Identifying water vapor sources of precipitation in forest and grassland in the north slope of the Tianshan Mountains,Central Asia

Identifying water vapor sources in the natural vegetation of the Tianshan Mountains is of significant importance for obtaining greater knowledge about the water cycle,forecasting water resource changes,and dealing with the adverse effects of climate change.In this study,we identified water vapor sources of precipitation and evaluated their effects on precipitation stable isotopes in the north slope of the Tianshan Mountains,China.By utilizing the temporal and spatial distributions of precipitation stable isotopes in the forest and grassland regions,Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,and isotope mass balance model,we obtained the following results.(1)The Eurasia,Black Sea,and Caspian Sea are the major sources of water vapor.(2)The contribution of surface evaporation to precipitation in forests is lower than that in the grasslands(except in spring),while the contribution of plant transpiration to precipitation in forests(5.35%)is higher than that in grasslands(3.79%)in summer.(3)The underlying surface and temperature are the main factors that affect the contribution of recycled water vapor to precipitation;meanwhile,the effects of water vapor sources of precipitation on precipitation stable isotopes are counteracted by other environmental factors.Overall,this work will prove beneficial in quantifying the effect of climate change on local water cycles.

Composition of stable isotope in precipitation and its influences by different vapor sources in the eastern Qilian Mountains

To better understand the process of precipitation and water cycle, the composition of stable isotope in precipitation and its influences by different vapor sources in the eastern of Qilian Mountains were conducted from June 2013 to May 2014. The total of 100 precipitation samples were collected in Wushaoling national meteorological station located in the eastern of Qilian Mountains. The analysis indicates that the slope of Local Meteoric Water Line is lower than that of Global Meteoric Water Line. The average values of δ18 O and δD in precipitation are higher in summer but lower in winter. Except for negative correlation with relative humidity, the stable isotope values in precipitation are positive correlations with temperature, precipitation and water vapor pressure. Influenced by water vapor source, the values of d-excess are lower for the Westerly wind and the South Asia Monsoon onJuly and the Westerly wind and the East Asia Monsoon on August, but they are higher for the Westerly wind on other months, that they are also influenced by the weather conditions in rainfall process. The variation of stable isotope in precipitation exhibited significant temperature effect, and there is also some precipitation amount effect in spring and summer.

Diagnostic Analysis of Rainstorm and Backward Trajectory Simulation of Water Vapor in Jilin Province in July,2010

[Objective] The research aimed to analyze the rainstorm process and backward trajectory simulation of water vapor condition in Jilin Province in July,2010.[Method] Based on the actual situation data of routine weather chart,NCEP (2.5°×2.5°) reanalysis data per 6 h and GBL data of NOAA,the rainstorm process was carried out the diagnostic analysis of physical quantity in Jilin Province in July,2010.Moreover,HYSPLIT backward trajectory mode was used to simulate the water vapor source.[Result] The coexistence of upper-level divergence and low-level convergence generated the ascending motion,which was the dynamic condition of rainstorm appearance.The unstable energy induced by the low-level shear promoted the generation of heavy rainstorm.The water vapor source of precipitation process was divided into the water vapor in the southern sea area,northern high-altitude water vapor transportation and local water vapor source.[Conclusion] The research provided some reference basis for the forecast and analysis of rainstorm.

Collinear Velocity-map Photoelectron Imaging Spectrometer for Cluster Anions

We describe a collinear velocity-map photoelectron imaging spectrometer, which combines a Wiley-McLaren time-of-flight mass analyzer with a dual-valve laser vaporization source for investigating size-selected cluster and reaction intermediate anions. To generate the reaction anions conveniently, two pulsed valves and a reaction channel are employed instead of premixing carrier gas. The collinear photoelectron imaging spectrometer adopts modified velocity-map electrostatic lens, and provides kinetic energy resolution better than 3%. The performance of the instrument is demonstrated on the photodetachment of Si4^- at 532 and 355 nm, and SiaC^- at 532 nm, respectively. In both cases, photoelectron spectra and anisotropy parameters are obtained from the images. For Si4^-, the spectra show two well- resolved vibrational progressions which correspond to the ground state and the first excited state of the neutral Si4 with peak spacing of 330 and 312 cm^-1, respectively. Preliminary results suggest that the apparatus is a powerful tool for characterizing the electronic structure and photodetachment dynamics of cluster anions.

Design and analysis of a novel dual source vapor injection heat pump using exhaust and ambient air

A novel dual source vapor injection heat pump(DSVIHP)using exhaust and ambient air is proposed.The air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator.A vapor injection(VI)compressor of two inlets is connected with the low and medium pressure evaporators.It’s first time that a VI compressor is employed to recover the ventilation heat.The system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste heat.Fundamentals of the proposed DSVIHP are illustrated.Mathematical models are built.Both energetic and exergetic analyses are carried out under variable conditions.The results indicate that the DSVIHP has superior thermodynamic performance.The superiority is more appreciable at a lower ambient temperature.It has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3%and 23.2%respectively at an ambient temperature of-10°C and condensation temperature of 45°C.The waste heat recovery ratio from the exhaust air is more than 100%.The novel DSVIHP has great potential in the cold climate area application.

Variations in the oxygen isotopic composition of precipitation in the Tianshan Mountains region and their significance for the Westerly circulation

Proxy records of the oxygen isotopic composition of meteorological precipitation （δ^18Op） preserved in archives such as ice cores, lacustrine carbonates and stalagmite calcite are important for paleoclimatic studies. Therefore, knowledge of the variations and controlling mechanisms of modern δ^18Op on different time scales is necessary. Here, we investigate the linear correlations between δ^18Op and corresponding temperature and precipitation on monthly and inter-annual timescales, using data from the Urumqi （1986-2003） and Hotan stations of the Global Network of Isotopes in Precipitation （GNIP）, and δ^18O data from 4 ice cores in the adjacent Tianshan Mountains. Consistent with previous reported results, modern δ^18Op variations on a seasonal time scale in the Tianshan region are mainly controlled by a ＇temperature effect＇ （indicated by a significant positive correlation between δ^18Op and temperature）, with more positive δ^18Op values occurring in summer. However, on an inter-annual timescale, there is a weak inverse correlation between weighted average annual δ^18Op and annual average temperature at Urumqi station. This finding is supported by the inversely varying trends of δ^18Op data from 4 ice cores in the central and eastern Tianshan Mountains compared to annual average temperatures in the same region during the past 40-50 years. The data from Urumqi station and the 4 ice cores demonstrate that there is inverse correlation between δ^18Op and temperature on inter-annual to decadal time scales. Analysis of water vapor sources and pathways for the warm year of 1997 and the cold year of 1988 reveal that relatively more water vapor for the Tianshan region was derived from long-distance transport from high-latitude sources than during the warm year of 1997; and that more water vapor was transported from more proximal sources from mid- to low-latitude areas during the cold year of 1988. In addition, the δ^18Op values are more negative in the high latitude areas than those in mid- to low-latitude areas in the Eurasian continent at the upper wind direction of Tianshan Mountains region, according to the weighted averaged warm season （May to September）δ^18Op values for 14 GNIP stations in the years 1997 and 1988. Due to the distribution of δ^18Op within the Eurasian continent, the relative shift of water vapor sources between warm and cold years convincingly explains the observed variations of δ^18Op in the Tianshan Mountains region. Therefore, we conclude that variations in 518OD in this region are mainly controlled by changes in water vapor sources which are ultimately caused by northward and southward shifts in the Westerly circulation.