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, respectively. The samples were transported to the laboratory and stored in refrigeration at 4°C before analysis. Fig . 3. The 24-h accumulated rainfall (mm), ending at 0800 LT 22 Jul 2012 [modified after Zhang et al. (2013) ]. The black box represents Shihua Cave, our sampling site. Stable isotopes were analyzed with a Picarro L2130-i laser absorption water isotope spectrometer in the Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese
, respectively. The samples were transported to the laboratory and stored in refrigeration at 4°C before analysis. Fig . 3. The 24-h accumulated rainfall (mm), ending at 0800 LT 22 Jul 2012 [modified after Zhang et al. (2013) ]. The black box represents Shihua Cave, our sampling site. Stable isotopes were analyzed with a Picarro L2130-i laser absorption water isotope spectrometer in the Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese
). Understanding the means by which the modern PNA affects the spatial and temporal patterns of precipitation isotopes across the United States is especially important as we seek to fully interpret climate signals recorded in natural isotopic archives. For instance, analysis of paleo–water isotope proxies preserved in lake sediments, tree rings, and speleothems is increasingly employed to infer PNA fluctuations ( Kirby et al. 2001 ; Edwards et al. 2008 ; Field et al. 2010 ; Hubeny et al. 2011 ). Fully
). Understanding the means by which the modern PNA affects the spatial and temporal patterns of precipitation isotopes across the United States is especially important as we seek to fully interpret climate signals recorded in natural isotopic archives. For instance, analysis of paleo–water isotope proxies preserved in lake sediments, tree rings, and speleothems is increasingly employed to infer PNA fluctuations ( Kirby et al. 2001 ; Edwards et al. 2008 ; Field et al. 2010 ; Hubeny et al. 2011 ). Fully
decadal variations ( Fig. 2c ). To better assess and confirm the results of correlation analysis, we average the frequency of daily patterns when the deuterium isotope anomaly was higher than one standard deviation and compare it with the corresponding frequencies averaged over the periods when deuterium anomaly was lower than minus one standard deviation. This composite analysis confirms the results of correlation analysis. The frequency of only a few patterns varies significantly for high
decadal variations ( Fig. 2c ). To better assess and confirm the results of correlation analysis, we average the frequency of daily patterns when the deuterium isotope anomaly was higher than one standard deviation and compare it with the corresponding frequencies averaged over the periods when deuterium anomaly was lower than minus one standard deviation. This composite analysis confirms the results of correlation analysis. The frequency of only a few patterns varies significantly for high
part of the sample was immediately transferred to airtight 30-mL polyethylene bottle and wrapped with parafilm to prevent sample loss and evaporation. All the samples were stored at 4°C until further isotopic analysis. In addition, air temperature, relative humidity, and precipitation amount were also recorded during the observation period. Precipitation samples were analyzed using a liquid water isotope analyzer (LGR-DLT100, United States) at the Key Laboratory of the College of Resources and
part of the sample was immediately transferred to airtight 30-mL polyethylene bottle and wrapped with parafilm to prevent sample loss and evaporation. All the samples were stored at 4°C until further isotopic analysis. In addition, air temperature, relative humidity, and precipitation amount were also recorded during the observation period. Precipitation samples were analyzed using a liquid water isotope analyzer (LGR-DLT100, United States) at the Key Laboratory of the College of Resources and
purification system is to procure CH 3 Br from the ambient atmosphere in sufficient purity and quantity and without method-induced isotope fractionation so as to allow high-precision Br isotope analysis; this paper describes reaching these goals. A secondary goal is trapping sufficient CH 3 Cl for Cl isotope analysis. Our current analytical method for bromine isotopes [gas chromatography hyphenated with inductively coupled plasma multicollector mass spectrometry (GC-ICP-mcMS)] has a limit of quantification
purification system is to procure CH 3 Br from the ambient atmosphere in sufficient purity and quantity and without method-induced isotope fractionation so as to allow high-precision Br isotope analysis; this paper describes reaching these goals. A secondary goal is trapping sufficient CH 3 Cl for Cl isotope analysis. Our current analytical method for bromine isotopes [gas chromatography hyphenated with inductively coupled plasma multicollector mass spectrometry (GC-ICP-mcMS)] has a limit of quantification
June '1993)ABSTRACT A methodology for the collection of large ( 1000 L) air samples for isotopic analysis of atmospheric carbonmonoxide is presented. A low-background, high-pressure, high-flow sampling system with a residual backgroundof less than 2 ppbv CO has been built and employed for collection of samples both from the ground and froman aircraft platform. The time required for obtaining a 1000-L sample pressurized to 600 psi was approximately30 min on the ground, and 75 min at 8-km altitude
June '1993)ABSTRACT A methodology for the collection of large ( 1000 L) air samples for isotopic analysis of atmospheric carbonmonoxide is presented. A low-background, high-pressure, high-flow sampling system with a residual backgroundof less than 2 ppbv CO has been built and employed for collection of samples both from the ground and froman aircraft platform. The time required for obtaining a 1000-L sample pressurized to 600 psi was approximately30 min on the ground, and 75 min at 8-km altitude
stable isotopes provides an independent evaluation of the modeled water cycle and climate. Moreover, the consistent physical framework of the model enables analysis of the climatic controls on the spatial and temporal precipitation isotopic compositions, on global or regional scales. Based on our present-day capabilities, isotopic AGCMs have also been used to explore the temporal stability of the isotope–climate relationship under varying paleoclimate boundary conditions (e.g., glacial climate, or
stable isotopes provides an independent evaluation of the modeled water cycle and climate. Moreover, the consistent physical framework of the model enables analysis of the climatic controls on the spatial and temporal precipitation isotopic compositions, on global or regional scales. Based on our present-day capabilities, isotopic AGCMs have also been used to explore the temporal stability of the isotope–climate relationship under varying paleoclimate boundary conditions (e.g., glacial climate, or
et al. 2006 ). A total of 6081 samples were analyzed for δ 18 O and δ D at the National Isotope Centre, GNS Science, with an analytical precision of 0.1‰ and 1.0‰, respectively. All results are reported with respect to Vienna Standard Mean Ocean Water (VSMOW) and normalized to internal standards. This study also employs gridded European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) data, available at 1.5° resolution from 1989 onward ( Dee et al. 2011
et al. 2006 ). A total of 6081 samples were analyzed for δ 18 O and δ D at the National Isotope Centre, GNS Science, with an analytical precision of 0.1‰ and 1.0‰, respectively. All results are reported with respect to Vienna Standard Mean Ocean Water (VSMOW) and normalized to internal standards. This study also employs gridded European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) data, available at 1.5° resolution from 1989 onward ( Dee et al. 2011
to tropical rainfall, the multiscale influences on the isotopic composition of midlatitude precipitation do not lend themselves well to univariate regression analysis because different processes can dominate the isotope signature at different spatiotemporal scales; for example, the air mass may have an opposing influence compared to within-event and life cycle effects ( Berkelhammer et al. 2012 ; Sturm et al. 2010 ). This has resulted in difficulties in calibrating isotopic records. Studies of
to tropical rainfall, the multiscale influences on the isotopic composition of midlatitude precipitation do not lend themselves well to univariate regression analysis because different processes can dominate the isotope signature at different spatiotemporal scales; for example, the air mass may have an opposing influence compared to within-event and life cycle effects ( Berkelhammer et al. 2012 ; Sturm et al. 2010 ). This has resulted in difficulties in calibrating isotopic records. Studies of
Occasional Publication 3, University of Rhode Island, 277–374 . Dirmeyer, P. A. , and Brubaker K. L. , 2007 : Characterization of the global hydrologic cycle from a back-trajectory analysis of atmospheric water vapor . J. Hydrometeor. , 8 , 20 – 37 , doi: 10.1175/JHM557.1 . Dubbert, M. , Cuntz M. , Piayda A. , Maguás C. , and Werner C. , 2013 : Partitioning evapotranspiration—Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes . J
Occasional Publication 3, University of Rhode Island, 277–374 . Dirmeyer, P. A. , and Brubaker K. L. , 2007 : Characterization of the global hydrologic cycle from a back-trajectory analysis of atmospheric water vapor . J. Hydrometeor. , 8 , 20 – 37 , doi: 10.1175/JHM557.1 . Dubbert, M. , Cuntz M. , Piayda A. , Maguás C. , and Werner C. , 2013 : Partitioning evapotranspiration—Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes . J
