bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring Cohesive Sediment Flocculation With Surface Heterogeneity: A Theoretical Lagrangian‐Type Flocculation Model
Authors: Cui Zhenghui , Huang Lei , Fang Hongwei , Han Dong , Bombardelli Fabian 
Published: November 2023

AbstractThe flocculation of cohesive sediments significantly influences the particle size, concentration, and settling velocity and further influences sediment transport and pollutant transformation in the natural environment. The population balance equation (PBE) was used to model flocculation processes, including aggregation and floc breakup. This paper presents a theoretical Lagrangian‐type flocculation dynamic model established by solving the PBE using moment methodology and similarity transformation. The influence of surface heterogeneities (F2a) of the particles was incorporated. Sensitivity tests revealed that the model performance was significantly related to the aggregation and breakup parameters, which varied with ambient conditions. Furthermore, the effects of the shear rate, sediment concentration, particle size, and surface heterogeneity were analyzed theoretically. A critical shear rate distinguishes two cases: an increasing shear rate tends to increase the equilibrium floc size (Dfe) under low‐shear conditions, whereas a negative correlation exists at high‐shear levels. The dependence of Dfe on sediment concentration is complex, and increasing the initial concentration can enhance or limit the propensity to flocculate at different shear levels. Additionally, the enlargement of the primary particle size and surface heterogeneity reduces the propensity for flocculation. This study proposes a preliminary theoretical analysis method of flocculation processes considering factors such as surface heterogeneity, showing the possibility of further enhancing the knowledge of cohesive sediment transport.
Depth Variance of Organic Matter Respiration Stoichiometry in the Subtropical North Atlantic and the Implications for the Global Oxygen Cycle
Authors: Gerace Skylar D. , Fagan Adam J. , Primeau François W. , Moreno Allison R. , Lethaby Paul , Johnson Rodney J. , Martiny Adam C. 
Published: November 2023

AbstractClimate warming likely drives ocean deoxygenation, but models still cannot fully explain observed declines in oxygen. One unconstrained parameter is the oxygen demand per carbon respired for complete remineralization of organic matter (i.e., the total respiration quotient, rΣ‐O2:C). Here, we tested if rΣ‐O2:C declined with depth by quantifying suspended concentrations of particulate organic carbon (POC), particulate organic nitrogen (PON), particulate organic phosphorus (POP), particulate chemical oxygen demand (PCOD), and total oxygen demand (Σ‐O2 = PCOD + 2PON) down to a depth of 1,000 m in the Sargasso Sea. The respiration quotient (r‐O2:C = PCOD:POC) and total respiration quotient (rΣ‐O2:C = Σ‐O2:POC) declined with depth in the euphotic zone, but increased vertically in the disphotic zone. C:N and rΣ‐O2:N changed with depth, but surface values were similar to values at 1,000 m. C:P, N:P, and rΣ‐O2:P mostly decreased with depth. We hypothesize that rΣ‐O2:C is linked to multiple environmental factors that change with depth, such as phytoplankton community structure and the preferential production/removal of biomolecules. Using a global model, we show that the global distribution of dissolved oxygen is equally sensitive to r‐O2:C varying between surface biomes versus vertically during remineralization. Additionally, adjusting the model's r‐O2:C with depth to match our observations resulted in less dissolved oxygen throughout the upper ocean. Most of this loss occurred in the tropical Pacific thermocline, where oxygen models underestimate deoxygenation the most. This study aims to improve our understanding of biological oxygen demand as warming‐induced deoxygenation continues.
Amplified Subsurface Signals of Ocean Acidification
Authors: Fassbender Andrea J. , Carter Brendan R. , Sharp Jonathan D. , Huang Yibin , Arroyo Mar C. , Frenzel Hartmut 
Published: November 2023

AbstractWe evaluate the impact of anthropogenic carbon (Cant) accumulation on multiple ocean acidification (OA) metrics throughout the water column and across the major ocean basins using the GLODAPv2.2016b mapped product. OA is largely considered a surface‐intensified process caused by the air‐to‐sea transfer of Cant; however, we find that the partial pressure of carbon dioxide gas (pCO2), Revelle sensitivity Factor (RF), and hydrogen ion concentration ([H+]) exhibit their largest responses to Cant well below the surface (>100 m). This is because subsurface seawater is usually less well‐buffered than surface seawater due to the accumulation of natural carbon from organic matter remineralization. pH and aragonite saturation state (ΩAr) do not exhibit spatially coherent amplified subsurface responses to Cant accumulation in the GLODAPv2.2016b mapped product, though nonlinear characteristics of the carbonate system work to amplify subsurface changes in each OA metric evaluated except ΩAr. Regional variability in the vertical gradients of natural and anthropogenic carbon create regional hot spots of subsurface intensified OA metric changes, with implications for vertical shifts in biologically relevant chemical thresholds. Cant accumulation has resulted in subsurface pCO2, RF, and [H+] changes that significantly exceed their respective surface change magnitudes, sometimes by >100%, throughout large expanses of the ocean. Such interior ocean pCO2 changes are outpacing the atmospheric pCO2 change that drives OA itself. Re‐emergence of these waters at the sea surface could lead to elevated CO2 evasion rates and reduced ocean carbon storage efficiency in high‐latitude regions where waters do not have time to fully equilibrate with the atmosphere before subduction.
Eleven‐Year Survey of the Magmatic‐Hydrothermal Fluids From Peteroa Volcano: Identifying Precursory Signals of the 2018–2019 Eruption
Authors: Agusto Mariano , Lamberti María Clara , Tassi Franco , Carbajal Fabricio , Llano Joaquín , Nogués Victoria , Núñez Nicolás , Sánchez Hernán , Rizzo Andrea , García Sebastián , Yiries Jazmín , Vélez María Laura , Massenzio Antonella , Velasquez Gabriela , Bucarey Claudia , Gómez Martín , Euillades Pablo , Ramos Víctor 
Published: November 2023

AbstractOver the past decade, we have conducted geochemical and isotopic monitoring of the fumarolic gases of the Peteroa volcano (Argentina‐Chile). Using the resulting data set, we constructed a conceptual model that describes the evolution of the magmatic‐hydrothermal system and identifies precursory geochemical signals of the last eruption. Our data set includes new chemical and isotopic analyses of fumarolic gas samples collected from 2016 to 2021, as well as previously published data from the 2010–2015 period. After an eruptive period in 2010–2011, the activity was characterized by low degassing rates and seismic activity. However, an increase in seismic activity and fumarolic gas emissions was observed from 2016 to 2018–2019 eruptive episode, leading to a major phreato‐magmatic eruption. Fumarole gases show different compositions during quiescent versus unrest/eruptive degassing related to the interaction of deep (magmatic) and shallow (hydrothermal) fluid contributions. During quiescent periods, fumaroles exhibited low SO2/H2S, HF/CO2, and HCl/CO2 ratios (<0.1), revealing a dominant hydrothermal contribution. In contrast, during pre‐and syn‐eruptive periods, fumaroles showed ratios up to 100 times higher indicative of an enhanced magmatic input. When compared to the evolution of the seismic activity, the increment of magmatic‐related strong acidic gases suggests repeated inputs of hot magmatic fluids, which are only partially dissolved into the hydrothermal system feeding the fumaroles. Interestingly, the 3He/4He and δ13C‐CO2 values remained relatively constant during the magmatic and hydrothermal degassing in 2016–2021, suggesting that the deep magmatic gas source did not significantly change throughout variations in Peteroa's activity.
The Short‐Term Effects and Burden of Ambient Air Pollution on Hospitalization for Type 2 Diabetes: Time‐Stratified Case‐Crossover Evidence From Sichuan, China
Authors: Jiang Wanyanhan , Chen Han , Li Hongwei , Zhou Yuelin , Xie Mengxue , Zhou Chengchao , Yang Lian 
Published: November 2023

AbstractType 2 diabetes mellitus (T2DM), a complicated metabolic disease, might be developed or exacerbated by air pollution, resulting in economic and health burden to patients. So far, limited studies have estimated associations between short‐term exposure to air pollution and disease burden of T2DM in China. Hence, we aimed to estimate the associations and burden of ambient air pollutants (NO2, PM10, PM2.5, SO2, and CO) on hospital admissions (HAs) for T2DM using a time‐stratified case‐crossover design. Data on HAs for T2DM during 2017–2019 were collected from hospital electronic health records in nine cities in Sichuan Province using conditional poisson regression. Totally, 92,381 T2DM hospitalizations were recorded. There were significant short‐term effects of NO2, PM10, PM2.5, SO2 and CO on HAs for T2DM. A 10 μg/m3 increment of NO2, PM10, PM2.5, SO2 and CO as linked with a 3.39% (95% CI: 2.26%, 4.54%), 0.33% (95% CI: 0.04%, 0.62%), 0.76% (95% CI: 0.35%, 1.16%), 12.68% (95% CI: 8.14%, 17.42%) and 79.00% (95% CI: 39.81%, 129.18%) increase in HAs for T2DM at lag 6. Stratified analyses modified by age, sex, and season showed old (≥65 years) and female patients linked with higher impacts. Using WHO's air quality guidelines of NO2, PM10, PM2.5, and CO as the reference, the attributable number of T2DM HAs exceeding these pollutants exposures were 786, 323, 793, and 2,127 during 2017–2019. Besides, the total medical costs of 25.83, 10.54, 30.74, and 67.78 million China Yuan were attributed to NO2, PM10, PM2.5, and CO. In conclusion, short‐term exposures to air pollutants were associated with higher risks of HAs for T2DM.
Enhanced Denudation of the Emeishan Large Igneous Province and Precipitation Forcing in the Late Permian
Authors: Yang Jianghai , Cawood Peter A. , Yuan Xiaoping , Yuan Dongxun , Zhou Yinsheng , Liu Ao , Liu Jianzhong , Du Yuansheng 
Published: November 2023

AbstractHydroclimate is an important factor controlling landscape evolution. But establishing the impact of hydroclimate is complicated by the influences of other processes and is especially hard to prove for those in deep time from geological record. During the late Permian, voluminous basaltic sediments were derived from the erosion of the Emeishan large igneous province in western South China. They provide a unique record critical in understanding the responses of tropical basaltic erosion to hydroclimate change without impacts of orogenic uplift, lithologic variation, vegetational difference and glacial‐interglacial change. Sampled successions define a negative carbon isotope excursion capable of making regional and global stratigraphic correlations in the middle Wuchiapingian interval corresponding to the final phase of the late Paleozoic ice age. This interval is associated with a petrofacies shift and a decreasing source weathering intensity, a downward shift of erosion loci, and a reduced coastal water paleosalinity. Applying present‐day temperature dependence pattern of basaltic weathering and using land surface temperatures approximated from nearby paleo‐seawaters, denudation rates were calculated for the Emeishan basaltic province and shows an increase from ∼71 to ∼107 m/Ma. This erosional acceleration is temporally correlated with a decrease in paleosalinity and likely linked to enhanced freshwater discharge in the middle Wuchiapingian. Scaling and landscape erosion modeling suggest ∼80%–130% increase in catchment precipitation could have driven this acceleration in denudation. Our work provides a positive test for the hydroclimate forcing on landscape erosion in deep time and underlines the mechanistic linkage of sediments with erosion and climate change.
Sensitivity of Tropical Cyclone Development to the Vortex Size Under Vertical Wind Shear
Authors: Huang Qijun , Ge Xuyang 
Published: November 2023

AbstractThe sensitivity of tropical cyclone (TC) intensification to its inner size in a sheared environment is investigated in this study. Previous research indicated that TCs with smaller sizes spin up more quickly in a quiescent environment. In contrast, our idealized numerical simulations show that TCs with larger inner‐core sizes experience faster growth within a certain size range under the vertical wind shear (VWS) because stronger upper‐level outflows are established quickly for larger TCs. The presence of strong outflow diminishes the impact of VWS, causing the TC re‐alignment. In more detail, the stronger outflow locally reduces the shear, allowing the convective asymmetry to propagate to the upshear side and migrate inward toward the TC center more rapidly. The upshear convection leads to a stronger outflow and thus a greater blocking effect on the upper‐level wind, effectively reducing the VWS and thus allowing subsequent faster TC growth. Our analysis reveals that the TC re‐alignment at an earlier stage allows for significant differences in surface heat flux (surface latent heat flux [SLHF]) distribution based on size. Larger TCs exhibit larger areas of high SLHF, which create favorable thermodynamic conditions for TC developments. Conversely, smaller vortices have limited SLHF underneath, resulting in a prolonged intensification process. Furthermore, the boundary layer recovery mechanism effectively counteracts the low‐level ventilation pathway imposed by the shear. This mechanism supports the downstream deep convection development on the upshear side. This study presents a new perspective, highlighting that the impact of shear on TCs is contingent upon their sizes upon entering a sheared environment.
A New CCN Number Concentration Prediction Method Based on Multiple Linear Regression and Non‐Negative Matrix Factorization: 2. Application to Obtain CCN Spectra in and Around the Korean Peninsula
Authors: Park Minsu , Yum Seong Soo , Seo Pyosuk , Ahn Chanwoo , Kim Najin , Anderson Bruce E. , Thornhill Kenneth L. 
Published: November 2023

AbstractThe new cloud condensation nuclei (CCN) number concentration (NCCN) prediction method that combines multiple linear regression and non‐negative matrix factorization, hereafter the MLRNMF method, to the aerosol number size distribution data is evaluated and applied to the Korea‐United States air quality (KORUS‐AQ) airborne measurement data. The mean fractional bias (MFB) and the mean fractional error (MFE) were used as performance metrics. The performance metrics of the MLRNMF method for the test data set at several supersaturations (S) (0.4%, 0.6%, 0.8%, and 1.0%) met the performance goal values (MFB and MFE being less than or equal to ±30% and +50%, respectively), and thus, it implies that the MLRNMF method is appropriate at various S. Applying the MLRNMF method to KORUS‐AQ airborne measurement data, it was demonstrated that aerosols in Seoul, Korean Peninsula, East Sea, and South Sea had similar hygroscopicity to each other, and aerosols over the Yellow Sea and the East China Sea showed similar hygroscopicity values during the KORUS‐AQ field campaign. Based on the MLRNMF method, two parameterizations of CCN spectra for a full S range representing various regions in and around the Korean Peninsula in springtime were formulated (Twomey relationship and logarithmic fitting curve). Additionally, it was found that NCCN decreased exponentially with altitude, and the scale height was approximately 1,700 m in the Seoul metropolitan area. The MLRNMF method can be used to create a global distribution map of NCCN or CCN spectra in many regions around the world.
Mechanisms Controlling the 4D Distribution of Rainfall and Latent Heating Over the Rainiest Region on Earth
Authors: Poveda Germán 
Published: November 2023

AbstractGlobal Precipitation Measurement satellite and ERA5 reanalysis data are used to study the 4D (latitude, longitude, altitude, time) distribution of rainfall intensity and latent heating fields over the rainiest region on Earth, located over western Colombia and the far eastern equatorial Pacific. The annual and interannual variability and the location of both variables' maxima are identified, and their spatiotemporal correlations are quantified. Static analyses of the winds show that the colder Choco low‐level jet (LLJ) and the warmer Caribbean‐Panama jet form a tropical frontal system. Dynamic analyses of 3D streamlines reveal that the Choco LLJ is at the core of a quasi‐permanent mini‐Hadley cell over the Pacific, with sinking motion between 6°S‐Equator and rising motion at 5°N–8°N, comprised between 1,000 and 700 hPa. Such vortex dynamics enhances the convergence of the northerly winds and the Panama jet, and exacerbates deep convection in association with the orographic lifting over the Colombian Andes. The large‐scale branches of that flow illuminate the shape and dynamics of the Walker cell over tropical South America. Correlation analyses illustrate the connections between rainfall and 3D winds as moisture transport mechanisms. Correlation and singular value decomposition analyses suggest that oceanic (continental) evaporation is associated with rainfall during the drier (wetter) season, and the importance of high‐levels temperatures and vertical integrals of diverse thermal and energy variables on rainfall bolster the view that the condensational heating is strongly coupled with the moisture transport flow and the convective ascent required to explain such extraordinary amounts of rainfall.
Defining Arctic Stratospheric Polar Vortex Intensification Events
Authors: Huang Jinlong , Hitchcock Peter 
Published: November 2023

AbstractUsing the ERA5 reanalysis data, we identify seven easily calculable indices of the strength of the Arctic stratospheric vortex: zonal winds at 10 hPa and temperature or height anomalies at 10 , 50, and 100 hPa. We then compare the climatological statistics and meteorological properties of strong and weak events based on these indices. We particularly consider the sensitivity of the event statistics to the choice of thresholds, the use of these indices in capturing stratosphere–troposphere coupling, and meteorological conditions relevant to chemical ozone depletion. The frequency, seasonal distribution, and interdecadal variability of strong events is more sensitive to threshold or index choice compared to weak events. Composites of polar‐cap geopotential height anomalies are found to differ significantly based on the choice of index. In particular, height‐based events reveal a strong and immediate barotropic response near the central date due to surface pressure fluctuations, making it more difficult to regard central dates of height‐based events as purely stratospheric in origin. We further characterize the relationship of all indices to conditions relevant to chemical ozone depletion, finding that temperature‐based indices in the lower stratosphere perform best. Finally, we present four dynamical benchmarks used to assess and compare the representation of strong events in climate models. Our results highlight the challenges in determining the optimal definition for strong events and emphasize the implications of different choices, providing valuable insights for guiding future studies in defining strong events.
High‐Resolution Mapping of Regional NMVOCs Using the Fast Space‐Time Light Gradient Boosting Machine (LightGBM)
Authors: Lu Bingqing , Liu Chao , Meng Xue , Zhang Zekun , Herrmann Hartmut , Li Xiang 
Published: November 2023

AbstractAccurate spatiotemporal estimation of non‐methane volatile organic compounds (NMVOCs) plays a pivotal role in establishing sophisticated early warning systems and formulating strategies to combat air pollution. Despite these critical applications, robust estimation of high spatiotemporal resolution NMVOCs concentrations remains a challenge. In this study, we develop a space‐time Light Gradient Boosting Machine (STLGB) model, which successfully renders hourly maps of NMVOCs concentrations across Shanghai from 2019 to 2022 by integrating spatiotemporal information. After extensive training, the STLGB model demonstrates remarkable estimation performance for NMVOCs, accounting for multiple spatiotemporal variables (R2 = 0.92, RMSE = 34.52 ppb). With the developed model, we provide first high‐resolution (1 km) hourly NMVOCs concentration maps, uncovering previously overlooked spatiotemporal variations. Further, SHapley Additive exPlanation (SHAP) regression values reveal significant local interpretation capabilities of the STLGB model, emphasizing the strong influence of emissions on NMVOCs estimation, whilst acknowledging the important contribution of space and time term. Our study of the pandemic lockdown further showcases the model's adaptability to unique events influenced by policy changes. The superior performance of the STLGB model, with its minimal computational memory requirements and faster speed, makes it an ideal tool for air pollutant estimation, adaptable to any region with NMVOCs monitoring capabilities.
Background Topography Affects the Degree of Three‐Dimensionality of Tidal Sand Waves
Authors: Krabbendam Janneke , Nnafie Abdel , Borsje Bas , de Swart Huib 
Published: November 2023

AbstractOffshore tidal sand waves on the sandy bed of shallow continental shelf seas are more three‐dimensional (3D) in some places than others, where 3D refers to a pattern that shows variations in three spatial directions. Such sand waves have crestlines that meander, split or merge. The degree of three‐dimensionality seems to vary especially when large‐scale bedforms, such as tidal sand banks, are present underneath the sand waves. Understanding this behavior is important for offshore activities, such as offshore windfarm construction or the maintenance of navigation channels. In this study, the degree of three‐dimensionality of sand waves at five sites in the North Sea is quantified with a new measure. Results show that tidal sand waves on top of tidal sand banks are more two‐dimensional (2D) than those on bank slopes or in open areas. These differences in sand wave pattern are supported by numerical simulations performed with a new long‐term sand wave model. The primary cause of these differences is attributed to the deflection of tidal flow over a sand bank, which causes sand wave crests to be more aligned with the bank at its top than at its slopes. It is subsequently made plausible that the different patterns result from the competition between two known mechanisms. These mechanisms are nonlinear interactions between sand waves themselves (SW‐SW interactions) and nonlinear interactions between sand banks and sand waves (SB‐SW interactions). On bank tops, SB‐SW interactions favor a 2D pattern, while SW‐SW interactions, which elsewhere produce a 3D pattern, are less effective.