Transport Of Mass Research Articles

Investigating the factors contributing to the maintenance of high levels of warm season nocturnal ozone in a basin city.

In recent years, ozone (O3) pollution in many Chinese cities has worsened. Several cities have also experienced incidents where nocturnal O3 concentrations did not decrease as expected, and instead remained at high levels (above 50 ppb). However, there have been few detailed studies on the causes of these events. The present study used air quality and meteorological monitoring data, along with the Hybrid Single-Particle Lagrangian Integrated Trajectory model, to investigate the causes contributing to nocturnal O3 remaining at high values (NORHV) in Linfen City, a typical basin city in the Fenhe River Basin, characterized by severe O3 pollution. These events are influenced by the individual or combined impacts of mountain-valley breezes, along with vertical and horizontal transport of O3-rich air masses. In addition, the influencing mechanisms of three NORHV events were identified as: 1) the alternating effect of the descent of upper-level air masses enriched with O3, CO, and SO2 and downslope mountain breezes carrying the O3-rich air mass; 2) the interaction between the transport of polluted air masses across mountains and downslope mountain breezes on both sides of the two mountains in urban areas; and 3) the O3-rich air mass from high-altitude regions descended into the urban area following two LLJ events. These conclusions were supported by vertical distributions of O3 concentrations in the three cases simulated using the WRF-CMAQ model. In addition, the NORHV events resulted in higher initial O3 concentrations on the following day compared to normal days, exacerbating O3 pollution. The results of this study demonstrate the significant contributions of complex synergistic effects, such as mountain-valley breezes and vertical transport, to the occurrence of NORHV events in basin cities. These findings may be applicable to other basin cities around the world.

Kinematic Characteristics and Water Mass Transports of Submesoscale Coherent Vortices in the Northeastern South China Sea

AbstractAs a unique phenomenon occurring in the subsurface ocean, submesoscale coherent vortices (SCVs) are believed to have a pivotal role in the long‐distance ocean tracer transports. SCVs have been widely observed in the global oceans; however, most of them are captured accidentally, and their kinematic characteristics and water mass transports have only been studied in a limited number of regions. Here, we use 4‐year observations of velocity, temperature, and salinity from five moorings in the northeastern South China Sea (NESCS) to examine dozens of newly discovered SCVs. A total of 34 SCVs were identified during the observational period, including 25 convex lens‐like anticyclones and 9 concave lens‐like cyclones. The maximum swirl velocity, mean radius, and vertical length scale of the anticyclones (cyclones) are 0.19 ± 0.07 m s−1 (0.19 ± 0.07 m s−1), 26.4 ± 13.9 km (17.0 ± 5.4 km), and 204 ± 62 m (188 ± 53 m), respectively. Vertically, the velocity structure of the observed SCVs conforms to a Gaussian function when the effect of stratification is removed. Water mass analysis suggests that 88% (30/34) of the SCVs carried Kuroshio water, which demonstrates the mechanism proposed by Zhang et al. (2022), https://doi.org/10.1029/2021jc018117 that they are formed by Kuroshio‐islands interactions in the Luzon Strait. This category of SCVs is therefore named Luzon Strait island wake eddies (Liddies). We further estimate that Liddies can result in an equivalent mean volume transport of 0.20 Sv westward across the Luzon Strait, which suggests that they play a non‐negligible role in the subsurface water transports between the NESCS and the northwestern Pacific.

High-dimensional experiments for the downward continuation using the LRFMP algorithm

AbstractTime-dependent gravity data from satellite missions like GRACE-FO reveal mass redistribution in the system Earth at various time scales: long-term climate change signals, inter-annual phenomena like El Niño, seasonal mass transports and transients, e. g. due to earthquakes. For this contemporary issue, a classical inverse problem has to be considered: the gravitational potential has to be modelled on the Earth’s surface from measurements in space. This is also known as the downward continuation problem. Thus, it is important to further develop current mathematical methods for such inverse problems. For this, the (Learning) Inverse Problem Matching Pursuits ((L)IPMPs) have been developed within the last decade. Their unique feature is the combination of local as well as global trial functions in the approximative solution of an inverse problem such as the downward continuation of the gravitational potential. In this way, they harmonize the ideas of a traditional spherical harmonic ansatz and the radial basis function approach. Previous publications on these methods showed proofs of concept. In this paper, we report on the progress of our developments towards more realistic scenarios. In particular, we consider the methods for high-dimensional experiment settings with more than 500 000 grid points which yields a resolution of 20 km at best on a realistic satellite geometry. We also explain the changes in the methods that had to be done to work with such a large amount of data. The corresponding code (updated for big data use) is available at https://doi.org/10.5281/zenodo.8223771 under the licence CC BY-NC-SA 3.0 Germany.

Characteristics and Source Apportionment of Ambient Volatile Organic Compounds in Shijiazhuang High-tech Industrial Development Zone in Autumn

Utilizing the online monitoring data of volatile organic compounds （VOCs） and ozone （O3） in the Shijiazhuang high-tech industrial development zone during October 2020, the pollution characteristics of VOCs were analyzed. Subsequently, ·OH estimation, secondary organic aerosol formation potential （SOAP）, and ozone formation potential （OFP） were applied to assess the chemical reactivity of VOCs. Additionally, the source apportionment was identified using the positive matrix factorization （PMF） model. The results revealed that the hourly φ[total VOCs （TVOCs）] were （11-281）×10-9, and the components were ranked by volume fraction in the following order： oxygenated volatile organic compounds （OVOCs） （60.83%）, alkanes （19.98%）, halohydrocarbons （5.64%）, aromatics （5.91%）, alkenes （4.83%）, and alkynes （2.48%）. Although the VOC concentration levels posed negligible non-carcinogenic risks to human health, benzene and ethylbenzene presented carcinogenic risks. The m/p-xylene to ethylbenzene ratio （X/E） varied from 2.5 to 3.4, indicating short-range transport of fresh air masses. Based on the X/E value, the ·OH concentration was 1.75×106 molecule·cm-3, and the ·OH exposure from 07：00 to 14：00 was calculated as 3.77×1010 molecule·s·cm-3. Aromatics played a dominant role in SOA, with a contribution rate as high as 93.35%, while alkenes dominated O3 formation, with the OFP contribution rate reaching up to 46.79%. By applying the PMF model, five major VOC sources were identified, including industrial sources （37.20%）, process flow and solvent use （33.80%）, vehicle and oil/gas evaporation sources （15.47%）, combustion sources （8.03%）, and plant emissions （5.50%）. Industrial and process emissions emerged as the primary contributors to VOCs in the ambient air of the high-tech zone, necessitating targeted control measures within this region.

Assessment of the Water Mass Dynamics Over the Algero‐Provencal Basin (Western Mediterranean Sea) in the MEDRYS1V2 Reanalysis

AbstractWe present an assessment of the water mass dynamics in a reanalysis of the Mediterranean Sea with a focus on the Algero‐Provencal basin. We use a θ‐S‐based algorithm to compute the fractions of the main western Mediterranean water masses: Atlantic and modified Atlantic Waters (AW and mAW), Western and Eastern Intermediate Waters (WIW and EIW), Tyrrhenian and Western Mediterranean Deep Water (TDW and WMDW). The reanalysis retains the known mean characteristics of the water masses, their seasonal to interannual variabilities, and main circulation patterns when compared with the literature. The imprint of winter mixing is particularly obvious with coherent variations of water mass volumes, mainly the yearly creation of WIW from mAW on northernmost shelves and of WMDW from all surface and intermediate layers during years of deep water formation (DWF). The results also highlight some unrealistic events of variability of the WMDW volume that are likely due to the data assimilation process. Recomputation of water mass volumes and transports without these altered years allowed to highlight the possible disruption of large‐scale barotropic cyclonic circulation in the East Algerian basin in response to major DWF events over the Gulf of Lion and the induced surface consequence on Algerian Eddies' trajectories.

Influence of terrestrial and marine air mass on the constituents and intermixing of bioaerosols over a coastal atmosphere

Abstract. Coastal environments provide an ideal setting for investigating the intermixing processes between terrestrial and marine aerosols. In this study, fine particulate matter (PM2.5) samples categorized into terrestrial, marine, and mixed air masses were collected from a coastal location in northern China. The chemical and biological constituents, including water-soluble ions (WSIs), metallic elements, and bacterial and fungal aerosols, were investigated from January to March 2018, encompassing both the winter heating and spring dust seasons. Terrestrial air masses constituted 59.94 % of the total air masses throughout the sampling period, with a significant increase during severe haze pollution (up to 90 %). These air masses exhibited a higher concentration of PM2.5 (240 µg m−3) and carried more water-soluble ions and metal elements. The terrestrial air mass also contained a larger number of animal parasites or symbionts, as well as human pathogens from anthropogenic emissions, such as Staphylococcus, Deinococcus, Sphingomonas, Lactobacillus, Cladosporium, and Malassezia. Conversely, a significant quantity of saprophytic bacteria such as hydrocarbon-degrading and gut bacteria from the genera Comamonas, Streptococcus, Novosphingobium, and Aerococcus and the saprophytic fungus Aspergillus were the most abundant species in the marine air mass samples. The mixed air mass elucidates the intermixing process of terrestrial and marine sources, a result of microorganisms originating from both anthropogenic and terrestrial emissions, which includes pathogenic microorganisms from hospitals and sewage treatment plants, and a multitude of soil bacteria. A stronger correlation was noted between microorganisms and continental elements in both terrestrial and mixed air mass samples, specifically K+, Mg2+, and Ca2+ derived from soil dust. Marine air masses exhibited a significant correlation with sea salt ions, specifically Na+. In the mixed air mass sample, a fusion of marine and terrestrial microorganisms is characterized by alterations in the ratio of pathogenic to saprophytic microorganisms when compared to samples derived from either terrestrial or marine sources. This study on the constituents and amalgamation of bioaerosols over the coastal atmosphere encompassing distinct air masses is crucial to understand the transport, intermixing processes, and health implications of terrestrial and marine air masses.

The Influence of Surface Fluxes on Export of Southern Ocean Intermediate and Mode Water in Coupled Climate Models

AbstractThe Southern Ocean (SO) plays a crucial role in the process of sequestering heat and carbon dioxide from the atmosphere and transferring them to the deep ocean. This process is intricately linked to the formation of Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW), which are pivotal components of the Meridional Overturning Circulation (MOC) and have a substantial impact on the global climate balance. AAIW and SAMW take shape in specific regions of the Southern Ocean due to the influence of strong winds, buoyancy fluxes, and their effects, such as convection, the development of thick mixed layers, and wind‐driven subduction. These water masses subsequently flow northward, contributing to the ventilation of the intermediate layers within the subtropical gyres. In this study, our focus lies on investigating the regional aspects of AAIW and SAMW transformation in CMIP6 models. We accomplish this by analyzing the relationship between the meridional transport of these water masses and air‐sea fluxes, particularly Ekman pumping, freshwater fluxes, and heat fluxes. Our findings reveal that the highest transformation rates occur in the Indian sector of the Southern Ocean, with notable values also observed in the southeast Pacific and south of Africa. Additionally, we assess the potential changes in these formation regions under future scenarios projected for the end of the 21st century. Although the patterns of formation regions remain consistent, there is a significant decrease in the transformation process.

Migration of Accreting Planets and Black Holes in Disks

Nascent planets are thought to lose angular momentum (AM) to the gaseous protoplanetary disk via gravitational interactions, leading to inward migration. A similar migration process also applies to stellar-mass black holes (BHs) embedded in the disks of active galactic nuclei. However, AM exchange via accretion onto the planet/BH may strongly influence the migration torque. In this study, we perform 2D global hydrodynamic simulations of an accreting planet/BH embedded in a disk, where AM exchange between the planet/BH and disk via gravity, accretion, pressure, and viscosity are considered. When accretion is turned off, we recover the linear estimate for Type I migration torque. However, for the two planet masses we investigated with our accreting simulations, we find outward migration due to the positive AM deposited onto the accreting body by the disk gas. Our simulations achieve the global steady state for the transport of mass and AM: The mass and AM fluxes are constant across the disk except for jumps ( ΔṀ and ΔJ̇ ) at the planet’s location, and the jumps match the accretion rate and torque on the planet. Our findings suggest that caution is needed when applying the standard results of disk migration to accreting planets and BHs.

Filling in Munk’s ‘orbital gap’ in climate and sea-level variability

Abstract This study explores the linkage between lunar precessions, solar activity, plus their interactions, and the interannual variability of climate indices and Australian sea level. The focus is on variability longer than the lunar nodal cycle (18.6 years), but shorter than millennia, also known as orbital gap. Climate indices include the Pacific Decadal Oscillation, El Niño-Southern Oscillation, the Southern Oscillation Index, the Indian Ocean Dipole, and the Southern Annular Mode. Long-term (> 100 years) sea-level data were examined at Fremantle (Western Australia) and Fort Denison (Sydney, Eastern Australia). Periodicities associated with gravitational and radiational forces were fitted to 3-yr- and 5-yr-filtered records of each climate index and of sea-level records. All fits, 10 for climate indices and 12 for sea level, explained the variance of all filtered records remarkably well (>60%). Findings suggest that lunar precessions and their interactions with solar activity may be connected to interannual variations in oceanic mixing. Mixing leads to climate variability through transport of heat, mass and solutes in the atmosphere and ocean, and ultimately relates to interannual sea-level variability. This study represents the possibility of astronomic effects on Earth’s environmental variables, beyond the internal variability of the ocean-atmosphere system.

Numerical study of multi-phase flow in ultrashort pulse laser processing

Ultrashort pulse laser processing is highly valued due to its enormous potential for high micromachining quality while it comprises complicated physical mechanisms especially when the pulse width falls in the regime about 10 ps. This study presents a complete mathematical modeling on multi-phase phenomena in ultrashort pulse laser processing, such as melting, vaporization, and solidification. The volume of fluid (VOF) technique is used to capture the interface during phase transition. Based on this hybrid model, the transport of energy and mass are investigated to study the influence of laser parameters on the formation of laser ablation hole. This work develops the incompressible multiphase laser ablation solver based on PIMPLE algorithm. The calculation results are validated by different references under different laser processing parameters which emphasize the importance of mechanism on thermal ablation and hydrodynamics in picosecond laser processing. More calculation results about the trends in hole depth over pulse laser width, laser fluence, and the number of pulses show the intricate influence of laser parameters.

Modeling with generalized flux theory for computational investigation of thermal enhancement in fluid with tri‐, di‐, and mono‐nanoparticles

AbstractTo study the influence of several factors (tri‐nanoparticles and relaxation time related to momentum, thermal, and concentration) on non‐Fourier transport of heat and mass, mathematical models are developed. The cases of tri‐, di‐, and mono‐nanofluids are considered. Flow and transport scenarios are translated into mathematical equations for which conservation laws and correlations for thermophysical properties are used. Boundary layer simplifications are used to approximate these mathematical models. The nondimensional set of problems is numerically solved using the finite element method (FEM). The solutions that are convergent and mesh‐free are obtained. The outcomes are compared to existing benchmarks. There is excellent consistency between the current and published results. The viscoelastic behaviors related to momentum, thermal, and solutal relaxation times are examined. It is also investigated how tri‐nanoparticles improve heat transmission in flow. The wall shear stresses for the mono‐, di‐, and tri‐nanofluids are calculated against momentum relaxation time. It is observed that tri‐nanofluid exerts the highest stress on the surfaces over which it flows. Therefore, while using these fluids, the surface should be ensured to bear the stresses; otherwise, failure of the system may take place. Thus, industrial applications and additional capability of surface be ensured. This looks at influence the Deborah number on the fluid motion. Deborah number is straightforwardly connected with relaxation time and it is found that higher is Deborah number lower will be the speed of fluid. As a consequence, viscous region will be narrow down. Thus, viscous dominant region is controllable by the using fluid of higher relaxation time. A significant enhancement in the thermal performance of Maxwell fluid occurs via the dispersion of tri‐nanoparticles ().

A computational study of Eyring‐Powell fluid model over a rotating cone with magnetic field and joule heating effect

AbstractIn this research, we investigate mixed convection transport of mass and heat transfer in the unsteady boundary layer flow of the Eyring‐Powell fluid around a rotating cone in the presence of Brownian and thermophoresis effects. Rotating cones are widely used in conical diffusers, medical devices, Aerospace Engineering and a variety of rheometric and viscosimetry applications. Specifically, we focus on the flow of the Eyring‐Powell fluid around the cone in the presence of magnetohydrodynamics and nanofluid. The modeled momentum, energy, and concentration equations of the problem are transformed into nonlinear dimensionless, nonlinear ordinary equations by utilizing the similarity variables. These nonlinear coupled ordinary differential equations are solved numerically via Bvp4c, and the outcomes for important physical parameters on momentum, energy, and concentration equations are presented graphically. The computational outcomes of physical parameters for skin friction coefficient, local Nusselt number, and Sherwood are also presented in tabular form.

Direct Entrainment as a Measure of Dilution

Abstract The turbulent transport of mass, energy, moisture, and momentum between the clouds and the surrounding environment plays a central role in determining the vertical structure of the troposphere. This article investigates the connection between net entrainment, defined here as the net transport of air into individual clouds, and net dilution, defined as the tendencies of passive tracers such as static energy or total water mixing ratio. Entrainment and detrainment rates for 2.6 × 106 individual cloud samples are obtained from a large-eddy simulation of shallow convective boundary layer atmosphere that explicitly calculates the turbulent fluxes across the cloud boundaries. The equations describing the tendencies of cloud mass and tracer concentrations are derived as a function of directly calculated entrainment and detrainment rates of the individual clouds, and used to calculate net entrainment and dilution rates. Directly calculated net entrainment and dilution rates agree well with cloud mass and tracer tendencies and give a dilution time scale of 13 min. In contrast, the traditional bulk-plume approximation overestimates the effect of entrainment and detrainment on the dilution of cloud field properties due to the differential tracer transport through the moist shell surrounding the cloud. Using direct measures of entrainment and detrainment for individual clouds separates different processes that influence the turbulent mass transport between the clouds and their environment.

Examples of entropy: from physics to nature

Abstract This paper aims to give a short history of how the concept of entropy has been developed and how it is used today in diverse scientific disciplines in our quest for understanding ourselves and our environment. The first part of the paper gives a historical perspective, which starts with the invention of the first heat engines, continues with the verbal formulation of the laws of thermodynamics and ends with the formulation of the mathematical equations that tell the complete story of thermodynamics by describing the transport of mass, momentum, energy and entropy. The second part of the paper focusses on the use of entropy beyond heat engines and shows how entropy has influenced the thinking in scientific disciplines such as chemistry, biology, ecology, communication, economy and sociology. Both a historical summary and the examples presented in this paper are limited to within the domain of classical mechanics. Although entropy has ignited powerful ideas and has many uses in both relativistic and quantum mechanics, these are not within the scope of this paper.

Low-temperature reactivity, extinction, and heat release rate of non-premixed cool flame at elevated pressures

Understanding the fundamental characteristics of high-pressure cool flames is crucial for the development of advanced and efficient low-temperature combustion engine technologies. The pressure dependency of multi-oxygen addition branching reactions in low-temperature chemistry significantly influences the dynamics, structure, and reactivity of cool flame. This study investigates the non-premixed cool flame of diethyl ether (DEE) at elevated pressures. The results show that pressure rise promotes low-temperature chemistry and significantly extends the extinction limit of cool flame. It is found that the cool flame heat release rate is correlated with the product of pressure and the square root of the pressure-weighted strain rate, Q∼aP·P, which is different from that of hot flames, Q∼aP. The radical index concept for atmospheric cool flames is extended to high-pressure cool flames allowing to decouple the mass and thermal transports from the chemical kinetics term to evaluate the fuel reactivity at elevated pressures. The radical index shows that the low-temperature reactivity of DEE is enhanced with the pressure and is higher than n-dodecane by a factor of 19, 18.3, and 16.4 for 1, 3, and 5 atm, respectively. Kinetic analysis reveals that pressure rise results in QOOH stabilization and promotions of the second O2 addition and the chain-branching reaction pathway for multiple OH radical productions.

Modelling the ejection of primary aerosols during the fast pyrolysis of biomass anisotropic particles

A model for the fast pyrolysis of anisotropic biomass particles is presented which considers bubbling dynamics within the liquid intermediate phase (metaplast) and aerosol ejection from this phase. The model employs the population balance equation and the method of moments to estimate the production rate and resultant size distribution of aerosol ejections, incorporating a detailed CRECK reaction mechanism, and considers the effect of anisotropic biomass microstructure on the intraparticle transport of mass and energy. This study investigates the impact of particle size, heating rate (heat transfer coefficient), and lignocellulosic composition on aerosol ejection. The model predicts that, at high heating rates (convective heat transfer coefficient of 359 W/m2.K), aerosols can contribute over 20% to the heavy fraction yield in bio-oil for small particles (1 mm diameter, 4 mm length). The model can predict aerosol size distribution and surface area, indicating an average size of 20 μm for bubbles and 5 μm for aerosols during increased bubble production and aerosol ejection rates. These findings are consistent with prior experimental results and provide essential information for future modeling of extra-particle reactions of the aerosols as they progress through the reactor.

Magnetically Arrested Circumbinary Accretion Flows

Binary systems with comparable masses and a surrounding accretion disk can accrete gas through spiral accretion streams penetrating the central cavity formed by tidal interactions. Using three-dimensional Newtonian magnetohydrodynamics simulations, we investigate the possibility of a magnetically arrested accretion flow through the cavity. Rather than solely continuously feeding the binary through spiral accretion streams, the accretion is regulated by the strong magnetic field inside the cavity. Transport of mass and angular momentum onto the binary then proceeds largely periodically in magnetic flux eruption episodes. The ejected flux tubes carry angular momentum outward and away from the binary, inject hot plasma into the disk, and can launch flares. This likely intermittent scenario could have potential implications for the emission signatures of supermassive black hole binaries and shed light onto the role magnetic fields play in the binary’s orbital evolution.

Thermal Imprints of Mesoscale Eddies in the Global Ocean

Abstract Mesoscale eddies have been widely documented for their significant role in regulating oceanic heat absorption and redistribution. However, our understanding of their thermal impacts on a global scale has been hampered by the scarcity of eddy-targeted observations. Here, we perform a comprehensive global analysis of over 2 million historical hydrographic profile measurements collocated with satellite-based eddy observations between 1993 and 2019, revealing rich geographical variability in the intensity, vertical extent, and asymmetry of the temperature anomalies induced by eddies. In tropical and subtropical oceans, temperature anomalies within eddies are dominated by eddy pumping and heavily influenced by near-surface vertical stratification, resulting in a relatively shallow extent of eddy effects (around 500 m) with subsurface maximum temperature anomalies occurring near 100 m. In midlatitude main current systems with sharp horizontal temperature gradients, the impact of eddy trapping becomes evident, leading to temperature anomalies extending to depths of 1000 m, with vertical peak values exceeding 4°C between 300 and 700 m, equivalent to perturbations in the local mean-state temperature of nearly 30%. This process also results in substantial temperature anomalies on isopycnal surfaces, indicating notable cross-frontal transport of heat and water mass with varying properties. The estimated meridional heat transport by eddy movement is on the order of O(1) MW, generally one order of magnitude smaller than previous estimates of the time-varying meridional heat transport (). However, this does not imply that they are unimportant, as this long-range cross-frontal heat transport may have significant consequences on regional temperature extremes and biogeochemical environments. Significance Statement Mesoscale eddies with a horizontal scale of O(100) km play a crucial role in modulating oceanic heat absorption and redistribution. However, their activities vary significantly across the global ocean, and our understanding of their thermal impacts remains incomplete. In this study, we conduct a global analysis of the influence of eddies on ocean temperature using over 2 million historical in situ temperature and salinity profile measurements combined with satellite-based eddy observations. Our analysis reveals substantial regional variability in the intensity, vertical extent, and asymmetry of temperature anomalies within eddies of different polarities and discusses the underlying mechanisms. Additionally, we estimate the meridional heat transport caused by eddy movement within each 2° × 2° grid, providing insights into the efficient pathways for eddy heat transport in western boundary currents and their extensions. These results enhance our understanding of the global-scale thermal impact of eddies and provide valuable references for assessing their biogeochemical and ecological consequences.

Local and Remote Atmosphere‐Ocean Coupling During Extreme Warming Events Impacting Subsurface Ocean Temperature in an Antarctic Embayment

AbstractCoastal ocean temperatures can respond to different atmospheric and oceanic processes at local spatial scales or through remote teleconnections. This study focused on subsurface ocean temperatures (subT) at 10 m depth in Maxwell Bay, northern Antarctic Peninsula from February 2017 and January 2022. It investigated extreme warming events during austral summers and their interaction with atmospheric and oceanic conditions regionally and locally. The analysis identified active and extreme Marine Heat Waves (MHWs) in March 2017 and January‐February 2020 associated with a significantly negative Southern Annular Mode index observed 3–4 months before the temperature increase. In March 2017, temperatures exceeded the climatological mean by over 1°C. This anomaly was linked to a strengthened Amundsen Sea Low and a blocking anticyclone moving between the Scotia Sea and the South‐West Atlantic Ocean that deflected westerly winds and facilitated the anomalous transport of warmer northern air masses to the AP. In January‐February 2020, the highest recorded subT was observed (2.97°C), although air‐sea heat fluxes did not show a similar pattern. In February 2020, one of the most intense atmospheric heatwaves ever recorded in West Antarctica was observed. This heatwave corresponded with maximum subT and positive sea surface temperature anomalies extending throughout the western region of the Southern Ocean, related to an extremely negative Southern Annular Mode. This study provides valuable insights into the impact of strong MHWs, a phenomenon that has been less documented in Antarctic coastal regions.

Fungal aerosols over the Northwest Pacific to Arctic Ocean: The influence of air mass and environmental factors

Bioaerosols, prevalent in the atmosphere, serve as carriers for microbe transmission and can also act as Cloud Condensation Nuclei (CCN) and Ice Nuclei (IN), exerting significant influence on cloud microphysics, radiative forcing, precipitation processes, and global climate dynamics. In this study, we conducted a comprehensive study of airborne fungi from the Northwest Pacific to the Arctic Ocean. During the 9th Chinese National Arctic Research Expedition (Chinare, 2018) cruise, total suspended particulate matter (TSP) samples were collected, followed by high-throughput sequencing to determine the microbial community's structure. Ascomycota and Basidiomycota are widespread in marine fungal aerosols along this route, with a notably higher abundance of Epicoccum and Cladosporium in fungal aerosols from the low-latitude Northwest Pacific compared to the high-latitude Arctic Ocean region. The composition of fungal communities depended on air mass transport processes and environmental factors. Long-range transport of terrestrial air masses not only enriches the abundance of fungal aerosols but also increases the relative abundance of dominant genera such as Basidiomycota, Epicoccum and Cladosporium. The knowledge gap about fungal aerosols over the Arctic route from the Northwest Pacific to the Arctic Ocean was filled in part by this work. This study deepens our understanding of how environmental factors and terrestrial air masses influence the composition and distribution of fungal community, offering valuable insights into the interconnections between marine and terrestrial ecosystems and their potential impacts on climate and atmospheric processes.