Relative Dispersion Research Articles

THERMAL INFLUENCE ON THE MICROSTRUCTURE AND THE MICRO HARDNESS OF A CARBON STEEL WELD PROBES

During welding, the heat produced during the process can affect the microhardness and the microstructure of the material. The change in the microstructure and the microhardness can be discovered by carrying out a microhardness test on the welded sample and compare changes in the three different zones i.e the base, the weld and the Heat affected zone or by carrying out a micro structural examination on the welded sample and see the grain dispersion in relation to their sizes. In this work, weld quality of manual arc welded samples of low-carbon steel St3spdestined for bridge construction to be used in Cameroon has been investigated. After a chemical analysis of the material, a micro hardness test and a micro structural examination was also done. Results show that a composition of pearlite and ferrite was seen with the print of the id enter of the micro hardness test. The formation of pearlite and ferrite in base metalis composed of 20/80 respectively. For weld zone and HAZ it changes due to thermal processes. So the microstructure analysis shows that the base metal is a ferrite and pearlite having a grain size of 11-12 on a scale corresponding to an average grain diameter ≈ 7 microns. The structure of the weld metal is also made up of ferrite and pearlite with columnar crystals of cast metal. The HAZ is made up of Widmanstätten. The width of the HAZ zone is about 1,5 mm. In different areas of heat affected zone is observed fine-grained ferrite-pearlite structure with a high degree of dispersion.

High Birefringence and Negative Dispersion Based Modified Decagonal Photonic Crystal Fibers: A Numerical Study

Abstract In this paper, an extremely birefringent PCF based on a modified decagonal (MD-PCF) arrangement is studied for broadband compensation covering the S-, C- and L-communication bands wavelength ranging from 1460 to 1625 nm. It is made known in theory that it is conceivable to attain negative dispersion coefficient about − 448 to − 835 ps/nm/km covering S-, C- and L-communication bands as well as a relative dispersion slope near to single mode fiber (SMF) of 0.0036 nm−1. On the basis of simulation results incorporating finite-element method based COMSOL multiphysics software, birefringence is obtained as high as 1.7 × 10−2, which is definately greater than conventional step-index fiber (SIF) and circular air- holes PCF so far. We also discuss the characteristics of chromatic dispersion, effective area and confinement loss of the designed PCF.

Noise-based ballistic wave passive seismic monitoring – Part 2: surface waves

SUMMARYWe develop a new method to monitor and locate seismic velocity changes in the subsurface using seismic noise interferometry. Contrary to most ambient noise monitoring techniques, we use the ballistic Rayleigh waves computed from 30 d records on a dense nodal array located above the Groningen gas field (the Netherlands), instead of their coda waves. We infer the daily relative phase velocity dispersion changes as a function of frequency and propagation distance with a cross-wavelet transform processing. Assuming a 1-D velocity change within the medium, the induced ballistic Rayleigh wave phase shift exhibits a linear trend as a function of the propagation distance. Measuring this trend for the fundamental mode and the first overtone of the Rayleigh waves for frequencies between 0.5 and 1.1 Hz enables us to invert for shear wave daily velocity changes in the first 1.5 km of the subsurface. The observed deep velocity changes (±1.5 per cent) are difficult to interpret given the environmental factors information available. Most of the observed shallow changes seem associated with effective pressure variations. We observe a reduction of shear wave velocity (–0.2 per cent) at the time of a large rain event accompanied by a strong decrease in atmospheric pressure loading, followed by a migration at depth of the velocity decrease. Combined with P-wave velocity changes observations from a companion paper, we interpret the changes as caused by the diffusion of effective pressure variations at depth. As a new method, noise-based ballistic wave passive monitoring could be used on several dynamic (hydro-)geological targets and in particular, it could be used to estimate hydrological parameters such as the hydraulic conductivity and diffusivity.

A closing call’s impact on market quality: evidence from Abu Dhabi stock exchange

Purpose This paper aims to look at the effects of the closing call auction on market quality and behavior by using the natural experiment of its introduction at the Abu Dhabi Stock Exchange. Design/methodology/approach Current paper studies the effect of closing call auction on various market quality factors such as liquidity, bid-ask spreads, volatility and market efficiency. Liquidity is proxied by trading volume. Bid-ask spreads provide a measure for the cost of trading in the market. Volatility is measured by using Parkinson’s (1980) volatility as in Huang and Tsai (2008). Last but not least, efficiency will be obtained by estimating a relative return dispersion measure as in Huang and Tsai (2008). Findings The introduction of the closing call auction leads to a significant decrease in the trading volume toward the end of the continuous trading. At the same time, trading activity taking place during the call auction significantly increases. This implies a redistribution of liquidity. The implementation of the closing call auction also improves market quality by reducing market inefficiency in terms of firm-specific noise. The study also documents that there exists no significant change in the cost of trading and intraday volatility in the post-period following the adoption of closing call auction. Originality/value This current study is the first one looking at this topic for the Abu Dhabi Stock Exchange. Specifically, this paper looks at the changes in trading volume, bid-ask spreads, intraday return volatility and market efficiency after the implementation of the closing call mechanism.

Preparation and dispersion of multi-walled carbon nanotubes in Ti6Al4V metal matrix powders

Abstract This study investigated the preparation and dispersion of graphitized multi-walled carbon nanotubes (MWCNTs) into Ti6Al4V metal matrix powders. As-received MWCNTs powder was subjected to graphitization treatment for 5 h at 1800 °C in a vacuum atmosphere. 0, 1, 2 and 3 wt. % of the graphitized MWCNTs were dispersed by high energy ball milling (HEBM) into the Ti6Al4V matrices. The milled composite powders were thereafter characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques respectively. The results showed the optimized HEBM technique that was used for the MWCNTs dispersion achieved a relative homogeneous dispersion of the reinforcement powder into Ti6Al4V. There was minimal damage to the MWCNTs during the dispersion processing by milling, as interfacial reactions between defective MWCNTs and the metal matrix was effectively controlled

Economic Benefits of Product Recommendations to Consumers: Estimates from a Field Experiment

Do personalized offerings enabled by big data only bring economic benefits to firms but not to consumers? In this paper, we seek to address this question by examining a particular category of personalized offerings provided by algorithmic product recommendation systems. While the economic value of algorithmic product recommendations to firms is mostly understood, their benefits to consumers are not well quantified in the literature. We conduct a randomized field experiment on an apparel retailer’s website in the US to estimate the benefits of recommendations to consumers. We find that recommendations helped consumers discover lower-priced products on the website, which results in a higher probability of product purchase (lower likelihood of failed search efforts) and a lower price of purchased products. Specifically, an additional recommended product page view due to recommendations leads to a 15 percent increase in purchase probability and a $1.59 decrease in the purchase price. The product recommendations are particularly beneficial to consumers for product categories with a higher relative price dispersion and a higher proportion of niche products. Due to these benefits, consumers substitute 0.14 keyword search page views and 0.63 product category page views for each recommended product page view under recommendations. The recommendations generated a surplus of $56,631 (3.8 percent of the total sales), two-thirds of which the retailer captured as additional revenue, and the remaining one-third the consumers as price savings.

Quality Differentiation and Spatial Clustering among Restaurants

To explore the relationship between spatial location and quality differentiation, we build a dataset of over 30,000 restaurants rated by TripAdvisor, across large UK cities. Whereas top-rated restaurants tend to locate close to other top restaurants, bottom-rated restaurants tend to locate away from each other and closer to top ones. Our theoretical model can explain the main features of observed spatial patterns. We find that an increase in the population density in the city center reduces the spatial dispersion of both top and bottom restaurants but this reduction is larger in magnitude for top restaurants. Also, a larger quality difference between top and bottom restaurants increases both the absolute and relative dispersion of top restaurants.

Two-Dimensional Nanomaterials-Based Polymer Composites: Fabrication and Energy Storage Applications

Polymers have been widely used for their low density, low cost, corrosion resistance, easy design, and processing. The addition of nanomaterials into polymer matrices has been studied for a long history due to their enhancement on properties of polymers, such as the electrical conductivity, thermal conductivity, corrosion resistance, and wear resistance. Two-dimensional materials, a new class of nanomaterials, have been intensively studied as a filler for polymer composites in recent years, which can significantly enhance the performance at even extremely small loading. In this review, firstly, the preparing and modifying method of 2D materials, such as graphene, graphene oxide, and hexagonal boron nitride, as a filler for polymer composites are organized. The related dispersion methods of 2D materials in the polymers, surface treatments of 2D materials, interface bonding between 2D materials and polymers are discussed alongside. Secondly, the applications of 2D materials/polymer composites for energy storage in lithium ion battery separators and supercapacitors are summarized. Finally, we have concluded the challenges in preparing 2D materials/polymer composites, and future perspectives for using this class of new composites have also been discussed.

Small-Scale Dispersion in the Presence of Langmuir Circulation

AbstractWe present an analysis of ocean surface dispersion characteristics, on 1–100-m scales, obtained by optically tracking a release of bamboo plates for 2 h in the northern Gulf of Mexico. Under sustained 5–6 m s−1 winds, energetic Langmuir cells are clearly delineated in the spatially dense plate observations. Within 10 min of release, the plates collect in windrows with 15-m spacing aligned with the wind. Windrow spacing grows, through windrow merger, to 40 m after 20 min and then expands at a slower rate to 50 m. The presence of Langmuir cells produces strong horizontal anisotropy and scale dependence in all surface dispersion statistics computed from the plate observations. Relative dispersion in the crosswind direction initially dominates but eventually saturates, while downwind dispersion exhibits continual growth consistent with contributions from both turbulent fluctuations and organized mean shear. Longitudinal velocity differences in the crosswind direction indicate mean convergence at scales below the Langmuir cell diameter and mean divergence at larger scales. Although the second-order structure function measured by contemporaneous GPS-tracked surface drifters drogued at ~0.5 m shows persistent r2/3 power law scaling down to 100–200-m separation scales, the second-order structure function for the very near surface plates observations has considerably higher energy and significantly shallower slope at scales below 100 m. This is consistent with contemporaneous data from undrogued surface drifters and previously published model results indicating shallowing spectra in the presence of direct wind-wave forcing mechanisms.

The influence of leakage magnetic slit on imaging performance of framing camera

A pulse-dilation framing camera is designed using a combination of magnetic lenses. The axial magnetic field distribution, electronic trajectory and imaging distribution on the object plane are simulated, and the influence of leakage magnetic slit on imaging performance of camera is analyzed. Results show that increasing the leakage magnetic slit improves the imaging performance away from axial area. At an acceleration energy of 3keV, the width of magnetic slit increases from 10 to 70mm, the relative imaging dispersion degree between on-axis and off-axis decreases from 0.27 to 0.06, and the relative mean deflection angle decreases from 65.17° to 59.44°. These features contribute towards further optimization of structural parameters of the magnetic lens and provide design guidelines for achieving a pulse-dilation framing camera with better imaging performance.

Seasonality of surface stirring by geostrophic flows in the Bay of Bengal

Stirring of passive tracers in the Bay of Bengal driven by altimetry derived daily geostrophic surface currents, is studied on subseasonal timescales. To begin with, Hovmöller plots, wavenumber-frequency diagrams and power spectra confirm the multiscale nature of the flow. Advection of latitudinal and longitudinal bands highlights the chaotic nature of stirring in the Bay via repeated straining and filamentation of the tracer field. An immediate finding is that stirring is local, i.e. of the scale of the eddies, and does not span the entire basin. Further, stirring rates are enhanced along the coast of the Bay and are relatively higher in the pre- and post-monsoonal seasons. Indeed, Finite Time Lyapunov Exponent (FTLE) and Finite Size Lyapunov Exponent (FSLE) maps in all the seasons are patchy with minima scattered through the interior of the Bay. Further, these maps bring out a seasonal cycle wherein rapid stirring progressively moves from the northern to southern Bay during pre- and post-monsoonal periods, respectively. The non-uniform stirring of the Bay is reflected in long tailed probability density functions of FTLEs, that become more stretched for longer time intervals. Quantitatively, advection for a week shows the mean FTLE lies between 0.13±0.07 day−1, while extremes reach almost 0.6 day−1. Averaged over the Bay, Relative dispersion initially grows exponentially, followed by a power-law at scales between approximately 100 and 250 km, which finally transitions to an eddy-diffusive regime. Quantitatively, below 250 km, a scale dependent diffusion coefficient is extracted that behaves as a power-law with cluster size, while above 250 km, eddy-diffusivities range from 6×103−1.6×104 m2s−1 in different regions of the Bay. These estimates provide a useful guide for resolution dependent diffusivities in numerical models that hope to properly represent surface stirring in the Bay.

Impact of driving dynamics in RDE test on NOx emissions dispersion

EU6D emission regulation intends to bridge the gap between laboratory tests and the real driving conditions by introducing real drive emission testing. It requires the measurement of real drive emission to be an additional type approval test in order to take into account the influence of road profile, ambient conditions and traffic situations. An important amendment has been included in Commission regulation (European Union) 2016/646, limiting the driving dynamics and hence avoiding the biased testing of the vehicle. In this work, a drive cycle generator has been developed to synthesise cycles meeting all the regulatory requirements of the real drive emission testing. The generator is based on the transition probability matrix obtained from each phase of the World harmonised Light vehicle Test Procedure cycle. Driving dynamics have been varied based on real drive emission regulations, and several trips have been generated with dynamics ranging from soft to aggressive. A direct injection compression ignition 1.5 L engine with a state-of-the-art aftertreatment system has been utilised to run the generated synthetic cycles. The analysis of the results obtained in the tests (all of them complying with real drive emission restrictions in terms of driving dynamics) points out a noticeable 60% relative dispersion in the NO x emissions downstream of the catalyst. The contribution of the proposed method lies not only in the fact that it synthesises driving cycles as stochastic process and is capable of tuning the driving dynamics based on real drive emission regulations, but it also presents the range of dispersion possible in NO x emissions solely due to the driving dynamics. The methodology followed in the present work could be an essential step in future engine developments, where testing engine prototypes on the entire range of driving dynamics in the engine test bench facility could provide interesting insights about the expected NO x emissions in real drive emission testing.

To remain or leave: Dispersal variation and its genetic consequences in benthic freshwater invertebrates.

Variation in dispersal capacity may influence population genetic variation and relatedness of freshwater animals thus demonstrating how life‐history traits influence patterns and processes that in turn influence biodiversity. The majority of studies have focused on the consequences of dispersal variation in taxa inhabiting riverine systems whose dendritic nature and upstream/downstream gradients facilitate characterizing populations along networks. We undertook extensive, large‐scale investigations of the impacts of hydrological connectivity on population genetic variation in two freshwater bryozoan species whose dispersive propagules (statoblasts) are either attached to surfaces (Fredericella sultana) or are released as buoyant stages (Cristatella mucedo) and that live primarily in either lotic (F. sultana) or lentic environments (C. mucedo). Describing population genetic structure in multiple sites characterized by varying degrees of hydrological connectivity within each of three (or four) UK regions enabled us to test the following hypotheses: (1) genetic diversity and gene flow will be more influenced by hydrological connectivity in populations of C. mucedo (because F. sultana dispersal stages are retained); (2) populations of F. sultana will be characterized by greater genetic divergence than those of C. mucedo (reflecting their relative dispersal capacities); and (3) genetic variation will be greatest in F. sultana (reflecting a propensity for genetic divergence as a result of its low dispersal potential). We found that hydrological connectivity enhanced genetic diversity and gene flow among C. mucedo populations but not in F. sultana while higher overall measures of clonal diversity and greater genetic divergence characterized populations of F. sultana. We suggest that genetic divergence over time within F. sultana populations reflects a general constraint of releasing propagules that might eventually be swept to sea when taxa inhabit running waters. In contrast, taxa that primarily inhabit lakes and ponds may colonize across hydrologically connected regions, establishing genetically related populations. Our study contributes more nuanced views about drivers of population genetic structures in passively dispersing freshwater invertebrates as outlined by the Monopolization Hypothesis (Acta Oecologica, 23, 2002, 121) by highlighting how a range of demographic and evolutionary processes reflect life‐history attributes of benthic colonial invertebrates (bryozoans) and cyclically parthenogenetic zooplankton. In addition, growing evidence that genetic divergence may commonly characterize populations of diverse groups of riverine taxa suggests that organisms inhabiting lotic systems may be particularly challenged by environmental change. Such change may predispose riverine populations to extinction as a result of genetic divergence combined with limited dispersal and gene flow.Open Research Badges This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.5061/dryad.1tm8705.

Experimental investigation of vertical turbulent transport of a passive scalar in a boundary layer: Statistics and visibility graph analysis

The dynamics of a passive scalar plume in a turbulent boundary layer is experimentally investigated via vertical turbulent transport time-series. Data are acquired in a rough-wall turbulent boundary layer that develops in a recirculating wind tunnel set-up. Two source sizes in an elevated position are considered in order to investigate the influence of the emission conditions on the plume dynamics. The analysis is focused on the effects of the meandering motion and the relative dispersion. First, classical statistics are investigated. We found that (in accordance with previous studies) the meandering motion is the main responsible for differences in the variance and intermittency, as well as the kurtosis and power spectral density, between the two source sizes. On the contrary, the mean and the skewness are slightly affected by the emission conditions. To characterize the temporal structure of the turbulent transport series, the visibility algorithm is exploited to carry out a complex network-based analysis. Two network metrics -- the average peak occurrence and the assortativity coefficient -- are analysed, as they can capture the temporal occurrence of extreme events and their relative intensity in the series. The effects of the meandering motion and the relative dispersion of the plume are discussed in the view of the network metrics, revealing that a stronger meandering motion is associated with higher values of both the average peak occurrence and the assortativity coefficient. The network-based analysis advances the level of information of classical statistics, by characterizing the impact of the emission conditions on the temporal structure of the signals in terms of extreme events and their relative intensity. In this way, complex networks provide -- through the evaluation of network metrics -- an effective tool for time-series analysis of experimental data.

Geometric characteristics of collagen have independent prognostic significance in breast ductal carcinoma in situ: an image analysis study

Collagen plays a key role in normal and malignant tissue homeostasis. While the prognostic significance of collagen fiber remodeling in invasive breast cancer has been studied, its role in ductal carcinoma in situ (DCIS) remains poorly defined. Using image analysis, we aimed to evaluate the prognostic significance of the geometric characteristics of collagen surrounding DCIS. A large well-characterized cohort of DCIS comprising pure DCIS (n = 610) and DCIS coexisting with invasive carcinoma (n = 180) were histochemically stained for collagen using picrosirius red. ImageJ software was used to assess collagen density, degree of collagen fiber dispersion and directionality in relation to DCIS ducts' boundary. We developed a collagen prognostic index and evaluated its prognostic significance. A poor index was observed in 24% of the pure DCIS and was associated with determinants of high-risk DCIS including higher nuclear grade, comedo type necrosis, hormonal receptor negativity, HER2 positivity and high proliferation index. High collagen prognostic index was associated with the collagen remodeling protein prolyl-4-hydroxlase alpha subunit 2 and the hypoxia-related protein hypoxia inducible factor 1α. DCIS coexisting with invasive breast cancer had a higher collagen prognostic index than pure DCIS ( p < 0.0001). High index was an independent poor prognostic factor for DCIS recurrence for all recurrences (HR = 2.3, p = 0.005) and just invasive recurrences (HR = 3.4, p = 0.003). Interaction between collagen prognostic index and radiotherapy showed that the index was associated with poor outcome even with adjuvant radiotherapy ( p = 0.0001). Collagen reorganization around DCIS is associated with poor outcome and provides a potential predictor for disease progression and resistance to radiotherapy. Mechanistic studies are warranted to decipher the underlying mechanisms.

Kalman Filter-Based Novel Methodology to Assess Insulin Pump Accuracy.

Background: Insulin pump or continuous subcutaneous insulin infusion (CSII) system is a widely adopted contemporary treatment for type 1 diabetes and is a major component of an artificial pancreas (AP). CSII accuracy is essential for glycemic control and to-date such metric has not been given sufficient study, especially at the range of the lowest basal rate. The gold-standard assessment method IEC (International Electrotechnical Commission) 60601-2-24 has some limitations. Our study presents a new accurate and reactive method for CSII system evaluation based on direct flow measurement. Materials and Methods: A leading-edge assessment method based on a double measurement approach utilizing a direct mass flow meter and a time-stamped microgravimetric bench test was combined with a Bayesian-based mathematical filter (Kalman). The performance of this new method was evaluated while assessing the delivery precision of an off-the-shelf insulin pump at several basal rates. The proposed methodology offers a double reading-volume and flow rate-which provides direct instantaneous flow rate. CSII dose errors were evaluated using mean absolute relative dispersion (MARD) at different time intervals windows over the whole test. Results: The metrological aspect of the measurements and filtering performance were consistent. CSII precision is shown to be different in terms of the flow rate value: MARD15min (2 UI/h) = 12.7%, MARD15min (0.5 UI/h) = 20.4%, and MARD15min (0.1 UI/h) = 65.0%. MARD240min (2 UI/h) = 8.1%, (0.5 UI/h), MARD240min (0.5 UI/h) = 18.8%, and MARD240min (0.1 UI/h) = 18.4%. Instantaneous flow rate results highlight an irregular stroke-based delivery. Conclusion: This new method to assess insulin pump administration has been validated and highlights the current imprecision in insulin delivery, especially for the lowest basal rate, which is mainly used in pediatric cases and AP system delivery. This leading-edge method should be used to precisely compare several CSII performances in those contexts.

The Adiabatic Invariant of Dark Matter in Spiral Galaxies

Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.

Design Of Low Power 6t-Sram Cell For Advanced Processors

The Static Random Access Memory (SRAM) is one of the feature of the robotized world. Everything thought of it as, channels creature level of intensity &amp; bomb wretchedly zone. In that point of confinement wide investigate in the SRAM is an advancing related power dispersal, memory chip zone &amp; supply voltage major. This paper SRAM assessment to the degree Static Noise Margin, Data Retention Voltage, Read Margin &amp; Write Margin for low control application is considered. The Static Noise Margin (SNM) is one of the very peak head for essentials of dealing with memory since it effects read edge sensibly as the structure_ edge. In the SRAM cell SNM is identified with the NMOS &amp; PMOS contraption's most purged point respects. The High Read &amp; Write Noise Margin is other than true bugs in the structure of the SRAM information retention Voltage is consented to 6T-SRAM cell for the applications requiring lively works out. The Various sorts of wind are taken unmistakably to examinations to the 6t-SRAM by fluctuating the size of the transistor. The Execution appraisal is examined in 6T-SRAM oversaw and finished in 32nm progression.

Frequency-dependent impedance and surface waves on the boundary of a stratified dielectric medium.

We analyse waves propagating along the interface between half-spaces filled with a perfect dielectric and a Lorentz material. We show that the corresponding interface condition leads to a generalization of the classical Leontovich condition on the boundary of a dielectric half-space. We study when this condition supports propagation of (dispersive) surface waves. We derive the related dispersion relation for waves along the boundary of a stratified half-space and determine the relationship between the loss parameter, frequency and wavenumber for which interfacial waves exist.This article is part of the theme issue ‘Modelling of dynamic phenomena and localization in structured media (part 1)’.

Coincident Observations of Dye and Drifter Relative Dispersion over the Inner Shelf

AbstractCoincident Lagrangian observations of coastal circulation with surface drifters and dye tracer were collected to better understand small-scale physical processes controlling transport and dispersion over the inner shelf in the Gulf of Mexico. Patches of rhodamine dye and clusters of surface drifters at scales of O(100) m were deployed in a cross-shelf array within 12 km from the coast and tracked for up to 5 h with airborne and in situ observations. The airborne remote sensing system includes a hyperspectral sensor to track the evolution of dye patches and a lidar to measure directional wavenumber spectra of surface waves. Supporting in situ measurements include a CTD with a fluorometer to inform on the stratification and vertical extent of the dye and a real-time towed fluorometer for calibration of the dye concentration from hyperspectral imagery. Experiments were conducted over a wide range of conditions with surface wind speed between 3 and 10 m s−1 and varying sea states. Cross-shelf density gradients due to freshwater runoff resulted in active submesoscale flows. The airborne data allow characterization of the dominant physical processes controlling the dispersion of passive tracers such as freshwater fronts and Langmuir circulation. Langmuir circulation was identified in dye concentration maps on most sampling days except when the near surface stratification was strong. The observed relative dispersion is anisotropic with eddy diffusivities O(1) m2 s−1. Near-surface horizontal dispersion is largest along fronts and in conditions dominated by Langmuir circulation is larger in the crosswind direction. Surface convergence at fronts resulted in strong vertical velocities of up to −66 m day−1.