF) Model to the use of different planetary boundary layer (PBL) parameterizations focusing on air temperature and extreme heat conditions. This work aims to evaluate the performance of the WRF Model in simulating temperatures across the Middle East–North Africa (MENA) domain, explain the model biases resulting from the choice of different PBL schemes, and identify the best-performing configuration for the MENA region. Three different PBL schemes are used to downscale the ECMWF ERA-Interim climate over the MENA region at a horizontal resolution of 24 km, for the period 2000–10. These are the Mellor–Yamada–Janjić (MYJ), Yonsei University (YSU), and the asymmetric convective model, version 2 (ACM2). For the evaluation of the WRF runs, we used related meteorological variables from the ERA5 reanalysis, including summer maximum and minimum 2-m air temperature and heat extreme indices. Our results indicate that simulations tend to overestimate maximum temperatures and underestimate minimum temperatures, and we find that model errors are very dependent on the geographic location. The possible physical causes of model biases are investigated through the analysis of additional variables (such as boundary layer height, moisture, and heat fluxes). It is shown that differences among the PBL schemes are associated with differences in vertical mixing strength, which alters the magnitude of the entrainment of free-tropospheric air into the PBL. The YSU is found to be the best-performing scheme, and it is recommended in WRF climate simulations for the MENA region.

Wind regimes above and below a dense oil palm canopy: Detection of decoupling and its implications on CO2 flux estimates

In tall vegetation canopies, calm weather conditions may result in the formation of an isolated below-canopy air layer. Especially during night, below-canopy carbon dioxide (CO2) fluxes may be concealed from above-canopy eddy covariance (EC) measurements, masking the magnitude of CO2 net ecosystem exchange (NEE). Particular attention to this “nighttime problem” needs to be paid in oil palm (Elaeis guineensis Jacq.) plantations, which can form a dense top canopy and which are grown in tropical regions where wind speeds are often low. Here, we investigated EC-based NEE measurements, wind and micrometeorological patterns, and LiDAR-derived terrain and canopy structure in a mature commercial oil palm plantation in the tropical lowlands of Jambi province, Sumatra, Indonesia. Over 3 years, we assessed the strength of turbulent and thermal mixing and tested five different methods to determine decoupling: (i) single-level (above-canopy) and (ii) two-level (above- and below-canopy) friction velocity (u*), (iii) above- and below-canopy standard deviation of the vertical wind (σw), (iv) bulk Richardson number (Rib), and (v) vertical turbulence intensity (ITurb). Our results show that decoupling is a common phenomenon in this plantation, with the two-level filters of σw and u* being most sensitive in its determination, showing ∼93% nocturnal decoupling. Decoupling is driven by the oil palm canopy structure, which develops a marked blocking layer at ∼10 m above the ground, high frequency of calm weather conditions, inverse temperature gradients and a terrain slope of 3° which was enough to create a thermally-induced drainage flow. Filtering NEE data, especially the two-level filters of σw and u*, challenged estimations of the plantation's CO2 balance due to high uncertainties in nocturnal respiration rates which could not be reduced by adding storage components to the measured fluxes highlighting the importance of additional below-canopy CO2 flux measurements, especially in such a weak-wind and dense-canopy tropical environment.

Three-dimensional flow structures and scalar mixing of a sand dune-inspired jet in crossflow

This paper performed particle image velocimetry (PIV) measurements and delayed detached-eddy simulations (DDES) to comprehensively investigate the flow and mixing behaviors of a sand dune(SD)-inspired JICF (jet in crossflow). PIV measurements were conducted in planes parallel to the mid-plane (Z/D = 0, 0.5, and 1), and three velocity ratios (VR = 0.4, 0.8, and 1.2) were studied. The time-averaged and turbulent flow features behind the sand dune-inspired JICF is strongly three-dimensional: the jet tends to move from the mid-plane to the outer planes and can stay attached well to the wall even at Z/D = 1. Then DDES method was applied to reveal detailed three-dimensional flow structures and mixing characteristics of the SD-inspired JICF, and a cylindrical JICF was also simulated as a benchmark for comparison. The horseshoe vortex, arch-shaped shear layer vortices, and streamwise rollers are mainly responsible for the formation of the anti-counter rotating vortex pair (anti-CRVP) observed in the mean flow field of SD configuration. Analysis of concentration distributions indicates that scalar mixing between the jet and the mainstream is highly correlated to the flow features and vortex structures, and the mixing strength of the sand dune-inspired JICF is generally weaker than that of the cylindrical JICF.

Constraining gas metal mixing strength in simulations using observations of the Milky Way’s disc

ABSTRACT This work explores the mixing rate of metals in the interstellar medium (ISM), comparing observational constraints from our solar neighbourhood to high resolution cosmological hydrodynamical simulations of Milky Way (MW)-like galaxies. The mixing rate, described by the coefficient C, is varied in simulations between 0 and 0.05, with resultant simulated galaxies compared to observations of metallicity dispersion in young star clusters, H ii regions and neutral gas in the disc of the MW. A value of C between 0.003125 and 0.0125 is found to self-consistently match a range of observables, with a best estimate of C = 0.0064 ± 0.0004. We demonstrate that the relationship between metal dispersion in young stars, H ii regions and neutral gas, versus the coefficient C, can be described by a power law. These constrained mixing rates infer a comparatively well-mixed ISM in the solar neighbourhood, at odds with some recent observations that have reported a highly inhomogeneous ISM. The degree of mixing suggested by this work is lower than what often employed in many hydrodynamical simulations. Our results have implications for studying the metallicity distribution of stars as well as of gas in the interstellar and circum-galactic media.

Anomalous Reentrant 5/2 Quantum Hall Phase at Moderate Landau-Level-Mixing Strength.

A successful probing of the neutral Majorana mode in recent thermal Hall conductivity measurements opines in favor of the particle-hole symmetric Pfaffian (PH-Pf) topological order, contrasting the theoretical predictions of Pfaffian or anti-Pfaffian phases. Here we report a reentrant anomalous quantized phase that is found to be gapped in the thermodynamic limit, distinct from the conventional Pfaffian, anti-Pfaffian, or PH-Pf phases, at an intermediate strength of Landau level mixing. Our proposed wave function consistent with the PH-Pf shift in spherical geometry rightly captures the topological order of this phase, as its overlap with the exact ground state is very high and it reproduces low-lying entanglement spectra. A unique topological order, irrespective of the flux shifts, found for this phase, possibly corroborates the experimentally found topological order.

How does buoyancy behavior impact microplastic transport in an estuarine environment?

Much is still unknown about the transport behavior of microplastic pollutants within the marine environment, particularly smaller scale coastal systems such as estuaries. Through the use of a Lagrangian particle-tracking model coupled with a validated 3D hydrodynamic model, we examined the transport, pathway and ultimate fate of microplastic particles, both in an idealized estuary and Galveston Bay, Texas, USA. Emphasis was placed on differences based on settling behavior (neutrally versus negatively buoyant), use of random walk for diffusion processes, and release location. For Galveston Bay, settling behavior had a noteworthy impact on both the transport pathway of microplastic particles, as well as overall time spent within the bay. Particles with negative buoyancy were retained approximately seven times longer than those with neutral buoyancy. Negatively buoyant particles also showed a tendency to be dispersed eastward to Trinity Bay through the bottom baroclinic flow, while neutrally buoyant particles took a more direct route along the ship channel to the mouth of the bay. Idealized model simulations suggest impact of settling depends on the vertical mixing strength. For a system with stronger tidal mixing, negatively buoyant particles with small settling velocities may still behave similarly to neutrally buoyant particles, and differences only become apparent for particles that sink rather quickly (> 10 m d−1). Future sea-level rise or channel deepening tends to flush out neutrally buoyant particles more quickly, while increasing the retention time for negatively buoyant particles. Our results suggest that plastics within estuaries could show substantially different behavior depending on their buoyancy characteristics, highlighting a need to quantify specific settling velocities of plastic pollutants entering the coastal estuarine system.

A rotating white dwarf shows different compositions on its opposite faces.

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen or helium1,2. Several mechanisms compete with gravitational settling to change a white dwarf's surface composition as it cools3, and the fraction of white dwarfs with helium atmospheres is known to increase by a factor of about 2.5 below a temperature of about 30,000 kelvin4-8; therefore, some white dwarfs that appear to have hydrogen-dominated atmospheres above 30,000 kelvin are bound to transition to be helium-dominated as they cool below it. Here we report observations of ZTF J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface9-11. ZTF J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs-together with GD 323 (ref. 12), a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.

Effect of recycled oyster shell powder on hydration and strength development of magnesium phosphate cement

Using oyster shell powder (OSP) to prepare magnesium phosphate cement (MPC) not only reduces the pollution caused by the wasted oyster shell disposal, but also benefits the development of more environmentally friendly cement. The effect of OSP on the hydration and strength development of MPC was studied. An axial compression experiment including 45 cuboid specimens was executed to investigate the compressive strength, failure mode, stress–strain relationship, and energy absorption of MPC mixing with different mass contents (0% to 12%) of OSP over the curing times of 7, 14, and 28 days. Scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy were utilized for measuring the variation of MPC microstructure and hydration products caused by OSP. Results indicated that a new reactant CaHPO4·2H2O was formed, which optimized matrix strength. The substitution of OSP could reduce the cost of MPC by 2–9% without decreasing the strength. Compared with MPC without OSP, the compressive strength of the specimen with 3% OSP is increased by 6%. However, with the continuous increase of OSP, the compressive strength gradually decreases. Similarly, the elastic modulus of MPC increases first and then decreases with the increase of OSP.

Impacts of Quasi-Biennial Oscillation and El Niño–Southern Oscillation on Stratospheric Isentropic Mixing Process

The present study investigates the influences of stratospheric quasi-biennial oscillation (QBO) and El Niño–Southern Oscillation (ENSO) on the intensity of stratospheric isentropic mixing based on ERA-Interim and MERRA-2 reanalysis products. It is found that isentropic mixing in the stratosphere is modulated by QBO and ENSO. An analysis of the QBO basis function in the multiple regression model reveals that isentropic mixing in the lower stratosphere is suppressed in the equatorial region in the WQBO phase, while the mixing enhances in the subtropical and mid-latitude regions. This result is not consistent with the Holton–Tan mechanism. However, isentropic mixing in the mid-latitudes becomes stronger in the middle stratosphere in the EQBO phase, which agrees well with the Holton–Tan effect. Composite analysis indicates that QBO-induced changes in the direction and speed of the stratospheric zonal wind can affect wave propagation and wave breaking. In the WQBO phase, zonal wind weakens, and a planetary wave is anomalously converging near 30°N, which leads to an increase in isentropic mixing; on the contrary, wind speed becomes large, and the upward propagation of planetary wave divergence, which lead to the isentropic mixing, becomes weak near 60°N. In the EQBO phase, the wind is relatively weak around 60°N, and the isentropic mixing is strong. Multiple regression analysis reveals the ENSO impact on the intensity of isentropic mixing, which shows weak mixing in the middle and high latitudes and strong mixing in the low latitudes of the lower stratosphere in the El Niño years. In the middle stratosphere, isentropic mixing enhances in the mid-latitude region due to intensified upward propagation of planetary waves but weakens in the polar region. Composite analysis reveals a clear relationship between the mixing strength zones of the El Niño and La Niña years with the position of the polar jet and changes in zonal wind speed.

The contrast in suspended particle dynamics at surface and near bottom on the river-dominated northern South China Sea shelf in summer: implication on physics and biogeochemistry coupling

To understand the process-response relations among physical forcing and biogeochemical properties of suspended particles (SPs) in the river-dominated northern South China Sea shelf, a 5-day shipboard observation was conducted at a fixed location on the dispersal pathway of the Zhujiang (Pearl) River plume (ZRP) in the summer of 2016. Instrumented moorings were deployed near the sampling site to record the flow and wave fields every 10 minutes. Hydrographic properties were measured hourly to identify different water masses. Water and SPs samples at the surface (3 m) and near the bottom (3 m above the bed) were taken every 3 h for the analyses of nutrients, chlorophyll-a (Chl-a), and particulate organic matter (POM including POC, PN, and δ13CPOC). Meanwhile, the grain-size composition of SPs and seafloor sediment were also analyzed. Results showed that monsoon winds drove cold upwelling and ZRP waters at the surface. Both the upwelling and ZRP regimes contained newly produced marine phytoplankton based on low POC/Chl-a ratio (PC ratio) and enriched δ13CPOC. However, SPs in the ZRP regime were smaller (<153 µm), having denser particle bulk density, and less enriched δ13CPOC, indicating different bio-communities from the upwelling regime. EOF analysis of the surface data suggested that mixing processes and the dispersal of the ZRP regime were mainly controlled by far-field storm winds, tidal modulation, and strength of mixing. On the other hand, a bottom nepheloid layer (BNL) was observed, mainly consisting of SPs<63 μm with higher bulk density than SPs at the surface. POM in the BNL was degraded and δ13CPOC-depleted according to the PC ratio and δ13CPOC. EOF analysis of the near-bottom data indicated that the dominant physical processes influencing the biogeochemical properties of SPs in the BNL were jointly the upwelling-associated lateral transport (first order) and tide-related resuspension (second order). Our study identified the contrast between the surface and near-bottom regimes with the coupling patterns among physical forcing and physiochemical properties of SPs using good constraints on particle dynamics and particle sources.