Vertical Distribution Research Articles

High-resolution stratigraphy and characterization of reservoir-critical heterogeneities in the giant Tupi Field, pre-salt Santos Basin, Brazil

Abstract The large oil discoveries that have occurred in recent decades in the pre-salt section of the South Atlantic sedimentary basins have promoted a significant volume of scientific research regarding the origin of these deposits. Most of the current studies of this stratigraphic interval focus on regional aspects or sedimentological and diagenetic processes. However, few studies encompass the geological characteristics of the pre-salt deposits from a reservoir-scale perspective. This work addresses the construction of a detailed reservoir-oriented stratigraphic framework for the giant Tupi Field. Discovered in 2006 following a successful exploratory campaign in the southeastern Brazilian deep-water, the Tupi Field's main reservoirs are sag-phase carbonates from the Aptian-aged Barra Velha Formation. These rocks accumulated in alkaline to highly alkaline lacustrine settings, which allowed the development of unusual syngenetic elements, such as magnesian clays, calcitic spherulites and calcitic shrubs. The reservoirs' depositional organization was essentially conditioned by climatic oscillations and tectonic activity, which controlled sedimentation rates and accommodation styles through space and time. The high-resolution stratigraphic framework established in this article supports a detailed understanding, at different scales, of the Tupi Field's sedimentological evolution and its main vertical and lateral facies distribution. These aspects have, in turn, provided essential inputs for reservoir characterization and constrained critical heterogeneities of the 3D geocellular model, even in reservoirs affected by diagenetic processes.

Early frost detection in wheat using machine learning from vertical temperature distributions

Frost damage significantly reduces global wheat production. Temperature development in wheat crops is a complex and dynamic process. During frost events, a vertical temperature gradient develops from soil to canopy due to the heat loss from the soil and canopy boundary. Understanding these temperature gradients is essential for improving frost management strategies in wheat crops. We hypothesise that the relationship between the temperatures of the canopy, plant and ground can be an early indicator of frost. We collected infrared thermal (IRT) images from field-grown wheat crops and extracted the temperatures from the canopy, plant and ground layers. We analysed these temperatures and applied four machine learning (ML) models to detect coldness scales leading to frost nights with different degrees of severity. We implemented a gated recurrent unit, convolutional neural network, random forest and support vector machines to evaluate the classification. Our study shows that in these three layers, temperatures have a relationship that can be used to determine frost early. The patterns of these three temperatures on a frost night differ from a cold no-frost winter night. On a no-frost night we observed that the canopy is the coldest, plant is warm, and the soil is warmest, and these three temperatures did not converge. On the other hand, on a frost night, before the frost event, the canopy and plant temperatures converged as the cold air penetrated through the canopy. These patterns in temperature distribution were translated into an ML problem to detect frost early. We classified coldness scales based on the temperatures conducive to frost formation of a certain severity degree. Our results show that the ML models can determine the coldness scales automatically with 93%–98% accuracy across the four models. The study presents a strong foundation for the development of early frost detection systems.

Experience of using the portable gamma spectrometer MKS AT6101D for in situ measurements of the density of <sup>137</sup>Cs soil contamination in the Bryansk region of Russia

We have tested applicability of the commercially available portable spectrometer-dosimeter MKS AT6101D (the manufacturer: ATOMTEX, Belarus) to measure the density of 137Cs soil contamination (inventory of 137Cs in soil) in situ. The study was performed in 2015–2020 at the territories of the Bryansk region of Russia contaminated due to the Chernobyl accident. The in situ measurements were performed in the 17 ground plots (7 grasslands and 10 kitchengargens) for which the 137Cs inventory and the mean migration depth of the radionuclide in soil was available from laboratory (ex situ) measurements of soil samples. It was found that the in situ data obtained with the method that was provided by the manufacturer of the instrument required additional correction on the vertical distribution of 137Cs in the soil. The correction procedure was developed; in 2020–2021, it has been successfully tested in 114 kitchengarden plots located at the settlements in the zones of radioactive contamination in the Bryansk region.

Vertical Distribution of Thiosulfate and Sulfite in the Black Sea

Vertical Distribution of Thiosulfate and Sulfite in the Black Sea

The Influence of Time, Tide, and Place on Fine-Scale Nekton Distribution: Insights from the San Francisco Estuary

The location of estuarine organisms varies based on geophysical cycles and environmental conditions, which can strongly bias understanding of organism abundance and distribution. In the San Francisco Estuary, California, extensive monitoring surveys have provided insight into the life history and ecology of certain commercially important or legislatively protected fish species. However, there remains substantial uncertainty in factors influencing the vertical and lateral distributions of many other nekton species in the San Francisco Estuary, including longfin smelt Spirinchus thaleichthys, for whom such distributional information may highly influence interpretation of existing data. We carried out paired sampling using surface and demersal gears to address three questions: (1) Does diel phase influence the vertical position of nekton (e.g., surface versus demersal)? (2) Do environmental conditions, specifically turbidity, influence the vertical and lateral positions of nekton (e.g., center channel versus peripheral shoal)? (3) Does tidal variability influence vertical and lateral distributions of nekton? We documented variability in sampled nekton densities across diel phase (day/night), vertical position (surface/bottom), and lateral position (channel/shoal). Tidal phase and turbidity concentration influenced vertical and lateral distributions for some species at certain locations. Although infrequently encountered, we documented associations of longfin smelt with the lower water column and shoal habitats, with some evidence for upward vertical shifts in low light conditions brought about by nightfall or elevated turbidity. Observed habitat associations provide insight into how interacting geophysical and environmental factors may influence the distribution of nekton and thus the vulnerability of individual species to detection by sampling gears.

An Indacenodithienothiophene-Based Wide Bandgap Small Molecule Guest for Efficient and Stable Ternary Organic Solar Cells.

The strategic and logical development of the third component (guest materials) plays a pivotal and intricate role in improving the efficiency and stability of ternary organic solar cells (OSCs). In this study, a novel guest material with a wide bandgap, named IDTR, is designed, synthesized, and incorporated as the third component. IDTR exhibits complementary absorption characteristics and cascade band alignment with the PM6:Y6 binary system. Morphological analysis reveals that the introduction of IDTR results in strong crystallinity, good miscibility, and proper vertical phase distribution, thereby realizing heightened and balanced charge transport behavior. Remarkably, the novel ternary OSCs have exhibited a significant enhancement in photovoltaic performance. Consequently, open-circuit voltage (VOC), short-circuit current (JSC), and fill factor (FF) have all witnessed substantial improvements with a remarkable power conversion efficiency (PCE) of 18.94% when L8-BO replaced Y6. Beyond the pronounced improvement in photovoltaic performance, superior device stability with a T80 approaching 400h is successfully achieved. This achievement is attributed to the synergistic interplay of IDTR, providing robust support for the overall enhancement of performance. These findings offer crucial guidance and reference for the design and development of efficient and stable OSCs.

Vertical distribution characteristics and potential sources of atmospheric pollutants in the North China Plain basing on the MAX-DOAS measurement

The mechanism for the generation of atmospheric pollution sources can be further investigated through the examination of atmospheric evolution and diffusion characteristics. The authors of this study conducted a 3-month MAX-DOAS (multi-axis differential optical absorption spectroscopy) vertical observation in Shijiazhuang City, North China Plain, in the summer of 2020 in response to the long-standing air pollution issues in the region. The vertical distribution profiles of aerosol, NO2, HCHO, and CHOCHO were generated, and the inversion findings showed good agreement with the TROPOMI (tropospheric monitoring instrument) satellite remote sensing validation, demonstrating the validity and accuracy of the observations. The near-surface boundary layer is home to the majority of the NO2, HCHO, and CHOCHO species. The species’ daytime evolution trends varied, with the highest NO2 peaks occurring in the morning and evening commute, the highest HCHO peaks occurring in the morning at 10:00 a.m., and CHOCHO's concentration during the day declined. Two minor aerosol pollution processes took place in Shijiazhuang City during the summer observation period. The elevated concentrations of NO2, CO, and the PM2.5/PM10 ratio during the pollution processes suggest that anthropogenic emissions, particularly biomass burning, were responsible for the large number of fine particles generated during the pollution events. Based on the examination of pollutant concentration profiles and meteorological data, it was determined that local emissions and north wind transport were the primary causes of Shijiazhuang's high NO2 values. Meanwhile, the southern region of Shijiazhuang was primarily responsible for the majority of the potential sources of atmospheric HCHO, and local emissions were also a major factor affecting the high CHOCHO values. Shijiazhuang's local near-surface volatile organic compounds (VOCs) are mostly caused by human emissions, although biomass burning and its regional transportation have a greater influence on the middle and upper boundary layers. This study systematically sorted the evolution characteristics and potential sources of pollutants in Shijiazhuang City during the summer based on the joint observations of various pollutants, including NO2, HCHO, and CHOCHO. These results can be used to support the development of appropriate policies for the prevention and control of pollutants in the Shijiazhuang local area of the North China Plain.

Vertical and latitudinal distribution of bottom-up and top-down controls of heterotrophic prokaryotes in the Red Sea

Heterotrophic prokaryotes (HPs) represent the largest fraction of living biomass in the ocean. Comprehensively understanding the spatio-temporal variability of their controlling factors remains a challenge in microbial oceanography, especially in little explored low latitude regions such as the Red Sea, one of the hottest and saltiest basins on Earth. In this study, we assessed the vertical (5–1000 m) and latitudinal (16°-27° N) variations in HPs and their bottom-up (resource availability) and top-down controls (protistan grazing and viral lysis) at eight stations along the Red Sea, in three cruises carried out between 2017 and 2019. The decrease in HPs abundances with depth was less pronounced than that of heterotrophic nanoflagellates (HNFs) and viruses. We found that inorganic nutrient and dissolved organic carbon (DOC) concentrations do not vary significantly from north to south, thus suggesting a similar bottom-up control on HPs abundances along the latitudinal gradient. We found significant southward increase in the HP:HNF ratio (r = 0.56, p < 0.0001, n = 140), suggesting that HNFs have a lower impact on their HPs prey in the southern Red Sea. The preference of HNFs for larger HPs cells with depth was found only in the spring cruise. Viral abundances do not show any marked latitudinal gradient but show a significant positive relationship with HPs abundances in the water column in all seasons. The higher linear regression slope found in summer suggests that viruses are more important for HPs mortality in the warmer months. This study strengthens the importance of top-down controls in maintaining lower HPs stocks in the Red Sea and suggests that both latitudinal and seasonal variations have minor but measurable roles.

Use of resistivity and density borehole image logs to identify and distribute facies in the Pikka unit — A case study from the Nanushuk Formation, North Slope, Alaska

Over the past few decades, the North Slope of Alaska has yielded several major hydrocarbon discoveries in the deltaic topsets of the Brookian Nanushuk Formation. Together, the Nanushuk topsets and genetically related foreset and bottomset beds of the Torok Formation comprise part of a giant clinothem system that prograded across the Colville Foreland Basin during the lower Cretaceous (the Aptian through the Cenomanian). The Nanushuk Topset Play contains stratigraphically trapped hydrocarbons within multiple fairways trending roughly north to south along the basin’s extent. Inside the Pikka Unit, the Nanushuk Formation represents a shelf-edge delta and attached shoreface system, defined primarily from sedimentological interpretations of conventional cores integrated with 3D seismic reflection data and well-log motifs. In this study, we build a structural and stratigraphic framework for the Nanushuk reservoir across the Pikka Unit through integrated observations of the borehole image logs, seismic data, and core. In the described workflow, the boundaries delimiting dip zones interpreted in the wells are correlated to higher order stratigraphic cycles within the Nanushuk clinothem zone. These boundaries are observed in seismic profiles and provide the basis of the structural framework. In addition, core facies interpretations are calibrated to CT-scan data to establish each facies character and vertical distribution within the wells. In the absence of core data, core-calibrated borehole images are instrumental in guiding sedimentological and structural interpretations. This extrapolation is dependent on the image log quality and resolution. The calibrated facies interpretations are applied to wells without core data and guided by seismic amplitude interpretation to extrapolate reservoir presence and distribution across the area.

Vertical distribution of edaphic oribatid mites (Acari: Oribatida) in two artificial forests planted on temperate grasslands

Context Oribatid mites are the most abundant taxon in forest soils that rely on porosity and organic matter availability. Exotic forests of Pinus radiata and Eucalyptus globulus planted over native grasslands in the Pampas region of Argentina have produced modification in soil properties, which can affect the composition and structure of native oribatids communities. Aims To compare oribatid communities in soils under artificial woodlands of pine and eucalyptus and to assess the vertical distribution of oribatids in relation to edaphic variables. Methods In each forest, oribatids were collected from three levels of the A horizon: (1) litter layer; (2) 0–5 cm; and (3) 5–10 cm. Edaphic variables measured were penetration resistance, bulk density, total porosity, pH and water content and luminosity at soil level. Density, species richness, diversity and evenness of oribatids were calculated in each level of each forest. Comparisons were made through multivariate analyses. Key results Edaphic variables showed no significant differences between plots but litters were structurally different. Richness and diversity showed no differences between plots whereas evenness was significantly higher in plot P. Density had higher values in the litter layer of both forests. Canonical Analysis of Principal Coordinates (CAP) showed that Pine plots had a more defined vertical distribution. Conclusions The structure and composition of litters promoted differences in the vertical distribution of oribatids. In Pinus, thick unaltered litter showed a marked vertical gradient of mites along levels while in Eucalyptus, thin and easily decomposing litter, showed no vertical patterns. Implications Assessment and management of soil biodiversity in artificial woodlands.

Analysis of the Production Characteristics of Heterogeneous Reservoirs Assisted by Shallow Gas by Depressurization Path

The problems of low gas production rate and low gas production restrict the commercial production of natural gas hydrate. The combined production of hydrate reservoirs and underlying shallow gas reservoirs is expected to make up for this shortcoming. Most natural gas hydrates in the formation exhibit vertical heterogeneous distribution characteristics; There is still little research on the mechanism of its impact on the characteristics of co harvesting. This work focuses on the interaction between vertical heterogeneous hydrate reservoirs and shallow gas layers, and analyzes the mechanism of the impact of depressurization pathway on the characteristics of combined production. The results indicate that before the pressure in the shallow gas layer is equal to the pressure in the hydrate layer, the change in pressure reduction method cannot significantly affect the characteristics of pressure changes in the shallow gas layer; In addition, there is a significant hysteresis effect in the pressure evolution of shallow gas layers compared to hydrate layers. Not limited to this, the presence of shallow gas layers will also weaken the impact of pressure reduction paths on the gas production characteristics of combined production, which makes the gas production characteristics at this time more inclined towards the gas production characteristics under direct pressure reduction. In summary, in order to effectively increase the temperature of shallow gas and enhance hydrate decomposition, it is necessary to flexibly adjust the pressure reduction indicators of the pressure reduction path in different mining stages. The results can lay the foundation for clarifying the mechanism of interlayer interference in multiple gas source reservoirs.

Evaluating a Novel Approach to Detect the Vertical Structure of Insect Damage in Trees Using Multispectral and Three-Dimensional Data from Drone Imagery in the Northern Rocky Mountains, USA

Remote sensing is a well-established tool for detecting forest disturbances. The increased availability of uncrewed aerial systems (drones) and advances in computer algorithms have prompted numerous studies of forest insects using drones. To date, most studies have used height information from three-dimensional (3D) point clouds to segment individual trees and two-dimensional multispectral images to identify tree damage. Here, we describe a novel approach to classifying the multispectral reflectances assigned to the 3D point cloud into damaged and healthy classes, retaining the height information for the assessment of the vertical distribution of damage within a tree. Drone images were acquired in a 27-ha study area in the Northern Rocky Mountains that experienced recent damage from insects and then processed to produce a point cloud. Using the multispectral data assigned to the points on the point cloud (based on depth maps from individual multispectral images), a random forest (RF) classification model was developed, which had an overall accuracy (OA) of 98.6%, and when applied across the study area, it classified 77.0% of the points with probabilities greater than 75.0%. Based on the classified points and segmented trees, we developed and evaluated algorithms to separate healthy from damaged trees. For damaged trees, we identified the damage severity of each tree based on the percentages of red and gray points and identified top-kill based on the length of continuous damage from the treetop. Healthy and damaged trees were separated with a high accuracy (OA: 93.5%). The remaining damaged trees were separated into different damage severities with moderate accuracy (OA: 70.1%), consistent with the accuracies reported in similar studies. A subsequent algorithm identified top-kill on damaged trees with a high accuracy (OA: 91.8%). The damage severity algorithm classified most trees in the study area as healthy (78.3%), and most of the damaged trees in the study area exhibited some amount of top-kill (78.9%). Aggregating tree-level damage metrics to 30 m grid cells revealed several hot spots of damage and severe top-kill across the study area, illustrating the potential of this methodology to integrate with data products from space-based remote sensing platforms such as Landsat. Our results demonstrate the utility of drone-collected data for monitoring the vertical structure of tree damage from forest insects and diseases.

Satellite NO2 Retrieval Complicated by Aerosol Composition over Global Urban Agglomerations: Seasonal Variations and Long-Term Trends (2001-2018).

Tropospheric nitrogen dioxide (NO2) poses a serious threat to the environmental quality and public health. Satellite NO2 observations have been continuously used to monitor NO2 variations and improve model performances. However, the accuracy of satellite NO2 retrieval depends on the knowledge of aerosol optical properties, in particular for urban agglomerations accompanied by significant changes in aerosol characteristics. In this study, we investigate the impacts of aerosol composition on tropospheric NO2 retrieval for an 18 year global data set from Global Ozone Monitoring Experiment (GOME)-series satellite sensors. With a focus on cloud-free scenes dominated by the presence of aerosols, individual aerosol composition affects the uncertainties of tropospheric NO2 columns through impacts on the aerosol loading amount, relative vertical distribution of aerosol and NO2, aerosol absorption properties, and surface albedo determination. Among aerosol compositions, secondary inorganic aerosol mostly dominates the NO2 uncertainty by up to 43.5% in urban agglomerations, while organic aerosols contribute significantly to the NO2 uncertainty by -8.9 to 37.3% during biomass burning seasons. The possible contrary influences from different aerosol species highlight the importance and complexity of aerosol correction on tropospheric NO2 retrieval and indicate the need for a full picture of aerosol properties. This is of particular importance for interpreting seasonal variations or long-term trends of tropospheric NO2 columns as well as for mitigating ozone and fine particulate matter pollution.

Spontaneous intersibling polymorphism in the development of dopaminergic neuroendocrine cells in sea urchin larvae: impacts on the expansion of marine benthic species.

The plasticity of the nervous system plays a crucial role in shaping adaptive neural circuits and corresponding animal behaviors. Understanding the mechanisms underlying neural plasticity during development and its implications for animal adaptation constitutes an intriguing area of research. Sea urchin larvae offer a fascinating subject for investigation due to their remarkable evolutionary and ecological diversity, as well as their diverse developmental forms and behavioral patterns. We conducted immunochemical and histochemical analyses of serotonin-containing (5-HT-neurons) and dopamine-containing (DA-positive) neurons to study their developmental dynamics in two sea urchin species: Mesocentrotus nudus and Paracentrotus lividus. Our approach involved detailed visualization of 5-HT- and DA-positive neurons at gastrula-pluteus stages, coupled with behavioral assays to assess larval upward and downward swimming in the water column, with a focus on correlating cell numbers with larval swimming ability. The study reveals a heterochronic polymorphism in the appearance of post-oral DA-positive neuroendocrine cells and confirms the stable differentiation pattern of apical 5-HT neurons in larvae of both species. Notably, larvae of the same age exhibit a two- to four-fold difference in DA neurons. An increased number of DA neurons and application of dopamine positively correlate with larval downward swimming, whereas 5-HT-neurons and serotonin application induce upward swimming. The ratio of 5-HT/DA neurons determines the stage-dependent vertical distribution of larvae within the water column. Consequently, larvae from the same generation with a higher number of DA-positive neurons tend to remain at the bottom compared to those with fewer DA-positive neurons. The proportion of 5-HT and DA neurons within larvae of the same age underlies the different potentials of individuals for upward and downward swimming. A proposed model illustrates how coordination in humoral regulation, based on heterochrony in DA-positive neuroendocrine cell differentiation, influences larval behavior, mitigates competition between siblings, and ensures optimal population expansion. The study explores the evolutionary and ecological implications of these neuroendocrine adaptations in marine species.

The persistence of high altitude non-equilibrium diffuse ionized gas in simulations of star-forming galaxies

ABSTRACT Widespread, high altitude, diffuse ionized gas with scale heights of around a kiloparsec is observed in the Milky Way and other star-forming galaxies. Numerical radiation-magnetohydrodynamic simulations of a supernova-driven turbulent interstellar medium show that gas can be driven to high altitudes above the galactic mid-plane, but the degree of ionization is often less than inferred from observations. For computational expediency, ionizing radiation from massive stars is often included as a post-processing step assuming ionization equilibrium. We extend our simulations of an Milky Way-like interstellar medium to include the combined effect of supernovae and photoionization feedback from mid-plane OB stars and a population of hot evolved low mass stars. The diffuse ionized gas has densities below 0.1 ${\rm \,cm^{-3}}$, so recombination time-scales can exceed millions of years. Our simulations now follow the time-dependent ionization and recombination of low density gas. The long recombination time-scales result in diffuse ionized gas that persists at large altitudes long after the deaths of massive stars that produce the vast majority of the ionized gas. The diffuse ionized gas does not exhibit the large variability inherent in simulations that adopt ionization equilibrium. The vertical distribution of neutral and ionized gas is close to what is observed in the Milky Way. The volume filling factor of ionized gas increases with altitude resulting in the scale height of free electrons being larger than that inferred from H $\alpha$ emission, thus reconciling the observations of ionized gas made in H $\alpha$ and from pulsar dispersion measurements.

Sensitivities of the West Greenland Current to Greenland Ice Sheet Meltwater in a Mesoscale Ocean/Sea ice Model

Abstract Meltwater from the Greenland Ice Sheet can alter the continental shelf/slope circulation, cross-shelf freshwater fluxes, and limit deep convection in adjacent basins through surface freshening. We explore the impacts on the West Greenland Current and Eastern Labrador Sea with different vertical distributions of the meltwater forcing. In this study, we present results from global coupled ocean/sea-ice simulations, forced with atmospheric reanalysis, that are mesoscale eddy-active (~2–3 km horizontal spacing) and eddy-permitting (~6–7 km horizontal spacing) in the study region. We compare the West Greenland Current in mesoscale eddy-active and eddy-permitting without meltwater to highlight the role of small scale features. The mesoscale eddy-active configuration is then used to assess the change in the Eastern Labrador Sea when meltwater is added to the surface or vertically distributed to account for mixing within fjords. In both simulations with meltwater, the West Greenland and West Greenland Coastal Currents are faster than in the simulation with no meltwater; their mean surface speeds are highest in the vertical distribution case. In the latter case, there is enhanced baroclinic conversion at the shelf break compared to the simulation with no meltwater. When meltwater is vertically distributed, there is an increase in baroclinic conversion at the shelf break associated with increased eddy kinetic energy. In addition, in the Eastern Labrador Sea the salinity is lower and the meltwater volume greater when meltwater is vertically distributed. Therefore, the West Greenland Current is sensitive to how meltwater is added to the ocean with implications for the freshening of the Labrador Sea.

Study on the decompression behavior during large-scale pipeline puncture releases of CO2 with various N2 compositions: Experiments and mechanism analysis

Impurities in the captured CO2 stream from various industrial sources may introduce uncertainty into the transient releases of transportation pipelines. Due to limitations in the experimental scale, there is currently limited analysis of the vertical cross-sectional temperature distribution and the pressure response along the pipeline during the releases of impure CO2. The mechanism by which impurities affect the decompression wave and the alterations in phase-change pathways remains unclear. In this study, building upon the existing large-scale pipeline, we established an impurity injection system. Using the common impurity, N2, as a variable, the decompression behavior of the CO2+N2 mixture in the puncture releases and the influence mechanism of N2 were investigated. The results show that the effect of N2 on sound velocity causes a significant decrease in the decompression wave speed. N2 raises the minimum temperature, and it is more pronounced in large-diameter releases; for instance, the minimum temperature during the 100 mm release is always higher than that in the 50 mm release. The gas-liquid mixture closely follows the dew point line, conforming to the Gibbs equilibrium criterion. The experimental scale mirrors real-world operating conditions, endowing the research findings with practical applicability. Concurrently, it furnishes dependable data for numerical researches.

Image analysis technique for quantifying fluorescein concentration profiles in clays

The image analysis technique approach links the dye concentration and color intensity, enabling quantification of spatial and temporal dye dynamics in clay media. In this study, batch adsorption tests and two-dimensional diffusion experiments with three types of clays (kaolinite, montmorillonite, and bentonite) were conducted for quantifying the vertical distribution of fluorescein dye tracer to evaluate the feasibility of the image analysis technique. In clay domains, color intensities were measured using images obtained during diffusion experiments, and these intensities were converted to aqueous fluorescein concentrations. Concentration profiles simulated from a one-dimensional analytical solution agreed well with those measured by the LRV technique with a single-channel application for kaolinite (blue channel, EB = 0.94 and 0.96) and montmorillonite (green channel, EG = 0.99 and 0.91) in the early (31.1, 54.6 PVs) and later (75.7, 93.9 PVs) diffusion times, respectively. The single-channel application for the bentonite was appropriate for concentration ranges of 0 − 400 mg/L for the blue channel and 400 − 1800 mg/L for the green channel. For quantifying the bentonite concentration profile with a wide range of dye concentrations (0 − 1800 mg/L), multi-channel application (blue + green channels) was required. Measured LRV concentration profiles with the multi-channel application showed better agreement (EB+G = 0.94) with simulated concentration profiles from the analytical solution than those with the single-channel application (EB = 0.56). The results of this study offer guidance on the application of the LRV approach as a non-destructive optical dye measurement method to diffusion problems between high and low permeability zones.

Note on the unparallel vertical distribution of nitrate and sulfate in Mollisols

AbstractSoil fertility diagnosis often omits subsoil measurements, impacting precision. Our objective was to compare the vertical distribution of nitrate and sulfate in agricultural Mollisols. Both anions were measured in 34 Mollisols of the Pampean region (Argentina) sampled to 160‐cm depth at 20 cm intervals. Nitrate exhibited a continuous downward trajectory, with maximum values at 0–20 cm (12.7 mg N kg−1) and minimum values at 140–160 cm (3.3 mg N kg−1). Sulfate displayed a sinuous pattern, with a minimum at 60–80 cm (3 mg S kg−1). The 60–160/0–160 cm concentration ratio was 42% for nitrate and 60% for sulfate, indicating greater topsoil stratification for nitrate. Predicting deep‐layer nitrate concentrations from topsoil data was more accurate than for sulfate. This poses a challenge for assessing soil S bioavailability, as subsoil sulfates go undetected in conventional sampling.

A grid model for vertical correction of precipitable water vapor over the Chinese mainland and surrounding areas using random forest

Abstract. Various ground-based observing techniques provide precipitable water vapor (PWV) products with different spatial resolutions. To effectively integrate these products, especially in terms of vertical orientation, spatial interpolation is essential. In this context, we have developed a model to characterize PWV variation with altitude over our study area. Our model, known as RF-PWV (a PWV vertical correction grid model with a 1° × 1° resolution), is constructed using random forest based on the relationship between the differences in different pressure level PWV data from the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis (ERA5) monthly average hourly data and corresponding differences in their height differences over time. When validated against 1 h ERA5 PWV profiles, RF-PWV exhibits a 99.84 % reduction in bias and a 63.41 % decrease in the RMSE compared with the most recent model, C-PWVC1. Furthermore, when validated against radiosonde data, RF-PWV shows a 96.36 % reduction in bias and a 5 % decrease in the RMSE compared with C-PWVC1. Additionally, RF-PWV outperforms C-PWVC1 in terms of resistance to seasonal and height difference interference. The model eliminates the need for meteorological parameters, allowing for high-precision PWV vertical correction by inputting only time and height differences. Consequently, RF-PWV can significantly reduce errors in vertical correction, enhance PWV fusion product accuracy, and provide insights into PWV vertical distribution, thereby contributing to climate research.