Lagrangian Model Research Articles

Modeling SO2 dispersion from future eruptions in the Auckland Volcanic Field, New Zealand

Auckland city (pop. 1.7 M) is Aotearoa New Zealand’s largest city and an important economic hub. The city is built upon the active intraplate basaltic Auckland Volcanic Field (AVF). An AVF eruption would cause considerable impacts. An important component of volcanic risk management is assessing the likely volcanic hazards to help inform emergency planning and other preparedness activities. Previous volcanic hazard assessments for the AVF, particularly those for emergency planning scenarios, have modeled multiple volcanic hazards including lava flows, pyroclastic density currents, ballistic projectiles and tephra fall. Despite volcanic gas being an important and impactful hazard from intraplate basaltic field eruptions, there has been limited consideration of volcanic gas in AVF hazard assessment to date. This project is one of the first to quantitatively assess potential volcanic gas hazards for an explosive eruption scenario. For basaltic volcanism, sulfur dioxide (SO2) gas is typically the most consequential volcanic gas emitted. The aim of this exploratory study was to model SO2 dispersion from a high impact eruption during weather conditions conducive to high ground level pollutant concentrations. Since ground level SO2 concentrations are influenced by complex wind patterns resulting from interactions of locally driven flow circulations and topographically influenced weather, we modeled SO2 dispersion using the HYSPLIT model, a state-of-the art hybrid Eulerian and Lagrangian dispersion model widely used for volcanic gases, using high-resolution meteorological forcing fields given by the Weather Research and Forecasting (WRF) model.Modeled air parcel trajectories and ground level SO2 concentrations illustrate the effect of the converging sea breeze winds on SO2 dispersion. Under worst-case dispersion conditions, extensive areas of up to hundreds of square kilometers to the north and northwest of the eruption location would exceed New Zealand short-term (24 h) air quality standards and guidelines for SO2, indicating heightened health risks to downwind communities. Using this numerical modeling approach, this work presents a methodology for future applications to other AVF eruption scenarios, with a wider range of meteorological conditions that can help in exploring consequences for health services such as anticipated emergency department respiratory admissions.

Analysis of flux footprints in fragmented, heterogeneous croplands

An accurate quantification of fluxes from heterogeneous sites and further bifurcation into contributing homogeneous fluxes is an active field of research. Among such sites, fragmented croplands with varying surface roughness characteristics pose formidable challenges for footprint analysis. We conducted two flux monitoring experiments in fragmented croplands characterized by two dissimilar surfaces with objectives to: (i) evaluate the performance of two analytical footprint models in heterogeneous canopy considering aggregated roughness parameters and (ii) analyze the contribution of fluxes from individual surfaces under changing wind speed. A set of three eddy covariance (EC) towers (one each capturing the homogenous fluxes from individual surfaces and a third, high tower capturing the heterogeneous mixed fluxes) was used for method validation. High-quality EC fluxes that fulfill stationarity and internal turbulence tests were analyzed considering daytime, unstable conditions. In the first experiment, source area contribution from a surface is gradually reduced by progressive cut, and its effect on high-tower flux measurements is analyzed. Two footprint models (Kormann and Meixner ‘KM’; analytical solution to Lagrangian model ‘FFP’) with modified surface roughness parameters were applied under changing source area contributions. FFP model has consistently over predicted the footprints (RMSEFFP = 0.31 m−1, PBIASFFP = 19.00), whereas KM model prediction was gradually changed from over prediction to under prediction towards higher upwind distances (RMSEKM = 0.02 m−1, PBIASKM = 8.50). Sensitivity analysis revealed that the models are more sensitive to turbulent conditions than surface characteristics. This motivated to conduct the second experiment, where the fractional contribution of individual surfaces (α and β) to the heterogeneous fluxes measured by the high tower (T3) was estimated using the principle of superposition (FT3 = α FT1 + β FT2). Results showed that α and β are dynamic during daylight hours and strongly depend on mean wind speed (U) and friction velocity (u*). The contribution of fluxes from adjoining fields [1 − (α + β)] is significant beyond 80% isopleth. Our findings provide guidelines for future analysis of fluxes in heterogeneous, fragmented croplands.

Larval dispersal and climate models provide insights into present and future distribution of a tropical sardine

ABSTRACT Climate change impacts the distribution of marine organisms and threatens fisheries. Marine protected areas (MPAs) may buffer the detrimental effects of environmental change by acting as biodiversity spillover to neighboring areas. Yet, it is uncertain whether MPAs on islands favor passive dispersal of species through oceanic currents, and how fish abundance and distribution will be impacted by ongoing global warming. Using the Brazilian-endemic scaled-sardines (Harengula sp.) as model, we implemented a Lagrangian particle-tracking model to estimate dispersal in the Brazilian coast and four MPAs in islands. Then, we projected an ecological niche model (ENM) of Harengula sp. to three climatic scenarios in 2100. Dispersal models suggested that three MPAs in islands export eggs and larvae acting as source of biomass to the coast. ENMs indicated a decrease in environmental suitability for Harengula sp. at the Equatorial Brazilian coast and a southward shift that increases as the climatic scenario is aggravated. Ocean warming may lead to a decrease in suitability for Harengula sp. in the northernmost part of its current distribution concomitant with an increase in offshore zones in the south of its current distribution. Ecosystem disturbance with environmental suitability shifts can aggravate the isolation of populations in islands.

Three-component volume of fluid method coupling with interface compression method and Eulerian–Lagrangian spray atomization surface density model for prediction of cavitating sprays

In this work, a new three phase cavitation model with Eulerian–Lagrangian Spray Atomization (ELSA) and Interface Capturing Method (ICM) coupling is presented to allow for, in a unified approach, physical insight of the surface evolution of cavitating sprays at the Sub-Grid Scale (SGS). Phase change is accounted for in the framework via mass transfer across a liquid and corresponding vapor phase. The surface density model was validated against direct numerical simulation data of an atomizing jet with a systematic variation of mesh resolutions. The sensitivity of the adjustable parameters such as the critical Weber number was also demonstrated. Then, experimental comparisons were made with a more realistic orthogonal spray geometry within a cavitating and turbulent non-cavitating system. These comparisons include both large scale visualizations and small scale SGS quantities such as the Sauter mean diameter. To our knowledge, this is the first study that presents the performance of a three phase cavitating framework with SGS ELSA-ICM coupling.

A numerical assessment to select the optimal geometry of a specific cyclone separator of wheat flour processing

AbstractIn this study, the effect of the cyclone body height on the flow field within the specific cyclone and also on the performance parameters of the cyclone has been investigated. The five heights of the cyclone as various configurations were I = 600, II = 675, III = 750, IV = 825, and V = 900 mm. A pressure‐based solver was used and the turbulent Reynolds stress model was utilized to simulate the flow. Then, the Lagrangian discrete phase model was used to simulate the solid phase. As the height of the cyclone increases, the pressure drop decreases. Also, the best separation efficiency and the highest particle velocity value were achieved at a height of 750 mm. The maximum values of turbulence intensity, skin friction coefficient, and strain rate were obtained as negative components of cyclone performance at the cyclone body height of 900 mm. The height of 750 mm was recognized as the best height of the cyclone's body.Practical ApplicationsApplying numerical simulation in food processing is a novel method to minimize equipment construction and reach a high‐accuracy design. Computational fluid dynamics can provide an accurate and detailed flow analysis in the cyclone separators utilized in the flour processing plant. The dimensional analysis can help the researchers to achieve the optimum design and enhance the cyclone performance by reducing pressure drop and increasing separation efficiency. Also, the maintenance cost would be significantly reduced due to detecting the critical sections and strengthening them.

Wall-resolved large eddy simulation of mixed-size sand-laden flow

Most of the existing numerical studies on wind-blown sand flow simplify sands into single-size particles, whereas natural wind-blown sand flow is a two-phase flow with mixed-size particles, thus, the simulation of mixed-size sand-laden flow is necessary. In the present work, wall-resolved large eddy simulations of mixed-size sand-laden flows are realized. Each sand in the wind field is tracked using the Lagrangian point-particle model. The transport characteristics of sand particles in mixed-size sand-laden flow are investigated under the premise of considering bed erosion. Considering the significant influence of sand-bed collision on simulation, the splash function is modified in the present simulation according to the previous experimental results. It reveals that in mixed-size sand-laden flow, the fraction of rebound sand particles in all the saltation particles is approximately 0.6, which is twice times of the ejected sand particles, and the modification of the sand rebound angle greatly affects the simulation results of mixed-size sand-laden flow. Meanwhile, the mean size of the saltation sand particles decreases with height and is 20% lower at the top of the saltation layer than that near the sand bed in the present simulation. Further analysis by grouping of sands with their size shows that the sand transport intensity of small sands decreased more rapidly with increasing height. The volume fraction and sand transport intensity of small sand particles exceed those of medium and large sand particles at heights y/δ = 0.05 and y/δ = 0.1.

Validation and Assessment of a Hybrid VOF-Lagrangian Numerical Methodology for Turbulent Liquid Fuel Jets in High-Speed Crossflow

Abstract For gas turbine combustors, injecting liquid fuel in crossflow can achieve superior mixing characteristics to improve performance and reduce emissions. Robust numerical design tools are needed to accelerate the development of low-emissions technologies. Atomization modeling is often facilitated by using the Lagrangian approach rather than the more complex and computationally expensive Volume-of-Fluid (VOF) approach. However, most Lagrangian breakup models rely on empirical constants that must be fully calibrated for jets in crossflow and representative conditions. A hybrid approach could deliver a better compromise between accuracy and computational cost. This study proposes and validates a novel numerical methodology for coupling the VOF and Lagrangian approaches using a stochastic breakup model with Adaptive Mesh Refinements for turbulent liquid fuel jets in crossflow under more representative gas turbine conditions. The predictions were validated in the near and far-field regions using datasets at high pressures (1–8 bar), Weber numbers (720–1172), and momentum flux ratios (6–33). The predictive capabilities and computational cost were also compared to the Lagrangian approach coupled with large eddy simulations (LES) and with the unsteady Reynolds-Averaged Navier–Stokes (RANS) methodology previously developed and validated by the authors. The effect of different VOF-Lagrangian transition criteria on the computational cost was also assessed and recommendations were provided for further improvements. The overall LES predictions were significantly improved by the proposed hybrid methodology. Although it tends to underpredict the spray trajectory and Sauter Mean Diameter compared to the URANS methodology, it better captures the diameter in the wake region and the droplet velocities.

Unveiling non-flat profiles within magnetic islands in tokamaks

The presence of non-flat profiles on magnetic island is studied for the first time through gyrokinetic simulations alongside a simplified Lagrangian model. We have identified that inside a magnetic island, the non-flatness of density and temperature profiles is controlled by a dimensionless parameter α≡w*ŝϵ/qρ*, which is a function of normalized island width w*=w/a0, magnetic shear ŝ, inverse aspect ratio ϵ=a0/R, safety factor q, and normalized gyroradius ρ*=ρ/a0. The gyroradius ρ* dependence of the control parameter α leads to a species-selective transition of profiles from flat to concave only for electrons having high α∼O(1). The finding elucidates that electron profiles tend to increasingly deviate from the flat state for a larger magnetic island, in contrast to the conventional wisdom.

Analysis of the flow field of kerosene-fueled rotating detonation engine with film cooling

The advance of the rotating detonation engine (RDE) toward practical applications demands the integration of effective cooling schemes. In this study, a three-dimensional simulation of the hydrogen-enhanced kerosene-air RDE with inclined cylindrical film cooling holes is conducted to analyze the influence of the cooling flow on the two-phase rotating detonation flow field based an Eulerian–Lagrangian model. The liquid kerosene is injected at the ambient temperature with hydrogen-assisted combustion enhancement. Results suggest that a stable propagation of the kerosene-fueled rotating detonation wave can be maintained after the introduction of cooling air and the three-dimensional structure of the flow field is analyzed. It is found that the periodic sweeping action of the detonation wave leads to temporary blockages of the film cooling holes, causing interruptions in the outflow of cooling air. Additionally, the investigation highlights the intensified heating and evaporation of kerosene droplets near the outer wall of the RDE, whereas the presence of cooling air prevents the accumulation of kerosene vapor near the outer wall. It is revealed that the film cooling efficiency exhibits a lower value in the vicinity of the fuel injection surface, but gradually increases along the length of the combustion chamber.

Numerical investigation on design parameters of orifice plate for positioning of workpiece in cavitation zone for cavitation machining

ABSTRACT The recent development of non-traditional machining techniques, such as cavitation machining (CM), has been gaining traction amongst researchers due to its sustainable nature. The present research focuses on the use of computational fluid dynamics (CFD) model to predict the location of workpiece in the fluid domain and bubble distribution during CM process. For efficient CM, the correct positioning of a workpiece in cavitation zone is essential, as the implosion of the cavity bubble leads to formation of micro-jet and shock waves for a few milli-to-microseconds generating high temperature and pressure on workpiece. The aim is to harness cavitation phenomena in material processing, particularly by using orifice plates as a common tool to induce hydrodynamic cavitation. To generalise the investigation, the flow simulation through orifice plate with different aspect ratios (l/d) are carried out. For the bubble distribution and their diameters, the Lagrangian discrete phase model (DPM) is used in the downstream side of the flow domain. Using this information, bubble dynamics have also been investigated using the Keller–Miksis (KM) model to compute the implosion time and intensity in the zone. The presented exploration determines the orifice dimensions to optimize implosion intensity, ensuring precise workpiece placement in real-time CM.

Distribution and Environmental Impact of Expanded Polystyrene Buoys from Korean Aquaculture Farms

Expanded polystyrene (EPS) buoys, commonly employed in South Korean aquaculture farms, are prone to fragmentation, generating substantial marine debris. The trajectories of EPS buoys dislocated from aquaculture farms were investigated using a Lagrangian particle-tracking model. Daily ocean current data from the 1/12° Hybrid Coordinate Ocean Model analysis and wind data from the 1/4° European Center for Medium-Range Weather Forecasts reanalysis were used as inputs. The particles were released daily, and the initial positions and number of particles were determined based on the usage of EPS buoys. Because EPS buoys are highly buoyant, both wind and ocean currents considerably influence their movement. To account for variations in the buoyancy of these buoys, three experiments were conducted, each considering different levels of windage. The simulation results closely aligned with the observed coastal distribution patterns of the large EPS debris. As the windage increases, the particles exhibit a swifter deviation from their original locations, highlighting the need for effective local management. Moreover, this increased windage affects the distribution patterns in regional seas, reducing the number of particles that flow into the East Sea, while increasing the number of particles that migrate into the Yellow Sea and East China Sea.

Vector-borne disease models with Lagrangian approach.

We develop a multi-group and multi-patch model to study the effects of population dispersal on the spatial spread of vector-borne diseases across a heterogeneous environment. The movement of host and/or vector is described by Lagrangian approach in which the origin or identity of each individual stays unchanged regardless of movement. The basic reproduction number [Formula: see text] of the model is defined and the strong connectivity of the host-vector network is succinctly characterized by the residence times matrices of hosts and vectors. Furthermore, the definition and criterion of the strong connectivity of general infectious disease networks are given and applied to establish the global stability of the disease-free equilibrium. The global dynamics of the model system are shown to be entirely determined by its basic reproduction number. We then obtain several biologically meaningful upper and lower bounds on the basic reproduction number which are independent or dependent of the residence times matrices. In particular, the heterogeneous mixing of hosts and vectors in a homogeneous environment always increases the basic reproduction number. There is a substantial difference on the upper bound of [Formula: see text] between Lagrangian and Eulerian modeling approaches. When only host movement between two patches is concerned, the subdivision of hosts (more host groups) can lead to a larger basic reproduction number. In addition, we numerically investigate the dependence of the basic reproduction number and the total number of infected hosts on the residence times matrix of hosts, and compare the impact of different vector control strategies on disease transmission.

Land reclamation and its consequences: A 40-year analysis of water residence time in Doha Bay, Qatar.

Qatar's rapid industrialization, notably in its capital city Doha, has spurred a surge in land reclamation projects, leading to a constriction of the entrance to Doha Bay. By reducing and deflecting the ocean circulation, land reclamation projects have reduced the effective dispersion of wastewater introduced into the bay and hence degraded the water quality. Here, we assess fluctuations in water residence time across three distinct eras (1980, 2000, and 2020) to gauge the impact of successive land reclamation developments. To do this, we couple the multi-scale ocean model SLIM with a Lagrangian model for water residence time within Doha's coastal area. We consider three different topographies of Doha's shoreline to identify which artificial structures contributed the most to increase water residence time. Our findings reveal that the residual ocean circulation in Doha Bay was predominantly impacted by northern developments post-2000. Between 1980 and 2000, the bay's residence time saw a modest rise, of about one day on average. However, this was followed by a substantial surge, of three to six days on average, between 2000 and 2020, which is mostly attributable to The Pearl mega artificial island development. Certain regions of the bay witnessed a tripling of water residence time. Given the ongoing population expansion along the coast, it is anticipated that the growth of artificial structures and coastal reclamation will persist, thereby exacerbating the accumulation of pollutants in the bay. Our findings suggest that artificial offshore structures can exert far-reaching, non-local impacts on water quality, which need to be properly assessed during the planning stages of such developments.

Turbulent Heat Transfer of Hybrid Nanofluid with Nano-Encapsulated Phase Change Material in a Square Channel

Investigation of turbulent mixed convection of different working fluids, namely, pure water, CuO/water nanofluid, n-octadecane/water nanofluid (or slurry), and a hybrid water-based suspension of CuO and n-octadecane nanoparticles in a uniformly heated vertical square channel is carried out. The shear stress transport/kappa-omega model is applied to simulate the turbulent flow. Eulerian–Lagrangian two phase model and homogeneous model are employed to simulate the nanofluid flow. It is shown that Eulerian–Lagrangian two-phase model predicts higher Nusselt number and friction factor than single-phase model and the results of two-phase model are closer to experimental data. It is found that a new hybrid nanofluid with dispersed nano-encapsulated phase change material particles provides better thermal and hydrodynamic performances compared to other nanofluids. Slurry containing 5% n-octadecane provides an improvement of nearly 37.2%, while hybrid nanofluid (1% CuO + 5% n-octadecane) offers added convective heat transfer enhancement of almost 60%. With increasing volume fraction, friction factor becomes slightly larger than that of pure water. For 5% n-octadecane/water and 1% CuO + 5% n-octadecane/water nanofluids, friction factor increases by 2.5% and 1.7%, respectively. Due to dominance of thermal entropy generation, total entropy generation reduces by increasing Reynolds number and volume fraction.

Assessment of Pollution of the Waters in the South Kuril Fishing Zone of Russia by Radioactive Waters from the Fukushima-1 NPP Based on Lagrangian Modeling

Assessment of Pollution of the Waters in the South Kuril Fishing Zone of Russia by Radioactive Waters from the Fukushima-1 NPP Based on Lagrangian Modeling

Larval Dispersal Modelling of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) from the Crab Banks along the Coast of Trang Province, Southern Thailand

In Thailand, the populations of a commercially important crab Portunus pelagicus (Linnaeus, 1758) have been decreasing due to overfishing, raising concerns about the conservation efforts of this crab species. The Crab Bank Project has recently been established to restore crab populations by releasing crab larvae from each crab bank station. However, the fate of crab larvae after the release is poorly understood. Here, we assessed the dispersal and settlement patterns of the larvae P. pelagicus released from crab banks along the coast of Trang Province, Southern Thailand. The Lagrangian particle tracking model was employed to simulate the larval dispersal and settlement patterns after release from the crab banks during the inter-monsoon, southwest monsoon, and northeast monsoon. Our simulation revealed that virtual larvae were predominantly retained within inshore areas after the release for 14 days, regulated by tidal-driven currents, wind-induced currents, and local coastal topography. Monsoon periods affected the larval dispersal, with some larvae being transported into estuaries due to the SW monsoonal effects. After the 14-day release period, our modelled simulations suggested that the crab larvae arrived at numerous seagrass meadows along the coast, indicating potential settlement and growth. This result highlights the connectivity of sources and sinks for crab larvae after release from crab banks. Moreover, significant implications for conservation efforts and the fishery management of P. pelagicus were also discussed based on our modelled simulations.

A multi-scenario Lagrangian trajectory analysis to identify source regions of the Asian tropopause aerosol layer on the Indian subcontinent in August 2016

Abstract. The Asian tropopause aerosol layer (ATAL) is present during the Asian summer monsoon season affecting the radiative balance of the atmosphere. However, the source regions and transport pathways of ATAL particles are still uncertain. Here, we investigate transport pathways from different regions at the model boundary layer (MBL) to the ATAL by combining two Lagrangian transport models (CLaMS, Chemical Lagrangian Model of the Stratosphere; MPTRAC, Massive-Parallel Trajectory Calculations) with balloon-borne measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) above Nainital (India) in August 2016. Trajectories are initialised at the measured location of the ATAL and calculated 90 d backwards in time to investigate the relation between the measured, daily averaged, aerosol backscatter ratio and source regions at the MBL. Different simulation scenarios are performed to find differences and robust patterns when the reanalysis data (ERA5 or ERA-Interim), the trajectory model, the vertical coordinate (kinematic and diabatic approach) or the convective parameterisation are varied. The robust finding among all scenarios is that the largest continental air mass contributions originate from the Tibetan Plateau and the Indian subcontinent (mostly the Indo-Gangetic Plain), and the largest maritime air mass contributions in Asia come from the western Pacific (e.g. related to tropical cyclones). Additionally, all simulation scenarios indicate that the transport of maritime air from the tropical western Pacific to the region of the ATAL lowers the backscatter ratio (BSR) of the ATAL, while most scenarios indicate that the transport of polluted air from the Indo-Gangetic Plain increases the BSR. While the results corroborate key findings from previous ERA-Interim-based studies, they also highlight the variability in the contributions of different MBL regions to the ATAL depending on different simulation scenarios.

Evaluation of vertical transport in ERA5 and ERA-Interim reanalysis using high-altitude aircraft measurements in the Asian summer monsoon 2017

Abstract. During the Asian monsoon season, greenhouse gases and pollution emitted near the ground are rapidly uplifted by convection up to an altitude of ∼ 13 km, with slower ascent and mixing with the stratospheric background above. Here, we address the robustness of the representation of these transport processes in different reanalysis data sets using ERA5, ERA-Interim and ERA5 1∘×1∘. This transport assessment includes the mean age of air from global three-dimensional simulations by the Lagrangian transport model CLaMS (Chemical Lagrangian Model of the Stratosphere), as well as different trajectory-based transport times and associated ascent rates compared with observation-based age of air and ascent rates of long-lived trace gases from airborne measurements during the Asian summer monsoon 2017 in Nepal. Our findings confirm that the ERA5 reanalysis yields a better representation of convection than ERA-Interim, resulting in different transport times and air mass origins at the Earth's surface. In the Asian monsoon region above 430 K, the mean age of air driven by ERA-Interim is too young, whereas the mean age of air from ERA5 1∘×1∘ is too old but somewhat closer to the observations. The mean effective ascent rates derived from ERA5 and ERA5 1∘×1∘ back trajectories are in good agreement with the observation-based mean ascent rates, unlike ERA-Interim, which is much faster above 430 K. Although a reliable CO2 reconstruction is a challenge for model simulations, we show that, up to 410 K, the CO2 reconstruction using ERA5 agrees best with high-resolution in situ aircraft CO2 measurements, indicating a better representation of Asian monsoon transport in the newest ECMWF reanalysis product, ERA5.

Trajectory tracking control of autonomous vehicles based on Lagrangian neural network dynamics model

The autonomous vehicles make decisions and plans based on the environmental perception and generate the target command of the control layer. The vehicle dynamics model is an important factor that affects the vehicle control. The dynamic mechanism model has strong interpretability and good stability. However, in extreme conditions, the model accuracy is reduced due to the tire entering the nonlinear region. The data-driven dynamic model achieves high modeling accuracy. However, due to the lack of physical constraints and rationality in the data-driven models, the interpretability and stability of the control is reduced, which in turn increases the unpredictable risk in the driving process. This paper innovatively proposes a deep Lagrangian neural network dynamics model (DeLaN) for autonomous vehicles based on the Lagrangian mechanics and uses a neural network to encode the differential equations. This not only retains the interpretability of the physical model but also makes full use of the learning ability and fitting ability of the neural network to effectively capture the complex dynamic characteristics of the vehicle. To improve the robustness of the control system, this work uses DeLaN as feed-forward control and preview error feedback control to form a closed loop of trajectory tracking control for autonomous vehicles. The experimental results show that the trajectory tracking error of the proposed DeLaN is significantly reduced, the yaw stability and comfort are significantly improved, good longitudinal and lateral cooperative control performance is achieved, and the physical rationality of the neural network is also improved. Therefore, the proposed DeLaN has important engineering application value.

Identifying the Moisture Sources in Different Seasons for Abaya-Chamo Basin of Southern Ethiopia Using Lagrangian Particle Dispersion Model

Understanding the sources of precipitation and their impacts is crucial for basin-wide water balance research. Previous research concentrated on the sources of moisture in Ethiopia. The southern part’s moisture sources, however, were not investigated. The primary objective of this study is to trace the source of atmospheric moisture in the Abaya-Chamo sub-basin of southern Ethiopia using numerical water vapor tracers like Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Exploring the possible regions of atmospheric vapor roots and the path of moist air initiating rainfall that reaches the basin was feasible for the year 2018–2020. The anticyclone from the Arabian High, which is positioned in the Arabian and Mediterranean seas, was the primary source of moisture supply in the study area during the Belg (March to May) season, according to the back trajectory cluster analysis results. Additionally, the Indian Ocean adds moisture resulting from Mascarene highs brought by equatorial easterlies. Furthermore, during Kiremt (June to September), air masses from the Congo basin were the potential moisture source region for the study areas in combination with air masses originating from the Mascarene highs, located in the South Indian Ocean, and the St. Helena high, centered in the subtropical southern Atlantic Ocean. This study primarily focuses on the complex dynamics of atmospheric moisture sources around Abaya-Chamo sub-basin of southern Ethiopia, offering insight into seasonal fluctuations and contributing various components. These findings contribute to basin-specific water balance research by filling gaps in the previous studies.