The existence of saturated vapors in the deep source region of 2017Pohang earthquake evidenced from seismic tomography

Geothermal resources are a promising approach to clean renewable energy;90%of them are deep reservoirs of hot dry rock that require hydraulic fracturing to create a network of connections among wells to enable efficient heat exchange,known as an Enhanced Geothermal System(EGS).The Pohang EGS project in south Korea led to a devasting Mw5.5 earthquake,triggered by the reservoir's EGS stimulation,the largest earthquake known to have been induced by EGS development.Detailed investigations have been conducted to understand the cause of the Pohang earthquake;the conclusion has been that overpressurized injected fluids migrated into an unknown fault triggering this large earthquake.Detailed velocity images for the source zone of the 2017 Pohang earthquake,which could be helpful for further understanding its inducing mechanism,are unavailable.However,we have assembled detailed aftershock data recorded by 41 local stations installed within about three months after the Mw5.5 Pohang earthquake,and have then applied the V_(p)/V_(s)model's consistency-constrained double-difference seismic tomography method to determine the high-resolution three-dimensional Vp(compressional wave velocity),Vs(shear wave velocity),and V_(p)/V_(s)models of the source region that we report here,as well as earthquake locations within the source region.The velocity images reveal that the deep source area of the 2017 Pohang earthquake is dominated by low Vp,high Vs,and low V_(p)/V_(s)anomalies,a pattern that can be caused by overpressurized vapors due to high temperatures at these depths.Based on aftershock locations and velocity features,our studies support the conclusion that the 2017Pohang earthquake was triggered by injected EGS fluids that migrated into a blind fault.

A Qualitative Investigation of Volatile Organic Components of Antimicrobial Oil Smoke Vapors

A petroleum middle distillate, known as fog oil (FO), has been used in the United military battlefield to create obscurant smoke screens. During studies on the feasibility of replacing FO with relatively environmentally benign natural oil esters, with similar flow properties, such as methyl soyate (MS), it was observed that FO and MS aerosols and vapors were lethal to Salmonella typhimurium strains (Ames strains used to test for mutagenic activity in the Modified Ames Assay) even after very short exposures. It was further shown that vapors produced from the vegetable oil esters under certain conditions exhibited antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria. In this study, we examined the antimicrobial properties of volatile organic compounds detected in vegetable oil ester vapors. The experiments involved introduction of a known amount of specific compounds present in oil smoke vaors, individually and in combination, into an exposure chamber containing nutrient agar petri dishes inoculated with Salmonella typhimurium. Petri dishes were removed from the chamber after varied exposure periods to determine survival of the bacteria. The results of the experiments showed that individual compounds exhibited antimicrobial activity but lower than the vapors produced during thermal aerosol generation process suggesting the antimicrobial activity of the vapors is likely a synergistic activity of multiple components of the vapors.

Analysis on Concentration and Source Rate of Precursor Vapors Participating in Particle Formation and Growth at Xinken in the Pearl River Delta of China

Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, 03, CO, non-methane hydrocarbon （NMHC） and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 10^7 to 2.17 × 10^8 molecules cm^-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 10^6 and 1.16 × 10^7 molecules cm^-3 s^-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h^-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10^8 to 2.80 × 10^8 molecules cm^-3 with corresponding source rate between 7.26 × 10^6 and 1.64 × 10^7 molecules cm^-3 s^-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.

Effect of Height and Geographic Latitude of Location of GPS Station on Ratio of Total Amount of Water Vapors on Wet Delay of GPS Signals

The averaged integrated parameter representing the mean value of ratio of total water vapors on wet delay at the chosen distance of latitude is suggested. The function of interrelation of such parameters as height of location site and latitude is suggested. It is shown, that the optimal function does exist which bring the averaged integrated parameter to its minimal value.

Fluorescent-Dye Doped Thin-Film Sensors for the Detection of Alcohol Vapors

Fluorescence sensors based on a trifluoroacetophone compound doped in ethyl cellulose (EC) thin films have been developed for the detection of methanol, ethanol, and 2-propanol (isopropanol, PriOH) vapors. Thin-film sensors are prepared with 4-dibutylamino-4’-(trifluoroacetyl)stilbene (Chromoionophore IX or CIX) as the fluorescent dye and its solution in EC was spin-coated onto glass slides. The luminescence intensity of the dye (555 nm) is quenched when exposed to alcohol vapor. Tested in the range of ca. 0 - 1.5?× 104 ppm (wt) for MeOH and EtOH, and ca. 0 - 2.3 × 104 ppm for PriOH, the sensors gave detection limits of 9, 13, 21 ppm and quantification limits of 32, 43, and 70 ppm, respectively. To enhance the sensitivity of the sensors, TiO2 particles have been added to the films to induce Mie scattering, which increases the incident light interaction with the sensing films. The sensors in this work have been designed to work in a multianalyte platform for the simultaneous detection of multiple gas analytes.

STUDIES ON THE DYNAMIC COMPETITIVE ADSORPTION OF ORGANIC VAPORS ON THE ACTIVATED CARBON FIBERS ACTIVATED WITH PHOSPHORIC ACID

The dynamic competitive adsorption behaviors of different binary organic vapor mixtures on ACF-Ps under different operation conditions were investigated by gas chromatography in this paper. The studied mixtures included benzene/toluene, toluene/xylene, benzene/isopropylbenzene, ethyl acetate/toluene and benzene/ethyl acetate. Experimental results show that various ACF-Ps, as with ACF-W, can remove both vapors in binary vapor mixtures with over 99% of removal efficiency before the breakthrough point of the more weakly adsorbed vapor. In dynamic competitive adsorption, the more weakly adsorbed vapor not only penetrates early, but also will be displaced and desorbed consequently by stronger adsorbate and therefore produces a rolling up in the breakthrough curve. The ACF-Ps prepared at different temperatures have somewhat different adsorption selectivity. The feed concentration ratio of vapors, the length/diameter ratio and the thick of bed have effect on competitive adsorption. The competitive adsorption ability of a vapor is mainly related to its boiling point. Usually, the higher the boiling point, the stronger the vapor adsorbed on ACF-P.

Jet formation and penetration performance of a double-layer charge liner with chemically-deposited tungsten as the inner liner

This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.

Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.

Research progress on the water vapor channel within the Yarlung Zsangbo Grand Canyon, China

The Second Tibetan Plateau Scientific Expedition and Research Program tasked a research team with the“Investigation of the water vapor channel of the Yarlung Zsangbo Grand Canyon(INVC)”in the southeastern Tibetan Plateau(TP).This paper summarizes the scientific achievements obtained from the data collected by the INVC observation network and highlights the progress in investigating the development of heavy rainfall events associated with water vapor changes.The rain gauge network of the INVC can represent the impacts of the Yarlung Zsangbo Grand Canyon(YGC)topography on precipitation at the hourly scale.The microphysical characteristics of the precipitation in the YGC are different than those in the lowland area.The GPM-IMERG(Integrated MultisatellitE Retrievals for Global Precipitation Measurement)satellite precipitation data for the YGC region should be calibrated before they are used.The meridional water vapor flux through the YGC is more important than the zonal flux for the precipitation over the southeastern TP.The decreased precipitation around the YGC region is partly due to the decreased meridional water vapor flux passing through the YGC.High-resolution numerical models can benefit precipitation forecasting in this region by using a combination of specific schemes that capture the valley wind and water vapor flux along the valley floor.

Influence of vapor pressure deficit on vegetation growth in China

Vapor pressure deficit(VPD)plays a crucial role in determining plant physiological functions and exerts a substantial influence on vegetation,second only to carbon dioxide(CO_(2)).As a robust indicator of atmospheric water demand,VPD has implications for global water resources,and its significance extends to the structure and functioning of ecosystems.However,the influence of VPD on vegetation growth under climate change remains unclear in China.This study employed empirical equations to estimate the VPD in China from 2000 to 2020 based on meteorological reanalysis data of the Climatic Research Unit(CRU)Time-Series version 4.06(TS4.06)and European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis 5(ERA-5).Vegetation growth status was characterized using three vegetation indices,namely gross primary productivity(GPP),leaf area index(LAI),and near-infrared reflectance of vegetation(NIRv).The spatiotemporal dynamics of VPD and vegetation indices were analyzed using the Theil-Sen median trend analysis and Mann-Kendall test.Furthermore,the influence of VPD on vegetation growth and its relative contribution were assessed using a multiple linear regression model.The results indicated an overall negative correlation between VPD and vegetation indices.Three VPD intervals for the correlations between VPD and vegetation indices were identified:a significant positive correlation at VPD below 4.820 hPa,a significant negative correlation at VPD within 4.820–9.000 hPa,and a notable weakening of negative correlation at VPD above 9.000 hPa.VPD exhibited a pronounced negative impact on vegetation growth,surpassing those of temperature,precipitation,and solar radiation in absolute magnitude.CO_(2) contributed most positively to vegetation growth,with VPD offsetting approximately 30.00%of the positive effect of CO_(2).As the rise of VPD decelerated,its relative contribution to vegetation growth diminished.Additionally,the intensification of spatial variations in temperature and precipitation accentuated the spatial heterogeneity in the impact of VPD on vegetation growth in China.This research provides a theoretical foundation for addressing climate change in China,especially regarding the challenges posed by increasing VPD.

Analysis of the effect of the 2021 Semeru eruption on water vapor content and atmospheric particles using GNSS and remote sensing

Mount Semeru,an active volcano in East Java,Indonesia,erupted on December 4,2021,following extreme rainfall that caused an avalanche of hot pyroclastic flows and lava.The tropospheric conditions and dominant particle components in the atmosphere can be monitored using Global Navigation Satellite System(GNSS)technology and remote sensing satellites.GNSS signal propagation delay in Precise Point Positioning(PPP)processing can be used to determine Zenith Tropospheric Delay(ZTD)and Precipitable Water Vapor(PWV)variables so that atmospheric conditions can be generated.In addition,by using remote sensing satellite data,it is possible to obtain rainfall data with high temporal resolution as well as the dominant particle and gas content values during eruptions.During the eruption period,the high value of PWV was dominated by the high intensity of precipitation during the rainy season.High rainfall before the eruption caused activity inside the mountain to increase,which occurred in avalanche type eruption.Apart from that,the atmosphere around Semeru was also dominated by SO_(2)content,which spreaded for tens of kilometers.SO_(2)content began to be detected significantly by remote sensing sensors on December 7,2021.In this study,deformation and atmospheric monitoring were also carried out using low-cost GNSS at the Semeru Monitoring Station on September 9-15,2022.The results of the ZTD and ZWD values show the dominance of the wet component,which is directly proportional to rainfall activity in this period.

The GNSS PWV retrieval using non-observation meteorological parameters based on ERA5 and its relation with precipitation

The pressure and temperature significantly influence precipitable water vapor(PWV) retrieval. Global Navigation Satellite System(GNSS) PWV retrieval is limited because the GNSS stations lack meteorological sensors. First, this article evaluated the accuracy of pressure and temperature in 68 radiosonde stations in China based on ERA5 Reanalysis data from 2015 to 2019 and compared them with GPT3model. Then, the accuracy of pressure and temperature calculated by ERA5 were estimated in 5 representative IGS stations in China. And the PWV calculated by these meteorological parameters from ERA5(ERA5-PWV) were analyzed. Finally, the relation between ERA5-PWV and precipitation was deeply explored using wavelet coherence analysis in IGS stations. These results indicate that the accuracy of pressure and temperature of ERA5 is better than the GPT3 model. In radiosonde stations, the mean BIAS and MAE of pressure and temperature in ERA5 are-0.41/1.15 hpa and-0.97/2.12 K. And the mean RMSEs are 1.35 hpa and 2.87 K, which improve 74.77% and 40.58% compared with GPT3 model. The errors of pressure and temperature of ERA5 are smaller than the GPT3 model in bjfs, hksl and wuh2, and the accuracy of ERA5-PWV is improved by 18.77% compared with the GPT3 model. In addition, there is a significant positive correlation between ERA5-PWV and precipitation. And precipitation is always associated with the sharp rise of ERA5-PWV, which provides important references for rainfall prediction.

Effect of trace oxygen on plasma nitriding of titanium foil

Titanium nitride films are prepared by plasma enhanced chemical vapor deposition method on titanium foil using N_(2) as precursor. In order to evaluate the effect of oxygen on the growth of titanium nitride films, a small amount of O_(2) is introduced into the preparation process. The study indicates that trace O_(2) addition into the reaction chamber gives rise to significant changes on the color and micro-morphology of the foil, featuring dense and long nano-wires. The as-synthesized nanostructures are characterized by various methods and identified as TiN, Ti_(2) N, and TiO_(2) respectively. Moreover, the experiment results show that oxide nanowire has a high degree of crystallinity and the nitrides present specific orientation relationships with the titanium matrix.

The Influence of Airflow Transport Pathways on Precipitation during the Rainy Season in the Liupan Mountains of Northwest China

This study investigates the influence of airflow transport pathways on seasonal rainfall in the mountainous region of the Liupan Mountains(LM) during the rainy seasons from 2020 to 2022, utilizing observational data from seven ground gradient stations located on the eastern slopes, western slopes, and mountaintops combined with backward trajectory cluster analysis. The results indicate 1) that the LM's rainy season, characterized by overcast and rainy days, is mainly influenced by cold and moist airflows(CMAs) from the westerly direction and warm and moist airflows(WMAs) from a slightly southern direction. The precipitation amounts under four airflow transport paths are ranked from largest to smallest as follows: WMAs, CMAs, warm dry airflows(WDAs), and cold dry airflows(CDAs). 2) WMAs contribute significantly more to the intensity of regional precipitation than the other three types of airflows. During localized precipitation events,warm airflows have higher precipitation intensities at night than cold airflows, while the opposite is true during the afternoon. 3) During regional precipitation events, water vapor content is the primary influencing factor. Precipitation characteristics under humid airflows are mainly affected by high water vapor content, whereas during dry airflow precipitation, dynamic and thermodynamic factors have a more pronounced impact. 4) During localized precipitation events, the influence of dynamic and thermodynamic factors is more complex than during regional precipitation, with the precipitation characteristics of the four airflows closely related to their water vapor content, air temperature and humidity attributes, and orographic lifting. 5) Compared to regional precipitation, the influence of topography is more prominent in localized precipitation processes.

Remote plasma enhanced cyclic etching of a cyclosiloxane polymer thin film

The continuous evolution of chip manufacturing demands the development of materials with ultra-low dielectric constants.With advantageous dielectric and mechanical properties,initiated chemical vapor deposited(iCVD)poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane)(pV3D3)emerges as a promising candidate.However,previous works have not explored etching for this cyclosiloxane polymer thin film,which is indispensable for potential applications to the back-end-of-line fabrication.Here,we developed an etching process utilizing O2/Ar remote plasma for cyclic removal of iCVD pV3D3 thin film at sub-nanometer scale.We employed in-situ quartz crystal microbalance to investigate the process parameters including the plasma power,plasma duration and O2 flow rate.X-ray photoelectron spectroscopy and cross-sectional microscopy reveal the formation of an oxidized skin layer during the etching process.This skin layer further substantiates an etching mechanism driven by surface oxidation and sputtering.Additionally,this oxidized skin layer leads to improved elastic modulus and hardness and acts as a barrier layer for protecting the bottom cyclosiloxane polymer from further oxidation.

Consistency of Tropospheric Water Vapor between Reanalyses and Himawari-8/AHI Measurements over East Asia

High spatiotemporal resolution radiances from the advanced imagers onboard the new generation of geostationary weather satellites provide a unique opportunity to evaluate the abilities of various reanalysis datasets to depict multilayer tropospheric water vapor(WV),thereby enhancing our understanding of the deficiencies of WV in reanalysis datasets.Based on daily measurements from the Advanced Himawari Imager(AHI)onboard the Himawari-8 satellite in 2016,the bias features of multilayer WV from six reanalysis datasets over East Asia are thoroughly evaluated.The assessments show that wet biases exist in the upper troposphere in all six reanalysis datasets;in particular,these biases are much larger in summer.Overall,we find better depictions of WV in the middle troposphere than in the upper troposphere.The accuracy of WV in the ERA5 dataset is the highest,in terms of the bias magnitude,dispersion,and pattern similarity.The characteristics of the WV bias over the Tibetan Plateau are significantly different from those over other parts of East Asia.In addition,the reanalysis datasets all capture the shift of the subtropical high very well,with ERA5 performing better overall.

Relationship between disorder,magnetism and band topology in Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals

We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals grown by large-temperature-gradient chemical vapor transport method.It is found that the ferromagnetic MnSb_(2)Te_(4) changes to antiferromagnetism with Bi doping when x≥0.25.Further analysis implies that the occupations of Mn ions at Sb/Bi site Mn_(Sb/Bi) and Mn site Mn_(Mn) have a strong influence on the magnetic ground states of these systems.With the decrease of Mn_(Mn) increase of Mn_(Sb/Bi),the system will favor the ferromagnetic ground state.In addition,the rapid decrease of T_(C/N) with increasing Bi content when x ≤0.25 and the insensitivity of T_(N) to x when x> 0.25 suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.

Edge effect during microwave plasma chemical vapor deposition diamond-film:Multiphysics simulation and experimental verification

This study focused on the investigation of the edge effect of diamond films deposited by microwave plasma chemical vapor de-position.Substrate bulge height△h is a factor that affects the edge effect,and it was used to simulate plasma and guide the diamond-film deposition experiments.Finite-element software COMSOL Multiphysics was used to construct a multiphysics(electromagnetic,plasma,and fluid heat transfer fields)coupling model based on electron collision reaction.Raman spectroscopy and scanning electron microscopy were performed to characterize the experimental growth and validate the model.The simulation results reflected the experimental trends observed.Plasma discharge at the edge of the substrate accelerated due to the increase in△h(△h=0-3 mm),and the values of electron density(n_(c)),molar concentration of H(C_(H)),and molar concentration of CH_(3)(C_(CH_(3)))doubled at the edge(for the special concave sample with△h=−1 mm,the active chemical groups exhibited a decreased molar concentration at the edge of the substrate).At=0-3 mm,a high diamond growth rate and a large diamond grain size were observed at the edge of the substrate,and their values increased with.The uniformity of film thickness decreased with.The Raman spectra of all samples revealed the first-order characteristic peak of dia-mond near 1332 cm^(−1).When△h=−1 mm,tensile stress occurred in all regions of the film.When△h=1-3 mm,all areas in the film ex-hibited compressive stress.

基于创新性内侧壁成型工艺的多光学通道微型碱金属原子气室

Existing microfabricated atomic vapor cells have only one optical channel,which is insufficient for supporting the multiple orthogonal beams required by atomic devices.In this study,we present a novel wafer-level manufacturing process for fabricating multi-optical-channel atomic vapor cells and an innovative method for batch processing the inner sidewalls of millimeter glass holes to meet optical channel requirements.Surface characterization and transmittance tests demonstrate that the processed inner sidewalls satisfy the criteria for an optical channel.In addition,the construction of an integrated processing platform enables multilayer non-isothermal anode bonding,the filling of inert gases,and the recovery and recycling of noble gases.Measurements of the absorption spectra and free-induction decay signals of xenon-129(^(129)Xe)and xenon-131(^(131)Xe)under different pump-probe schemes demonstrate the suitability of our vapor cell for use in atomic devices including atomic gyroscopes,dual-beam atomic magnetometers,and other optical/atomic devices.The proposed micromolding technology has broad application prospects in the field of optical-device processing.

Linkage between precipitation isotopes and water vapor sources in the monsoon margin:Evidence from arid areas of Northwest China

The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change.The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors.In this study,the precipitation samples were collected at five sampling sites(Baiyin City,Kongtong District,Maqu County,Wudu District,and Yinchuan City)of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen(δD)and oxygen(δ18O)isotopes.We analyzed the impact of meteorological factors(temperature,precipitation,and relative humidity)on the composition of precipitation isotope at daily level by regression analysis,utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events,and adopted the potential source contribution function(PSCF)and concentration weighted trajectory(CWT)to analyze the water vapor sources.The results showed that compared with the global meteoric water line(GMWL),the slope of the local meteoric water line(LMWL;δD=7.34δ^(18)O-1.16)was lower,indicating the existence of strong regional evaporation in the study area.Temperature significantly contributed toδ18O value,while relative humidity had a significant negative effect onδ18O value.Through the backward trajectory analysis,we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area,of which moisture from the Indian Ocean to South China Sea(ITSC)and the western continental(CW)had the greatest influence on precipitation in the study area.The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass.In addition,the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area.