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We have assessed the quality of four co-located GNSS stations by studying time series of estimated linear horizontal gradients in the signal delay. The stations have different electromagnetic environments. We also examine the consistency of the results by using two different GNSS softwares, GipsyX and c5++, and applying three different elevation cutoff angles: 5 ° , 10 ° , and 20 °. The estimated gradients are compared with the corresponding ones estimated from microwave radiometer observations acquired during six months (April–September 2021). For all four stations and using both softwares we find that is is possible to track gradient variations over time scales from less than one hour using GPS observations only. We have indications that it is an advantage to equip the area below the GNSS antenna with microwave absorbing material. However, the differences are small, a reduction in rms differences in the gradients compared to those from the microwave radiometer of less than 2 %. More studies are needed to decide if such an investment is reasonable in terms of cost and maintenance. [ABSTRACT FROM AUTHOR]

A non-equilibrium plasma is created in a micro-capillary quartz tube (800 µ m of internal diameter), by a DC-pulsed micro-dielectric barrier discharge (micro-DBD) and the propagation of an ionisation wave, in mixtures of He/H2O/VOC at atmospheric pressure where the studied volatile organic compounds (VOCs) are representative of molecules belonging to different chemical families: alcohols (methanol, ethanol, isopropanol, tert-butanol), ketones (acetone), nitriles (acetonitrile), and aromatic hydrocarbons (toluene). The conversion efficiency of these VOCs is studied as a function of the applied voltage on the micro-DBD (or electrical energy deposited in the plasma) and of the initial concentration of the molecules in the range from 1 ppm up to 3000 ppm (depending on the molecule), with the help of high-resolution real-time mass spectrometry Fourier transform ion cyclotron resonance associated to chemical ionisation (CI-FTICR) using H3O+ as precursor ion. A variety of by-products resulting from the conversion of VOCs are identified and quantified, emphasising that the micro-capillary plasma is able to induce a complex chemical reactivity. A qualitative analysis of the involved kinetics, based on the existing literature, reveals that helium species (ions and metastable states) and radicals coming from the dissociation of the water molecules (O and OH) are the most probable candidates to explain the formation of all compounds detected by the CI-FTICR apparatus. Quenching processes of the metastable He(23S) by the VOCs, leading to the dissociation of the molecules, are suggested to explain some of the experimental results. [ABSTRACT FROM AUTHOR]

Model alloy, Fe-20Cr (wt%), was oxidized in two gas mixtures Ar-5H2O-(5H2) (vol%) at 850 °C. The alloy formed Cr2O3 scales in both gases. The Cr2O3 scale developed faster in Ar-5H2O-5H2 and contained fine pores, whilst that grown in Ar-5H2O was dense. Experiments with inert SiO2 marker revealed that the Cr2O3 scale growth in Ar-5H2O-(5H2) was controlled mainly by outward Cr diffusion. When adjusted for grain boundary diffusion effects, Wagner's theory was successful in describing the hydrogen effect, provided that the Cr2O3 scales are n-type. [ABSTRACT FROM AUTHOR]

Present manufacturing norms globally demand usage of sustainable practices by the machining firms. There is also demand for better product quality and higher production rates with constraints on cost. The superalloy Inconel 718 finds plenty of applications in aerospace, automobiles, chemical plants and power plants. However it poses lot of challenges in machining due to its difficult-to-cut characteristics. To address these issues, the current paper explores the high-speed turning of Inconel 718 using coated carbide inserts and the eco-friendly cutting fluid as water vapour. The novelty of the work lies in use of very minutely explored eco-friendly cutting fluid as water vapour, use of unique tool holder with integrated cutting fluid delivery channel for precise jetting at tool-work interface, incorporation of high-speed machining regime for better productivity, use of economic carbide tooling as opposed to the costly ceramics and CBNs, and thus implementing sustainability in machining. Central composite design based on response surface methodology was used for experimentation as the process parameters were limited and their exploratory ranges already known. This also enabled to study effect of multiple factors simultaneously with fewer experimental combinations. Cutting speed, feedrate and pressure of water vapour was varied in the range of 72.96-157.04 m/min, 0.05–0.15 mm/rev and 0.20–0.70 bar respectively. The machinability characteristics have been assessed in terms of chip deformation coefficient, cutting forces and mainly surface roughness. Increase of pressure led to reduction in chip deformation coefficient, cutting forces and surface roughness on account of better water vapour penetrability into machining zone. However increase of feedrate led to higher values of cutting force and surface roughness. The feedrate and pressure were found to be highly dominating factors influencing the surface roughness with their contribution being 18.29% and 58.23% respectively. Analysis of micrographs of machined surfaces revealed presence of surface alterations consisting of feedmarks, grooves, micro-particle deposits and material side-flow to variable extends depending on machining conditions. [ABSTRACT FROM AUTHOR]

In the atmosphere, the interrelationship between dynamics and chemistry results in mutual influence and interaction. The behavior of internal gravity waves is influenced by the thermal effects caused by chemical components present in the atmosphere. In this investigation, the equations determining gravity waves are coupled with those characterizing the behavior of ozone and water vapor. To investigate the coupled equations, numerical analyses are conducted, and the resulting numerical results are presented. Internal gravity waves have been observed to influence the distribution of ozone and water vapor within the Earth's atmosphere. It has been demonstrated, based on our findings, that wave fluctuations play a significant role in exerting a substantial effect. In addition, it has been observed that the influence of ozone and water vapor-induced heating on gravity waves is significant, particularly near the critical level where the mean flow induced by gravity waves plays a significant role. [ABSTRACT FROM AUTHOR]

The Thar is the most densely populated desert in the world, which supports diverse ecosystems and human endeavours such as agriculture and socioeconomic activities. Water demand and supply in the Thar play an essential role in regulating the socioeconomic activities of the region. Inland water and precipitation aid the movement of water in the Thar Desert. Precipitation in the Thar is governed by the Indian Summer Monsoon (ISM), during which the winds distribute water vapour to regulate precipitation across the region. Therefore, we analyse the water vapour, its sources and its relation with precipitation using satellite measurements and reanalysis data in the Thar during ISM. Like other regions, a clear seasonal cycle of water vapour is observed in the Thar, with very high values (> 45 kg/m2) during ISM and low in winter (< 15 kg/m2). Evapotranspiration and moisture transport have significant effects on the amount of water vapour during ISM. There is a significant increase in water vapour in the troposphere, with high trends at the surface (0.032 g/kg/year) and small at the tropopause (0.00002 g/kg/year). A significant increase in column water vapour is also estimated in the Thar during ISM, with high trends in the eastern and southern areas, at about 0.15–0.35 kg/m2/year. The rise in water vapour in the Thar can be attributed to the increase in evapotranspiration (0.03–0.07 mm/day/year) and water vapour transport (> 0.5 kg/m/s/year) from the Arabian Sea and Indian Ocean. The rise in water vapour can lead to an increase in precipitation in the Thar, as it shows significant positive trends (0.05–0.1 mm/day/year) in the eastern areas during ISM. The increase in precipitation and water vapour in the arid Thar Desert can have significant implications for the regional environment and agriculture. [ABSTRACT FROM AUTHOR]

The predicted rotation-vibration absorption spectrum of the radioactive isotopically substituted water molecule, H214O, is presented. Variational nuclear-motion calculations are performed using the DVR3D software package based on the use of a high-precision potential energy function and an accurate dipole moment surface. Line centres, intensity and Einstein coefficients are calculated, and air pressure broadening coefficients are estimated. The calculation was carried out over a wide wavenumber range from 0 to 25000 cm $ {}^{-1} $ − 1 and total angular momentum up to J = 20. Isotopologue extrapolation rules based on experimental data on the energy levels of the stable isotopologues H216O, H $ {}_{2}^{16} $ 2 16 O H217O and H218O were also used to improve the predicted line positions. Spectral ranges best suited to the detection of H214O are identified. [ABSTRACT FROM AUTHOR]

Winter extreme cold events (ECEs) have profound impacts on human health, transportation, energy consumption and the economy, particularly associated with high‐humidity conditions. Recent research has indicated a growing interest in extreme temperature events that account for the presence of water vapour. However, the characteristics of humidity‐related ECEs (HECEs) remain unclear. Given the rise in atmospheric moisture due to global warming, understanding the influence of water vapour on HECEs becomes crucial. This study examined variations in HECEs identified using the wet‐bulb globe temperature (WBGT) in China during 1959–2020 and quantified the impacts of water vapour. The results revealed a decrease in the intensity and frequency of HECEs in China during this period, except for in northern China, where the intensity increased, which contrasts with the trends in traditional ECEs. Furthermore, strong HECEs were found to exhibit greater frequency, duration and intensity in northern China than weak HECEs. Additionally, the specific humidity for all categories of HECEs in China exhibited an upward trend, with a more rapid increase for strong HECEs. The findings indicated that the intensity of HECEs is positively correlated with the increase in water vapour. Defining a water vapour amplification factor revealed amplified intensity and duration at most grid points, particularly across northern China. Therefore, while winter warming reduces traditional ECEs, HECEs persist and even intensify as humidity increases, confirming significant amplification by water vapour. Our results emphasized the importance of increasing water vapour, driven by global warming, which may increase the risk of HECEs in the future. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of shale–water interaction by water vapour adsorption is crucial for predicting shale gas productivity. In this study, equilibrium adsorption data of water vapour on four different shales of the Sichuan Basin at three temperatures (298, 308, and 318 K) were measured using static gravity techniques. The water vapour adsorption isotherms were simulated by three statistical physics models. Steric parameters, including the number of water vapour molecules adsorbed per site (n), monolayer adsorption amount (q0), and adsorption energy (ΔEa), and thermodynamic parameters such as configuration entropy (Sa), internal energy (Eint), and free energy (Ga) derived from the selected model were used to explain the adsorption mechanism. The model analyses suggest that the adsorbed water vapour molecules are attached to the shale surface in a multi‐anchorage manner. The adsorption of the first layer shows a Type I characteristics, while the adsorption of the subsequent layer is of Type III. The calculated adsorption energies indicate that the physical adsorption takes place on the water vapour molecules on the shale, and the main interaction forces are hydrophilic bonding forces and van der Waals forces. Negative Eint and Ga values indicate that the spontaneous properties are for water vapour adsorption and that the system requires the release of energy to capture the water vapour molecules. [ABSTRACT FROM AUTHOR]

In the present study, trends and variations in carbon dioxide (CO2), temperature and water vapour are analysed using 9 years (2003–2011) of mid-tropospheric (300–500 hPa) Atmospheric Infrared Sounder (AIRS) data. The focus of analysis remains on both a global as well as regional (India) scale along with improved understanding of their inter relationship. It was observed that the mid-tropospheric carbon dioxide increased from ~ 373 to ~ 393 ppm and ~ 373 to ~ 392 ppm, respectively, over the globe and the Indian region during 9 years. However, no substantial trends (increasing or decreasing) were observed in the temperature and water vapour observations for the same period of time. De-trended data of CO2, temperature and water vapour were further analysed to understand the inter relationship between these parameters and the influence of two greenhouse gases (CO2 and water vapour) on temperature. Analysis suggests a very high correlation (~ 0.90) between temperature and water vapour, however, no significant correlation was observed between temperature and carbon dioxide data, indicating that change in water vapour may have stronger influence on temperature compared to the change in CO2, this feature can play a more significant role as a greenhouse gas than CO2. [ABSTRACT FROM AUTHOR]

A key point for the development of a renewable energy economy at a large scale is the possibility to use the current natural gas network and storage capacity to transport and store hydrogen. This study is dedicated to evaluate the integrity of materials used for underground aquifer storage regarding hydrogen embrittlement in a gaseous environment saturated with water vapour and containing few amounts of H 2 S. In this environment, the water vapour content in the gas stored may reach saturation at bottom well pressure and temperature. It is known that the presence of impurities in the gas, such as H 2 O, can promote or inhibit hydrogen embrittlement phenomenon, depending on the nature of the steel. This work investigates mechanical properties of a tempered martensite N80-Q steel, and a ferrite-perlite L360-NB C–Mn steel issued from a completion and a collect tube respectively. The testing environments are NG, NG + H 2 S, NG + 25%H 2 and NG + 25%H 2 + H 2 S saturated in water vapour at 8.5 MPa and room temperature. These environmental conditions aim at replicating the storage service conditions. Fracture toughness and fatigue crack growth properties are assessed. So far, the mechanical behaviour of such steels under hydrogen gas pressure saturated with water vapour and low amount of H 2 S has poorly been addressed. Regarding toughness properties, the two steels present different behaviour: for the L360 NB crack has not propagated for any testing environments, while cracks propagated in all the tests for the N80 Q. Despite this difference, for the two steels, the toughness does not seem to be affected by hydrogen as the results obtained in NG + 25%H 2 + H 2 O and NG + H 2 O are similar. Based on the literature C–Mn steels toughness is affected by the presence of dry hydrogen. Hence, the results presented here show that H 2 O inhibits hydrogen embrittlement as far as toughness is concerned. The L360NB, however, presented a slight decrease in toughness properties with the combination of NG + 25%H 2 + H 2 S + H 2 O. FCG (fatigue crack growth) results, on the opposite, clearly highlight the influence of hydrogen on the mechanical behaviour of the two steels. The FCG rates are faster from a factor five (resp. 10) in NG + 25%H 2 + H 2 O compared to NG + H 2 O for the N80 Q (resp. L360). In this article, toughness and FGC results on the two steels are discussed in terms of microstructure and mechanical loading modes, aiming to quantify and better understand the influence of H 2 O and H 2 S on the sensitivity of low alloy steels to hydrogen embrittlement. • The hydrogen embrittlement of metallic components used for underground hydrogen storage is studied. • The fracture toughness and fatigue crack growth properties in 8.5 MPa H 2 are discussed. • The effect of a gas saturated with water vapour and/or containing small amount of H 2 S is studied. • Water vapour mitigates hydrogen deleterious effect on fracture toughness of the two studied steels (ferritic and martensitic). • A synergetic hydrogen embrittlement effect between water vapour and H 2 S is highlighted. [ABSTRACT FROM AUTHOR]

Approximately 40 % of the final energy is used for heating and cooling of buildings. Of this, as much as 75 % is used in residential buildings. The proportion of energy needed in buildings is relatively high, so it is necessary to start using technologies that have low energy consumption, use it efficiently or provide it from renewable sources. One such technology is thermal energy storage, which allows us to store excess energy for later when we need extra energy. The paper presents two experiments in the field of adsorption space heating. In the first experiment, measurements were carried out on the adsorbents - zeolite 13X and zeolite NaYBFK, which were placed into a duct, through which humid air was transported by means of a centrifugal fan. In the second experiment, water vapour as the working medium was used. With the first experiment we achieved better water uptake on NaYBF, while the second experiment shows the increase of water uptake of zeolite 13X. [ABSTRACT FROM AUTHOR]

The Asian Summer Monsoon (ASM) exhibit different modes of variability in which the active and break phases is one of the most prominent intraseasonal scale variability of the ASM. The shift in convective centres to more polluted regions coupled with the associated circulation features during these phases results in a redistribution of trace species in the upper troposphere and lower stratosphere (UTLS) region. Apropos to this, this study presents a quantitative assessment of the variability in the spatial distribution of ozone, carbon monoxide (CO) and water vapour (H2O) in the UTLS during the active and break phase of ASM with respect to the seasonal mean background using fifteen years (2005–2019) of Aura-MLS observations in conjunction with reanalysis data sets, cloud-top brightness temperatures and trajectory analysis. These 15-years of data is used to make composite maps of tracer anomalies to investigate the varying influence of monsoon convection, transport and ASMA dynamics in the UTLS region during the active/break phase. This study shows that, while the distribution of trace species during both phases is determined by the combined role of convection and transport in the upper troposphere, changes in ASMA modes, transport and tropopause dynamics during the active/break phases controls the spatial pattern of both tropospheric and stratospheric species near the tropopause level. [ABSTRACT FROM AUTHOR]

The diurnal temperature range (DTR) has generally decreased at global scale according to the IPCC reports and previous publications. Here, we examined the change in DTR within the past four decades and found that DTR decreased in wet areas, but it increased in dry areas. This is because the daily minimum air temperature (Tmin) increased at a slower rate than the daily maximum air temperature (Tmax) in the dry areas, while it increased more rapidly in the wet areas. The changes in cloud cover, water vapour and moisture flux were observed to have contributed to the observed change in DTR. The change in moisture flux largely contributed to this change through the indirect effect on the change in water vapour across the aridity gradient. The significant impact of moisture flux is linked to the differential change in moisture flux between the dry and wet zones. [ABSTRACT FROM AUTHOR]

Quantification of the greenhouse effect is a routine procedure in the framework of hydrological calculations of evaporation. According to the standard practice, this is made considering the water vapour in the atmosphere, without any reference to the concentration of carbon dioxide (CO2), which, however, in the last century has increased from 300 to about 420 ppm. As the formulae used for the greenhouse effect quantification were introduced 50–90 years ago, we examine whether these are still representative or not, based on eight sets of observations, distributed across a century. We conclude that the observed increase of the atmospheric CO2 concentration has not altered, in a discernible manner, the greenhouse effect, which remains dominated by the quantity of water vapour in the atmosphere, and that the original formulae used in hydrological practice remain valid. Hence, there is no need for adaptation of the original formulae due to increased CO2 concentration. [ABSTRACT FROM AUTHOR]

The interest in nonthermal discharge plasma has recently increased over the last few decades due to the ability to generate new radicals at atmospheric pressure. This paper presents a comprehensive analysis of the dissociation processes and reaction rates of various water vapour samples by dielectric barrier discharge plasma (DBD). The influence of water contamination and the presence of ammonia (NH 3) on hydrogen production from water vapour was investigated. A novel reaction rate expression was proposed to fit the plasma-water vapour experiment results. The hydrogen production and conversion rate of pure reverse osmosis (RO) water samples showed greater results than the contaminated water samples in all experiments at different tested bubbling temperatures. The higher conversion rate was obtained from RO water combined with 1%NH 3 at a bubbling temperature of 50 °C and was 1.17%. The water contamination influenced the generated DBD plasma micro discharges, consequently decreasing the electron collisions, leading to lower water vapour conversion into constituent elements H 2 and O 2. It was also found that the influence of ammonia on the water vapour decomposition was related to the NH 3 concentration. Moreover, the reaction rate showed good agreement with the experimental results. It was observed that the energy efficiencies were obtained at an operating temperature of 50 °C for pure RO, GTW, and CTW water samples enhanced by adding 1%NH 3 , for example, the RO energy efficiency value at a bubbling temperature of 50 °C increased from 0.133% to 1.15% because of more hydrogen was generated. It implies that the water vapour decomposition processes are influenced by the following parameters: input gas temperature, reaction time, plasma power, oven or reactor heating temperature, the separation method, sampling method, and sampling collection time. [Display omitted] • The hydrogen production from various water types by DBD plasma is investigated. • The presence of ammonia enhanced the hydrogen production of water vapour. • The water contamination has a negative effect on the plasma water decomposition. • The new rate equation showed a good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Noctilucent clouds (NLC) are sensitive indicators in the upper mesosphere, reflecting changes in the background atmosphere. Studying NLC responses to the solar cycle is important for understanding solar-induced changes and assessing long-term climate trends in the upper mesosphere. Additionally, it enhances our understanding of how increases in greenhouse gas concentration in the atmosphere impact the Earth's upper mesosphere and climate. This study presents long-term trends in the response of NLC and the background atmosphere to the 11-year solar cycle variations. We utilised model simulations from the Leibniz Institute Middle Atmosphere (LIMA) and the Mesospheric Ice Microphysics and Transport (MIMAS) over 170 years (1849 to 2019), covering 15 solar cycles. Background temperature and water vapour (H2O) exhibit an apparent response to the solar cycle, with an enhancement post-1960, followed by an acceleration of greenhouse gas concentrations. NLC properties, such as maximum brightness (βmax), calculated as the maximum backscatter coefficient, altitude of βmax (referred to as NLC altitude) and ice water content (IWC), show responses to solar cycle variations that increase over time. This increase is primarily due to an increase in background water vapour concentration caused by an increase in methane (CH4). The NLC altitude positively responds to the solar cycle mainly due to solar cycle-induced temperature changes. The response of NLC properties to the solar cycle varies with latitude, with most NLC properties showing larger and similar responses at higher latitudes (69° N and 78° N) than mid-latitudes (58° N). [ABSTRACT FROM AUTHOR]

Model alloys, Fe–20Cr and Fe–20Cr–20Ni (wt%) with and without 1% Si, were exposed to four different gas mixtures Ar–10H2O, Ar–10H2O–0.1HCl, Ar–10H2O–0.1HCl–10CO2, Ar–10H2O–0.1HCl–10CO2–0.5SO2 (vol.%) at 650 °C. The Fe–20Cr and Fe–20Cr–20Ni alloys underwent breakaway corrosion in Ar–10H2O–(0.1HCl)–(10CO2), forming Cr2O3 and Fe-rich oxide nodules. Silicon addition markedly increased corrosion resistance for both alloys by forming an additional SiO2 layer beneath the Cr2O3 scale. Addition of SO2 to Ar–10H2O–0.1HCl–10CO2 significantly suppressed the formation of Fe-rich oxide nodules on Fe–20Cr. Corrosion in the SO2-bearing gas resulted in (Cr, Fe, S)-rich precipitates in all alloys. The effects of gas composition and Si alloying on corrosion of both alloys are discussed in terms of transport processes within the scales. [ABSTRACT FROM AUTHOR]

In the present work, the high-temperature decarburization of the austenitic stainless steel S304HCu in Ar–4%H2–xH2O at temperatures between 1000 and 1150 °C was investigated. The focus was on determining parameters that influence the decarburization rate during heat treatment. Thermogravimetric experiments were performed with simultaneous measurements of CO release from the sample using a mass spectrometer. The variation of the experimental parameters included the composition of the atmosphere during pre-oxidation and decarburization, the temperature and the sample thickness. The results indicate that the loss of carbon from the specimen occurs faster through reaction of Cr2O3 with C from the steel compared to the reaction of C at the steel surface with H2O, provided that in the former case CO can easily evaporate. The overall decarburization process is governed by competing reactions; the destruction of chromium oxide by C and the formation of oxide scale by water vapour. The relative rates of these two reactions determines whether decarburization will occur or whether formation of a protective oxide stops the release of CO, the latter being promoted at lower temperatures and high water vapour contents. A dense, sufficiently thick chromia scale retards the onset of decarburization but does eventually not stop the carbon loss. Indications were found that the destruction of a pre-formed chromia scale by carbon involves a two-step process whereby presence of hydrogen is important. [ABSTRACT FROM AUTHOR]

A Hall Effect Thruster propelled by water vapour is investigated at the Imperial Plasma Propulsion Laboratory. For that purpose, a water vapour feed system is designed, optimized and tested, with the major objective of keeping water in vapour state at all times. This system primarily consists of a mass flow controller, a flow restrictor, and a heating and pressure monitor system capable of identifying under which conditions water condensation occurs. A hanging pendulum thrust balance is used to measure the thrust on the power range of P d = 600 – 1600 W. Different magnetic field strengths and mass flows are investigated to determine the conditions in which the highest efficiency can be achieved. Then, a comparison between water vapour and oxygen (intended to be the propellant of a water electrolysis Hall Effect Thruster) is included. The results show that oxygen is approximately 20% more efficient than water vapour under the same operating conditions. Overall, the highest thrust measurement recorded with water vapour was 20. 0 ± 0. 2 mN; with a specific impulse of 2039 ± 20 s and an anode efficiency of 12. 5 ± 0. 3 % at the largest discharge power of investigation ( P d = 1600 ± 1 W). • Thrust, specific impulse and efficiency of a water vapour Hall Effect Thruster. • Mass flow rates and magnetic field strength performance evaluation. • Studies of cross sections of oxygen (from water electrolysis) and water vapour. • Trade-off analysis between water electrolysis versus water vapour propulsion. [ABSTRACT FROM AUTHOR]

Balloon-borne cryogenic frost-point hygrometer (CFH) observations over two tropical stations Trivandrum (8.53° N, 76.87° E) and Hyderabad (17.47° N, 78.58° E) [2014–2017] along with Microwave Limb Sounder (MLS) observations [2011–2017] are used to examine the signatures of local and regional dynamics in the distribution of lower stratospheric water vapour over the Indian region. The column-integrated water vapour in the lower stratosphere (IWVLS) varies in the range 2.5–5 g/m2 with low values during winter and high values during summer monsoon and post monsoon seasons. About 50–75% of IWVLS lies in the lower regime of the lower stratosphere, the region from cold point tropopause (CPT) to 21 km (LS1). Hygropause is very near to the CPT in winter and pre-monsoon and 2–3 km above the CPT in summer-monsoon and post-monsoon. The CPT and the minimum in saturated mixing ratio (SMRmin) altitudes show a positive correlation, with SMRmin mostly occurring below the CPT. Though water vapour mixing ratio (WVMR) at CPT increases with increase in SMRmin, it is mostly less than the corresponding SMRmin value. CFH observations showed that the tape recorder signal in the LS1 is disturbed by the local/regional dynamics. While the amount of water vapour entering the lower stratosphere is higher over Hyderabad in winter and summer monsoon, it is higher over Trivandrum in the other two seasons. Hydration at the tropopause level is mainly determined by the overshooting/deep convection, monsoon dynamics and horizontal transport and dehydration is determined by temperature variations in the tropical tropopause layer (TTL). [ABSTRACT FROM AUTHOR]

Global navigation satellite system (GNSS) meteorology is utilized in predicting and monitoring extreme weather events using tropospheric products like precipitable water vapour for horizontal 2D detail and water vapour density profiles for 3D detail. In water vapour (WV) tomography, the slant delays from GNSS observations are used to model 4D variations of wet refractivity in the atmosphere above the study area. We present a comprehensive review on the evolution of GNSS WV tomography since its inception, the current state of the art, the challenges faced by the meteorology community, and a qualitative analysis of various techniques used in the process. With the growing infrastructure of meteorologically oriented GNSS station networks as well as increasing utilization of multi-source earth observation datasets powered with machine learning tools, GNSS tomography has shown improvements in producing accurate WV profiles. These new improvements have created the need for conducting multi-factor canonical analyses to understand the efficiency of these well-established methods in controlling the accuracy of the output field. [ABSTRACT FROM AUTHOR]

This work reports a novel method of determining the atmospheric water vapour feedback by utilizing the simultaneously retrieved atmospheric column concentrations of carbon dioxide (xCO2), the total column of water vapour (H2O) and the temperature (T7) at 700 hPa obtained from Orbiting Carbon Observatory-2 (OCO-2) and Orbiting Carbon Observatory-3 (OCO-3) data. The study areas are the tropical land cover of India and the surrounding deep seas. The methodology involves annual mean values for xCO2, H2O and T7 defined by averaging over a full year. The practical range of variation of saturation vapour pressure with surface temperature allows a linear approximation of the annual mean H2O versus xCO2. The linear correlation of the annual mean xCO2 and H2O values over the years 2016–2022 for OCO-2 and 2020–2022 for both OCO-2 and OCO-3 revealed an opposite trend of temporal variation for populated land and unpopulated deep sea regions. A feedback for water vapour was defined in terms of the long-term variation of annual mean H2O with annual mean xCO2 over years 2016–2022 and the corresponding variation with annual mean T7. The water vapour feedback for each ppm increase of annual mean xCO2 was equivalent to approximately 0.015 W m−2 and 0.007 W m−2 for populated and deep sea regions, respectively. The corresponding changes in T7 were an increase of 0.0267 K and a decrease of 0.0044 K, respectively. [ABSTRACT FROM AUTHOR]

Silicon-bearing vapour at low pressure was used to deposit SiO2 during exposure of pure chromium, Fe-30Cr (wt.%) and Kanthal APM alloy to an Ar-10H2O-0.1HCl mixture (vol.%) at 650 °C. Pure Cr formed porous chromia blades on top of a polycrystalline Cr2O3 scale containing SiO2. A model Fe-30Cr alloy formed a scale consisting of a thick, amorphous (Cr,Si)Ox outer layer and a thin, polycrystalline Cr2O3 inner layer. Kanthal alloy formed a thin scale containing a Si-rich oxide outer layer and an inner layer of Fe, Cr, and Al oxides. Amorphous (Cr,Si)Ox nodules formed locally on top of (Cr,Fe)23C6 precipitates at the Kanthal surface. [ABSTRACT FROM AUTHOR]

High-resolution spectra of H2O with a high signal/noise ratio (2500 at the absorbance equal 1) were recorded with a Bruker IFS 125 FTIR spectrometer covering H2O transitions from 5090 to 7490 cm−1 at the spectral resolution of 0.01 cm−1. The multispectrum fitting procedure has been applied to recover the spectral line parameters from measurements using quadratic speed-dependent Voigt (qSDV) profiles which made it possible to describe the experimental profile at the noise level. The H216O line broadening and shift coefficients for 439 lines of 7 vibrational bands 2ν3, ν2 + ν3, 2ν2 + ν3, ν1 + ν3, ν1 + ν2, ν1 + 2ν2 and 2ν1 were measured. A total of 339 lines were studied for the first time. The uncertainty of the broadening coefficients for the unblended H2O absorption lines was 2–4%. The determined parameters are compared to HITRAN12 and experimental values. The ratio between HITRAN data and our broadening coefficient varied from 0.82 to 1.21. The calculations of broadening and shift coefficients were performed in a framework of the semi-classical method and by using an empirical function whose parameters were taken from the literature. The uncertainty of calculations was 5% for the air broadening half-widths on average. [ABSTRACT FROM AUTHOR]

Oxidation behaviour of undoped β-NiAl and β-NiAl-0.05Hf single crystals were investigated at 1100 °C in 20 vol% O2 + Ar and 15 vol% H2O + Ar, respectively. On contrary to the well-known beneficial effect of Hf additions on the oxidation behaviour of polycrystalline β-NiAl, severe-scale spallation is observed for β-NiAl-0.05Hf single-crystal alloy, especially in dry atmosphere. It is proposed that the presence of the grain boundaries in the polycrystalline substrate enables proper content of Hf segregating at the grain boundaries of the oxide scale and at the scale–substrate interface, which promotes the conditions required for reactive element effect. Once the reactive element effect of Hf does not work, its strong affinity with oxygen will accelerate the process of high-temperature oxidation. However, the absence of the grain boundaries as fast diffusion paths partially compromises the adverse influence of water vapour on cyclic oxidation resistance of β-NiAl single crystal, resulting in considerable suppression of the oxidation rate and less loss of protection compared with that in dry atmosphere. In addition, interfacial cavities are observed in dry and humid atmospheres, which may eventually result in the spallation of the oxide scale. [ABSTRACT FROM AUTHOR]

Despite being rare, large volcanic eruptions can have a long-lasting impact on the chemistry, radiation, and dynamics of the stratosphere. This study attempts to quantify the changes in the stratospheric water vapour and its relationship to temperature and ozone observed from space-based Microwave Limb Sounder (MLS) observations during the submarine volcano eruption Hunga Tonga-Hunga Ha'apai that occurred on 15 January 2022. The most notable aspect of this eruption is the plumes, which are water vapour columns that reached higher altitudes (1 hPa (47.6 km)) than earlier eruptions. We discovered that the eruption injected a record amount of water vapour (6–8 ppmv) directly into the stratosphere from 38–10 hPa vertically, which is present even after one year. The majority of water vapour is confined to the Southern Hemisphere (SH) tropics, i.e., 30°S to 5°N, and gradually descends to the SH polar latitudes over time. The WV from the lower stratosphere reaches mesospheric altitudes during January 2023. We quantify the impact of increased water vapour on temperature and ozone as well. Temperatures begin to fall during the month of March in the regions where there is an increase in water vapour. A ~5 K cooling occurs in July and August as a result of the thermal adjustment to the extra water vapour IR cooling. Our analysis shows a decrease in ozone caused by an increase in water vapour. Significant variability is observed in all three parameters at 26 km compared to other levels. Further, we noticed that after one year of eruption, the water vapour, Temperature and Ozone did not reach the background values. It is possible that this unusual eruption produced a different atmospheric reaction than other significant volcanic eruptions that have been well investigated. [ABSTRACT FROM AUTHOR]

The diurnal water‐vapour cycle is a critical component of the hydrological cycle, yet it is one of the hardest components to accurately reproduce in forecast and climate models. Previous studies have shown that both forecast and climate models underrepresent the diurnal water‐vapour cycle, which leads to errors in precipitation, cloud, and radiative transfer parameters. Most diurnal cycle studies were conducted in the Tropics, and very few model evaluations of this process exist for the Arctic. Additionally, the majority of studies focus on total column water‐vapour cycles; almost none use height‐resolved measurements. In this study, we evaluate the diurnal water‐vapour cycles in Environment and Climate Change Canada's Global Environmental Multiscale–High Resolution Deterministic Prediction System (GEM–HRDPS) numerical weather forecast model and the European Centre for Medium‐Range Weather Forecasts Reanalysis v5 (ERA5) using a Vaisala preproduction differential absorption lidar (DIAL) and a co‐located Global Positioning System (GPS) located in Iqaluit, Nunavut (63.75° N, 68.55° W). Both numerical products reproduce the phase of the diurnal cycle well below 1 km year‐round. However, ERA5's diurnal amplitudes are significantly smaller than the DIAL and GPS amplitudes. GEM–HRDPS amplitudes are consistently larger in the first few hundred metres but smaller above 1 km; it also underrepresents the amplitude of the total column diurnal cycle. Neither ERA5 nor GEM–HRDPS accurately reproduce the 12‐hr component of the diurnal cycle in either the height‐resolved or total column cycles. The inability to accurately reproduce the 12‐hr component in both numerical products suggests that the representation of some underlying process is incomplete, which can impact the accuracy of precipitation and radiative transfer algorithms. In conclusion, we find that the numerical products are able to reproduce the general behaviour and shape of the cycle but still require improvement at certain altitudes. [ABSTRACT FROM AUTHOR]

This study aims to assess the impacts of assimilating the clear-sky radiances from the Advanced Geosynchronous Radiation Imager (AGRI) onboard the Fengyun-4A (FY-4A) satellite on 72-h forecasts. First, we compare the water vapour (WV) brightness temperature (TB) in July 2018 from the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS) analyses and Weather Research and Forecasting (WRF) forecasts with the clear-sky AGRI WV channel observations. The results suggest that the NCEP GDAS analyses are more consistent with the AGRI observations than the WRF forecasts, and the AGRI observations can be utilized to improve the initial conditions of the WRF model by data assimilation, especially in water vapour and surface temperature. After the preliminary verification, two identical cycling assimilation experiments are performed with and without the AGRI WV TB assimilation for a month. The results reveal that the WRF forecasts with AGRI TB assimilation are closer to satellite observations than the first guess in both WV channels. The validation with WV channel data of the Microwave Humidity Sounder (MHS) and SAPHIR sensors indicates that after the AGRI data assimilation, the errors are smaller than in the control experiment (without AGRI assimilation). The assimilation of the TB observed by AGRI WV channels shows a remarkable positive impact on moisture forecasts at middle and upper levels. Comparison of the TB from the WRF forecasts with the MHS observations suggests that the AGRI WV channel assimilation can improve the predictions. Overall, assimilating AGRI WV observations can positively influence the WRF analyses and forecasts. [ABSTRACT FROM AUTHOR]

Rainforests play an important role in hydrological and carbon cycles, both at regional and global scales. They pump large quantities of moisture from the soil to the atmosphere and are major rainfall hotspots of the world. Satellite-observed stable water isotope ratios have played an essential role in determining sources of moisture in the atmosphere. Satellites provide information about the processes involving vapour transport in different zones of the world, identifying sources of rainfall and distinguishing moisture transport in monsoonal systems. This paper focuses on major rainforests of the world (Southern Amazon, Congo and Northeast India) to understand the role of continental evapotranspiration in influencing tropospheric water vapour. We have used satellite measurements of 1H2H16O/1H216O from Atmospheric InfraRed Sounder (AIRS), evapotranspiration (ET), solar-induced fluorescence (SIF), precipitation (P), atmospheric reanalysis-derived moisture flux convergence (MFC) and wind to discern the role of ET in influencing water vapour isotopes. A global map of the correlation between δ2Hv and ET-P flux indicates that densely vegetated regions in the tropics show the highest positive correlation (r > 0.5). Using mixing models and observations of specific humidity and isotopic ratio over these forested regions, we discern the source of moisture in pre-wet and wet seasons. [ABSTRACT FROM AUTHOR]

In climate change context, the precipitable water vapour (PW) is key parameter of atmospheric process and dynamics and its variation is very high in space and time. It's accuracy is paramount for any geodetic or climatic study. The main objective of this study is to compute precipitable water vapour from ERA5 reanalysis for 4 stations in Algeria which have different types of climate. We opt for using integration method for different level of pressure with ERA5. The values of water vapour are also compared with radiosondes profiles. The results of this work shows good agreement with a correlation that is not less than not 0.95 and 0.70 compared as radiosondes profiles. The first results are encouraging, in particular for meteorological applications with good hope to introduce another dataset as GNSS to more understand the variation and behavior of water vapour over a long period of observation.

A compact photoacoustic gas sensor based on variable diameter T‐shaped cell for trace gas detection was developed. The acoustic pressure distribution in the variable diameter T‐shaped cell and conventional T‐shaped photoacoustic cell with the same size were simulated by COMSOL Multiphysics software, which indicated that at the first resonance frequency, the acoustic pressure at the end of the resonance tube of the designed photoacoustic cell is significantly stronger than that at the same position of the conventional T‐shaped cell. The performance of the sensor based on the variable diameter T‐shaped and conventional one were evaluated by detection of water vapor in atmospheric environment, the comparison shows that the signal‐to‐noise ratio of the variable diameter T‐shaped cell is about 1.6 times greater than that of the conventional one and a detection limit of 6.4 ppmv for water vapor detection was obtained. [ABSTRACT FROM AUTHOR]

Environment Barrier Coatings (EBCs) working in real service process meet not only environment of high-temperature water vapour, but also face of calcium and magnesium corrosion. In this paper, EBCs made by plasma spray with Yb2Si2O7 coatings were tested by thermal shock in a calcium/magnesium-included water vapour environment at 1 250 °C for 300 cycles. The results showed that there formed two-layer corrosion structures at the coating surface. The topmost layer sustained calcium corrosion, forming obvious multi-phase structure with large pores with phases of (Yb/Ca)2 Si2 O7, (Yb/Ca)2 SiO5 and (Ca/Yb)2 SiO4. The subsurface layer sustained both calcium and magnesium corrosion but mainly the magnesium corrosion, also forming multi phases (Yb/Mg/Ca)2SiO5 and (Mg/Ca/Yb)2SiO4 with relatively dense structure. Via analyses on surface morphology, cross section microstructure, micro-EDS composition and XRD phase structures, the chemical reaction mechanism of the EBC coatings was studied under the calcium/magnesium-included water-vapour thermal shock environment, and the failure mechanism of the coating was provided. [ABSTRACT FROM AUTHOR]

Noctilucent clouds (NLC) are sensitive indicators in the upper mesosphere, reflecting changes in the background atmosphere. Studying NLC responses to the solar cycle is important for understanding solar-induced changes and assessing long-term climate trends in the upper mesosphere. Additionally, it enhances our understanding of how increases in greenhouse gas concentration in the atmosphere impact the Earth’s upper mesosphere and climate. This study presents long-term trends in the response of NLC and the background atmosphere to the 11-year solar cycle variations. We utilised model simulations from the Leibniz Institute Middle Atmosphere (LIMA) and the Mesospheric Ice Microphysics and Transport (MIMAS) over 170 years (1849 to 2019), covering 15 solar cycles. Background temperature and water vapour (H2O) exhibit an apparent response to the solar cycle, with an enhancement post-1960, followed by an acceleration of greenhouse gas concentrations. NLC properties, such as maximum brightness (βmax), calculated as the maximum backscatter coefficient, altitude of βmax (referred to as NLC altitude) and ice water content (IWC), show responses to solar cycle variations that increase over time. This increase is primarily due to an increase in background water vapour concentration caused by an increase in methane (CH4). The NLC altitude positively responds to the solar cycle mainly due to solar cycle-induced temperature changes. The response of NLC properties to the solar cycle varies with latitude, with most NLC properties showing larger and similar responses at higher latitudes (69° N and 78° N) than mid-latitudes (58° N).

The high-temperature oxidation behaviour of oxide dispersion strengthened FeCrAl (ODS-FeCrAl) alloys was studied at 1100 °C in dry and wet atmospheres for use as candidate accident-tolerant fuel (ATF) cladding materials. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze qualitatively and quantitatively the oxides microstructure of oxidized ODS-FeCrAl alloys. The oxidation rate of ODS-FeCrAl alloys in dry atmosphere was lower than that in wet atmosphere. The amount of nodular oxides were rich in Y, Zr, and Ti at the gas/scale interface in dry atmosphere was significantly larger than that in wet atmosphere. In addition, the grains size of columnar alumina formed on the alloy surface in dry atmosphere was larger than that in wet atmosphere. A mechanism of water vapour increasing the oxidation rate of ODS-FeCrAl alloys was well proposed.

The pronounced increase of ozone observed at the Alpine station Zugspitze (2962 m a.s.l.) since the 1970s has been ascribed to an increase of stratospheric air descending to the Alps. In this paper, we present a re-analysis of the data from 1978 to 2011 for both ozone and carbon monoxide, extended until 2020 by the data from the Global Atmosphere Watch site Schneefernerhaus (UFS, 2671 m a.s.l.) just below the Zugspitze summit. The analysis is based on data filtering utilizing the isotope 7Be (measured between 1970 and 2006) and relative humidity (1970 to 2011, UFS: 2002 to 2020). We estimate both the influence of stratospheric intrusions directly descending to the northern rim of the Alps from the full data filtering and the aged (“indirect”) intrusions from partial filtering with the 7Be data. The evaluated total stratospheric contribution to the annual-average ozone rises roughly from 12 ppb in 1970 to 24 ppb in 2003. It turns out that the increase of stratospheric influence is particularly strong in winter. A lowering in positive trend is seen afterwards, almost parallel to the beginning decrease of solar irradiation. The air masses hitting the Zugspitze summit have become drier in the percentile range up to at least 25 % until 2003, and we see the growing stratospheric contribution as an important factor to this drying. Both an increase of lower-stratospheric ozone and a growing width of the intrusion layer departing downward from just above the tropopause must be taken into consideration. Carbon monoxide in intrusions did not change much during the full measurement period 1990 to 2020, with perhaps a slight increase until 2005 and an almost constant behaviour afterwards. This is remarkable since outside intrusions a decrease by approximately 44 % was found, indicating a substantial improvement of the tropospheric air quality. [ABSTRACT FROM AUTHOR]

The permeability of fiber-based materials and general medical textiles is very important, and it is commonly believed that air permeability and water permeability are correlated. This property is expressed as the breathability of the material. Knowing the air permeability is helpful in predicting the water vapour permeability as well, but whether this really works for textiles at different pressures and humidities still needs to be explored. In this study, this hypothesis is examined, and it is discovered that this phenomenon does not show significant corelation. Moreover, the non-standardised unit of measurement of breathability makes the comparison much more complex in terms of textiles. The articles focuses on any possible relationship between the air and water vapour permeability of textiles. [ABSTRACT FROM AUTHOR]

First observations on the vertical structure of diurnal variability of water vapour in the lower and middle atmosphere using 13 years of COSMIC-1 and 18 years of SABER observations over the Asian summer monsoon region are presented in this paper. The most significant and new observation is that the middle stratospheric water vapour (SWV) enhancement is observed between 9 and 18 LT, whereas it is between 6 and 15 LT near tropopause in all the seasons. The diurnal amplitude of water vapour near tropopause is between 0.3 and 0.4 ppmv. Bimodal peaks are found in the diurnal amplitude of SWV, maximizing between 25 and 30 km (~ 0.4 ppmv), and between 45 and 50 km (~ 0.6 ppmv). The analysis reveals that the diurnal variability in the lower SWV is controlled by the tropical tropopause temperature, whereas the middle and upper SWV is primarily controlled by methane oxidation. The results are presented and discussed in the light of present understanding. [ABSTRACT FROM AUTHOR]

According to the latest report from the intergovernmental panel on climate change (IPCC), currently, global warming due to methane (CH4) alone is about 0.5°C while due to carbon dioxide (CO2) alone is about 0.75°C. As CH4 emissions will continue growing, in order to limit warming to 1.5˚C, some of the most effective strategies are rapidly reducing CH4 emissions and developing large scale CH4 removal methods. The aim of this review article is to summarise and propose possible methods for atmospheric CH4 removal, based on the hydroxyl radical (°OH), which is the principal natural sink of many gases in the atmosphere and on many water surfaces. Inspired by mechanisms of °OH generation in the atmosphere and observed or predicted enhancement of °OH by climate change and human activities, we proposed several methods to enhance the °OH sink by some physical means using water vapour and artificial UV radiation. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study, a self-designed test system for injecting water vapour was used to pyrolyse oil shale from Barkol, Xinjiang, China. The internal structure of oil shale samples after water vapour pyrolysis at different temperatures was characterised using micro-computed tomography (micro-CT). The results showed that under the action of high-temperature water vapour, oil shale underwent evident thermal cracking and pyrolysis, and the porosity increased from 0.08% of the original state to 16.73% at 550 °C. At 300 °C, the maximum pore group was distributed along the bedding plane due to the influence of thermal cracking, and the equivalent diameter was 1201.73 μm. When the water vapour temperature increased from 300 °C to 400 °C, the organic matter at a low boiling point in oil shale began to pyrolyse, forming several pores. These pores were gradually connected with adjacent fractures. The pores with an equivalent diameter of approximately100â500 μm in oil shale accounted for > 60% of the total pore volume. The maximum pore cluster expanded perpendicular to the bedding plane, but there was still no effective seepage channel. With an increase in the water vapour temperature, the large-scale pyrolysis of organic matter began and the pores and fractures in oil shale were continuously generated and gradually connected; at 450 °C, the seepage channel connecting the entire digital core area began to form. At 550 °C, the equivalent diameter of the maximum pore group reached 5756.72 μm, accounting for 69.65% of the total pore volume.

The paper deals with a detailed analysis of published analytical relations for heat transfer during steam condensation in a vertical tube. The historical development of the approaches and the chronological development of the used analytical relations are presented. Attention is focused on the description of the processes at the gas phase-condensate film interface as well as on the inclusion of the influence of the presence of non-condensable gases. The analytical relations in 12 modifications are compared with each other for the same geometrical configuration of the vertical tube and identical boundary conditions. The authors performed comparative experimental measurements of the heat transfer coefficient during condensation of the vapour-gas mixture in vertical tubes of three diameters, namely 16, 20 and 26 mm. Based on a comparison of the experimental results and analytical relations, recommendations are made on the validity interval of the tested relations.

Current trends towards saving energy and designing sustainable buildings result in most designers focusing on achieving the best thermal parameters, thereby neglecting a careful moisture analysis. Excessive moisture content in building partitions degrades the mechanical properties of materials, reduces thermal insulation properties (which leads to an increase in the demand for thermal energy) and worsens the microclimate in rooms. Modern digital solutions help create appropriate models of partitions that work for many years in good environmental conditions. According to the analysis of air parameters, 1 m3 of air at 20 °C contains approx. 17.3 g of water. When the temperature of the air reaches the dew point temperature, water vapour condenses. The dew point depends on air temperature and relative air humidity; for instance, at the same air temperature of 20 °C, the dew point temperature at 40% relative air humidity is 6 °C, whereas at 90% relative humidity, it is over 18 °C. This means that the higher the value of relative humidity in the room at a certain temperature, the lower the temperature that will cause condensation. The article presents a numerical analysis of the insulation work of flexible materials within the layers of ventilated partitions in an 8-year simulated period of varying environmental conditions. The aim of the article is to analyze different models and variants of ventilated partition operation with respect to the advisability of using a vapour barrier to avoid the problem of destruction of thermal insulation and finishing layers of a ventilated roof. [ABSTRACT FROM AUTHOR]

Continuous measurements of Aerosol Optical Depth (AOD), columnar water vapor (WV) and Ozone (O 3) concentrations were made over a semi-arid urban location Rajkot (22.29°N, 70.74°E, and 142 m AMSL) in the western India. The annual mean values of AOD, WV and O 3 were 0.37 ± 0.15, 1.44 ± 0.6 gm cm−2 and 243 ± 18 DU during 2016–2019. AOD showed large seasonal variability mostly dominated by abundant coarse mode aerosols (Angstrom Exponent, AE < 0.65 and AOD ∼ 0.37) during pre-monsoon and monsoon, mainly caused by wind-blown and transported dust from nearby Thar and Kutch desert. Mixture of fine and coarse mode aerosols were abundant (AE = 1.13 ± 0.26) during post-monsoon influenced by both anthropogenic and natural sources. Columnar WV were also higher in pre-monsoon and monsoon seasons. The O 3 concentrations is higher during pre-monsoon (247 DU) and lower during monsoon (230 DU). The vertical distribution of aerosol extinction coefficient derived from satellite (CALIPSO) based observations revealed the dominance of dust aerosols (∼74 %) in pre-monsoon; smoke and polluted dust in winter and post monsoon period. The trajectory clusters and concentration weighted trajectory maps also indicated the combined effect of anthropogenic (especially from the northern part of India) and natural aerosol sources during the post-monsoon period. Associated with the higher anthropogenic components during post-monsoon season, aerosol direct radiative forcing depicted surface dimming as high as − 48.7 ± 12.6 Wm−2, resulting in atmospheric forcing of 42.6 ± 12.5 Wm−2. [ABSTRACT FROM AUTHOR]