Through-Thickness Vertically Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing
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99 GENERAL AND MISCELLANEOUS↗
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Investigations of vertical wind variations at a mountain top in the Himalaya using Doppler Lidar observations and model simulations
Hight-resolved observations of vertical winds remain nearly non-existing over the Himalayas, despite of anticipated crucial role of vertical motions in transporting pollution across the Himalayan hms. The present study analyze the vertical wind observations from surface to 1 km above ground level over Manora Peak (29.4° N; 79.5° E; 1958 m ams!) in the Himalaya performed using a Doppler Lidar during the Ganges Valley Aerosol Experiment (GVAX). Vertical wind exhibited a pronounced diurnal variability at Manora Peak comprising of upward motions during the daytime (05-10 UT) and downward motions during nighttime typical of a mountainvalley system. Mean vertical wind speeds are observed to be varying from -0.8 to +0.8 ms- 1 during the study period with a variance of 0.1-1.5 m2s·2, which is attributed to the thermally driven turbulence. Mean vertical winds are observed to be stronger in the Doppler Lidar profiles above Manora Peak (-0_8 to 0.8 ms- 1) as compared to near surface measurements at this station using an ultrasonic anemometer ( -0.4 to 0.4 ms - 1 ), and low altitude stations in India. Daytime vertical wind speeds are observed to be higher during pre-monsoon (0.81 ms- 1), as compared to post-monsoon (0.24 ms- 1) and winter (0.33 ms- 1)_ Average Black Carbon (BC) concentrations are significantly higher during strong upward vertical winds, which indicates efficient transport of polluted air mass from low-altitude regions to the Himalaya. Weather Research and Forecasting (WRF) model reproduces the observed diurnal pattern in the vertical wind at the observation site however the model underestimates the variability.
Shukla, K K.↗
Hard-switching reliability studies of 1200 V vertical GaN PiN diodes
Here, we report on reliability testing of vertical GaN (v-GaN) devices under continuous switching conditions of 500, 750, and 1000 V. Using a modified double-pulse test circuit, we evaluate 1200 V-rated v-GaN PiN diodes fabricated by Avogy. Forward current–voltage characteristics do not change over the stress period. Under the reverse bias, the devices exhibit an initial rise in leakage current, followed by a slower rate of increase with further stress. The leakage recovers after a day's relaxation which suggests that trapping of carriers in deep states is responsible. Overall, we found the devices to be robust over the range of conditions tested.
36 MATERIALS SCIENCE↗
Data for Impact of Vertical and Seasonal Variation in Leaf Traits on Simulating Soybean Canopy Photosynthesis via 1D and 3D Modeling
Accurate modeling of photosynthesis is crucial for predicting crop productivity and quantifying the carbon cycle in agroecosystems. Leaf traits are essential inputs for modeling canopy photosynthesis. Yet, many existing models still use fixed plant functional type (PTF)-based values to parameterize leaf traits under a big-leaf or two-big-leaf assumption, neglecting their vertical profiles and seasonal changes. This simplification may introduce significant uncertainties in estimating gross primary productivity (GPP). In this study, we simulated soybean GPP and tested the effects of vertical and seasonal variation in three key leaf photosynthetic traits: the maximum carboxylation rate at 25 °C (Vcmax25), leaf chlorophyll content (LCC), and leaf mass per area (LMA) in the 1D-SCOPE and 3D-Helios models. Weekly field measurements were conducted during the growing season of 2024 to support the simulation. We designed ten leaf trait parameterization schemes by incorporating different combinations of vertical profiles and seasonal changes, while assuming homogeneous canopy architecture in both models. Our results revealed that Vcmax25 vertical and seasonal variation had the strongest influence on simulated GPP in both 1D and 3D models, while LCC and LMA effects were minimal. Particularly, the scheme with an empirically parameterized Vcmax25 profile achieved comparable performance to the scheme with the measured Vcmax25 profile. Both 1D-SCOPE and 3D-Helios accurately modeled GPP (SCOPE: R2 = 0.87, Bias = 0.55 µmol m⁻² s⁻¹; Helios: R2 = 0.9, Bias = 0.22 µmol m⁻² s⁻¹) under the most complex scheme, and their responses to vertical and seasonal variation in leaf traits were consistent, demonstrating the robustness of our findings. Based on our findings, we propose a scalable framework for parameterizing leaf traits to improve GPP simulations. This study contributes to improving the representation of leaf trait dynamics in canopy-level photosynthesis models, potentially enhancing our ability to predict crop productivity and understand agroecosystem carbon dynamics.
Photosynthesis↗
Improved sensing of vertical velocity for vertical position control using loop voltage signals on EAST
Vertical position control of shaped plasma is critical for all elongated tokamaks to achieve safe and stable plasma discharge. In EAST, the in-vessel coil (IC) is employed for fast control of plasma vertical motion which power supply capabilities limits the controllability of vertical instability. Moreover, adequate signal-to-noise ratio of vertical position measurement can also realize an improvement in vertical control. In EAST, plasma vertical position Z p is produced nearly by all integrated magnetics, fast Z error signal is obtained by filtering from Zp. Then this fast Z error and its derivative term (dz/dt) are controlled by IC with a separate PD controller. Yet, it has a low signal-to-noise ratio which limits the gains that can be used successfully in the PD control loops. To provide less noisy dz/dt signal, the successful use of multiple up/down loop voltage pairs instead of derivative of z derived from magnetic probe signals will be discussed. Experiment show that even a single pair of loop voltage signal has better signal-to-noise ratio than differentiation of Z p . In addition, flux loop pickup signals from the IC current are also measured with series of positive and negative IC current pulses.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk
We use the number density distributions of K and M dwarf stars with vertical height from the Galactic disk, determined using observations from the Sloan Digital Sky Survey, to probe the structure of the Milky Way disk across the survey’s footprint. Using photometric parallax as a distance estimator we analyze a sample of several million disk stars in matching footprints above and below the Galactic plane, and we determine the location and extent of vertical asymmetries in the number counts in a variety of thin- and thick-disk subsamples in regions of some 200 square degrees within 2 kpc in vertical distance from the Galactic disk. These disk asymmetries present wave-like features as previously observed on other scales and at other distances from the Sun. We additionally explore the scale height of the disk and the implied offset of the Sun from the Galactic plane at different locations, noting that the scale height of the disk can differ significantly when measured using stars only above or only below the plane. Moreover, we compare the shape of the number density distribution in the north for different latitude ranges with a fixed range in longitude and find the shape to be sensitive to the selected latitude window. We explain why this may be indicative of a change in stellar populations in the latitude regions compared, possibly allowing access to the systematic metallicity difference between thin- and thick-disk populations through photometry.
79 ASTRONOMY AND ASTROPHYSICS↗
Convective cloud vertical velocity and mass-flux characteristics from radar wind profiler observations during GoAmazon2014/5: VERTICAL VELOCITY GOAMAZON2014/5
A radar wind profiler data set collected during the 2 year Department of Energy Atmospheric Radiation Measurement Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign is used to estimate convective cloud vertical velocity, area fraction, and mass flux profiles. Vertical velocity observations are presented using cumulative frequency histograms and weighted mean profiles to provide insights in a manner suitable for global climate model scale comparisons (spatial domains from 20 km to 60 km). Convective profile sensitivity to changes in environmental conditions and seasonal regime controls is also considered. Aggregate and ensemble average vertical velocity, convective area fraction, and mass flux profiles, as well as magnitudes and relative profile behaviors, are found consistent with previous studies. Updrafts and downdrafts increase in magnitude with height to midlevels (6 to 10 km), with updraft area also increasing with height. Updraft mass flux profiles similarly increase with height, showing a peak in magnitude near 8 km. Downdrafts are observed to be most frequent below the freezing level, with downdraft area monotonically decreasing with height. Updraft and downdraft profile behaviors are further stratified according to environmental controls. These results indicate stronger vertical velocity profile behaviors under higher convective available potential energy and lower low-level moisture conditions. Sharp contrasts in convective area fraction and mass flux profiles are most pronounced when retrievals are segregated according to Amazonian wet and dry season conditions. During this deployment, wet season regimes favored higher domain mass flux profiles, attributed to more frequent convection that offsets weaker average convective cell vertical velocities.
54 ENVIRONMENTAL SCIENCES↗
Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota: Pore Water DOM composition in a peat bog
We characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and EEM-PARAFAC components within the peat column. In particular the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputs from surface vegetation. The intermediate-depth zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds (PAC) that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate-depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table and redox oscillation and porewater advection.
Environmental Molecular Sciences Laboratory↗
Improved performance in vertical GaN Schottky diode assisted by AlGaN tunneling barrier
In a vertical GaN Schottky barrier diode, the free electron concentration n in the 6-μm-thick drift layer was found to greatly impact the diode reverse leakage current, which increased from 2.1 × 10{sup −7} A to 3.9 × 10{sup −4} A as n increased from 7.5 × 10{sup 14 }cm{sup −3} to 6.3 × 10{sup 15 }cm{sup −3} at a reverse bias of 100 V. By capping the drift layer with an ultrathin 5-nm graded AlGaN layer, reverse leakage was reduced by more than three orders of magnitude with the same n in the drift layer. We attribute this to the increased Schottky barrier height with the AlGaN at the surface. Meanwhile, the polarization field within the graded AlGaN effectively shortened the depletion depth, which led to the formation of tunneling current at a relatively small forward bias. The turn-on voltage in the vertical Schottky diodes was reduced from 0.77 V to 0.67 V—an advantage in reducing conduction loss in power switching applications.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
A Polarimetric Radar Analysis of Ice Microphysical Processes in Melting Layers of Winter Storms Using S-Band Quasi-Vertical Profiles
Quasi-vertical profiles (QVPs) obtained from a database of U.S. WSR-88D data are used to document polarimetric characteristics of the melting layer (ML) in cold-season storms with high vertical resolution and accuracy. A polarimetric technique to define the top and bottom of the ML is first introduced. Using the QVPs, statistical relationships are developed to gain insight into the evolution of microphysical processes above, within, and below the ML, leading to a statistical polarimetric model of the ML that reveals characteristics that reflectivity data alone are not able to provide, particularly in regions of weak reflectivity factor at horizontal polarization Z H . QVP ML statistics are examined for two regimes in the ML data: Z H ≥ 20 dB Z and Z H < 20 dB Z . Regions of Z H ≥ 20 dB Z indicate locations of MLs collocated with enhanced differential reflectivity Z DR and reduced copolar correlation coefficient ρ hv , while for Z H < 20 dB Z a well-defined ML is difficult to discern using Z H alone. Evidence of large Z DR up to 4 dB, backscatter differential phase δ up to 8°, and low ρ hv down to 0.80 associated with lower Z H (from -10 to 20 dB Z ) in the ML is observed when pristine, nonaggregated ice falls through it. Positive correlation is documented between maximum specific differential phase K DP and maximum Z H in the ML; these are the first QVP observations of K DP in MLs documented at S band. Negative correlation occurs between minimum ρ hv in the ML and ML depth and between minimum ρ hv in the ML and the corresponding enhancement of Z H (Δ Z H = Z H max - Z H rain ).
Meteorology & Atmospheric Sciences↗
Vertically Resolved Convective–Stratiform Echo-Type Identification and Convectivity Retrieval for Vertically Pointing Radars
Using data from the airborne HIAPER Cloud Radar (HCR), a partitioning algorithm (ECCO-V) that provides vertically resolved convectivity and convective versus stratiform radar-echo classification is developed for vertically pointing radars. The algorithm is based on the calculation of reflectivity and radial velocity texture fields that measure the horizontal homogeneity of cloud and precipitation features. The texture fields are translated into convectivity, a numerical measure of the convective or stratiform nature of each data point. The convective–stratiform classification is obtained by thresholding the convectivity field. Subcategories of low, mid-, and high stratiform, shallow, mid-, deep, and elevated convective, and mixed echoes are introduced, which are based on the melting-layer and divergence-level altitudes. As the algorithm provides vertically resolved classifications, it is capable of identifying different types of vertically layered echoes, and convective features that are embedded in stratiform cloud layers. Its robustness was tested on data from four HCR field campaigns that took place in different meteorological and climatological regimes. The algorithm was adapted for use in spaceborne and ground-based radars, proving its versatility, as it is adaptable not only to different radar types and wavelengths, but also different research applications.
54 ENVIRONMENTAL SCIENCES↗
How Does Vertical Wind Shear Influence Updraft Characteristics and Hydrometeor Distributions in Supercell Thunderstorms?
Abstract Vertical wind shear is known to affect supercell thunderstorms by displacing updraft hydrometeor mass downshear, thereby facilitating the storms’ longevity. Shear also impacts the size of supercell updrafts, with stronger shear leading to wider, less dilute, and stronger updrafts with likely greater hydrometeor production. To more clearly define the role of shear across different vertical layers on hydrometeor concentrations and displacements relative to supercell updrafts, a suite of idealized numerical model simulations of supercells was conducted. Shear magnitudes were systematically varied across the 0–1, 1–6, and 6–12 km AGL layers, while the thermodynamic environment was held fixed. Simulations show that as shear magnitude increases, especially from 1 to 6 km, updrafts become wider and less dilute with an increase in hydrometeor loading, along with an increase in the low-level precipitation area/rate and total precipitation accumulation. Even with greater updraft hydrometeor loading amid stronger shear, updrafts are more intense in stronger shear simulations due to larger thermal buoyancy owing to wider, less dilute updraft cores. Furthermore, downshear hydrometeor displacements are larger in environments with stronger 1–6-km shear. In contrast, there is relatively less sensitivity of hydrometeor concentrations and displacements to variations in either 0–1- or 6–12-km shear. Results are consistent across free tropospheric relative humidity sensitivity simulations, which show an increase in updraft size and hydrometeor mass with increasing free tropospheric relative humidity owing to a reduction in entrainment-driven dilution for wider updrafts in moister environments. Significance Statement Rotating thunderstorms, known as supercells, are able to persist for multiple hours. One common explanation is that large changes in wind speed and/or direction with height, or shear, transport rain/hail away from supercell updrafts, supporting their maintenance. The strong shear within supercell environments, however, may also lead to greater rail/hail amounts, thereby leading to weaker storms due to this extra mass of water/ice within updrafts. Furthermore, the impact of shear across different height layers on supercell rain/hail characteristics has not been thoroughly investigated. In this study, computer simulations of supercells were conducted to determine that shear occurring between 1 and 6 km above ground level has a large impact on rain/hail distribution in supercells and that stronger shear in this layer leads to wider/stronger supercells with greater rain/hail accumulations at the surface. Additionally, some of the extra mass of water/ice is transported farther away from updrafts due to the stronger environmental storm-relative winds.
Meteorology & Atmospheric Sciences↗
Vertical Structure of Radiation-pressure-dominated Thin Disks: Link between Vertical Advection and Convective Stability
In the classic picture of standard thin accretion disks, viscous heating is balanced by radiative cooling through the diffusion process, and the radiation-pressure-dominated inner disk suffers convective instability. However, recent simulations have shown that, owing to the magnetic buoyancy, the vertical advection process can significantly contribute to energy transport. In addition, in comparing the simulation results with the local convective stability criterion, no convective instability has been found. In this work, following on from simulations, we revisit the vertical structure of radiation-pressure-dominated thin disks and include the vertical advection process. Our study indicates a link between the additional energy transport and the convectively stable property. Thus, the vertical advection not only significantly contributes to the energy transport, but it also plays an important role in making the disk convectively stable. Our analyses may help to explain the discrepancy between classic theory and simulations on standard thin disks.
79 ASTRONOMY AND ASTROPHYSICS↗
Large-scale vertical velocity, diabatic heating and drying profiles associated with seasonal and diurnal variations of convective systems observed in the GoAmazon2014/5 experiment
This study describes the characteristics of large-scale vertical velocity, apparent heating source ( Q 1 ) and apparent moisture sink ( Q 2 ) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) that were conducted from 15 February to 26 March 2014 (wet season) and from 1 September to 10 October 2014 (dry season) near Manaus, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) experiment. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia – i.e., locally occurring systems, coastal-occurring systems and basin-occurring systems – is also conducted to investigate the variability of the large-scale environment with different types of convective systems.
54 ENVIRONMENTAL SCIENCES↗
A data-driven approach to real-time vertical position estimation for NSTX-U vertical stability control
In this paper, a database of 77 996 plasma equilibrium reconstructions from 727 discharges during the initial operation of the NSTX-U spherical tokamak is analyzed to develop a statistically robust model of the plasma vertical position for real-time control. A variety of regression models are developed and tested, ranging in complexity from linear models to deep neural networks, and including input signals ranging from the four pairs of flux loops used historically on NSTX-U up to the full set of 389 real-time signals available to the plasma control system. A linear model based on 140 real-time magnetics signals is found to offer excellent accuracy, with a coefficient of determination R 2 = 0.906. The robustness of this model to limited training data, new operating scenarios, and signal errors is tested, and a procedure is demonstrated to tune the model parameters to optimize its robustness. A time-dependent plasma equilibrium solver, TokaMaker, is used to simulate vertical stability control in NSTX-U, demonstrating that it should be possible to iteratively tune the parameters of a linear vertical position model to stabilize both positive and negative triangularity plasmas in future experiments.
magnetic diagnostics↗