High Water Vapor Content Research Articles

Imaging Spectroscopy‐Based Estimation of Aboveground Biomass in Louisiana's Coastal Wetlands: Toward Consistent Spectroscopic Retrievals Across Atmospheric States

AbstractDeveloping accurate landscape‐scale aboveground biomass (AGB) maps is critical to understanding coastal deltaic wetland resilience, as AGB influences stability and elevation dynamics in herbaceous wetlands. Here we used AVIRIS‐NG imaging spectrometer (or “hyperspectral”) data from NASA's 2021 Delta‐X mission in coastal Louisiana to map seasonal changes in herbaceous AGB across two deltaic basins with contrasting sediment delivery and hydrologic regimes: the Atchafalaya (active) and Terrebonne (inactive). We assessed the impact of atmospheric effects on our retrievals, as high water vapor content in August 2021 caused significant noise in the 880–1,000 and 1,080–1,200 nm near‐infrared (NIR) wavelengths. We hypothesized that correcting these wavelengths with our conditional Gaussian interpolation algorithm would improve AGB estimates due to their association with plant canopy water content. We empirically assessed the performance of the corrected spectra on AGB estimates using Partial Least Squares Regression (PLSR), finding that the corrected NIR bands attained high variable importance and reduced estimation errors. Our Random Forest regression approach based on the corrected spectra attained equivalent error metrics via leave‐one‐out‐cross‐validation as the PLSR models (R2 = 0.43, mean absolute error = 257.3 g/m2) while greatly improving the AGB maps' visual quality, having better captured variability while reducing noise and discontinuities in AGB estimates across flightlines. The maps show differing seasonal growth, with the Atchafalaya and Terrebonne Basins' AGB increasing from means of 4.3–9.4 and 4.6–8.9 Mg/ha, respectively. We demonstrated that imaging spectroscopy can be applied to assess herbaceous biomass stocks, growth patterns, and resilience in coastal ecosystems.

ZnO Hexagonal Nano- and Microplates Modified with Nanomaterials as a Gas-Sensitive Material for DMS Detection-Extended Studies.

The detection of dimethyl sulphide (DMS) at levels between ppb and ppm is a significant area of research due to the necessity of monitoring the presence of this gas in a variety of environments. These include environmental protection, industrial safety and medical diagnostics. Issues related to certain uncertainties concerning the influence of high humidity on DMS measurements with resistive gas sensors, e.g., in the detection of this marker in exhaled air, of the still unsatisfactory lower detection limit of DMS are the subject of intensive research. This paper presents the results of modifying the composition of the ZnO-based sensor layer to develop a DMS sensor with higher sensitivity and lower detection limit (LOD). Improved performance was achieved by using ZnO in the form of hexagonal nano- and microplates doped with gold nanoparticles (0.75 wt.%) and by using a well-proven sepiolite-based passive filter. The modification of the layer composition with respect to the authors' previous studies contributed to the development of a sensor that is highly sensitive to 1 ppm DMS (S = 11.4) and achieves an LOD of up to 406 ppb, despite the presence of a high water vapour content (90% RH) in the analysed atmosphere.

An investigation on the H2O, unburned H2 and NO emission characteristics from a direct injection hydrogen engine

Hydrogen engines show great potential as a power source with good combustion performance, zero carbon emissions, and diverse sources. However, the exhaust emission characteristics with high water vapor (H2O) content have not yet been clarified. This study presents the exhaust emissions of a heavy-duty direct-injection hydrogen engine under various operational parameters, with a focus on the H2O content. The results reveal important exhaust emissions characteristics of the hydrogen engine, including lower exhaust temperature (200 °C–400 °C), higher unburned H2 emissions (up to 17100 ppm), less nitrogen oxide (NO) generation (<1000 ppm), and higher H2O content (6%–40%). Additionally, unburned H2 rises, and NO and H2O decrease as the excess air ratio (λ) increases. When λ is greater than 3, NO levels fall sharply to below 100 ppm. Optimal emissions performance is achieved with a 5 °CA BTDC ignition timing where low levels of H2, H2O, and NO are maintained. Increasing hydrogen injection pressure decreases H2 but raises exhaust temperature, H2O, and NO emissions. Excessively delaying hydrogen injection timing adversely affects the concentration gradient in the cylinder, increasing unburned H2 emissions. The best emissions performance is observed at a hydrogen injection timing of 110 °CA BTDC.

Experimental investigation on the high-temperature corrosion of 12Cr1MoVG boiler steel in waste-to-energy plants: Effects of superheater operating temperature and moisture

Waste-to-energy (WTE) technology via municipal solid waste incineration (MSWI) have developed very rapidly with the advantages of achievement on waste disposal and energy conversion. This technology is developing towards higher capacity and efficiency. Therefore, the operation parameters of WTE boilers must be improved. However, higher steam parameters means higher surface temperature of exchange tube in superheaters and reheaters in WTE boilers, resulting higher risk of engineering failure due to high-temperature corrosion. Additionally, the incineration of MSW releases flue gas with a high content of corrosive species and water vapor, which can cause severe high-temperature corrosion. This experimental investigation details the effect of surface temperature and water vapor concentration on the high-temperature corrosion behavior of 12Cr1MoVG boiler steel under an atmosphere mimicking MSWI. The corrosion test environment consists of high temperature, ash deposit and simulated flue gas of waste incineration according to a real WTE boiler. The experiment was conducted using a two-zone bench-scale tube furnace with a gas temperature of 600℃ and the sample temperatures of 380℃, 430℃, and 480℃. For the investigation of water vapor concentration effect, 18 % vol and 23 % vol were set up in this study. After 240 hours of exposure, the corrosion weight curves illustrated that the corrosion kinetics was highly dependent on the surface temperature of corrosion samples. Furthermore, an increase in water vapor concentration exacerbated the high-temperature corrosion. XRD analysis identified the corrosion products as metal chlorides and metal oxides. Cross-sectional SEM images and EDS analysis revealed that an increase in water vapor accelerated the corrosion rate of the steel samples due to chromium dilution behavior.

Enhancing ammonia sensing performance of Ag2MoO4-based mixed-potential sensor by introducing ionic and electronic conductance

The breath ammonia detection is crucial for the evaluation of the pathological state. Among the existing ammonia detection technologies, the mixed potential sensor exhibits promising potential owing to its high stability, good selectivity and small size. However, it remains challenging in application due to its insufficient limit of detection (LOD). To improve the performance of such sensor, a novel sensing material Ag2MoO4 was synthesized in this work. The electrode morphology was tuned for optimum performance by adjusting the sintering temperature. The response to 5 ppm NH3 at 425 °C is about −29.86 mV with response/recover times of 105/96 s and sensitivity of −49.55 mV/decade. In addition, the sensor exhibits good selectivity and outstanding detection capability of trace-level NH3 as low as 400 ppb. High concentrations of water vapor and CO2 can greatly affect its performance, but it can be easily eliminated by a filter. The research of its sensing mechanism reveals that Ag2MoO4 has both ionic conductance and electronic conductance, which transforms the electrochemical reaction site from two-dimensional three-phase boundaries (TPB) to a three-dimensional one distributed within the sensing material. Specifically, the sensor shows excellent NH3 detection ability with the number of reaction sites increases.

Investigation of Tropical Cyclones in the North Indian Ocean and the Linkage to Extreme Weather Events over Sri Lanka

Heavy rainfall due to tropical cyclones (TCs) in the North Indian Ocean (NIO) adversely impacts nations frequently. Though extensive research has focused on TCs in the NIO, less attention has been given to the connection between TCs and extreme events in Sri Lanka. This study examined atmospheric characteristics during sixteen extreme events, focusing on linkages between TCs, the Indian Ocean Dipole (IOD), and mechanisms behind heavy rainfall associated with TCs over Sri Lanka. The results showed that in the pre-monsoon period, TCs move northward with high water vapor (WV) content accumulated in the Southern Hemisphere. This main WV flow over the equatorial Indian Ocean (EIO) is connected with TCs, causing considerable damage in the southwestern part of Sri Lanka. During negative IOD years, strong westerly winds create cyclonic circulations on either side of the equator. Conversely, during the post-monsoon period, the IOD phase has no significant effect. TCs generally followed westward tracks, supported by winds from the Northern Hemisphere, and caused heavy rainfall in the Eastern, Northern, and Northcentral provinces in Sri Lanka. These TCs are isolated from the main WV flow over EIO. Such observed common characteristics during pre-monsoon and post-monsoon seasons are key factors contributing to extreme rainfall in Sri Lanka.

Online water vapor removal membrane inlet mass spectrometer for high-sensitivity detection of dissolved methane

Underwater mass spectrometry is characterized by excellent consistency, strong specificity, and the ability to simultaneously detect multiple substances, making it a valuable tool in research fields such as aquatic ecosystems, hydrothermal vents, and the global carbon cycle. Nevertheless, current underwater mass spectrometry encounters challenges stemming from the high-water vapor content, constituting proportions of nearly 90%. This results in issues such as peak overlap, interference with peak height, decreased ionization efficiency and, consequently, make it difficult to achieve low detection limits for extremely low concentrations of gases, such as methane, and impede the detection of background CH4 levels. In this study, we optimized the design of the sampling gas path and developed a high gas-tightness, high pressure-resistant membrane inlet system, coupled with a small-volume, low-power online water vapor removal system. This innovation efficiently eliminates water vapor while maintaining a high permeation flux of the target gases. By elevating the vacuum level to the order of 1E-6 Torr, the ionization efficiency and detection performance were improved. Based on this, we created an online water vapor removal membrane inlet mass spectrometer and conducted experimental research. Results indicated that the water removal efficiency approached 100%, and the vacuum level was elevated by more than 2 orders of magnitude. The detection limit for CH4 increased from over 600 nmol/L to 0.03 nmol/L, representing an improvement of over 4 orders of magnitude, and reaching the level of detecting background CH4 signals in deep-sea and lakes. Furthermore, the instrument exhibited excellent responsiveness and tracking capability to concentration changes on the second scale, enabling in situ analysis of rapidly changing concentration scenarios.

Numerical investigation of radiative transfer during oxyfuel combustion of hydrogen and hydrogen enriched natural gas in the container glass industry

The substitution of natural gas with hydrogen is one way to eliminate direct CO2 emissions. However, oxyfuel combustion of hydrogen or hydrogen enriched natural gas leads to different exhaust gas properties due to a changed composition compared to conventional combustion. In combustion simulation, the emissivity of a gas mixture is usually approximated using a Weighted Sum of Gray Gases (WSGG) model. Most of the existing WSGG models have been validated for natural gas combustion with air or oxyfuel and are therefore not applicable to hydrogen-oxyfuel combustion. CFD simulations showed, that none of the investigated WSGG models is able to predict the radiative heat transfer for all considered combustion scenarios with appropriate accuracy. In addition, in container glass manufacturing more than 95% of the heat flux to the glass surface is transferred by radiation because of the high process temperatures. Due to the changed gray gas emissivity, the high content of water vapor leads to a different emission spectrum of the exhaust gas. The influence of the changed emission spectrum on radiative heat transfer and the penetration depth of radiation in the glass melt is investigated using a simulation model of a pilot plant and non-gray modelling of the radiation transport. The CFD simulations show slightly enhanced radiative heat transfer to the glass and a slightly deeper penetration depth especially for wavelength below 2.2 μm for hydrogen-oxyfuel combustion.

Development of a Photoelectric Smoke Detector with a Built-in Function to Prevent False Alarms Owing to Humidity

In this study, a photoelectric smoke detector with a built-in function was developed to prevent false alarms owing to humidity. Smoke-detector sensitivity characteristics were analyzed through room-scale false alarm experiments and by generating humidity conditions measured using a type approval sensitivity tester. The results showed that when humidity was generated, more light scattering occurred as the humidity flowed into the detector chamber along with the smoke, increasing the smoke concentration of the smoke detector. It was found that smoke concentrations increased at a relative humidity of 85 %RH or higher. The findings confirm that false alarms occur owing to high concentrations of humidity in the summer. False alarms that occur owing to high concentrations of water vapor in summer can be prevented by detecting fires using a humidity + smoke concentration fire-detection algorithm that has been quantified through experiments.

Convection and Convective‐Organization in Hothouse Climates

AbstractIn a “hothouse” climate, warm temperatures lead to a high tropospheric water vapor concentration. Sufficiently high water vapor levels lead to the closing of the water vapor infrared window, which prevents radiative cooling of the lower troposphere. Because water vapor also weakly absorbs solar radiation, hothouse climates feature radiative heating of the lower troposphere. In recent work, this radiative heating was shown to trigger a shift into a novel “episodic deluge” precipitation regime, where rainfall occurs in short, intense outbursts separated by multi‐day dry spells. Here, we further examine the role of the lower tropospheric radiative heating (LTRH) in the transition into the “episodic deluge” regime. We demonstrate that under high sea‐surface temperature the “episodic deluge” regime could be formed even before the LTRH turns positive. In addition, we examine whether these oscillations operate on larger scales and how these oscillations, which represent “temporal” convective self‐organization, would manifest in the presence of traditional “spatial” self‐ or forced‐aggregation in large‐domain convection‐permitting simulations. We find that the temporal oscillations become much less synchronized throughout a large domain ( 1,000 km) because gravity waves cannot propagate fast enough to synchronize convection. We also show that temporal oscillations still dominate the rainfall distribution even when there is tropical convective self‐aggregation or a large‐scale overturning circulation. These results could have important implications for extreme precipitation events under a warming climate.

Variations in Ozone Concentration in Seven Regions Under Different Temperature and Humidity Conditions

In recent years, the situation of ozone pollution in China has become increasingly severe, with PM2.5 being the main pollutant in the atmospheric environment of several cities. Meteorological conditions, particularly temperature and humidity, have a great influence on ozone formation. Therefore, understanding and quantifying the impact of the variation in temperature and humidity on ozone level can effectively provide the theoretical basis for the government to prevent and control ozone pollution. By analyzing the relationship among the daily maximum temperature (Tmax), relative humidity (RH), and the maximum 8-h running average ozone (O3-8h) measured from January 1, 2015 to July 31, 2022, a linear positive correlation between O3-8h and Tmax was observed in the seven regions with serious ozone pollution, and the temperature penalty factor ranged from 2.1-6.0 μg·(m3·℃)-1; a nonlinear correlation between O3-8h and RH was also observed, and O3-8h was the highest when RH was 55%. The sensitivity of different regions to Tmax and RH was slightly different; generally, the most suitable meteorological conditions for ozone formation were 29℃ ≤ Tmax< 38℃ and 40% ≤ RH<70%. In the Yangtze River Delta, Jiangsu-Anhui-Shandong-Henan, and the middle reaches of the Yangtze River, under extreme high temperature conditions (Tmax ≥ 35℃), O3-8h stopped increasing with the increase in temperature and even dropped; simultaneously, it was often accompanied with a small increase in particulate matter. It may be related to the heterogeneous reaction of some precursors with higher water vapor content and the increase in ozone heterogeneous sink.

Fracture of Ni/YSZ Porous Material Under Water Vapor Environment in SOFC Anode: Reactive Molecular Dynamics Simulation

In SOFC anodes, the concentration of water vapor in the hydrogen fuel increases when the hydrogen fuel supply is insufficient due to an accident. Here, when Ni/YSZ porous material is used for anodes, the high concentration of water vapor causes oxidation and volume expansion of Ni particles, leading to the destruction of the anode structure. To develop an anode material with high durability against such oxidation-induced fracture, it is necessary to elucidate the fracture process of Ni/YSZ porous materials due to the oxidation by water and the stress by the volume expansion of Ni particles. In this study, the fracture processes induced by the oxidation are investigated by reactive molecular dynamics method, which can handle chemical reactions. Especially, fatigue simulation by cyclic tension and compression is performed on the Ni/YSZ porous structures under water vapor environment to elucidate the effects of water-induced oxidation and fatigue on fracture.A Ni/YSZ porous model of about 2 million atoms is constructed with Ni and YSZ particles. A mass ratio of Ni particles to YSZ particles is 46:54, and a porosity is set to 40%. To consider water vapor environment, water molecules are placed in the vacancies (Fig. 1). Here, amount of water molecules is equivalent to 1500 times normal pressure to accelerate the oxidation by water. In fatigue processes, cyclic stress induces crack generation, crack propagation, and fracture of materials. Therefore, to investigate the fatigue fracture process, cyclic tension and compression by controlling the strain along the x-axis direction is applied to the Ni/YSZ porous model with a temperature of 1073 K, a pressure of 1.0 atm, and a strain rate of 1.0 x 10-9 s-1.The fatigue simulation was performed by changing the strain (i) from 0.00 to 1.50 for the 1st tension, (ii) from 1.50 to -1.50 for the 1st compression, and (iii) from -1.50 to 1.50 for the 2nd tension. The stress-strain curve during the fatigue simulation is shown in Fig. 2. To clarify the effect of oxidation by water on the fracture of Ni/YSZ porous structure, we first compared the stress-strain curves during the 1st tension of the Ni/YSZ porous models under vacuum and water vapor environment. Under water vapor environment, the tensile strength is 0.57 GPa at the strain of 0.10. This indicates that the water vapor environment leads to the fracture of the Ni/YSZ porous structure when the tensile stress is more than 0.57 GPa. On the other hand, under vacuum environment, the stress-strain curve raises and the tensile strength does not appear. Here, the tensile stress reaches 0.60 GPa at the strain of 1.50. Then, the fracture will ocuur by the tensile stress higher than 0.60 GPa under vacuum environment.Next, we compared the stress-strain curves during the 2nd tension after the 1st compression. The tensile strengths are 0.90 and 1.07 GPa under water vapor and vacuum environment, respectively. The lower tensile strength under water vapor environment indicates that fracture of the Ni/YSZ porous structure during fatigue is more likely to occur under water vapor environment than under vacuum environment.To discuss the reason why the water vapor environment induces the fracture of the Ni/YSZ porous structure, we investigated the structural change in the Ni/YSZ porous models in the fatigue simulations. Figure 3 shows the structural change around the interface between the Ni and YSZ particles during the 1st tension under water vapor and vacuum environment. Under water vapor environment, some cracks are generated at the interface between the Ni and YSZ particles (Fig. 3b). Around the cracks, H atoms and OH groups derived from water molecules are adsorbed on the Ni atoms and on the Zr and Y atoms of the YSZ particles. On the other hand, under vacuum environment, the Ni particles are stretched and no crack is generated by tension (Fig. 3c). These results suggest that the chemical reaction by water promotes the formation and growth of cracks at the Ni/YSZ interface during the tension of Ni/YSZ porous structures. Moreover, plastic deformation occurs within the Ni particles during tension under vacuum environment. On the other hand, there is less plastic deformation under water vapor environment, because the Ni particles are not stretched due to the crack generation at the interface between the Ni and YSZ particles. Therefore, the tensile strength under water vapor environment is lower than that under vacuum environment. Then, we suggest that water vapor environment induces crack generation and propagation at the interface between the Ni and YSZ particles and fracture of the Ni/YSZ porous material during fatigue. Figure 1

Evaluation of radiative absorption effect to estimate mean radiant temperature in environments with high water vapor concentration such as in a sauna

The importance of modeling the radiative absorption in an environment with a high concentration of water vapor, such as inside a sauna, was studied through numerical analyses and fieldwork. Radiative heat transfer analysis using the discrete ordinate method (DOM) was performed using OpenFOAM software to evaluate the influence of thermal radiation inside a sauna. In a high-temperature environment, such as a sauna, the effect of radiation heat transfer in the surrounding medium gradually increases. Therefore, the effects of the medium cannot be ignored. A full-spectrum k-distribution (FSK) was adopted to model the radiative absorption of the medium, which was composed of carbon dioxide and water vapor. The mean radiant temperature (MRT) was also determined using numerical simulations to compare the results with those measured directly using a globe thermometer. The measured MRT was lower than the air temperature because of radiative cooling by the surroundings. To evaluate the quality of the radiative absorption model, the MRT obtained using the transparent gas and FSK methods were compared. When the distance from the cooling front window was approximately 4 m, the FSK method improved the prediction of MRT by approximately 1 °C when compared with the transparent gas method, which is the conventional method. The FSK method improved the MRT prediction from the conventional method by approximately 27% in terms of the Root Mean Square Error. This result indicates the importance of modeling the MRT by considering radiative absorption in the presence of high water vapor pressure.

О СВЯЗИ ЦИКЛОГЕНЕЗА В МЕКСИКАНСКОМ ЗАЛИВЕ С ПЕРЕНОСОМ ВОДЯНОГО ПАРА В ТРОПИЧЕСКОЙ АТЛАНТИКЕ (ПО СПУТНИКОВЫМ СВЧ-РАДИОМЕТРИЧЕСКИМ ДАННЫМ)

The results of satellite monitoring of the transatlantic transport of water vapor in the atmosphere from the western coast of Africa to the Gulf of Mexico are presented. Using the data of the DMSP, EOS Aqua, GCOM-W1 satellite microwave radiometer measurements, the zones with high concentrations of water vapor in the air over the tropical Atlantic are identified, and the dynamics of their movement towards the Gulf of Mexico in the periods preceding the initiation of hurricanes Bret (1999), Lorenzo (2007), Katia (2017) in the gulf is analyzed. The connection of the atmospheric water vapor transport over the tropical Atlantic to the cyclogenesis in the Gulf of Mexico is discussed.

Design and energy efficiency analysis of hydrogen - fueled SOFC-‘GT+ST’ combined cycle system

In order to enhance electricity generation efficiency of hydrogen-fueled fuel cell gas turbine combined cycle system abbreviated as SOFC-GT system, a new combined system of fuel cell with turbine abbreviated as SOFC-GT+ST system is based on the feature of high concentration of water vapor in the anode of hydrogen fuel cell and the introduction of steam turbine, and a system model based on ebsilon software is built to compare the system under the same parameter conditions. The system model is built based on ebsilon software, and the system power, power generating efficiency, and the loss of the electricity is comparatively studied under the same parameters, and improved SOFC-GT+ST is proposed. Research results show the following: the second system, which utilizes the spent gas of cathode and anode separately, effectively utilizes the thermal energy of water vapor in the anode spent gas and improves the power generation efficiency of the system; the improved SOFC-′GT+ST The improved SOFC-‘GT+ST’ system further improves the power generation efficiency of the system by recycling the hydrogen in the SOFC that does not participate in the electrochemical reaction, which reaches 65.88%. The research in this paper provides a reference for improving.

Study of the interaction between NH3 and NO in the reduction zone of air-staged ammonia combustion under high moisture atmosphere

NH3 is used as a hydrogen-rich fuel, and the water vapor content produced by combustion can reach 30%. However, high NOx emission is one of the main problems restricting its application. The air-staged combustion is an effective low-NOx combustion strategy, subdividing the combustion process into three typical sections: the main combustion zone, the reduction zone, and the burnout zone. Fully utilizing the reaction between NH3 and NO in the reduction zone is expected to achieve an effective control of NOx emission. This research aims to explore the reduction ability of the residual NH3 on NO reduction in the reduction zone under high moisture atmosphere formed by ammonia combustion. An isothermal flow reactor was used to study the kinetic characteristics of the NH3/NO reaction under no-oxygen or residual low-oxygen condition in a wide temperature range (1073–1773K) and a high water vapor content range (0–50%). Additionally, three chemical kinetic models were used in simulations. The results showed that oxygen significantly changes the effect of water vapor on the NH3/NO reaction. In the absence of oxygen, water vapor has less effect on NH3/NO reaction at lower temperatures (<1500K). In the presence of oxygen, the increase of water vapor content leads to a significant shift of the reaction temperature window to higher temperatures and a decrease of the maximum NO reduction efficiency. Finally, the remarks about using residual NH3 to complete NOx removal in ammonia combustion were discussed.

Antiexfoliating h-BN⊃In2O3 Catalyst for Oxidative Dehydrogenation of Propane in a High-Temperature and Water-Rich Environment

Hexagonal boron nitride (h-BN) is regarded as one of the most efficient catalysts for oxidative dehydrogenation of propane (ODHP) with high olefin selectivity and productivity. However, the loss of the boron component under a high concentration of water vapor and high temperature seriously hinders its further development. How to make h-BN a stable ODHP catalyst is one of the biggest scientific challenges at present. Herein, we construct h-BN⊃xIn2O3 composite catalysts through the atomic layer deposition (ALD) process. After high-temperature treatment in ODHP reaction conditions, the In2O3 nanoparticles (NPs) are dispersed on the edge of h-BN and observed to be encapsulated by ultrathin boron oxide (BOx) overlayer. A novel strong metal oxide-support interaction (SMOSI) effect between In2O3 NPs and h-BN is observed for the first time. The material characterization reveals that the SMOSI not only improves the interlayer force between h-BN layers with a pinning model but also reduces the affinity of the B-N bond toward O• for inhibiting oxidative cutting of h-BN into fragments at a high temperature and water-rich environment. With the pinning effect of the SMOSI, the catalytic stability of h-BN⊃70In2O3 has been extended nearly five times than that of pristine h-BN, and the intrinsic olefin selectivity/productivity of h-BN is well maintained.

Sea Surface Temperature Gradients Estimation Using Top-of-Atmosphere Observations from the ESA Earth Explorer 10 Harmony Mission: Preliminary Studies

The Harmony satellite mission was recently approved as the next European Space Agency (ESA) Earth Explorer 10. The mission science objectives cover several applications related to solid earth, the cryosphere, upper-ocean dynamics and air–sea interactions. The mission consists of a constellation of two satellites, flying with the Copernicus Sentinel 1 (C or D) spacecraft, each hosting a C-band receive-only radar and a thermal infrared (TIR) payload. From an ocean dynamics/air–sea interaction perspective, the mission will provide the unique opportunity to observe simultaneously the signature of submesoscale upper-ocean processes via synthetic aperture radar and TIR imagery. The TIR imager is based on microbolometer technology and its acquisitions will rely on four channels: three narrow-band channels yielding observations at a ≃1 km spatial sampling distance (SSD) and a panchromatic (PAN, 8–12 μm) channel characterized by a ≃300 m SSD. Our study investigates the potential of Harmony in retrieving spatial features related to sea surface temperature (SST) gradients from the high-resolution PAN channel, relying on top-of-atmosphere (TOA) observations. Compared to a standard SST gradient retrieval, our approach does not require atmospheric correction, thus avoiding uncertainties due to inter-channel co-registration and radiometric consistency, with the possibility of exploiting the higher resolution of the PAN channel. The investigations were carried out simulating the future Harmony TOA radiances (TARs), as well as relying on existing state-of-the-art level 1 satellite products. Our approach enables the correct description of SST features at the sea surface avoiding the generation of spurious features due to atmospheric correction and/or instrumental issues. In addition, analyses based on existing satellite products suggest that the clear-sky TOA observations, in a typical mid-latitude scene, allow the reconstruction of up to 85% of the gradient magnitudes found at the sea-surface level. The methodology is less efficient in tropical areas, suffering from smoothing effects due to the high concentrations of water vapor.

From Fossil‐Fueled to Hydrogen‐Fueled Annealing Furnaces: Effects on the Oxidation of Stainless Steels

The possibility of replacing methane with hydrogen as the fuel gas in an annealing furnace is studied regarding the oxidation of ferritic AISI 441 and austenitic AISI 304 stainless steels during simulated short‐term annealing. Oxide‐scale formation using the simulated atmospheres based on methane–air, methane–oxygen, and hydrogen–oxygen combustions with different oxidant gas excesses is compared at steel grades’ furnace temperature ranges in an annealing process. Thermogravimetry is used to determine variations of weight gain during oxidation, and field‐emission scanning electron microscopy and glow discharge optical emission spectroscopy are used to characterize oxide scales. The transition to H2 as the fuel gas is more suitable for the ferritic grade than the austenitic grade at the studied temperatures. High water vapor content in hydrogen– and methane–oxygen combustion atmospheres promotes breakaway oxidation for both steel grades. Nodule formation is significantly observed under the most demanding annealing conditions for the ferritic grade, while only the lightest conditions remain without the signs of breakaway oxidation for the austenitic grade. Changes in the oxide‐scale structures produced in both hydrogen–oxygen and methane–oxygen atmospheres are in significant, which can facilitate the exchanges between these atmospheres in relation to methane–air combustion.

Water Vapor in the Upper Troposphere above Syowa Station in the Antarctic: Its Variations and Causes

An intensive balloon-borne observation was performed at Syowa Station in the Antarctic (69.0°S, 39.6°E) in July 2016 using Cryogenic Frostpoint Hygrometers (CFH) and Electrochemical Concentration Cell (ECC) ozonesondes. High water vapor concentration was observed in the upper troposphere in two out of five observations. Trajectory analysis and atmospheric reanalysis data showed that moist air was transported into the upper troposphere due to the upwelling in front of a trough. While only isentropic transport was dominant in one case, both the isentropic transport and diabatic heating contributed to the upward transport in the other case. In another case where the air parcels came over the Antarctic continent, the water vapor concentration in the upper troposphere was lower than in the other cases. These results suggest that transport of air parcels with different origins by synoptic-scale disturbances controls water vapor concentration in the Antarctic upper troposphere.