Surface Elevation Research Articles

Traumatic prepatellar quadriceps continuation injury in an elite cyclist

Injury to the prepatellar quadriceps continuation is a lesser recognized extensor mechanism injury when compared to the more commonly encountered quadriceps and patellar tendon injuries. We present a case of a traumatic injury to the prepatellar quadriceps continuation in an elite cyclist without injury to the adjacent patellar or quadriceps tendons. The magnetic resonance imaging findings depict the anatomy of the prepatellar structures in detail, as well as the sequelae of trauma. These include, but are not limited to partial or complete tearing, stripping and elevation of the anterior surface of the patella, and traumatic reactive prepatellar bursitis. Cyclists may be predisposed to injury to the prepatellar quadriceps continuation due to background overuse prepatellar friction syndrome, but as in our case, injury can also be the result of an acute traumatic insult. These injuries can be managed conservatively with physiotherapy and result in a good outcome.

Establishment of mangroves on a new mud bank by a combination of UAS SfM photogrammetry and LiDAR monitoring

Abstract. Understanding how mangroves respond to sea level rise is critical for coastal management and conservation. This study investigates the feasibility of two remote sensing techniques, Light Detection and Ranging (LiDAR) and Structure-from-Motion (SfM) photogrammetry, to monitor changes in mud elevation that are critical to mangrove establishment dynamics. SfM photogrammetry can provide low-cost 3D modeling from imagery, while LiDAR provides high-precision elevation and vegetation data. Our analysis shows that SfM photogrammetry provides reasonably accurate surface elevation data with a root mean square error (RMSE) of 0.14 meters and a significant correlation coefficient (r = 0.74) compared to LiDAR measurements. This highlights the complementarity between the two, as the effectiveness of SfM photogrammetry is in the early stages of colonization, and then the need to use LiDAR with dense vegetation as the mangroves mature. This shows that a simple method of photogrammetry can remain effective until the vegetation reaches a certain threshold, and this can be particularly useful in the perspective of using mud elevation as a first low-cost diagnosis for potential mangrove rehabilitation project to assess the colonization suitability of mudflats.

Monitoring Activity of the Subglacial Lake Mercer Based on CryoSat-2 and ICESat-2 Altimetry Data from 2011 to 2023

Abstract. Active subglacial lakes are capable of exchanging and transporting water through water flow paths, thus having an important impact on ice sheet movement and even on the regional mass balance. The use of satellite altimetry can indirectly reveal internal subglacial hydrological activity through direct surface elevation observation, which plays an important role in the study of the evolution of active subglacial lakes. This paper monitors and analyzes the activity of the subglacial lake Mercer (SLM) in the Whillans and Mercer Ice Stream (WIS/MIS), using data from the CryoSat-2 satellite radar altimetry and ICESat-2 satellite laser altimetry. We adopt the differential DEM model and the repeat orbit model based on their respective data characteristics. Finally, we reveal the temporal and spatial evolution patterns of SLM during 2011-2023, and construct the elevation anomaly time series. The results show that the central and western parts of SLM were the areas with more significant elevation anomalies, and there were three significant fill-drain cycles during the time periods studied in this research, with the elevation anomaly range reaching about 8 m and 4 m for the first and second cycles, respectively, and the lake is currently in the third significant draining phase. Furthermore, the elevation anomalies obtained during the mission overlap time of CryoSat-2 and ICESat-2 data are in good agreement, which confirms the accuracy of our method.

DISTRIBUSI SEDIMEN PADA WADUK JATIBARANG, KOTA SEMARANG

The main issue in the operation of reservoirs is sedimentation. This can lead to silting and affect the reservoir's storage capacity. The distribution of sediments needs to be understood in order to gain an overview of their spread, so that measures can be taken to address sediment-related issues in the Jatibarang Reservoir. The analysis was conducted using sediment data from previous studies, which reported a total sediment volume of 6.64 million m³ over a period of 50 years. Based on topographic data, it was found that the Jatibarang Reservoir is classified as Type III, with a "hill" classification. The analysis results showed that the dimensionless factor F is 0.22, with a relative depth p of 0.53. Based on the sediment distribution analysis of the Jatibarang Reservoir with Empirical Area Reduction Method, it was found that after 50 years of operation, the new zero elevation of the reservoir would be at an elevation of +126.82 m. In comparison with the low water surface elevation at the existing dead storage of the Jatibarang Reservoir, which is at +136 m, it can be concluded that the Jatibarang reservoir can operate according to the planned lifespan and can still function for more than 50 years

An Urban Lake Drainage Catena: Influences of Terrain, Soils, and Precipitation

Urban lake drainage systems are heavily impacted by terrain, soil characteristics, and precipitation, which influence water infiltration and groundwater movement. This study focused on the drainage catena around Lake Nokomis in Minneapolis, Minnesota, where local residents have experienced wet basements and yards. The primary goal was to identify the factors contributing to these water-related problems, particularly soil permeability and how it responds to precipitation. By conducting soil borings, using pressure transducers, and measuring saturated hydraulic conductivity (Kfs), the study compared upland and lowland areas. Findings indicated that upland soils, primarily composed of sandy fill, had much higher infiltration rates, with Kfs values ranging from 72.4 cm/hr to 149 cm/hr. In contrast, lowland areas characterized by lacustrine and organic soils exhibited significantly lower Kfs values, ranging from 1 cm/hr to 14.8 cm/hr. Between 2022 and 2024, wet and dry seasons occurred, yet recorded more than 127.5 cm of rain and snow water equivalent, further contributing to groundwater rise and surface water presence in low-lying regions. The study concluded that increased precipitation, coupled with specific hydrogeologic conditions, was the main factor causing elevated groundwater levels and surface saturation in these areas. To address these challenges, Minnesota's water management authorities are encouraged to implement strategies that consider the increasing magnitude and intensity of precipitation events due to climate change. Incorporating hydrogeologic assessments into urban planning is recommended to better manage water infiltration, reduce flood risks, and strengthen the resilience of drainage systems to changing climate patterns.

GNSS reflectometry from low-cost sensors for continuous in situ contemporaneous glacier mass balance and flux divergence

Abstract Recent advances in remote sensing have produced global glacier surface elevation change data. Parsing these elevation change signals into contributions from the climate (i.e. climatic mass balance) and glacier dynamics (i.e. flux divergence) is critical to enhance our process-based understanding of glacier change. In this study, we evaluate three approaches for direct, continuous measurements of the climatic mass balance, flux divergence and elevation change at a site on Gulkana Glacier in Alaska using low-cost global navigation satellite system (GNSS) sensors, GNSS interferometric reflectometry (GNSS-IR), banded ablation stakes with time-lapse cameras and combinations thereof. Cumulative climatic mass balance over the season was 4.85 m and the three approaches were within 0.08 m through early July before the snowpack melted, and within 0.28 m through mid-August. The flux divergence increased from 0.52 ± 0.03 cm d−1 before June 3 to about 0.73 cm d−1 after June 27. We demonstrate a single GNSS system fixed atop an ablation stake can measure contemporaneous climatic mass balance, flux divergence and elevation change based on the antenna's position and GNSS-IR techniques. The ability of these systems to measure glacier mass balance and flux divergence offers unique opportunities for year-round observations on mountain glaciers in the future.

Fuzzy fractional shallow water wave equations: analysis, convergence of solutions, and comparative study with depth as triangular fuzzy number

Abstract We explore the integration of fuzzy fractional calculus into the modeling framework, recognizing its significance in capturing the inherent uncertainties and complexities present in Shallow Water Wave (ffSWW) dynamics. By incorporating fuzzy fractional calculus, we aim to enhance the accuracy and robustness of ffSWW equations, particularly in representing vague or imprecise parameters such as seabed topography, initial wave conditions, and material properties. In this article, we consider the time derivative as a fractional order instead of the traditional integer order, which allows us to interpret the behavior of the solution for different orders. Further, the sea depth has been considered as a Triangular Fuzzy Number (TFN). We employ the Homotopy Perturbation Transform Method (HPTM) to obtain the solution of ffSWW equations. The convergence of the obtained series solutions has been investigated theoretically and numerically. Also, the acquired results using the current method are validated through the comparison with pre-existing findings concerning integer order. Furthermore, simulation results for various fractional orders, as well as fuzzy lower and upper solutions of depth-averaged velocity and water surface elevation, are provided for triangular fuzzy numbers.

Initial Experimental Investigation of Hydraulic Characteristics at Right-Angle Diversion in a Combined Canal and Pipe Water Conveyance System

To enhance the efficiency of irrigation water utilisation, China is progressively converting irrigation ditches into pipelines. The water distribution outlets in irrigation zones are predominantly right-angled, and there are typically occurrences of erosion, sedimentation, and structural deterioration in the surrounding areas. This article employs a synthesis of indoor physical model experiments and theoretical analysis to examine the distribution of channel flow velocity and variations in water surface profile, pipeline flow rate, diversion ratio, circulation intensity, and turbulence energy across different relative water depths. The experimental results indicate that the water surface adjacent to the main canal wall demonstrates a pattern of initial decline, followed by an increase and subsequently another decline; furthermore, as the water level in the main channel rises, the magnitude of this fluctuation progressively diminishes. In some sections of the canal, the water surface elevation progressively increases, albeit with minimal amplitude. With a constant relative water depth, an increase in main channel flow results in a corresponding increase in pipeline flow; however, the diversion ratio is inversely related to the main channel flow. Conversely, when the main channel flow rate is constant, the diversion ratio increases as relative water depth rises. The vertical flow velocity near the water diversion outlet has a negative value, signifying the existence of a backflow zone, while the horizontal flow velocity varies considerably, facilitating the formation of circulation and resulting in localised deposition and erosion. The water flow near the pipe inlet downstream of the lower lip of 0.5 times the pipe diameter is impacted by the return zone, which has a higher turbulence energy and circulation strength and is more susceptible to siltation. The turbulence energy of the water flow is higher in the range of 0.5 times the pipe diameter upstream and downstream of the pipe inlet. This research is highly significant in facilitating the conversion of irrigation channels into pipelines.

Recognizing primary paleotopography utilizing Ichnofossils and 3-D models: Mill Canyon Dinosaur track site, Utah

Preservation and recognition of primary paleotopography along a bedding surface is often a neglected component in paleogeographic reconstruction. The Mill Canyon Dinosaur track site (MCDT) is a spectacular bedding plane exposure with a diverse assemblage of vertebrate ichnnofauna. Small-scale 3D-photogrammetric and ichnofossil analyses of two areas on the periphery of the MCDT surface demonstrate the presence of preserved primary paleotopography. The first area consists of a paleotopographic bench that drops off to a minimum of ∼0.5–0.6 meters. On this bench is at least one resting trace analogous to modern traces of crocodiles documented from topographic highs along rivers and lakes. At the second locality, systematic variations in track morphology indicate that the trackmaker gait was influenced by changes in surface elevation with movement across the ridge, thus affirming that paleorelief is preserved. The ichnofossils on this Cretaceous bedding surface likely represent months- to years-worth of biological activity.

Waves Generated by the Horizontal Motions of a Bottom Disturbance

Waves generated by a horizontally moving disturbance on the seabed have been studied by developing two numerical models, namely, the Navier–Stokes and the Green–Naghdi equations. Various geometries of the bottom disturbances are considered, and waves generated due to a single motion and multiple oscillatory motions of the bottom disturbances are investigated by the two models. Discussion is provided on how the motion of the disturbance on the seafloor results in the generation of surface waves. The wave-field parameters investigated include the surface elevation, velocity, pressure fields and wave celerity. A parametric study is conducted to assess the effect of the geometry of the disturbance and the kinematic characteristics on the wave generation. It is shown that both linear and nonlinear waves can be generated by a horizontally moving disturbance on the seabed. Long waves, followed by a series of dispersive waves, are produced by the single motion of the bottom disturbance. It is also found that, under appropriate conditions, there would be a balance between nonlinearity and dispersion, such that the generated waves propagate over a flat seafloor with little to no change in their form and shape.

New insights into the immunomodulatory potential of sialic acid on monocyte-derived dendritic cells

Sialic acids at the cell surface of dendritic cells (DCs) play an important immunomodulatory role, and their manipulation enhances DC maturation, leading to heightened T cell activation. Particularly, at the molecular level, the increased stability of surface MHC-I molecules in monocyte-derived DCs (MoDCs) underpins an improved DC: T cell interaction. In this study, we focused on the impact of sialic acid remodelling by treatment with Clostridium perfringens sialidase on MoDCs' phenotypic and functional characteristics. Our investigation juxtaposes this novel approach with the conventional cytokine-based maturation regimen commonly employed in clinical settings.Notably, C. perfringens sialidase remarkably increased MHC-I levels compared to other sialidases having different specificities, supporting the idea that higher MHC-I is due to the cleavage of specific sialoglycans on cell surface proteins. Sialidase treatment induced rapid elevated surface expression of MHC-I, MHC-II and CD40 within an hour, a response not fully replicated by 48 h cytokine cocktail treatment. These increases were also observable 48 h post sialidase treatment. While CD86 and PD-L1 showed significant increases after 48 h of cytokine maturation, 48 h post sialidase treatment showed a higher increase in CD86 and shorter increase in PD-L1. CCR-7 expression was significantly increased 48 h after sialidase treatment but not significantly affected by cytokine maturation. Both treatments promoted higher secretion of the IL-12 cytokine. However, the cytokine cocktail induced a more pronounced IL-12 production. SNA lectin staining analysis demonstrated that the sialic acid profile is significantly altered by sialidase treatment, but not by the cytokine cocktail, which causes only slight sialic acid upregulation. Notably, the lipid-presenting molecules CD1a, CD1b and CD1c remained unaffected by sialidase treatment in MoDCs, a finding also further supported by experiments performed on C1R cells. Inhibition of endogenous sialidases Neu1 and Neu3 during MoDC differentiation did not affect surface MHC-I expression and cytokine secretion. Yet, sialidase activity in MoDCs was minimal, suggesting that sialidase inhibition does not significantly alter MHC-I-related functions. Our study highlights the unique maturation profile induced by sialic acid manipulation in MoDCs. These findings provide insights into the potential of sialic acid manipulation as a rapid immunomodulatory strategy, offering promising avenues for targeted interventions in inflammatory contexts.

Integrating Multisource Data and Machine Learning for Supraglacial Lake Detection: Implications for Environmental Management and Sustainable Development Goals in High Mountainous Regions

The accurate detection and monitoring of supraglacial lakes in high mountainous regions are crucial for understanding their dynamic nature and implications for environmental management and sustainable development goals. In this study, we propose a novel approach that integrates multisource data and machine learning techniques for supra-glacial lake detection in the Passu Batura glacier of the Hunza Basin, Pakistan. We extract pertinent features or parameters by leveraging multisource datasets such as radar backscatter intensity VH and VV parameters from Sentinel-1 Ground Range Detected (GRD) data, near-infrared (NIR), NDWI_green, NDWI_blue parameters from Sentinel-2 Multi-spectral Instrument(MSI) data, and surface slope, aspect, and elevation parameters from topographic data. The entire dataset is partitioned into training and testing sets, with machine learning models including the artificial neural network (ANN), the support vector machine (SVM), logistic regression (LR), random forest (RF), and K-nearest neighbour (KNN) trained on the training data (70%). Accuracy assessment employs testing data and involves the evaluation of metrics such as ROC curves and confusion matrices. The best-performing model, ANN, is validated against manually digitized lake polygons derived from Sentinel-2 and Google Earth Pro imagery. Furthermore, the digitized lake polygons are used to analyze glacial lake dynamics from 2016 to 2022. Key findings of this research presented that the NDWI_green, Sigma0_VH, and elevation are the most significant predictors in detecting supra-glacial lakes. Among the various trained and evaluated models, the Artificial Neural Network (ANN) achieved the highest performance (accuracy: 95%, AUC: 0.99) and accurately mapped supra-glacial lakes regardless of their small size. The findings have significant implications for understanding glacial lake behavior in the context of climate change and informing future research and monitoring efforts.

Air effects on solitary waves impinging and overtopping an impermeable seawall

Considering the presence or absence of air, the solitary waves impinging on an impermeable structure were numerically investigated to discuss solitary wave characteristics such as surface elevation, pressure, vorticity, eddy viscosity, and force on structures under different initial conditions. The volume of fluid (VOF) model (Wu, 2004) was employed to simulate solitary waves impinging an impermeable structure. Besides, the LES turbulent module was utilized to capture the turbulent phenomenon generated by wave-structure interactions, particularly after wave breaking. The present model was verified by comparing the simulation results with the experimental data (Hsiao and Lin, 2010). The findings demonstrated that the model more accurately represents tsunami wave behavior compared to simulations that did not account for air, especially in cases where wave breaking occurs prior to overtopping, entraining more air into the water. Detailed comparisons between simulations with and without air presence reveal that simulations excluding air exhibited delayed wave breaking, a more distant breaking point, and the absence of an air pocket behind the seawall. Despite these differences, the simulations showed excellent agreement with the laboratory results. Moreover, it was shown that the presence of air dissipated part of wave energy. Earlier the stage of waves broke, the more air was entrained, making the effects of air on the waves more noticeable. The highest fluid velocity was observed at the breaking point in front of the structure, while the strongest forces were experienced by the structure at the breaking location behind it.

Assessment of Bleaching Stress Vulnerability of Lakshadweep Islands using Google Earth Engine (GEE)

Coral reefs, among the Earth’s most diverse and valuable ecosystems, face unprecedented challenges due to climate change. Coral bleaching is a phenomenon wherein corals lose their symbiotic zooxanthellae owing to various stressors, leading to a whitening effect of the coral tissues. In recent decades, climate change has intensified coral bleaching events. Multiple stressors, including elevated Sea Surface Temperature (SST), extreme irradiance levels, and various biotic and abiotic factors trigger bleaching events. Coral bleaching is primarily driven by thermal stress caused by elevated SSTs. Climate change has worsened bleaching’s frequency and intensity. Global bleaching events are often linked to planetary ocean-atmospheric circulation processes such as El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). This study focused on assessing the vulnerability of coral reefs in the Lakshadweep region of India from 2016 to 2023 using National Oceanic and Atmospheric Administration’s Climate Data Record Optimum Interpolation Sea Surface Temperature (NOAA CDR OISST) daily data. GOOGLE EARTH ENGINE (GEE) is a cloud computing platform which is used to collect and generate the base data for this study. The vulnerability assessment utilized two bleaching indices: SST anomaly and Degree Heating Week (DHW). Analysis of DHW data reveals that 2020 experienced the highest SST anomaly residence time due to IOD event of 2019, as compared to 2016 and 2023 which are known El Niño years. All Lakshadweep islands exhibited vulnerability, although in varying degrees across different areas. Based on the magnitude, intensity, and frequency of bleaching stress, the islands are categorized into different categories of vulnerability. This study identifies Baliyapaniyam, Cheriyam-Kalpeni and Suhelipar reefs as very highly vulnerable reefs in Lakshadweep. This study highlights the urgent need for monitoring and management measures to mitigate the impacts of climate change on coral reef ecosystems using spatial vulnerability patterns.

Potential to recover a record of Holocene climate and sea ice from Müller Ice Cap, Canada

Abstract Müller Ice Cap sits on Umingmat Nunaat (Axel Heiberg Island), Nunavut, Canada, ~ 80°N. Its high latitude and elevation suggest it experiences relatively little melt and preserves an undisturbed paleoclimate record. Here, we present a suite of field measurements, complemented by remote sensing, that constrain the ice thickness, accumulation rate, temperature, ice-flow velocity, and surface-elevation change of Müller Ice Cap. These measurements show that some areas near the top of the ice cap are more than 600 m thick, have nearly stable surface elevation, and flow slowly, making them good candidates for an ice core. The current mean annual surface temperature is −19.6 °C, which combined with modeling of the temperature profile indicates that the ice is frozen to the bed. Modeling of the depth-age scale indicates that Pleistocene ice is likely to exist with measurable resolution (300–1000 yr m−1) 20–90 m from the bed, assuming that Müller Ice Cap survived the Holocene Climatic Optimum with substantial ice thickness (~400 m or more). These conditions suggest that an undisturbed Holocene climate record could likely be recovered from Müller Ice Cap. We suggest 91.795°W, 79.874°N as the most promising drill site.

Hydraulics of Time-Variable Water Surface Slope in Rivers Observed by Satellite Altimetry

The ICESat-2 and SWOT satellite earth observation missions have provided highly accurate water surface slope (WSS) observations in global rivers for the first time. While water surface slope is expected to remain constant in time for approximately uniform flow conditions, we observe time varying water surface slope in many river reaches around the globe in the ICESat-2 record. Here, we investigate the causes of time variability of WSSs using simplified river hydraulic models based on the theory of steady, gradually varied flow. We identify bed slope or cross section shape changes, river confluences, flood waves, and backwater effects from lakes, reservoirs, or the ocean as the main non-uniform hydraulic situations in natural rivers that cause time changes of WSSs. We illustrate these phenomena at selected river sites around the world, using ICESat-2 data and river discharge estimates. The analysis shows that WSS observations from space can provide new insights into river hydraulics and can enable the estimation of river discharge from combined observations of water surface elevation and WSSs at sites with complex hydraulic characteristics.

Enhancement of PV and concentered PV panels using evaporative cooling during summer and winter seasons: A case study in Egypt

Numerous efforts are made to comprehend the performance evolution of photovoltaic (PV) panels. The elevated surface temperature causes a deterioration in PV panels' performance, hindering the expected increase in harvested energy associated with integrating solar reflectors. In this context, the year-round efficacy of cooling PV panels supported by reflective mirrors is investigated to assess the effectiveness of solar reflector implementation. A conventional PV panel, a CPV (cooled PV panel), and a CCPV (concentrated cooled PV panel) were compared side-by-side to determine their relative performance and energy productivity. Evaporative cooling pads are utilized to chill the two modified PV systems by varying the coolant flow rate during the summer and winter seasons of 2022 and 2023, respectively, in the environmental conditions of the Tenth of Ramadan City, Egypt. The findings indicate that the average daily power increment ratio (PIR) for CPV ranges from 4.7 % up to 7.4 %, while CCPV ranges from 6.7 % to 12 % for different climate conditions year-round. Finally, changing the setup configuration from CPV to CCPV increased the (PIR) 1.5 times during the summer tests and 1.7 times during the winter tests.

Methodological evaluation of river discharges derived from remote sensing and land surface models

This study assesses river discharges derived using remote sensing and hydrologic modeling approaches throughout the CONUS. The remote sensing methods rely on total water storage anomalies (TWSA) from the GRACE satellite mission and water surface elevations from altimetry satellites (JASON-2/3, Sentinel-3). Surface and subsurface runoff from two Land Surface Models (NOAH, CLSM) are routed using the Hillslope River Routing model to determine discharge. The LSMs are part of NASA’s Global Land Data Assimilation System (GLDAS). Differences in key physical processes represented in each model, model forcings, and use of data assimilation provide an intriguing basis for comparison. Evaluation is performed using the Kling Gupta Efficiency and USGS stream gauges. Results highlight the effectiveness of both satellite-derived discharge methods, with altimetry generally performing well over a range of discharges and TWSA capturing mean flows. LSM-derived discharge performance varies based on hydroclimatic conditions and drainage areas, with NOAH generally outperforming CLSM. CLSM-derived discharges may be impacted by the use of data assimilation (GLDAS v2.2). Low correlation and high variability contribute to lower KGE values. GLDAS models tend to perform poorly in snow dominated, semi-arid and water-regulated systems where both the timing and magnitude of the simulated results are early and overestimated.

Air‐Pyrolysis Precision Synthesis of Functional Porous Carbon Materials

AbstractCarbon materials play a pivo tal role across various advanced applications, yet their synthesis traditionally necessitates inert atmospheres to avert oxidation at high temperatures, thus inflating production costs and resource utilization. Achieving precision synthesis of functional porous carbon materials via air‐pyrolysis remains a formidable challenge. Herein, a streamlined, one‐step lava‐like carbonization approach is introduced enabling the fabrication of porous carbons boasting tailored morphologies (0‐3D), elevated specific surface areas (540.7–1047.6 m2g⁻¹), heteroatom doping, and commendable carbon yields (20‐39.1%) through direct pyrolysis within an air environment. Leveraging recyclable boric acid as a reaction medium, a lava‐like flowing protective barrier above 170 °C is engendered that spontaneously creates an oxygen‐free‐like milieu devoid of high pressure or intricate procedures. This boron‐containing lava serves dually as a template and chemical activator, facilitating pore formation and catalyzing porous carbon production. Notably, the method accommodates a spectrum of carbon sources, encompassing sugars, proteins, graphene oxide, and their metal mixtures. The resultant morphologically customizable carbons exhibit excellent performance in areas as diverse as microwave absorption and electrocatalysis. This work pioneers a novel pathway for large‐scale precision synthesis of high‐quality carbon materials via air‐pyrolysis under mild conditions.

Enhanced organic aerosol formation induced by inorganic aerosol formed in laboratory photochemical experiments

Atmospheric inorganic gases such as NOx, SO2, and NH3 have diverse effects on the formation of secondary organic aerosol (SOA). A comprehensive investigation is necessary to fully understand the atmospheric processing of SOA. In this study, we examined the photooxidation of xylene isomers in the presence of inorganic gases using a combined facility comprising a smog chamber (SC) and an oxidation flow reactor (OFR). SC experiments at higher xylene concentrations and humid conditions revealed SOA yields of 37%, 39%, and 39% with NH3, compared to 15%, 11%, and 13% without NH3, for o-, m-, and p-xylene, respectively. This increase was primarily attributed to the enhanced formation of secondary inorganic aerosol (SIA) in the presence of NH3, consequently increasing aerosol surface area and aerosol water content (AWC). Vapor wall losses (VWL), estimated using a kinetic method, were substantial even with the elevated aerosol surface area provided by SIA. Additional photochemical reactions in the OFR showed a gradual increase in SOA mass and yield over an atmospheric equivalent aging time of 0.5–4.0 days. In the OFR, the SOA yield increased significantly when negligible xylene remained after SC reactions. Fresh SOA formation in the OFR might have decreased the oxygen-to-carbon ratio and oxidation state of carbon, which gradually increased with increasing OFR aging. High OH radical exposure in the OFR likely caused the photodegradation of SC-formed ON, as evidenced by an abrupt decrease in the NO+/NO2+ ratio measured. This study indicates that SOA formation potential of the aromatic hydrocarbon is highly underestimated without considering the combined effects of inorganic gases along with aging.