An ocean circulation model in <Emphasis Type="Italic">σ</Emphasis>S-<Emphasis Type="Italic">z</Emphasis>-<Emphasis Type="Italic">σ</Emphasis>B hybrid coordinate and its validation

A 3D, two-time-level, σS-z-σB hybrid-coordinate Marine Science and Numerical Modeling numerical ocean circulation model (HyMOM) is developed in this paper. In HyMOM, the σ coordinate is employed in the surface and bottom regions, and the z coordinate is used in the intermediate layers. This method can overcome problems with vanishing surface cells and minimize the unwanted deviation in representing bottom topography. The connection between the σ and z layers vertically includes an expanded “ghost” method and the linear interpolation. The governing equations in the σS-z-σB hybrid coordinate based on the complete Reynolds-averaged Navier-Stokes equations are derived in detail. The two-level time staggered and Eulerian forward and backward schemes, which are of second-order of accuracy, are adopted for the temporal difference in internal and external mode, respectively. The computation of the baroclinic gradient force is tested in an analytic test problem; the errors for two methods in HyMOM, which are relatively large only in the bottom layers, are obviously smaller than those in the pure σ and z models in almost all of the vertical layers. A quasi-global climatologic numerical experiment is constructed to test the simulation performance of HyMOM. With the monthly mean Levitus climatology data as reference, the HyMOM can improve the simulating accuracy compared with its pure z or σ coordinate implementation.     

Simulating CO<Subscript>2</Subscript> transport into the ocean from a CO<Subscript>2</Subscript> lake at the seafloor using a <Emphasis Type="Italic">z</Emphasis>- and a <Emphasis Type="Italic">σ</Emphasis>-coordinate model

The ocean takes up approximately 2 GT carbon per year due to the enhanced CO₂ concentrations in the atmosphere. Several options have been suggested in order to reduce the emissions of CO₂ into the atmosphere, and among these are CO₂ storage in the deep ocean. Topographic effects of dissolution and transport from a CO₂ lake located at 3,000-m depth have been studied using the z-coordinate model Massachusetts Institute of Technology general circulation model (MITgcm) and the σ-coordinate model Bergen ocean model (BOM). Both models have been coupled with the general ocean turbulence model (GOTM) in order to account for vertical subgrid processes. The chosen vertical turbulence mixing scheme includes the damping effect from stable stratification on the turbulence intensity. Three different topographic scenarios are presented: a flat bottom and the CO₂ lake placed within a trench with depths of 10 and 20 m. The flat case scenario gives good correlation with previous numerical studies of dissolution from a CO₂ lake. When topography is introduced, it is shown that the z-coordinate model and the σ-coordinate model give different circulation patterns in the trench. This leads to different dissolution rates, 0.1 μmol cm^− 2 s^− 1 for the scenario of a 20-m-deep trench using BOM and 0.005–0.02 μmol cm^− 2 s^− 1 for the same scenario using the MITgcm. The study is also relevant for leakages of CO₂ stored in geological formations and to the ocean.     

Improved random noise attenuation using <Emphasis Type="Italic">f</Emphasis>−<Emphasis Type="Italic">x</Emphasis> empirical mode decomposition and local similarity

Conventional f?x empirical mode decomposition (EMD) is an effective random noise attenuation method for use with seismic profiles mainly containing horizontal events. However, when a seismic event is not horizontal, the use of f?x EMD is harmful to most useful signals. Based on the framework of f?x EMD, this study proposes an improved denoising approach that retrieves lost useful signals by detecting effective signal points in a noise section using local similarity and then designing a weighting operator for retrieving signals. Compared with conventional f?x EMD, f?x predictive filtering, and f?x empirical mode decomposition predictive filtering, the new approach can preserve more useful signals and obtain a relatively cleaner denoised image. Synthetic and field data examples are shown as test performances of the proposed approach, thereby verifying the effectiveness of this method.     

Limitations of <Emphasis Type="Italic">H</Emphasis>-<Emphasis Type="Italic">κ</Emphasis> stacking: ambiguous results caused by crustal layering

Over the past decade, the H-κ stacking technique of Zhu and Kanamori (J Geophys Res 105:2969–2980, 2000) has become a standard tool to determine the crustal thickness H and the bulk crustal v_P/v_S ratio κ from teleseismic receiver functions. It is obvious that unfavorable noise conditions as well as a complex 3D velocity structure can severely hamper the interpretation of receiver-function data. However, we observe that ambiguities can even arise from a simple 1D layered velocity structure which raises a high potential for misinterpretations. To analyze the feasibility and basic limitations of the H-κ stacking method, we conduct a series of tests based on synthetic data. The impact of different given elementary parameters, related either to the velocity structure or to the data processing, is evaluated in a series of eight individual tests. We deliberately exclude complications such as 3D structural variations and/or noise to show that even a simple 1D velocity structure, involving, e.g., an additional inter-crustal discontinuity, can have significant consequences for the interpretation of the results. However, our modeling suggests that more complex crustal structures may lead to even less reliable results. Additionally, our tests illustrate that time shifts of the maxima in the H-κ domain due to the superposition and merging of individual phases can lead to significantly overestimated v_P/v_S ratios. In general, the depth to the Moho (or other discontinuities of interest) is less significantly affected. Our tests indicate the necessity to accurately check delay times derived from the maxima of the H-κ stacks against corresponding phases in the receiver functions. Repeating the stacking with varied weighting factors and filter ranges can help to reduce the ambiguities and to avoid possible misinterpretation.     

Atypical soil behavior during the 2011 Tohoku earthquake (<Emphasis Type="Italic">М</Emphasis><Subscript><Emphasis Type="Italic">w</Emphasis></Subscript> = 9)

To understand physical mechanisms of generation of abnormally high peak ground acceleration (PGA; >1g) during the Tohoku earthquake, models of nonlinear soil behavior in the strong motion were constructed for 27 KiK-net stations located in the near-fault zones to the south of FKSH17. The method of data processing used was developed by Pavlenko and Irikura, Pure Appl Geophys 160:2365–2379, 2003 and previously applied for studying soil behavior at vertical array sites during the 1995 Kobe (М _w ?=?6.8) and 2000 Tottori (М _w ?=?6.7) earthquakes. During the Tohoku earthquake, we did not observe a widespread nonlinearity of soft soils and reduction at the beginning of strong motion and recovery at the end of strong motion of shear moduli in soil layers, as usually observed during strong earthquakes. Manifestations of soil nonlinearity and reduction of shear moduli during strong motion were observed at sites located close to the source, in coastal areas. At remote sites, where abnormally high PGAs were recorded, shear moduli in soil layers increased and reached their maxima at the moments of the highest intensity of the strong motion, indicating soil hardening. Then, shear moduli reduced with decreasing the intensity of the strong motion. At soft-soil sites, the reduction of shear moduli was accompanied by a step-like decrease of the predominant frequencies of motion. Evidently, the observed soil hardening at the moments of the highest intensity of the strong motion contributed to the occurrence of abnormally high PGA, recorded during the Tohoku earthquake.     

The ratio between corner frequencies of source spectra of <Emphasis Type="Italic">P</Emphasis>- and <Emphasis Type="Italic">S</Emphasis>-waves—a new discriminant between earthquakes and quarry blasts

This study analyzes and compares the P- and S-wave displacement spectra from local earthquakes and explosions of similar magnitudes. We propose a new approach to discrimination between low-magnitude shallow earthquakes and explosions by using ratios of P- to S-wave corner frequencies as a criterion. We have explored 2430 digital records of the Israeli Seismic Network (ISN) from 456 local events (226 earthquakes, 230 quarry blasts, and a few underwater explosions) of magnitudes Md?=?1.4–3.4, which occurred at distances up to 250 km during 2001–2013 years. P-wave and S-wave displacement spectra were computed for all events following Brune’s source model of earthquakes (1970, 1971) and applying the distance correction coefficients (Shapira and Hofstetter, Teconophysics 217:217–226, 1993; Ataeva G, Shapira A, Hofstetter A, J Seismol 19:389-401, 2015), The corner frequencies and moment magnitudes were determined using multiple stations for each event, and then the comparative analysis was performed.The analysis showed that both P-wave and especially S-wave displacement spectra of quarry blasts demonstrate the corner frequencies lower than those obtained from earthquakes of similar magnitudes. A clear separation between earthquake and explosion populations was obtained for ratios of P- to S-wave corner frequency f ₀(P)/f ₀(S). The ratios were computed for each event with corner frequencies f ₀ of P- and S-wave, which were obtained from the measured f ₀ ^I at individual stations, then corrected for distance and finally averaged. We obtained empirically the average estimation of f ₀(P)/f ₀(S)?=?1.23 for all used earthquakes, and 1.86 for all explosions. We found that the difference in the ratios can be an effective discrimination parameter which does not depend on estimated moment magnitude M _w .The new multi-station Corner Frequency Discriminant (CFD) for earthquakes and explosions in Israel was developed based on ratios P- to S-wave corner frequencies f ₀(P)/f ₀(S), with the empirical threshold value of the ratio for Israel as 1.48.     

The seasonal behavior of the <Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">z</Emphasis></Subscript> daily variations according to the monitoring at the Bishkek geodynamic site (1993–1995)

The algorithm for monitoring the magnetotelluric field has been briefly described, and the experimental data, obtained at the Bishkek geodynamic site, have been analyzed. The regularities in the seasonal behavior of the variations in the field vertical magnetic component have been revealed.     

Evaluation of the dynamic <Emphasis Type="Italic">p</Emphasis>–<Emphasis Type="Italic">y</Emphasis><Subscript>p</Subscript> loops of pile-supported structures on sloping ground

A key issue in the design of pile-supported structures on sloping ground is soil–pile interaction, which becomes more complicated in case of dynamic loading. This study aimed to evaluate the effect of slope on the dynamic behavior of pile-supported structures by performing a series of centrifuge tests. Three models were prepared by varying the slope and soil density of dry sand grounds. The mass supported on 3 by 3 group piles was shaken applying sinusoidal wave with various amplitudes. Test results showed that the location of maximum values and distribution shape of the bending moment below the ground surface varied noticeably with the pile position in the slope case. The relationship between the soil resistance and pile deflection (p–y_p loops) was carefully evaluated by applying the piecewise cubic spline method to fit the measured bending moment curves along piles. It was found that the shape of the p–y_p loops was irregular due to the effect of slope, and immensely influenced by the movement of the unstable zone. In addition, the effect of the pile group in the horizontal case was evaluated by comparing with the previously suggested curves that represent the relationship between the soil resistance and pile–soil relative displacement (p–y curves) to propose the multiplier coefficients.     

The <Emphasis Type="Italic">M</Emphasis><Subscript><Emphasis Type="Italic">w</Emphasis></Subscript> = 5.8 14 August 2016 middle Sakhalin earthquake on a boundary between Okhotsk and Eurasian (Amurian) plates

An earthquake with the moment magnitude M _w ?=?5.8 occurred in the middle part of the Sakhalin Island, Russian Federation, on 14 August 2016, at 11:17 a.m. UTC. The earthquake source was located west of the Central Sakhalin Fault Zone, which is considered to mark the boundary between the Okhotsk and Eurasian (Amurian) plates. Moment tensor solution of the mainshock as well as the configuration of aftershock cloud suggests that the earthquake was caused by slip on a SW-dipping reverse fault. For the first time for Sakhalin, we have got the felt reports unified in accordance with DYFI. We also analyzed observed PGA values and, based on them, produced shaking maps.     

The spatiotemporal analysis of the minimum magnitude of completeness <Emphasis Type="Italic">Mc</Emphasis> and the Gutenberg–Richter law <Emphasis Type="Italic">b</Emphasis>-value parameter using the earthquake catalog of Greece

Spatiotemporal mapping the minimum magnitude of completeness Mc and b-value of the Gutenberg–Richter law is conducted for the earthquake catalog data of Greece. The data were recorded by the seismic network of the Institute of Geodynamics of the National Observatory of Athens (GINOA) in 1970–2010 and by the Hellenic Unified Seismic Network (HUSN) in 2011–2014. It is shown that with the beginning of the measurements at HUSN, the number of the recorded events more than quintupled. The magnitude of completeness Mc of the earthquake catalog for 1970–2010 varies within 2.7 to 3.5, whereas starting from April 2011 it decreases to 1.5–1.8 in the central part of the region and fluctuates around the average of 2.0 in the study region overall. The magnitude of completeness Mc and b-value for the catalogs of the earthquakes recorded by the old (GINOA) and new (HUSN) seismic networks are compared. It is hypothesized that the magnitude of completeness Mc may affect the b-value estimates. The spatial distribution of the b-value determined from the HUSN catalog data generally agrees with the main geotectonic features of the studied territory. It is shown that the b-value is below 1 in the zones of compression and is larger than or equal to 1 in the zones dominated by extension. The established depth dependence of the b-value is pretty much consistent with the hypothesis of a brittle–ductile transition zone existing in the Earth’s crust. It is assumed that the source depth of a strong earthquake can probably be estimated from the depth distribution of the b-value, which can be used for seismic hazard assessment.     

Altitudinal effect of soil <Emphasis Type="Italic">n</Emphasis>-alkane <Emphasis Type="Italic">δ</Emphasis>D values on the eastern Tibetan Plateau and their increasing isotopic fractionation with altitude

Stable isotope paleoaltimetry has provided unprecedented insights into the topographic histories of many of the world’s highest mountain ranges. However, on the Tibetan Plateau (TP), stable isotopes from paleosols generally yield much higher paleoaltitudes than those based on fossils. It is therefore essential when attempting to interpret accurately this region’s paleoaltitudes that the empirical calibrations of local stable isotopes and the relations between them are established. Additionally, it is vital that careful estimations be made when estimate how different isotopes sourced from different areas may have been influenced by different controls. We present here 29 hydrogen isotopic values for leaf wax-derived n-alkanes (i.e., _δD_wax values, and abundance-weighted average δD values of C₂₉ and C₃₁) in surface soils, as well as the δD values of soil water (δD_sw) samples (totaling 22) from Mount Longmen (LM), on the eastern TP (altitude ~0.8–4.0 km above sea level (asl), a region climatically affected by the East Asian Monsoon (EAM). We compared our results with published data from Mount Gongga (GG). In addition, 47 river water samples, 55 spring water samples, and the daily and monthly summer precipitation records (from May to October, 2015) from two precipitation observation stations were collected along the GG transect for δD analysis. LM soil _δD_wax values showed regional differences and responded strongly to altitude, varying from?160‰ to?219‰, with an altitudinal lapse rate (ALR) of?18‰ km^?1 (R ²=0.83; p<0.0001; n=29). These _δD_wax values appeared more enriched than those from the GG transect by ~40‰. We found that both the climate and moisture sources led to the differences observed in soil _δD_wax values between the LM and GG transects. We found that, as a general rule, ε _wax/rw, ε _wax/p and ε _wax/sw values (i.e., the isotopic fractionation of _δD_wax corresponding to δD_rw, δD_p and δD_sw) increased with increasing altitude along both the LM and GG transects (up to 34‰and 50‰, respectively). Basing its research on a comparative study of _δD_wax, δD_p, δD_rw(δD_springw) and δD_sw, this paper discusses the effects of moisture recycling, glacier-fed meltwater, relative humidity (RH), evapotranspiration (ET), vegetation cover, latitude, topography and/or other factors on ε _wax/p values. Clearly, if ε _wax-p values at higher altitudes are calculated using smaller ε _wax-p values from lower altitudes, the calculated paleowaterδD_p values are going to be more depleted than the actual δD values, and any paleoaltitude would therefore be overestimated.     

Development of a predictive model for <Emphasis Type="Italic">Clostridium difficile</Emphasis> infection incidence in hospitals using Gaussian mixture model and Dempster–Shafer theory

Clostridium difficile infection is one of the major patient safety concerns in hospitals worldwide. Clostridium difficile infection can have high economic burden to patients, hospitals, and government. Limited work has been done in the area of predictive modeling. In this article, A new predictive model based on Gaussian mixture model and Dempster–Shafter theory is proposed to predict Clostridium difficile infection incidence in hospitals. First, the Gaussian mixture model and expectation–maximization algorithms are used to generate explicit probability criteria of risk factors based on the given data. Second, Dempster–Shafter theory is used to predict the Clostridium difficile infection incidence based on the generated probability criteria that have different beliefs attributing to their different credits. The main procedure includes (1) generate the probability criteria model using Gaussian mixture model and expectation–maximization algorithm; (2) determine the credit of the probability criteria; (3) generate the basic probability assignment; (4) discount the evidences; (5) aggregate the evidences using Dempster combining rule; (6) predict Clostridium difficile infection incidence using pignistic probability transformation. Results show that the model has a higher accuracy than an existing model. The proposed model can generate the criteria ratings of risk factors automatically, which would potentially prevent the imprecision caused by the subjective judgement of experts. The proposed model can assist risk managers and hospital administrators in the prediction and control of Clostridium difficile infection incidence with optimizing their resources.     

<Emphasis Type="Italic">Homo erectus pekinensis’s</Emphasis> age and environment— with discussion on the relationship among<Emphasis Type="Italic">Homo erectos</Emphasis> from Beijing,Nanjing and Chenjiawo

This paper inspects the relationship betweenHomo erectus from Beijing, Nanjing and Chenjiawo on the viewpoint of environmental variations. Pieces of evidence show that Nanjing and ChenjiawoHomo erectus lived in glacial age at the Marine Oxygen Isotope Stage (MIS) 16, whileHomo erectus pekinensis in major interglacial age at MISs 15-13. It is also recovered that the cave deposits in Tangshan, Nanjing, and Zhoukoudian, Beijing, as well as the deposits at theHomo erectus site in Chenjiawo, have undergone some similar development process. All of them originated from early-middle Middle Pleistocene, and have gone through the test of the major glacial age at MIS 16 and the major interglacial period at the paleosol stage S₅. At the same time, they were also closely connected with some environment events, such as the uplift of the Qinghai-Xizang Plateau, the formation of glaciations and the loess accumulations.     

<Emphasis Type="Italic">Prochlorococcus</Emphasis> viruses—From biodiversity to biogeochemical cycles

As the dominant primary producer in oligotrophic oceans, the unicellular picocyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic phytoplankton in the world and plays an important role in marine carbon cycling. Cyanophages that infect Prochlorococcus influence the growth, carbon fixation, diversity, evolution, and environmental adaptation of their hosts. Here, we review studies on the isolation, genomics, and phylogenetic diversity of Prochlorococcus viruses and their interactions with Prochlorococcus. We also review the potential effects of Prochlorococcus viruses on biogeochemical cycling in the ocean.     

Temporal and spatial variations of <Emphasis Type="Italic">δ</Emphasis><Superscript>15</Superscript>N and <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O for atmospheric N<Subscript>2</Subscript>O above the oceanic surface from Shanghai to Antarctica

During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship “Xuelong” and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N₂O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concentration (PreCon) of trace gases. The temporal and spatial variations of δ ¹⁵N and δ ¹⁸O in atmospheric N₂O were analyzed. The mean δ ¹⁵N and δ ¹⁸O-N₂O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ ¹⁵N (6.05‰–7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ ¹⁸O (43.05‰–48.78‰) showed a large fluctuation. The δ ¹⁵N negatively correlated with air temperature and N₂O concentration, and slightly positively correlated with δ ¹⁸O. The summertime variations of δ ¹⁵N and δ ¹⁸O-N₂O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N₂O concentration. The δ ¹⁵N and δ ¹⁸O-N₂O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N₂O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ ¹⁵N and δ ¹⁸O values were also discussed. The isotopic data given in this study can help to investigate the global and regional N₂O budgets. Supported by the National Natural Science Foundation of China (Grant Nos. 40676005 and 40406001)     

Methods and technique of measurements of ρ<Subscript><Emphasis Type="Italic">k</Emphasis></Subscript> variations by GEOMES-R6 device

Upgrading of the electrical resistance variometer GEOMES-R6 of the Institute of Geophysics of the Poland Academy of Sciences, with enhancement of functional capabilities of the GEOMES assemblage for its application in laboratory measurements on rock samples, has been carried out. The assemblage operation principle, specifications, and theory of operation are given. Results of the assemblage test at measurements on marble sample and concrete model are presented. It is shown that the installation allows long-duration registration of variations of the value ρ _k on high-ohmic samples.     

Hovsgol earthquake 5 December 2014, <Emphasis Type="Italic">M</Emphasis><Subscript>W</Subscript> = 4.9: seismic and acoustic effects

A moderate shallow earthquake occurred on 5 December 2014 (M _W = 4.9) in the north of Lake Hovsgol (northern Mongolia). The infrasonic signal with duration 140 s was recorded for this earthquake by the “Tory” infrasound array (Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Science, Russia). Source parameters of the earthquake (seismic moment, geometrical sizes, displacement amplitudes in the focus) were determined using spectral analysis of direct body P and S waves. The spectral analysis of seismograms and amplitude variations of the surface waves allows to determine the effect of the propagation of the rupture in the earthquake focus, the azimuth of the rupture propagation direction and the velocity of displacement in the earthquake focus. The results of modelling of the surface displacements caused by the Hovsgol earthquake and high effective velocity of propagation of infrasound signal (~ 625 m/s) indicate that its occurrence is not caused by the downward movement of the Earth’s surface in the epicentral region but by the effect of the secondary source. The position of the secondary source of infrasound signal is defined on the northern slopes of the Khamar-Daban ridge according to the data on the azimuth and time of arrival of acoustic wave at the Tory station. The interaction of surface waves with the regional topography is proposed as the most probable mechanism of formation of the infrasound signal.     

Ionospheric <Emphasis Type="Italic">N</Emphasis><Subscript>e</Subscript> disturbances before 2007 Pu’er,Yunnan, China,earthquake

Selecting three half orbits near the epicenter of Pu’er earthquake, we analyzed the N_e data recorded in their revisited orbits during a year before this earthquake, and extracted N_e precursors. The results show that: ① There are significant seasonal variations of ionospheric N_e in night time, which exhibit different shapes respectively in four seasons; ② There are three main shapes of N_e: single-peak, saddle-shaped and even-shaped, all of which may occur in four seasons, but each season with its typical shape relatively; ③ Spatial images of N_e showed high values near the epicenter in 30 days before the earthquake, and there is a good correlation between anomaly and distribution of earthquake in space and time, which reflects that these spatial anomalies were indeed concerned with the earthquake; ④ There shows a certain similarity of the N_e curves among revisited orbits, which can provide background information for distinguishing and identification of seismic anomaly.     

Temporal variations of <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O of atmospheric water vapor at Delingha

Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of climate. Atmospheric water vapor samples were collected at Dlingha, northeast of Tibetan Plateau during the period from July 2005 to February 2006. The variation of δ ¹⁸O and the relationships between δ ¹⁸O and both the temperature and specific humidity are analyzed in this paper. Results show that the seasonal variation of δ ¹⁸O of atmospheric water vapor at Delingha is remarkable with higher δ ¹⁸O in summer and lower δ ¹⁸O in winter. The temporal variation of vapor δ ¹⁸O shows obvious fluctuations, with magnitude of over 37‰ The daily variation of the δ ¹⁸O is highly correlated with air temperature. The relationship between δ ¹⁸O and atmospheric water vapor content is complex. Study shows that δ ¹⁸O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period. The δ ¹⁸O values of atmospheric water vapor are lower than those of precipitation at Delingha, and the average difference is 10.7‰ Variations of δ ¹⁸O of atmospheric water vapor is also found to be affected by precipitation events, The model results show that the precipitation effect could have caused the vapor δ ¹⁸O in the raining season to lower by 7% in average in July and August. Supported by the National Natural Science Foundation of China (Grant Nos. 40671043, 40571039 and 40771048) and National Basic Research Program of China (Grant No. 2005CB422002)