Small-scale Phenomena Research Articles

Inflationary Butterfly Effect: Nonperturbative Dynamics from Small-Scale Features.

For the first time, we investigate the nonperturbative dynamics of single field inflation with a departure from slow roll. Using simulations, we find that oscillatory features in the potential can drastically alter the course of inflation, with major phenomenological implications. In certain cases, the entire Universe gets trapped in a forever inflating de Sitter state. In others, only some regions get stuck in a false vacuum, offering an alternative channel for primordial black hole formation. Analogous to the flap of a butterfly, these results show that small-scale phenomena can have profound consequences on the evolution of the entire Universe. More generally, our work shows the power of simulations in the exploration of the small-scale physics of inflation, particularly in the regime relevant for gravitational-wave astronomy.

Lack of Small-Scale Changes in Breeding Birds after a Fire: Does the Resilience of Cork Oaks Favor Rapid Recolonization in Suburban Wood Patches?

Forest fires are disturbance events that can impact biological assemblages at multiple scales. In this study, the structures of breeding bird communities in cork oak patches located in an agro-mosaic suburban landscape of central Italy (Rome) were compared at the local scale with a fine-grained mapping method before (2018) and after (2023) a fire event occurred in July 2022. The analyses did not reveal any significant changes in the density of territorial pairs or in the diversity metrics, both univariate (Shannon–Wiener index, evenness, Margalef normalized richness) and bivariate (Whittaker and k-dominance plots, abundance/biomass curves) of diversity. Even when the guilds of strictly forest-related species were compared, no differences emerged before and after the fire. This counterintuitive phenomenon may be due to the characteristics of the dominant tree, the cork oak (Quercus suber), a sclerophilous tree that is very resilient to fires and able to recover foliage in the following spring season, thus allowing rapid bird recolonization. However, other small-scale phenomena (e.g., the ‘crowding effect’ and local dispersal of territorial pairs from remnant wood patches not affected by fire) may explain this lack of change in breeding bird density and diversity. Further studies should be carried out at larger spatial and temporal scales and at different levels of fire frequency and intensity to confirm these responses at the guild/community level in suburban cork oak wood patches.

Highly resolved peta-scale direct numerical simulations: Onset of Kelvin–Helmholtz Rayleigh–Taylor instability via pressure pulses

The study presents a comprehensive numerical investigation of the Kelvin–Helmholtz Rayleigh–Taylor Instability (KHRTI) onset using highly resolved peta-scale direct numerical simulations by solving the compressible Navier–Stokes equations (NSE). The numerical framework incorporates a three-dimensional (3D) cuboidal domain with differential heating applied to two air streams, fostering the development of the KHRTI. A novel numerical methodology with selective mesh refinement near critical regions is employed with the help of a non-uniform compact scheme to capture small-scale phenomena accurately. Analysis of pressure disturbances during early KHRTI stages reveal distinct wave propagation patterns influenced by Rayleigh–Taylor (RT) and Kelvin–Helmholtz (KH) mechanisms. Enstrophy dynamics are quantified through the compressible enstrophy transport equation (CETE), highlighting dominant contributions from viscous stresses during early receptivity stages. The study provides insights into KHRTI evolution, shedding light on shear-buoyancy-driven instabilities and their implications for transition to turbulence.

Universal thermodynamic constraints revealed in few-particle systems on 2D material surfaces

Abstract Our study reveals a profound connection between hidden thermodynamics and the properties of small systems, shedding light on fundamental properties of isolated particles, such as pressure and enthalpy. This research has allowed the identification of three universal regions within these systems, improving our understanding of small-scale phenomena.

Teenage pregnancy and parenthood, a review of the literature

Teenage parenthood involves adual transition to adulthood and parenthood. A small-scale phenomenon, there remains a gap between statistical reality and social perception. The media and politicians take up the issue as a synonym for socio-psychological difficulties. The literature points in particular to the consequences of these maternities on the future of mothers, children and their relationships. However, some studies qualify the literature by identifying different types of teenage pregnancy and parenthood profiles.

Constraints on Primordial Magnetic Fields from High Redshift Stellar Mass Density

Primordial magnetic fields (PMFs) play a pivotal role in influencing small-scale fluctuations within the primordial density field, thereby enhancing the matter power spectrum within the context of the ΛCDM model at small scales. These amplified fluctuations accelerate the early formation of galactic halos and stars, which can be observed through advanced high-redshift observational techniques. Therefore, stellar mass density (SMD) observations, which provide significant opportunities for detailed studies of galaxies at small scales and high redshifts, offer a novel perspective on small-scale cosmic phenomena and constrain the characteristics of PMFs. In this study, we compile 14 SMD data points at redshifts z > 6 and derive stringent constraints on the parameters of PMFs, which include the amplitude of the magnetic field at a characteristic scale of λ = 1 Mpc, denoted as B 0, and the spectral index of the magnetic field power spectrum, n B . At 95% confidence level, we establish upper limits of B 0 < 4.44 nG and n B < −2.24, along with a star formation efficiency of approximately f*0∼0.1 . If we fix n B at specific values, such as −2.85, −2.9, and −2.95, the 95% upper limits for the amplitude of the magnetic field can be constrained to 1.33, 2.21, and 3.90 nG, respectively. Finally, we attempt to interpret recent early observations provided by the James Webb Space Telescope using the theory of PMFs and find that by selecting appropriate PMF parameters, it is possible to explain these results without significantly increasing the star formation efficiency.

Probing the capacity of a spatiotemporal deep learning model for short-term PM2.5 forecasts in a coastal urban area

Accurate forecast of fine particulate matter (PM2.5) is crucial for city air pollution control, yet remains challenging due to the complex urban atmospheric chemical and physical processes. Recently deep learning has been routinely applied for better urban PM2.5 forecasts. However, their capacity to represent the spatiotemporal urban atmospheric processes remains underexplored, especially compared with traditional approaches such as chemistry-transport models (CTMs) and shallow statistical methods other than deep learning. Here we probe such urban-scale representation capacity of a spatiotemporal deep learning (STDL) model for 24-hour short-term PM2.5 forecasts at six urban stations in Rizhao, a coastal city in China. Compared with two operational CTMs and three statistical models, the STDL model shows its superiority with improvements in all five evaluation metrics, notably in root mean square error (RMSE) for forecasts at lead times within 12 h with reductions of 49.8 % and 47.8 % respectively. This demonstrates the STDL model's capacity to represent nonlinear small-scale phenomena such as street-level emissions and urban meteorology that are in general not well represented in either CTMs or shallow statistical models. This gain of small-scale representation in forecast performance decreases at increasing lead times, leading to similar RMSEs to the statistical methods (linear shallow representations) at about 12 h and to the CTMs (mesoscale representations) at 24 h. The STDL model performs especially well in winter, when complex urban physical and chemical processes dominate the frequent severe air pollution, and in moisture conditions fostering hygroscopic growth of particles. The DL-based PM2.5 forecasts align with observed trends under various humidity and wind conditions. Such investigation into the potential and limitations of deep learning representation for urban PM2.5 forecasting could hopefully inspire further fusion of distinct representations from CTMs and deep networks to break the conventional limits of short-term PM2.5 forecasts.

Validating Volumetric Measurements Using Helium-Filled Soap Bubbles in a Turbulent Boundary Layer And Wake Of An Axisymmetric Body Of Revolution

This study focuses on the validation of a volumetric measurement technique to characterize the turbulent boundary layers (TBL) and wake of a slender axisymmetric body. Specifically, Lagrangian Particle Tracking (LPT) was employed to analyse a TBL subjected to an adverse pressure gradient (APG) and transverse curvature at the tail of an axisymmetric body, with a Reynolds number based on model length of 3.95×10 6 . For the LPT method, a seeding rake with 100 nozzles was used to disperse helium-filled soap bubbles (HFSB), which served as tracers. These tracers were illuminated by high-powered LED arrays, allowing their motion to be captured by three high-speed cameras at acquisition rates up to 20 kHz. A key aspect of this research was using shadowgraphy to measure the diameter of the bubbles exiting the nozzles and obtaining their statistical variations across the various nozzles in the seeding rake. The study identified that the diameter of bubbles averaged 0.45 mm, indicating a state of near-neutral buoyancy. The LPT results were then obtained using the shake-the-box (STB) tracking alogirthm, while ensemble bin-averaging of the scattered particle tracks was used to obtain turbulence statistics on a regular grid. To validate the LPT results, comparisons were made with time-resolved 2D Particle Image Velocimetry (TR-PIV) and highly resolved hot-wire anemometry. This comparative analysis revealed good agreement of the mean profiles across the methodologies, highlighting the robustness and accuracy of the LPT technique. While the turbulence levels in the outer layer were well captured by the LPT, some discrepancies were observed near the wall in both PIV and LPT data, indicating limitations in capturing small-scale phenomena. The implications of these findings, particularly in understanding the complex 3D flow effects of such TBLs and the resulting wake flow field are discussed.

IMMISCIBLE VISCOUS FINGERING MODELING OF TERTIARY POLYMER FLOODING BASED ON REAL CASE OF HEAVY OIL RESERVOIR MODEL

In immiscible displacements, lower viscosity injected fluids with higher mobility than crude oil can create viscous fingers, affecting displacement efficiency. The Buckley–Leverett approach for relative permeabilities (kr) may not represent accurately 2D features like increased water saturation in viscous fingering. Based on the physics issue, this work applies Sorbie's 4-Steps methodology to a 3D simulation of an offshore heavy oil reservoir focusing on waterflooding and tertiary polymer flooding, assessing their impact on oil production forecasts. It also explores the application of this methodology to coarse grid simulation models, employing pseudo kr functions by data assimilation. During tertiary polymer injection, two processes were identified in oil displacement: viscous crossflow mechanism and oil bank mobilization by a second finger. This combination resulted in earlier and increased oil production. For both strategies, refining the grid increased simulation runtime from minutes to days compared to coarse grids, making it impractical for intensive processes. From data assimilation, the best solution with matched field indicators reduced runtime from days to minutes. This study expanded the 4-Steps methodology for 3D reservoir simulation, proposing kr as uncertainties. Data assimilation enhances the methodology, generating pseudo kr for coarser grid simulations, reducing computational costs, and capturing small-scale phenomena.

Prominence and coronal rain formation by steady versus stochastic heating and how we can relate it to observations

Prominences and coronal rain are two forms of coronal condensations for which we still lack satisfactory details on the formation pathways and conditions under which the two come to exist. Even more so, it is unclear why prominences and filaments appear in so many different shapes and sizes, with a vertical rather than a horizontal structure or vice-versa. It is also not clear why coronal rain is present in some cases and not in others. Our aim is to understand the formation process of prominences and coronal rain in more detail by exploring what influence two specific heating prescriptions can have on the resulting formation and evolution, using simulations. We try to determine why we see prominences with such a variety in their properties, particularly by looking at the large-scale topology and dynamics. We attempted to recreate some of these aspects by simulating different types of localised heating. Besides the differences we see on a large scale, we also attempted to determine what the smaller-scale phenomena are, such as reconnection, the influence of resistivity (or lack thereof), the influence of flows and oscillations. We compared prominences that formed via a steady versus stochastic type of heating. We performed 2.5D simulations using the open-source MPI-AMRVAC code. To further extend the work and allow for future direct comparison with observations, we used Lightweaver to form spectra of the filament view of our steady case prominence. With that, we analysed a reconnection event that shares certain characteristics with nanojets. We show how different forms of localised heating that induce thermal instability result in prominences with different properties. The steady form of heating results in prominence with a clear vertical structure stretching across the magnetic field lines. On the other hand, stochastic heating produces many threads that predominantly have a horizontal motion along the field lines. Furthermore, the specific type of heating also influences the small-scale dynamics. In the steady heating case, the prominence is relatively static; however, there is evidence of reconnection happening almost the entire time the prominence is present. In the case of stochastic heating, the threads are highly dynamic, with them also exhibiting a form of transverse oscillation (strongly resembling the decayless type) similar to the vertically polarised oscillations previously found in observations. The fact that the threads in the stochastic heating case are constantly moving along the field lines suppresses any conditions for reconnection. It, therefore, appears that, to first order, the choice of heating prescription defines whether the prominence-internal dynamics are oriented vertically or horizontally. We closely inspected a sample reconnection event and computed the synthetic optically thick radiation using the open-source Lightweaver radiative transfer framework. We find the associated dynamics to imprint clear signatures, both in Doppler and emission, on the resulting spectra that should be testable with state-of-the-art instrumentation such as DKIST.

Characteristics of Carbon Monoxide and Ethylene Generation in Mine’s Closed Fire Zone and Their Influence on Methane Explosion Limits

Methane explosions often occur during the closure process of mine fire zones, during which the concentration of combustible gases such as monoxide and ethylene produced by coal combustion dynamically changes, which changes the risk of methane explosion. Therefore, studying the gas concentration distribution and methane explosion limits during the process of mine closure is of great significance for disaster prevention and control. In this paper, a three-dimensional physical model of gob was built, and the distribution of monoxide and ethylene in the process of fire zone closure was investigated. Further, the explosion limits of methane enriched with CO and C2H4 in the closed fire zone of gob were analyzed. The results indicate that CO and C2H4 would form a small-scale accumulation phenomenon near the fire zone after the closure of the fire zone, and when the fire zone is closed for more than 15 min, the mixed combustible gases in the environment lose their explosiveness.

Evidence for Plasmoid-mediated Magnetic Reconnection during a Small-scale Flare in the Partially Ionized Low Solar Atmosphere

Magnetic reconnection plays a crucial role in the energy release process for different kinds of solar eruptions and activities. The rapid solar eruption requires a fast reconnection model. Plasmoid instability in the reconnecting current sheets is one of the most acceptable fast reconnection mechanisms for explaining the explosive events in the magnetohydrodynamics (MHD) scale, which is also a potential bridge between the macroscopic MHD reconnection process and microscale dissipations. Plenty of high-resolution observations indicate that the plasmoid-like structures exist in the high-temperature solar corona, but such evidences are very rare in the lower solar atmosphere with partially ionized plasmas. Utilizing joint observations from the Goode Solar Telescope and the Solar Dynamics Observatory, we discovered a small-scale eruptive phenomenon in NOAA Active Region 13085, characterized by clear reconnection cusp structures, supported by nonlinear force-free field extrapolation results. The plasmoid-like structures with a size of about 150 km were observed to be ejected downward from the current sheet at a maximum velocity of 24 km s−1 in the Hα line wing images, followed by enhanced emissions at around the postflare loop region in multiple wavelengths. Our 2.5D high-resolution MHD simulations further reproduced such a phenomenon and revealed reconnection fine structures. These results provide comprehensive evidences for the plasmoid-mediated reconnection in partially ionized plasmas, and suggest a unified reconnection model for solar flares with different length scales from the lower chromosphere to the corona.

Numerical analysis of turbulent nitrogen-diluted hydrogen flames stabilised by star-shaped bluff bodies

In this paper, we investigate the flow and flame dynamics within a combustion chamber supplied with nitrogen-diluted hydrogen fuel and air as oxidiser. The chamber is equipped with a bluff body that serves as a flame stabiliser. We focus primarily on the influence of the bluff body shape on the formation of large and small-scale vortical structures generated at the bluff body edge. We analyse how the geometry of the bluff body alters these structures and examine the impact of resulting modifications on flame characteristics, including key features such as flame length and radial extent, temperature and species field, and completeness of the combustion process. We consider four bluff body geometries, namely a typical cylindrical shape, a star-shaped wall, and a small triangular sharp and smooth wavy structure. The research employs the Large Eddy Simulation (LES) method, providing deep insight into the complex physics of unsteady flow. In the cylindrical bluff body configuration, the key mechanism driving the fuel-oxidiser mixing process is the periodic occurrence of large toroidal vortices shed at an exit of the oxidiser duct and on the bluff body edge. They exert the flow towards and away from a recirculation zone formed above the bluff body. When its geometry is irregular, the appearance of the large vortices is suppressed, however, the wall irregularities induce small-scale flow phenomena that enhance mixing in the shear layer formed between the recirculation zone and the oxidiser stream. The mixing efficiency is largely dependent on the shape of the bluff body wall, and it turns out that seemingly small changes (sharp vs. smooth small triangular parts), which in non-reactive regimes have only a minor effect on the flow dynamics, significantly change the flame length and fuel consumption rate. Compared to the cylindrical bluff body configuration, the small triangular parts cause an axial shift of the maximum temperature downstream and slow down fuel consumption. Contrary, large triangular elements in the star-shape bluff body clearly influence the flow both in non-reactive and reactive regimes. They cause the formation of local oxidiser streams directed towards the fuel-rich mixture. Consequently, the injected fuel burns at a rate similar to that observed in the case of the cylindrical bluff body, but the combustion process occurs at an average temperature approximately 200 K lower and its fluctuations are reduced. These factors may influence the thermal reduction of NOx. On the other hand, a negative aspect is the highest level of hydrogen in the closest vicinity of the bluff body, which in practical applications may accelerate the embrittlement of its surface.

Non-linear CMB lensing with neutrinos and baryons: FLAMINGO simulations versus fast approximations

ABSTRACT Weak lensing of the cosmic microwave background is rapidly emerging as a powerful probe of neutrinos, dark energy, and new physics. We present a fast computation of the non-linear CMB lensing power spectrum that combines non-linear perturbation theory at early times with power spectrum emulation using cosmological simulations at late times. Comparing our calculation with light-cones from the FLAMINGO 5.6 Gpc cube dark-matter-only simulation, we confirm its accuracy to $1{{\ \rm per\ cent}}$ ($2{{\ \rm per\ cent}}$) up to multipoles L = 3000 (L = 5000) for a νΛCDM cosmology consistent with current data. Clustering suppression due to small-scale baryonic phenomena such as feedback from active galactic nuclei can reduce the lensing power by $\sim 10{{\ \rm per\ cent}}$. To our perturbation theory and emulator-based calculation, we add SP(k), a new fitting function for this suppression, and confirm its accuracy compared to the FLAMINGO hydrodynamic simulations to $4{{\ \rm per\ cent}}$ at L = 5000, with similar accuracy for massive neutrino models. We further demonstrate that scale-dependent suppression due to neutrinos and baryons approximately factorize, implying that a careful treatment of baryonic feedback can limit biasing neutrino mass constraints.

Sensitivity of the polar boundary layer to transient phenomena

Abstract. Numerical weather prediction and climate models encounter challenges in accurately representing flow regimes in the stably stratified atmospheric boundary layer and the transitions between them, leading to an inadequate depiction of regime occupation statistics. As a consequence, existing models exhibit significant biases in near-surface temperatures at high latitudes. To explore inherent uncertainties in modeling regime transitions, the response of the near-surface temperature inversion to transient small-scale phenomena is analyzed based on a stochastic modeling approach. A sensitivity analysis is conducted by augmenting a conceptual model for near-surface temperature inversions with randomizations that account for different types of model uncertainty. The stochastic conceptual model serves as a tool to systematically investigate which types of unsteady flow features may trigger abrupt transitions in the mean boundary layer state. The findings show that the incorporation of enhanced mixing, a common practice in numerical weather prediction models, blurs the two regime characteristic of the stably stratified atmospheric boundary layer. Simulating intermittent turbulence is shown to provide a potential workaround for this issue. Including key uncertainty in models could lead to a better statistical representation of the regimes in long-term climate simulation. This would help to improve our understanding and the forecasting of climate change in high-latitude regions.

Case study of a bore wind-ramp event from lidar measurements and HRRR simulations over ARM Southern Great Plains

The rapid change of wind speed and direction on 21 August 2017 is studied using Doppler lidar measurements at five sites of the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) facility in north-central Oklahoma. The Doppler lidar data were investigated along with meteorological variables such as temperature, humidity, and turbulence available from the large suite of instrumentation deployed at the SGP Central Facility (C1) during the Land-Atmosphere Feedback Experiment in August 2017. Lidar measurements at five sites, separated by 55–70 km, allowed us to document the development and evolution of the wind flow over the SGP area, examine synoptic conditions to understand the mechanism that leads to the ramp event, and estimate the ability of the High-Resolution Rapid Refresh model to reproduce this event. The flow feature in question is an atmospheric bore, a small-scale phenomenon that is challenging to represent in models, that was generated by a thunderstorm outflow northwest of the ARM SGP area. The small-scale nature of bores, its impact on power generation, and the modeling challenges associated with representing bores are discussed in this paper. The results also provide information about model errors between sites of different surface and vegetation types.

Pulsar scintillation through thick and thin: bow shocks, bubbles, and the broader interstellar medium

ABSTRACT Observations of pulsar scintillation are among the few astrophysical probes of very small-scale (≲ au) phenomena in the interstellar medium (ISM). In particular, characterization of scintillation arcs, including their curvature and intensity distributions, can be related to interstellar turbulence and potentially overpressurized plasma in local ISM inhomogeneities, such as supernova remnants, H ii regions, and bow shocks. Here we present a survey of eight pulsars conducted at the Five-hundred-metre Aperture Spherical Telescope (FAST), revealing a diverse range of scintillation arc characteristics at high sensitivity. These observations reveal more arcs than measured previously for our sample. At least nine arcs are observed toward B1929+10 at screen distances spanning $\sim 90~{{\ \rm per\ cent}}$ of the pulsar’s 361 pc path length to the observer. Four arcs are observed toward B0355+54, with one arc yielding a screen distance as close as ∼105 au (&amp;lt;1 pc) from either the pulsar or the observer. Several pulsars show highly truncated, low-curvature arcs that may be attributable to scattering near the pulsar. The scattering screen constraints are synthesized with continuum maps of the local ISM and other well-characterized pulsar scintillation arcs, yielding a three-dimensional view of the scattering media in context.

Drone-Based Vertical Atmospheric Temperature Profiling in Urban Environments

The accurate and detailed measurement of the vertical temperature, humidity, pressure, and wind profiles of the atmosphere is pivotal for high-resolution numerical weather prediction, the determination of atmospheric stability, as well as investigation of small-scale phenomena such as urban heat islands. Traditional approaches, such as weather balloons, have been indispensable but are constrained by cost, environmental impact, and data sparsity. In this article, we investigate uncrewed aerial systems (UASs) as an innovative platform for in situ atmospheric probing. By comparing data from a drone-mounted semiconductor temperature sensor (TMP117) with traditional radiosonde measurements, we spotlight the UAS-collected atmospheric data’s accuracy and such system suitability for atmospheric surface layer measurement. Our research encountered challenges linked with the inherent delays in achieving ambient temperature readings. However, by applying specific data processing techniques, including smoothing methodologies like the Savitzky–Golay filter, iterative smoothing, time shift, and Newton’s law of cooling, we have improved the data accuracy and consistency. In this article, 28 flights were examined and certain patterns between different methodologies and sensors were observed. Temperature differentials were assessed over a range of 100 m. The article highlights a notable accuracy achievement of 0.16 ± 0.014 °C with 95% confidence when applying Newton’s law of cooling in comparison to a radiosonde RS41’s data. Our findings demonstrate the potential of UASs in capturing accurate high-resolution vertical temperature profiles. This work posits that UASs, with further refinements, could revolutionize atmospheric data collection.

Novel experimental and multiscale study of additively manufactured ABS-carbon nanotubes nanocomposites

The additively manufactured (3D printed) nanocomposite parts demonstrate challenges in terms of poor dispersion and agglomeration. To investigate such structures advanced computational models are required to capture smaller-scale phenomena. This study proposes a novel three-scale computational model for calculating the mechanical properties of 3D-printed nanocomposites. The study also proposes a novel water-quenching experimental technique to prepare in situ nanocomposite sheets during nanocomposite filament manufacturing. The computational model integrates Halpin Tsai and Eshelby Mori Tanaka model at the microscale integrated with the asymptotic homogenization model at meso and macro scales to calculate the effective elastic modulus of 3D printed nanocomposite parts. The experimental characterization was performed by using the water quenching method to prepare 0.5 wt%, 1 wt%, 1.5 wt%, and 2 wt% multiwalled carbon nanotube (MWCNT)-ABS nanocomposite filaments, 3D printed parts, and finally tensile testing them. Furthermore, morphological analysis was conducted to study the dispersion and agglomeration effect and effectiveness of the proposed new method. Finally, the computational results were compared with experimental results to validate the model. Elastic modulus showed an increase of 2.79 %, 6.5 %, 9.6 %, and 12.6 % for 0.5 wt%, 1 wt%, 1.5 wt%, and 2.0 wt% CNT-ABS filaments. Similarly, for 2 wt% CNT-ABS and 0.5 wt% CNT-ABS 3D printed parts, a 20.4 % and 10.3 % increase was reported. In comparison with literature reporting a decrease of 3.35 % and an increase of 1 % in the elastic modulus for 1 wt% and 2 wt% CNT-ABS filaments, the present method reported an increase of 6.54 % and 12.6 % respectively. Moreover, for 1 wt% 3D printed part, an increase of 14.2 % compared to 1 % in the literature is reported.

Aerial Drone Imaging in Alongshore Marine Ecosystems: Small-Scale Detection of a Coastal Spring System in the North-Eastern Adriatic Sea

The eastern coastline of the Gulf of Trieste (north-eastern Adriatic Sea, Italy) is characterized by the occurrence of coastal and submarine freshwater springs of karstic origin. In one of these areas, we performed a survey with a drone with a thermal camera installed, in tandem with in situ oceanographic sampling with a CTD. Drone images revealed a small time-space scale (i.e., up to a few meters) phenomenon of freshwater plumes floating over seawater. Comparing sea surface temperature data with those acquired in situ revealed that the phenomenon was not clearly detectable by the classical oceanographic monitoring, this surface spring freshwater layer being too thin. Instead, the drone’s thermal camera detected these dynamics with great accuracy, indicating that aerial drones can be efficiently used for studying fine-scale events involving surface waters (e.g., spills/pollution). The experience gained allowed us to discuss some of the advantages and disadvantages of using drone thermal imaging for monitoring alongshore areas.