Maximum Vertical Extent Research Articles

Evaluating CNN Architectures for the Automated Detection and Grading of Modic Changes in MRI: A Comparative Study.

Modic changes (MCs) classification system is the most widely used method in magnetic resonance imaging (MRI) for characterizing subchondral vertebral marrow changes. However, it shows a high degree of sensitivity to variations in MRI because of its semiquantitative nature. In 2021, the authors of this classification system further proposed a quantitative and reliable MC grading method. However, automated tools to grade MCs are lacking. This study developed and investigated the performance of convolutional neural network (CNN) in detecting and grading MCs based on their maximum vertical extent. In order to verify performance, we tested CNNs' generalization performance, the performance of CNN with that of junior doctors, and the consistency of junior doctors after AI assistance. A retrospective analysis of 139 patients' MRIs with MCs was conducted and annotated by a spine surgeon. Of the 139 patients, MRIs from 109 patients were acquired using Philips scanners from June 2020 to June 2021, constituting Dataset 1. The remaining 30 patients had MRIs obtained from both Philips and United Imaging scanners from June 2022 to March 2023, forming Dataset 2. YOLOv8 and YOLOv5 were developed in PyCharm using the Python language and based on the PyTorch deep learning framework, data enhancement and transfer learning were applied to enhance model generalization. The model's performance was compared with precision, recall, F1 score, and mAP50. It also tested generalizability and compared it with the junior doctor's performance on the second data set (Dataset 2). Post hoc, the junior doctor graded Dataset 2 with CNN assistance. In addition, the region of interest was displayed using the class activation mapping heat map. On the unseen test set, the YOLOv8 and YOLOv5 models achieved precision of 81.60% and 61.59%, recall of 80.90% and 67.16%, mAP50 of 84.40% and 68.88%, and F1 of 0.81 and 0.60 respectively. On Dataset 2, YOLOv8 and junior doctor achieved precision of 95.1% and 72.5%, recall of 68.3% and 60.6%. In the AI-assisted experiment, agreement between the junior doctor and the senior spine surgeon significantly improved from Cohen's kappa of 0.368-0.681. YOLOv8 in detecting and grading MCs was significantly superior to that of YOLOv5. The performance of YOLOv8 is superior to that of junior doctors, and it can enhance the capabilities of junior doctors and improve the reliability of diagnoses.

Life cycle of stratocumulus clouds over 1 year at the coast of the Atacama Desert

Abstract. Marine stratocumulus clouds of the eastern Pacific play an essential role in the earth's energy and radiation budget. Parts of these clouds off the western coast of South America form the major source of water to the hyperarid Atacama Desert coastal region at the northern coast of Chile. For the first time, a full year of vertical structure observations of the coastal stratocumulus and their environment is presented and analyzed. Installed at Iquique Airport in northern Chile in 2018/2019, three state-of-the-art remote sensing instruments provide vertical profiles of cloud macro- and micro-physical properties, wind, turbulence, and temperature as well as integrated values of water vapor and liquid water. Distinct diurnal and seasonal patterns of the stratocumulus life cycle are observed. Embedded in a land–sea circulation with a superimposed southerly wind component, maximum cloud occurrence and vertical extent occur at night but minima at local noon. Nighttime clouds are maintained by cloud-top cooling, whereas afternoon clouds reappear within a convective boundary layer driven through local moisture advection from the Pacific. During the night, these clouds finally re-connect to the maritime clouds in the upper branch of the land–sea circulation. The diurnal cycle is much more pronounced in austral winter, with lower, thicker, and more abundant (5×) clouds than in summer. This can be associated with different sea surface temperature (SST) gradients in summer and winter, leading to a stable or neutral stratification of the maritime boundary layer at the coast of the Atacama Desert in Iquique.

Numerical Study on Wave Run-up to Identify the Most Effective Design of Jakarta’s Outer Sea Dike

The National Capital Integrated Coastal Development (NCICD) is a construction megaproject around Jakarta Bay targeted environmental revitalization and flood mitigation. One of the main projects of NCICD is to develop the Jakarta’s outer sea dike to prevent future disasters triggered by the increase of the sea level around Jakarta Bay. In this paper, we aim to assess and optimize the design of Jakarta’s outer sea dike by investigating the wave run-up phenomenon, which is measured as the maximum vertical extent of wave uprush on a structure above the still water level. We used the Non-linear Shallow Water Equations (NSWE) as our mathematical model to simulate this phenomenon. The NSWE model was solved numerically using the finite volume method on a staggered grid with a wet-dry procedure to obtain accurate wave run-up height. To validate our numerical scheme, we conducted benchmark tests against a publicized experimental dataset, resulting in a good agreement between the numerical and experimental data, which confirms the robustness and accuracy of our model. We then simulate the wave run-up over three different sea dike profiles: single slope, single berm, and single berm with rocks. Our study shows that among the cases we investigated, the single berm with rocks is the most effective design of the sea dike as even small-sized rock units can significantly reduce the wave run-up height.

Identification and Tracking of Locust Swarms by Indian Doppler Weather Radar

The desert Locust swarms are a severe threat to the agriculture sector and have invaded northern India over large areas. Locust swarms are expected to give echoes comparable with those given by heavy precipitation since the Locusts contain more than 50% of their body weight as water. During June and July of 2020, the northern part of India experienced a Locust invasion and they were observed by two Doppler weather radars (DWRs) viz. Delhi and Lucknow. A strong echo in radar reflectivity is observed in both the radars throughout the Locust flight. The mean vertical profile shows echo strength of more than 40 dBZ for all Locust clusters and the maximum vertical extent up to a height of 1.5 km. The tracks were also compared with the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) and showed the possible tracks of Locust reaching Delhi and Lucknow on the day of observation. The five-day backward trajectories on June 27th and July 12th, 2020 indicate air parcel movements from Rajasthan toward Delhi and Lucknow, where the invasion of Locust was observed.

Surface wind and vertical extent features of the explosive cyclones in the Northern Hemisphere based on the ERA‐I reanalysis data

AbstractAlthough explosive cyclones (ECs) have long been a focus of research, there remains a lack of knowledge of the statistical characteristics of their associated maximum surface winds and vertical extents. This study fills this gap by conducting a targeted statistical analysis of ECs in the Northern Hemisphere using the ERA‐I reanalysis data during a 40‐year period. Some new findings are obtained: (a) The average location of formation of ECs undergoes a notable westward and equatorward shift from September to April in the next year which is consistent with the location variations of sea surface temperature's strong gradients in subtropical regions. (b) Extreme ECs with a deepening rate more than 2.0 Bergeron or with a longer lifespan more than 10 days tend to have a larger occurrence number over the Northern Atlantic Ocean than over the Northern Pacific. (c) The maximum surface wind associated with an EC tends to appear between the EC reaching its maximum deepening rate and reaching its minimum central pressure. (d) The northeastern quadrant of ECs accounts for the highest proportion of maximum surface wind and strongest wind speed, as the baroclinic energy conversion is generally strongest in this quadrant. (e) Over 60% of ECs belong to a type of vertically deep cyclone (ECs' top levels show close relationship to ascending motions within their central regions), and they tend to reach their maximum vertical extent around the time when they reach their minimum central pressures. (f) The highest top levels of ECs exhibit an overall upward extending trend as their minimum central pressure decreases or their maximum deepening rate increases.

Corrigendum: Development of a Machine Learning Model for Optimal Applicator Selection in High-Dose-Rate Cervical Brachytherapy

[This corrects the article DOI: 10.3389/fonc.2021.611437.].

The three-dimensional life cycles of potential vorticity cutoffs: a global and selected regional climatologies in ERA-Interim (1979–2018)

Abstract. The aim of this study is to explore the nature of potential vorticity (PV) cutoff life cycles. While climatological frequencies of such near-tropopause cyclonic vortices are well known, their life cycle and in particular their three-dimensional evolution is poorly understood. To address this gap, a novel method is introduced that uses isentropic air parcel trajectories to track PV cutoffs as three-dimensional objects. With this method, we can distinguish the two fundamentally different PV cutoff lysis scenarios on isentropic surfaces: complete diabatic decay vs. reabsorption by the stratospheric reservoir. This method is applied to the ERA-Interim dataset (1979–2018), and the first global climatology of PV cutoffs is presented that is independent of the selection of a vertical level and identifies and tracks PV cutoffs as three-dimensional features. More than 150 000 PV cutoff life cycles are identified and analyzed. The climatology confirms known frequency maxima of PV cutoffs and identifies additional bands in subtropical areas in the summer hemispheres and a circumpolar band around Antarctica. The first climatological analysis of diabatic decay and reabsorption shows that both scenarios occur equally frequently – in contrast to the prevailing opinion that diabatic decay dominates. Then, PV cutoffs are classified according to their position relative to jet streams (equatorward (Type I), between two jets (Type II), and poleward (Type III)). A composite analysis shows distinct dynamical scenarios for the genesis of the three types. Type I forms due to anticyclonic Rossby wave breaking above subtropical surface anticyclones and hardly results in precipitation. Type II results from anticyclonic Rossby wave breaking in mid-latitudes in regions with split-jet conditions and is frequently accompanied by surface cyclogenesis and substantial precipitation. Type III cutoffs preferentially form due to cyclonic Rossby wave breaking within extratropical cyclones in the storm track regions. We show that important track characteristics (speed, travel distance, frequency of decay and reabsorption, isentropic levels) differ between the categories, while lifetime is similar in all categories. Finally, 12 PV cutoff genesis regions in DJF and JJA are selected to study the regional characteristics of PV cutoff life cycles. As a particularly novel aspect, the vertical evolution of PV cutoffs along the life cycle is investigated. We find that, climatologically, PV cutoffs reach their maximum vertical extent about one day after genesis in most regions. However, while in some regions PV cutoffs rapidly disappear at lower levels by diabatic decay, they can grow downward in other regions. In addition, regional differences in lifetimes, the frequencies of diabatic decay and reabsorption, and the link to surface cyclones are identified that cannot be explained only by the preferred regional occurrence of the different cutoff types as defined above. Finally, we also show that in many regions PV cutoffs can be involved in surface cyclogenesis even after their formation. This study is an important step towards quantifying fundamental dynamical characteristics and the surface impacts of PV cutoffs. The proposed classification according to the jet-relative position provides a useful way to improve the conceptual understanding of PV cutoff life cycles in different regions of the globe. However, these life cycles can be substantially modified by specific regional conditions.

Development of a Machine Learning Model for Optimal Applicator Selection in High-Dose-Rate Cervical Brachytherapy.

PurposeTo develop and validate a preliminary machine learning (ML) model aiding in the selection of intracavitary (IC) versus hybrid interstitial (IS) applicators for high-dose-rate (HDR) cervical brachytherapy.MethodsFrom a dataset of 233 treatments using IC or IS applicators, a set of geometric features of the structure set were extracted, including the volumes of OARs (bladder, rectum, sigmoid colon) and HR-CTV, proximity of OARs to the HR-CTV, mean and maximum lateral and vertical HR-CTV extent, and offset of the HR-CTV centre-of-mass from the applicator tandem axis. Feature selection using an ANOVA F-test and mutual information removed uninformative features from this set. Twelve classification algorithms were trained and tested over 100 iterations to determine the highest performing individual models through nested 5-fold cross-validation. Three models with the highest accuracy were combined using soft voting to form the final model. This model was trained and tested over 1,000 iterations, during which the relative importance of each feature in the applicator selection process was determined.ResultsFeature selection indicated that the mean and maximum lateral and vertical extent, volume, and axis offset of the HR-CTV were the most informative features and were thus provided to the ML models. Relative feature importances indicated that the HR-CTV volume and mean lateral extent were most important for applicator selection. From the comparison of the individual classification algorithms, it was found that the highest performing algorithms were tree-based ensemble methods – AdaBoost Classifier (ABC), Gradient Boosting Classifier (GBC), and Random Forest Classifier (RFC). The accuracy of the individual models was compared to the voting model for 100 iterations (ABC = 91.6 ± 3.1%, GBC = 90.4 ± 4.1%, RFC = 89.5 ± 4.0%, Voting Model = 92.2 ± 1.8%) and the voting model was found to have superior accuracy. Over the final 1,000 evaluation iterations, the final voting model demonstrated a high predictive accuracy (91.5 ± 0.9%) and F1 Score (90.6 ± 1.1%).ConclusionThe presented model demonstrates high discriminative performance, highlighting the potential for utilization in informing applicator selection prospectively following further clinical validation.

Characteristics of mesoscale convection over northwestern Mexico, the Gulf of California, and Baja California Peninsula

AbstractMesoscale convective systems (MCSs) are frequent, but understudied, components of the warm season climatology in northwestern Mexico. This study provides an update of previous research on convective development and examines MCS life cycle, structure, and motion from July through September. It focuses on a region south of the North American monsoon core and, from 2009 to 2018 satellite observations, on patterns of cloud tops higher than 10 km above sea level. The diurnal cycle of convection shows cells initiating in the early afternoon over the Sierra Madre Occidental mountains and becoming better organized over the next few hours. These features typically move westward, grow upscale to reach maximum vertical extent near local sunset, and weaken during the night. However, there is a distinct region of deep convection over and off the coast of Nayarit (20–23°N), in the Pacific Ocean, that remains active through the night and into the early morning, producing heavy rainfall and frequent lightning. Occasionally, the inner structure of these MCSs can move across the Gulf of California and reach the southern Baja California Peninsula. One particular long‐lived, fast‐moving MCS from July 23 and 24, 2014 was selected for in‐depth analysis, because it was associated with weather conditions that included unusual precipitation and extreme winds. The MCS caused damage from sustained winds of tropical‐storm strength and an intense gust front in the Los Cabos area, in the southern tip of the peninsula. This extraordinary MCS developed in the most unstable and humid environment recorded during the 1976–2018 period, and was supported by a collocated upper‐level, inverted trough and a lower‐troposphere tropical wave. We also found that the 10 most unstable conditions have all occurred after 2011, possibly indicative of a trend toward more frequent and favourable environments to spawn MCSs over the Gulf of California entrance.

Effects of nonlinear wave loads on large monopile offshore wind turbines with and without ice-breaking cone configuration

In the present paper, the computational fluid dynamics (CFD) method is used to investigate the variation of linear and nonlinear wave loads on a 10-MW large-scale monopile offshore wind turbine under typical sea conditions in the eastern seas of China. The effect of adding a structural ice-breaking cone configuration close to the mean water level on the monopile’s hydrodynamic response is studied further. Results are derived with the use of the CFD model and are compared with the relevant results that are calculated using the Morison equation and the potential flow theory based on the high-order boundary element method. The fifth-order Stokes’ theorem is used to model the incoming wave kinematics, and the volume of fluid (VOF) method is used to capture the free surface of waves and to accurately calculate the wave run-up on the monopile and cone configuration. The influence of different water depths and wave heights on the wave maximum vertical extent of wave uprush on the structure, pressure and horizontal wave forces on the monopile is investigated for both with and without the use of the cone configuration. Up–downward cone configuration results in better performance compared to the inverted cone configuration in terms of reduction of hydrodynamic nonlinear excitation loads and wave maximum vertical extent of wave uprush on the structure.

Ice-Seabed interaction analysis in sand using a gene expression programming-based approach

Arctic subsea pipelines are usually buried for physical protection against the ice-induced scours. Determination of the maximum horizontal deformations for guaranteed operational integrity and cost-effective design is probably the most challenging aspect of subsea pipelines in ice-prone areas. The large uncertainties associated with the design of ice-protected subsea pipeline using the existing empirical equations, advanced experimental and sophisticated numerical studies with significant time and cost impacts are usually preferred to ensure the sufficiency and the cost-effectiveness of the pipeline design against the ice attack. This has caused the industry to keep looking for more effective and less-costly solutions for modeling the ice impact on buried pipelines. In this study, a Gene Expression Programming (GEP) model representing the Artificial Intelligence (AI) approaches was used for the first time to simulate the subgouge soil deformation in the sand. A database was constructed using some of the published experimental studies identifying the key input parameters including soil depth, bearing pressure, the maximum vertical extent of subgouge deformation, attack angle, and dilation index. Subsequently, six GEP models were developed and validated by using a K-fold cross-validation method. The performance of the GEP method was compared with an Artificial Neural Network (ANN) model, and uncertainty analysis (UA) along with a partial derivative sensitivity analysis (PDSA) was conducted to assess the influence domain of the key parameters. The study showed that the evolutionary numerical methods could be used as an accurate and cost-effective alternative for modeling of the ice-induced subgouge deformations.

Local anodic oxidation lithography on organic semiconductor crystals: Oxide depth revealed by conductance tomography

Abstract Nanopatterning electrically insulating oxide lines on organic electronic surfaces can play a role in fabricating future nanoscale devices. Here we write oxide features on rubrene single crystal surfaces by performing local anodic oxidation using the tip of an atomic force microscope. Oxide feature height increases with voltage bias and decreases with tip writing speed, and gaps as small as 22 nm at the surface between two parallel oxide lines were realised. Conductance tomography is employed in a unique way to determine the depths of oxide features, by exposing subsurface layers of the patterned material without using chemical etching while simultaneously mapping material conductance. The oxide line depth exceeds its height, with the depth-to-height ratio frequently being more than 1.6. A critical electric field of ∼3 × 106 V/cm is identified, below which the oxide growth ceases, resulting in a maximum oxide vertical extent of about ∼60 nm at a voltage bias of ∼20 V.

In Situ Temperature Measurements at the Svalbard Continental Margin: Implications for Gas Hydrate Dynamics

AbstractDuring expedition MARIA S. MERIAN MSM57/2 to the Svalbard margin offshore Prins Karls Forland, the seafloor drill rig MARUM‐MeBo70 was used to assess the landward termination of the gas hydrate system in water depths between 340 and 446 m. The study region shows abundant seafloor gas vents, clustered at a water depth of ∼400 m. The sedimentary environment within the upper 100 m below seafloor (mbsf) is dominated by ice‐berg scours and glacial unconformities. Sediments cored included glacial diamictons and sheet‐sands interbedded with mud. Seismic data show a bottom simulating reflector terminating ∼30 km seaward in ∼760 m water depth before it reaches the theoretical limit of the gas hydrate stability zone (GHSZ) at the drilling transect. We present results of the first in situ temperature measurements conducted with MeBo70 down to 28 mbsf. The data yield temperature gradients between ∼38°C km−1 at the deepest site (446 m) and ∼41°C km−1 at a shallower drill site (390 m). These data constrain combined with in situ pore‐fluid data, sediment porosities, and thermal conductivities the dynamic evolution of the GHSZ during the past 70 years for which bottom water temperature records exist. Gas hydrate is not stable in the sediments at sites shallower than 390 m water depth at the time of acquisition (August 2016). Only at the drill site in 446 m water depth, favorable gas hydrate stability conditions are met (maximum vertical extent of ∼60 mbsf); however, coring did not encounter any gas hydrates.

A Meta-Modelling Approach for Estimating Long-Term Wave Run-Up and Total Water Level on Beaches

ABSTRACT Gainza, J.; Rueda, A.; Camus, P.; Tomas, A.; Mendez, F.J.; Sano, M., and Tomlinson, R., 2018. A meta-modelling approach for estimating long-term wave run-up and total water level on beaches. Wave run-up is defined as the maximum vertical extent of wave up-rush on a beach or structure above the sea water level from wave breaking. Wave run-up is responsible for beach and dune erosion and can be an important component of coastal flooding. Run-up can be estimated using either empirical formulations or sophisticated wave-breaking models with high computational demand. On the other hand, meta-models are efficient approximations of physical-process models that enable researchers to obtain long-term time series of wave dynamics. These hybrid models are developed by combining statistical techniques and numerical models. In this study, a methodology to transform offshore sea conditions to long-term time series of wave run-up is described. The methodology combined the construction of two meta-models of offs...

3D implicit modeling of the Sishen Mine: new resolution of the geometry and origin of Fe mineralization

The Sishen deposit is one of the largest iron ore concentrations in current production. Hematite mineralization occurs along a strike length of 14 km, with a width of 3.2 km and a maximum vertical extent of 400 m below the original surface. The 986-Mt reserve incorporates a suite of individual orebodies, beneath a locally preserved tectonized unconformity, with a wide range of geometries, depths, and orientations. Fully constrained, implicit 3D modeling of the entire mining volume (> 70 km3), was undertaken to the original, pre-mining topography. The model incorporates 5287 mapping points and > 21,000 drillholes and provides exceptional insight into the original configuration of ore and its relationship to contacts, unconformities, and structures in the enclosing country rock. The bulk of ore occurs to the west of a strike-extensive, partially inverted normal fault (Sloep Fault), within an asymmetrical synclinal structure on its western flank. This linear, N-S distribution of deep, thick ore is punctuated by palaeosinkholes, wherein base-of-ore dips of greater than 45°, are concentrically arranged. Localized ore volumes also occur along faults and in fault-bounded, downthrown blocks, to the north of NW-SE- and NE-SW-trending strike-slip faults that show relatively minor uplift to the south, probably due to the Lomanian Namaqua-Natal Orogeny. The revised model demonstrates the proximity of ore to a tectonized unconformity and highlights the structural control on ore volumes, implying that Fe mineralization at Sishen cannot be exclusively attributed to supergene enrichment and concentric palaeosinkhole formation.

Dynamics of multiphase turbulent plumes with hybrid buoyancy sources in stratified environments

Deepwater oil blowouts typically generate multiphase hybrid plumes where the total inlet buoyancy flux is set by the combined presence of gas, oil, and heat. We numerically investigate the effects of combined sources of inlet buoyancy on turbulent plume dynamics by varying the inputs of a dispersed, slipping gas phase and a non-slipping buoyant liquid phase in thermally stratified environments. The ability of a single momentum equation, multiphase model to correctly reproduce characteristic plume heights is validated for both dispersed liquid phase and pure gas bubble plumes. A hybrid case, containing buoyancy contributions from both gas and liquid phases, is also investigated. As expected, on the plume centerline, the presence of a slipping gas phase increases both the vertical location of the neutrally buoyant equilibrium height and the maximum vertical extent of the liquid effluent relative to non-bubble plumes. While producing an overall increase in the plume height, the presence of a slipping gas phase also significantly enhances both the extent and magnitude of negatively buoyant downdrafts in the outer plume region. As a result, the intrusion or trapping height, the vertical distance where liquid phase plume effluent accumulates, is found to be significantly lower in both bubble and hybrid plumes. Below the intrusion level, the simulations are compared to an integral model formulation that explicitly accounts for the effects of the gas slip velocity in the evolution of the buoyancy flux. Discrepancies in the integral model and full solutions are largest in the source vicinity region where vertical turbulent volume fluxes, necessarily neglected in the integral formulation, are significant.

Paleoceanographic insights on recent oxygen minimum zone expansion: lessons for modern oceanography.

Climate-driven Oxygen Minimum Zone (OMZ) expansions in the geologic record provide an opportunity to characterize the spatial and temporal scales of OMZ change. Here we investigate OMZ expansion through the global-scale warming event of the most recent deglaciation (18-11 ka), an event with clear relevance to understanding modern anthropogenic climate change. Deglacial marine sediment records were compiled to quantify the vertical extent, intensity, surface area and volume impingements of hypoxic waters upon continental margins. By integrating sediment records (183-2,309 meters below sea level; mbsl) containing one or more geochemical, sedimentary or microfossil oxygenation proxies integrated with analyses of eustatic sea level rise, we reconstruct the timing, depth and intensity of seafloor hypoxia. The maximum vertical OMZ extent during the deglaciation was variable by region: Subarctic Pacific (~600-2,900 mbsl), California Current (~330-1,500 mbsl), Mexico Margin (~330-830 mbsl), and the Humboldt Current and Equatorial Pacific (~110-3,100 mbsl). The timing of OMZ expansion is regionally coherent but not globally synchronous. Subarctic Pacific and California Current continental margins exhibit tight correlation to the oscillations of Northern Hemisphere deglacial events (Termination IA, Bølling-Allerød, Younger Dryas and Termination IB). Southern regions (Mexico Margin and the Equatorial Pacific and Humboldt Current) exhibit hypoxia expansion prior to Termination IA (~14.7 ka), and no regional oxygenation oscillations. Our analyses provide new evidence for the geographically and vertically extensive expansion of OMZs, and the extreme compression of upper-ocean oxygenated ecosystems during the geologically recent deglaciation.

Radial intrusions from turbulent plumes in uniform stratification

Laboratory experiments investigate the radial spread of an intrusion created by a turbulent forced plume in uniformly stratified ambient fluid. The flow evolution is determined as it depends upon the ambient buoyancy frequency, N, and the source momentum and buoyancy fluxes, M0 and F0, respectively. The plume reaches its maximum vertical extent, Zm, collapses back upon itself as a fountain and then spreads radially outwards at its neutral buoyancy depth, Zs, where the intrusion has the same density as the ambient. Through theory and experiments we determine that Zs = f(σ)Hp, in which Hp = M03/4F0−1/2, σ = (M0N/F0)2, and f(σ) ∝ σ−3/8 for σ ≲ 50 and f(σ) ∝ σ−1/4 for σ ≳ 50. In the inertia-buoyancy regime the intrusion front advances in time approximately as Rf ∝ t3/4, consistent with models assuming a constant buoyancy flux into the intrusion. Where the intrusion first forms, at radius R1, its thickness h1 is approximately constant in time. The thickness of the intrusion as a whole, h(r, t), adopts a self-similar shape of the form h/h1 ≃ [(Rf − r)/(Rf − R1)]p, with p ≃ 0.55 ± 0.03. The comparison of these results to large volcanic plumes penetrating into and spreading in the stratosphere is discussed.

A numerical study of the evolution of a mesoscale convective vortex on the Meiyu front

The Advanced Research WRF (Weather Research and Forecasting) model is used to simulate the evolution of a mesoscale convective vortex (MCV) that formed on the Meiyu front and lasted for more than two days. The simulation is used to investigate the underlying reasons for the genesis, intensification, and vertical expansion of the MCV. This MCV is of a type of mid-level MCV that often develops in the stratiform regions of mesoscale convective systems. The vortex strengthened and reached its maximum intensity and vertical extent (from the surface to upper levels) when secondary organized convection developed within the mid-level circulation. The factors controling the evolution of the kinetic and thermal structure of the MCV are examined through an analysis of the budgets of vorticity, temperature, and energy. The evolution of the local Rossby radius of deformation reveals the interrelated nature of the MCV and its parent mesoscale convective system.

A buried glaciofluvial channel in the Anděl Col, Northern Bohemia: new evidence for the Middle Pleistocene ice sheets extent in Western Sudetes

This study presents a new finding of glaciofluvial sediments filling a buried channel in the Anděl Col (522 m a.s.l.) in the Jizera Mts., on the Czech-Polish border. At least 550 m long and 55–100 m wide channel filled by glaciofluvial sediments was determined by geophysical methods in the lowermost part of the col. The base of the channel was found at a depth of 14–19 m under the present ground surface, descending from east to west draining the ice sheet front in the same direction. The channel is incised in the bedrock representing thus a Nye channel and is filled by >13 m of glaciofluvial sand, gravel and mud, which is covered by 1–2 m thick colluvial deposits. The large part of the glaciofluvial package was deposited in subglacial environment reflecting the ice sheet decay events of higher release of the material from the ice sheet. The upper glaciofluvial part of sediments was deposited in front of the slowly decaying ice sheet front. No subglacial tills have been found in the col area, which is not unusual for such an exposed site. We reconstruct the maximum altitude limit of the ice sheet in the col as being at least at ~540 m and the ice thickness in the Anděl Col being few tens of metres. The Anděl Col is the highest known area in Northern Bohemia covered by an ice sheet and improves thus our knowledge about the maximum vertical extent of Middle Pleistocene ice sheets in Western Sudetes.