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1
Van Hale, Robert, and Russell D. Frew. "Rayleigh distillation equations applied to isotopic evolution of organic nitrogen across a continental shelf." Marine and Freshwater Research 61, no. 3 (2010): 369. http://dx.doi.org/10.1071/mf09041.
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The isotope enrichment of nitrate due to uptake by phytoplankton has previously been measured in a variety of ways, both in the field over time or space, and in vitro. This study provided an unusual opportunity to measure the isotopic fractionation of nitrate over an extended spatial scale. Results are presented from the Otago Continental shelf, New Zealand. δ15N-PON and [NO3–] was correlated using Rayleigh distillation equations to obtain isotope enrichment factors for the uptake of nitrate. The decrease in nitrate concentration during advection landward across the shelf was consistent with removal by phytoplankton, with an average enrichment factor (ϵ) of 8.2 per mil, as calculated using the Rayleigh accumulated product equation. The spatial evolution of δ15N-PON and [NO3–] across the Otago continental shelf led to the conclusion that cross-shelf advection is the predominant process bringing nutrients to the shelf. No Rayleigh distillation-type process is observable from monthly observations. However, in subantarctic surface water (SASW), a seasonal variation in δ15N-PON was seen that was in the opposite phase to that expected for isotopic enrichment of the nutrient pool. In SASW, δ15N-PON peaked at 4‰ in winter months and fell to –2‰ in the spring and summer.
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Shen, Hong, and Christopher J. Poulsen. "Precipitation <i>δ</i><sup>18</sup>O on the Himalaya–Tibet orogeny and its relationship to surface elevation." Climate of the Past 15, no. 1 (January 29, 2019): 169–87. http://dx.doi.org/10.5194/cp-15-169-2019.
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Abstract. The elevation history of the Himalaya–Tibet orogen is central to understanding the evolution and dynamics of both the India–Asia collision and the Asian monsoons. The surface elevation history of the region is largely deduced from stable isotope (δ18O, δD) paleoaltimetry. This method is based on the observed relationship between the isotopic composition of meteoric waters (δ18Op, δDp) and surface elevation, and the assumption that precipitation undergoes Rayleigh distillation under forced ascent. Here we evaluate how elevation-induced climate change influences the δ18Op–elevation relationship and whether Rayleigh distillation is the dominant process affecting δ18Op. We use an isotope-enabled climate model, ECHAM-wiso, to show that the Rayleigh distillation process is only dominant in the monsoonal regions of the Himalayas when the mountains are high. When the orogen is lowered, local surface recycling and convective processes become important, as forced ascent is weakened due to weaker Asian monsoons. As a result, the δ18Op lapse rate in the Himalayas increases from around −3 to above −0.1 ‰ km−1, and has little relationship with elevation. On the Tibetan Plateau, the meridional gradient of δ18O decreases from ∼1 to ∼0.3 ‰ ∘−1 with reduced elevation, primarily due to enhanced sub-cloud reevaporation under lower relative humidity. Overall, we report that using δ18Op or δDp to deduce surface elevation change in the Himalayan–Tibetan region has severe limitations and demonstrate that the processes that control annual-mean precipitation-weighted δ18Op vary by region and with surface elevation. In summary, we determine that the application of δ18O paleoaltimetry is only appropriate for 7 of the 50 sites from which δ18O records have been used to infer past elevations.
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Ádámkovics, Máté, and Jonathan L. Mitchell. "Search for methane isotope fractionation due to Rayleigh distillation on Titan." Icarus 275 (September 2016): 232–38. http://dx.doi.org/10.1016/j.icarus.2016.04.006.
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Mix, Hari, Sean Reilly, Andrew Martin, and Gavin Cornwell. "Evaluating the Roles of Rainout and Post-Condensation Processes in a Landfalling Atmospheric River with Stable Isotopes in Precipitation and Water Vapor." Atmosphere 10, no. 2 (February 19, 2019): 86. http://dx.doi.org/10.3390/atmos10020086.
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Atmospheric rivers (ARs), and frontal systems more broadly, tend to exhibit prominent “V” shapes in time series of stable isotopes in precipitation. Despite the magnitude and widespread nature of these “V” shapes, debate persists as to whether these shifts are driven by changes in the degree of rainout, which we determine using the Rayleigh distillation of stable isotopes, or by post-condensation processes such as below-cloud evaporation and equilibrium isotope exchange between hydrometeors and surrounding vapor. Here, we present paired precipitation and water vapor isotope time series records from the 5–7 March 2016, AR in Bodega Bay, CA. The stable isotope composition of surface vapor along with independent meteorological constraints such as temperature and relative humidity reveal that rainout and post-condensation processes dominate during different portions of the event. We find that Rayleigh distillation controls during peak AR conditions (with peak rainout of 55%) while post-condensation processes have their greatest effect during periods of decreased precipitation on the margins of the event. These results and analyses inform critical questions regarding the temporal evolution of AR events and the physical processes that control them at local scales.
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Baker, John M., and Timothy J. Griffis. "A simple, accurate, field-portable mixing ratio generator and Rayleigh distillation device." Agricultural and Forest Meteorology 150, no. 12 (December 15, 2010): 1607–11. http://dx.doi.org/10.1016/j.agrformet.2010.08.008.
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Galewsky, Joseph, and Kimberly Samuels-Crow. "Summertime Moisture Transport to the Southern South American Altiplano: Constraints from In Situ Measurements of Water Vapor Isotopic Composition." Journal of Climate 28, no. 7 (March 27, 2015): 2635–49. http://dx.doi.org/10.1175/jcli-d-14-00511.1.
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Abstract Austral summer transport of water vapor to the southern South American Altiplano is investigated using in situ measurements of water vapor isotopic composition collected from 1 November 2012 to 10 February 2013 on the Chajnantor Plateau in the Chilean Andes. Onset of the wet season in December was associated with an increase in mixing ratios from an average of 1500 ppmv during the winter dry season to 5400 ppmv in early December. Water vapor isotopes δD and δ18O increased from dry season averages of −235‰ and −31‰, respectively, to wet season averages of −142‰ and −17‰, reaching as high as −70‰ and −17‰, respectively. The highest water vapor δ values were close to those measured in coastal settings, suggesting little condensation during transport to the site. About 5% of the wet season data have δ values that are lower than expected for Rayleigh distillation and are associated with high relative humidity (>75%), easterly winds, and periods of low outgoing longwave radiation over the Altiplano, consistent with moistening by deep convection. The remainder of the data have δ values that are greater than expected for Rayleigh distillation, up to 250‰ above the Rayleigh curve. These data are consistent with mixing between very dry air and moist air from the boundary layer. The data show intraseasonal variability coherently linked to the position of the Bolivian high, with moist air associated with a southward displacement in the Bolivian high. The humidity over the southern Altiplano during the wet season reflects a balance among advective drying, advective moistening with little condensation, and convective moistening.
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Yongfei, Zheng. "Sulfur isotope fractionation in magmatic systems: Models of Rayleigh distillation and selective flux." Chinese Journal of Geochemistry 9, no. 1 (January 1990): 27–45. http://dx.doi.org/10.1007/bf02837946.
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Wang, Da, Youye Zheng, Ryan Mathur, and Song Wu. "The Fe-Zn Isotopic Characteristics and Fractionation Models: Implications for the Genesis of the Zhaxikang Sb-Pb-Zn-Ag Deposit in Southern Tibet." Geofluids 2018 (2018): 1–23. http://dx.doi.org/10.1155/2018/2197891.
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The genesis of the Zhaxikang Sb-Pb-Zn-Ag deposit remains controversial. Three different geological environments have been proposed to model mineralization: a hot spring, a magmatic-hydrothermal fluid, and a sedimentary exhalative (SEDEX) overprinted by a hot spring. Here, we present the electron probe microanalysis (EPMA) and Fe-Zn isotopic data (microsampled) of four samples from the first pulse of mineralization that show annular textures to constrain ore genesis. The Zn/Cd ratios from the EPMA data of sphalerite range from 296 to 399 and overlap the range of exhalative systems. The δ56Fe values of Mn-Fe carbonate and δ66Zn values of sphalerite gradually decrease from early to late stages in three samples. A combination of the EPMA and isotopic data shows the Fe-Zn contents also have different correlations with δ66Zn values in sphalerite from these samples. Rayleigh distillation models this isotope and concentration data with the cause of fractionation related to vapour-liquid partitioning and mineral precipitation. In order to verify this Rayleigh distillation model, we combine our Fe-Zn isotopic data with those from previous studies to establish 12 Fe-Zn isotopic fractionation models. These fractionation models indicate the δ56Fei and δ66Zni values (initial Fe-Zn isotopic compositions) of the ore-forming system are in the range of -0.5‰ ~−1‰ and -0.28‰ ~0‰, respectively. To conclude, the EPMA data, Fe-Zn isotopic characteristics, and fractionation models support the SEDEX model for the first pulse of mineralization.
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Li, Jie, Tao Tao, Zhonghe Pang, Ming Tan, Yanlong Kong, Wuhui Duan, and Yuwei Zhang. "Identification of Different Moisture Sources through Isotopic Monitoring during a Storm Event." Journal of Hydrometeorology 16, no. 4 (July 29, 2015): 1918–27. http://dx.doi.org/10.1175/jhm-d-15-0005.1.
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Abstract Rain samples were collected for isotopic analyses during the entirety of an extreme rainfall event in Beijing, China, on 21 July 2012, the city’s heaviest rainfall event in the past six decades. Four stages of the storm event have been identified with corresponding isotopic characteristics: 1) isotopes deplete as rain increases, 2) isotopes enrich as rain decreases, 3) isotopes quickly deplete as rain increases, and 4) isotopes remain constant as rain reduces to a small amount. The rainout effect dominates the depletion of isotopic composition in stages 1 and 3. The incursion of a new air mass with enriched heavy isotopes was the main cause for the enriched isotopic composition during stage 2. A Rayleigh distillation model was used to describe the isotopic trends during stages 1 and 3. The Rayleigh distillation model and a binary mixing model were used to estimate the initial isotopic composition of different air masses, which were found to be similar to δ18O of precipitation at nearby Global Network of Isotopes in Precipitation stations representing southwest and southeast trajectories. The results are in agreement with meteorological arrays analysis. This model also indicates that 29% of the initial vapor from the southwest trajectory was precipitated in stage 1, followed by a mixing process between southeast and southwest moisture. In stage 3, up to 56% of mixed moisture was precipitated, among which ~65%–100% was from southeast moisture.
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Sturm, Christophe, Georg Hoffmann, and Bärbel Langmann. "Simulation of the Stable Water Isotopes in Precipitation over South America: Comparing Regional to Global Circulation Models." Journal of Climate 20, no. 15 (August 1, 2007): 3730–50. http://dx.doi.org/10.1175/jcli4194.1.
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Abstract A simulation of the stable water isotope cycle over South America by the regional circulation model REMOiso is discussed. The performance of the regional model, with a resolution of 0.5° (∼55 km), is compared to simulations by the global circulation model ECHAMiso at two coarser resolutions and evaluated against observations of precipitation and δ18O. Here REMOiso is demonstrated to reproduce reasonably well climatic and isotopic features across South America. This paper explores further insights of δ18O as a climate proxy, based on REMOiso’s improvements as compared to ECHAMiso. In particular, the authors focus on the seasonal variation of the amount effect (δ18O decrease with precipitation amounts) and the anomalous δ18O continental gradient across the Amazon basin, as inferred from the REMOiso, ECHAMiso, and GNIP datasets. The finer resolution of topography in REMOiso enables a detailed analysis of the altitude effect: not only the first, but also the second derivative of δ18O with altitude is considered. It appears that high-altitude grid cells show an isotopic signature similar to Rayleigh distillation, in accordance with experimental studies. Finally, a Lagrangian reference frame is adopted to describe the evolution of δ18O in precipitation along its trajectory, in order to relate the simulation analysis to the fractionation mechanisms. This confirms that the amount effect, via Rayleigh distillation processes, is dominant during the wet season. During the dry season, the δ18O in precipitation is controlled by isotopic reequilibration of rain droplets with surrounding vapor, reflecting the impact of nonfractionating transpiration by the vegetation.
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Scott, K. M., X. Lu, C. M. Cavanaugh, and J. S. Liu. "Optimal methods for estimating kinetic isotope effects from different forms of the Rayleigh distillation equation." Geochimica et Cosmochimica Acta 68, no. 3 (February 2004): 433–42. http://dx.doi.org/10.1016/s0016-7037(03)00459-9.
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Dohnal, Vladimír, and Iveta Horáková. "A new variant of the Rayleigh distillation method for the determination of limiting activity coefficients." Fluid Phase Equilibria 68 (November 1991): 173–85. http://dx.doi.org/10.1016/0378-3812(91)85016-n.
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Salmon, Olivia E., Lisa R. Welp, Michael E. Baldwin, Kristian D. Hajny, Brian H. Stirm, and Paul B. Shepson. "Vertical profile observations of water vapor deuterium excess in the lower troposphere." Atmospheric Chemistry and Physics 19, no. 17 (September 12, 2019): 11525–43. http://dx.doi.org/10.5194/acp-19-11525-2019.
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Abstract. We use airborne measurements of water vapor (H2Ov) stable isotopologues and complementary meteorological observations to examine how boundary layer (BL) dynamics, cloud processing, and atmospheric mixing influence the vertical structure of δD, δ18O, and deuterium excess (d excess =δD–8×δ18O) in the BL, inversion layer (INV), and lower free troposphere (FT). Flights were conducted around two continental US cities in February–March 2016 and included vertical profiles extending from near the surface to ≤2 km. We examine observations from three unique case study flights in detail. One case study shows observations that are consistent with Rayleigh isotopic distillation theory coinciding with clear skies, dry adiabatic lapse rates within the boundary layer, and relatively constant vertical profiles of wind speed and wind direction. This suggests that the air mass retained the isotopic fingerprint of dehydration during moist adiabatic processes upwind of the study area. Also, observed d-excess values in the free troposphere were sometimes larger than Rayleigh theory predicts, which may indicate mixing of extremely dehydrated air from higher altitudes. The two remaining case studies show isotopic anomalies in the d-excess signature relative to Rayleigh theory and indicate cloud processes and complex boundary layer development. The most notable case study with stratocumulus clouds present had extremely low (negative) d-excess values at the interface of the inversion layer and the free troposphere, which is possibly indicative of cloud or rain droplet evaporation. We discuss how in situ H2Ov stable isotope measurements, and d excess in particular, could be useful for improving our understanding of water phase changes, transport, and mixing that occurs between the BL, INV, and FT.
14
Roche, D. M. "δ<sup>18</sup>O water isotope in the <i>i</i>LOVECLIM model (version 1.0) – Part 1: Implementation and verification." Geoscientific Model Development Discussions 6, no. 1 (March 4, 2013): 1467–94. http://dx.doi.org/10.5194/gmdd-6-1467-2013.
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Abstract. A new 18O stable water isotope scheme is developed for three components of the iLOVECLIM coupled climate model: atmospheric, oceanic and land surface. The equations required to reproduce the fractionation of stable water isotopes in the simplified atmospheric model ECBilt are developed consistently with the moisture scheme. Simplifications in the processes are made to account for the simplified vertical structure including only one moist layer. Implementation of these equations together with a passive tracer scheme for the ocean and a equilibrium fractionation scheme for the land surface leads to the closure of the (isotopic-)water budget in our climate system. Following the implementation, verification of the existence of usual δ18O to climatic relationships are performed for the Rayleigh distillation, the Dansgaard relationship and the δ18O–salinity relationship. Advantages and caveats of the approach taken are outlined.
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Griffis, Timothy J., Jeffrey D. Wood, John M. Baker, Xuhui Lee, Ke Xiao, Zichong Chen, Lisa R. Welp, et al. "Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer." Atmospheric Chemistry and Physics 16, no. 8 (April 25, 2016): 5139–57. http://dx.doi.org/10.5194/acp-16-5139-2016.
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Abstract. Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle – an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m) in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL) over a 3-year period (2010 to 2012). These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from −40.2 to −15.9 ‰ and δ2Hv ranged from −278.7 to −113.0 ‰) and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv) of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( > 25 mmol mol−1) indicate that regional evaporation can account for 40 to 60 % of the PBL water vapor. These estimates are in relatively good agreement with that derived from numerical weather model simulations. This relatively large fraction of evaporation-derived water vapor implies that evaporation has an important impact on the precipitation recycling ratio within the region. Based on multiple constraints, we estimate that the summer season recycling fraction is about 30 %, indicating a potentially important link with convective precipitation.
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Roche, D. M. "δ<sup>18</sup>O water isotope in the <i>i</i>LOVECLIM model (version 1.0) – Part 1: Implementation and verification." Geoscientific Model Development 6, no. 5 (September 12, 2013): 1481–91. http://dx.doi.org/10.5194/gmd-6-1481-2013.
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Abstract. A new 18O stable water isotope scheme is developed for three components of the iLOVECLIM coupled climate model: atmospheric, oceanic and land surface. The equations required to reproduce the fractionation of stable water isotopes in the simplified atmospheric model ECBilt are developed consistently with the moisture scheme. Simplifications in the processes are made to account for the simplified vertical structure including only one moist layer. Implementation of these equations together with a passive tracer scheme for the ocean and a equilibrium fractionation scheme for the land surface leads to the closure of the (isotopic-) water budget in our climate system. Following the implementation, verification of the existence of usual δ18O to climatic relationships are performed for the Rayleigh distillation, the Dansgaard relationship and the δ18O –salinity relationship. Advantages and caveats of the approach taken are outlined. The isotopic fields simulated are shown to reproduce most expected oxygen-18–climate relationships with the notable exception of the isotopic composition in Antarctica.
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Roche, D. M., and T. Caley. "δ<sup>18</sup>O water isotope in the <i>i</i>LOVECLIM model (version 1.0) – Part 2: Evaluation of model results against observed δ<sup>18</sup>O in water samples." Geoscientific Model Development 6, no. 5 (September 12, 2013): 1493–504. http://dx.doi.org/10.5194/gmd-6-1493-2013.
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Abstract. The H218O stable isotope was previously introduced in the three coupled components of the earth system model iLOVECLIM: atmosphere, ocean and vegetation. The results of a long (5000 yr) pre-industrial equilibrium simulation are presented and evaluated against measurement of H218O abundance in present-day water for the atmospheric and oceanic components. For the atmosphere, it is found that the model reproduces the observed spatial distribution and relationships to climate variables with some merit, though limitations following our approach are highlighted. Indeed, we obtain the main gradients with a robust representation of the Rayleigh distillation but caveats appear in Antarctica and around the Mediterranean region due to model limitation. For the oceanic component, the agreement between the modelled and observed distribution of water δ18O is found to be very good. Mean ocean surface latitudinal gradients are faithfully reproduced as well as the mark of the main intermediate and deep water masses. This opens large prospects for the applications in palaeoclimatic context.
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Roche, D. M., and T. Caley. "δ<sup>18</sup>O water isotope in the <i>i</i>LOVECLIM model (version 1.0) – Part 2: Evaluation of model results against observed δ<sup>18</sup>O in water samples." Geoscientific Model Development Discussions 6, no. 1 (March 4, 2013): 1495–525. http://dx.doi.org/10.5194/gmdd-6-1495-2013.
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Abstract. The H218O stable isotope was previously introduced in the three coupled components of the Earth System Model iLOVECLIM: atmosphere, ocean and vegetation. The results of a long (5000 yr) pre-industrial equilibrium simulation are presented and evaluated against measurement of H218O abundance in present-day water for the atmospheric and oceanic components. For the atmosphere, it is found that the model reproduces the observed spatial distribution and relationships to climate variables with some merit, though limitations following our approach are highlighted. Indeed, we obtain the main gradients with a robust representation of the Rayleigh distillation but caveats appear in Antarctica and around the Mediterranean region due to model limitation. For the oceanic component, the agreement between the modelled and observed distribution of water δ18O is found to be very good. Mean ocean surface latitudinal gradients are faithfully reproduced as well as the mark of the main intermediate and deep water masses. This opens large prospects for the applications in paleoclimatic context.
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Blättler, C. L., S. M. Stanley, G. M. Henderson, and H. C. Jenkyns. "Identifying vital effects in <i>Halimeda</i> algae with Ca isotopes." Biogeosciences Discussions 11, no. 3 (March 5, 2014): 3559–80. http://dx.doi.org/10.5194/bgd-11-3559-2014.
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Abstract. Geochemical records of biogenic carbonates provide some of the most valuable records of the geological past, but are often difficult to interpret without a mechanistic understanding of growth processes. In this experimental study, Halimeda algae are used as a test organism to untangle some of the specific factors that influence their skeletal composition, in particular their Ca-isotope composition. Algae were stimulated to precipitate both calcite and aragonite by growth in artificial Cretaceous seawater. The Ca-isotope fractionation of the algal calcite is much smaller than that for the algal aragonite, similar to the behaviour observed in inorganic precipitates. However, the carbonate from Halimeda is isotopically heavier than inorganic forms, likely due to Rayleigh distillation within the algal intercellular space. In identifying specific vital effects and the magnitude of their influence on Ca-isotope ratios, this study suggests that mineralogy has a first-order control on the Ca-isotope budget of the carbonate sink and the Ca-isotope composition of seawater.
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Lee, J., J. Worden, D. Noone, K. Bowman, A. Eldering, A. LeGrande, J. L. F. Li, G. Schmidt, and H. Sodemann. "Relating tropical ocean clouds to moist processes using water vapor isotope measurements." Atmospheric Chemistry and Physics Discussions 10, no. 7 (July 20, 2010): 17407–34. http://dx.doi.org/10.5194/acpd-10-17407-2010.
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Abstract. We examine the co-variations of tropospheric water vapor, its isotopic composition and cloud types and relate these distributions to tropospheric mixing and distillation models using satellite observations from the Aura Tropospheric Emission Spectrometer (TES) over the summertime tropical ocean. Interpretation of these process distributions must take into account the sensitivity of the TES isotope and water vapor measurements to variations in cloud, water, and temperature amount. Consequently, comparisons are made between cloud-types based on the International Satellite Cloud Climatology Project (ISSCP) classification; these are clear sky, non-precipitating (e.g., cumulus), boundary layer (e.g., stratocumulus), and precipitating clouds (e.g. regions of deep convection). In general, we find that the free tropospheric vapor over tropical oceans does not strictly follow a Rayleigh model in which air parcels become more dry and isotopically depleted through condensation. Instead, mixing processes related to convection as well as subsidence, and re-evaporation of rainfall associated with organized deep convection all play significant roles in controlling the water vapor distribution. The relative role of these moisture processes are examined for different tropical oceanic regions.
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Zhang, Haozhe, Xuehua Zhou, Jun Zou, Wuke Wang, Likun Xue, Qiuji Ding, Xinfeng Wang, et al. "A Review on the Methods for Observing the Substance and Energy Exchange between Atmosphere Boundary Layer and Free Troposphere." Atmosphere 9, no. 12 (November 22, 2018): 460. http://dx.doi.org/10.3390/atmos9120460.
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Atmosphere boundary layer (ABL or BL) acts as a pivotal part in the climate by regulating the vertical exchange of moisture, aerosol, trace gases and energy between the earth surface and free troposphere (FT). However, compared with research on the exchange between earth surface and ABL, there are fewer researches on the exchange between ABL and FT, especially when it comes to the quantitative measurement of vertical exchange flux between them. In this paper, a number of various methodologies for investigating the exchange of the substance and energy between ABL and FT are reviewed as follows: (1) methods to obtain entrainment rate, which include method by investigating the height of inversion layer, method of flux-jump, estimating with dataset from the ASTEX Lagrangian Experiments and method of using satellite observations and Microwave Imager; (2) mass budget method, which can yield quantitative measurements of exchange flux between ABL and FT; (3) qualitative measurements: method based on Rayleigh distillation and mixing processes, methods of ground-based remote sensing and airborne tracer-tracer relationship/ratio method.
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Blättler, C. L., S. M. Stanley, G. M. Henderson, and H. C. Jenkyns. "Identifying vital effects in <i>Halimeda</i> algae with Ca isotopes." Biogeosciences 11, no. 24 (December 17, 2014): 7207–17. http://dx.doi.org/10.5194/bg-11-7207-2014.
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Abstract. Geochemical records of biogenic carbonates provide some of the most valuable records of the geological past, but are often difficult to interpret without a mechanistic understanding of growth processes. In this experimental study, Halimeda algae are used as a test organism to untangle some of the specific factors that influence their skeletal composition, in particular their Ca-isotope composition. Algae were stimulated to precipitate both calcite and aragonite by growth in artificial Cretaceous seawater, resulting in experimental samples with somewhat malformed skeletons. The Ca-isotope fractionation of the algal calcite (−0.6‰) appears to be much smaller than that for the algal aragonite (−1.4‰), similar to the behaviour observed in inorganic precipitates. However, the carbonate from Halimeda has higher Ca-isotope ratios than inorganic forms by approximately 0.25‰, likely because of Rayleigh distillation within the algal intercellular space. In identifying specific vital effects and the magnitude of their influence on Ca-isotope ratios, this study suggests that mineralogy has a first-order control on the marine Ca-isotope cycle.
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Helsen, M. M., R. S. W. Van de Wal, and M. R. Van den Broeke. "The Isotopic Composition of Present-Day Antarctic Snow in a Lagrangian Atmospheric Simulation*." Journal of Climate 20, no. 4 (February 15, 2007): 739–56. http://dx.doi.org/10.1175/jcli4027.1.
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Abstract The isotopic composition of present-day Antarctic snow is simulated for the period September 1980–August 2002 using a Rayleigh-type isotope distillation model in combination with backward trajectory calculations with 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data as meteorological input. Observed spatial isotopic gradients are correctly reproduced, especially in West Antarctica and in the coastal areas. However, isotopic depletion of snow on the East Antarctic plateau is underestimated, a problem that is also observed in general circulation models equipped with isotope tracers. The spatial isotope–temperature relation varies strongly, which indicates that this widely used relation is not applicable to all sites and temporal scales. Spatial differences in the seasonal amplitude are identified, with maximum values in the Antarctic interior and hardly any seasonal isotope signature in Marie Byrd Land, West Antarctica. The modeled signature of deuterium excess remains largely preserved during the last phase of transport, though the simulated relation of deuterium excess with δ18O suggests that parameterizations of kinetic isotopic fractionation can be improved.
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Lee, J., J. Worden, D. Noone, K. Bowman, A. Eldering, A. LeGrande, J. L. F. Li, G. Schmidt, and H. Sodemann. "Relating tropical ocean clouds to moist processes using water vapor isotope measurements." Atmospheric Chemistry and Physics 11, no. 2 (January 26, 2011): 741–52. http://dx.doi.org/10.5194/acp-11-741-2011.
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Abstract. We examine the co-variations of tropospheric water vapor, its isotopic composition and cloud types and relate these distributions to tropospheric mixing and distillation models using satellite observations from the Aura Tropospheric Emission Spectrometer (TES) over the summertime tropical ocean. Interpretation of these process distributions must take into account the sensitivity of the TES isotope and water vapor measurements to variations in cloud, water, and temperature amount. Consequently, comparisons are made between cloud-types based on the International Satellite Cloud Climatology Project (ISSCP) classification; these are clear sky, non-precipitating (e.g., cumulus), boundary layer (e.g., stratocumulus), and precipitating clouds (e.g. regions of deep convection). In general, we find that the free tropospheric vapor over tropical oceans does not strictly follow a Rayleigh model in which air parcels become dry and isotopically depleted through condensation. Instead, mixing processes related to convection as well as subsidence, and re-evaporation of rainfall associated with organized deep convection all play significant roles in controlling the water vapor distribution. The relative role of these moisture processes are examined for different tropical oceanic regions.
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Fitzsimons, Sean, Sarah Mager, Russell Frew, Andrew Clifford, and Gary Wilson. "Formation of ice-shelf moraines by accretion of sea water and marine sediment at the southern margin of the McMurdo Ice Shelf, Antarctica." Annals of Glaciology 53, no. 60 (2012): 211–20. http://dx.doi.org/10.3189/2012aog60a155.
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AbstractA combination of ground-penetrating radar surveys, physical sedimentology and ice composition measurements has been used to characterize ice and sediment accreted to the southern margin of the McMurdo Ice Shelf, Antarctica. The radar data and surface observations show that the ice-shelf margin consists of strongly layered debris-rich ice that contains marine sediment and fossils. A modified Rayleigh-based distillation system has been used to model the isotopic fractionation from sea water to ice in a closed system. The model of ice formation is consistent with formation during almost complete freezing of a sea-water reservoir. By contrast, ice on the upstream side of the grounding line has formed during the early stages of freezing in which a small fraction of the sea-water reservoir has frozen. The model results and the presence of delicate, well-preserved marine fossils are interpreted as evidence of anchor ice formation on the seabed, and rafting of glaciomarine sediment into the bottom of the ice shelf. We argue that repeated accretion of sea water and marine sediment has produced a stacked sequence of ice and glaciomarine debris that forms shore-parallel ice-cored moraines.
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Kindler, P., M. Guillevic, M. Baumgartner, J. Schwander, A. Landais, and M. Leuenberger. "NGRIP temperature reconstruction from 10 to 120 kyr b2k." Climate of the Past Discussions 9, no. 4 (July 22, 2013): 4099–143. http://dx.doi.org/10.5194/cpd-9-4099-2013.
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Abstract. In order to reconstruct Greenland NGRIP temperature, measurements of δ15N from the beginning of the Holocene to Dansgaard–Oeschger (DO) event 8 have been performed. Together with previously measured and mostly published δ15N data, we are now able to present for the first time a NGRIP temperature reconstruction for the whole last glacial period (beginning of the Holocene back to 120 kyr) including every DO event based on δ15N isotope measurements using a firn densification and heat diffusion model. The detected temperature rises at DO events range from 5 °C (DO 25) up to 16.5 °C (DO 11), ± 3 °C. To bring measured and modelled data into agreement, we had to reduce the accumulation rate given by the ss09sea06bm time scale in some periods significantly, especially during the last glacial maximum (LGM). A comparison between reconstructed temperature and δ18Oice data confirms that the isotopic composition of the stadial was strongly influenced by seasonality. We continuously calculated α (δ18Oice to temperature sensitivity) on a 10 kyr running time window. α variations show an anticorrelation with obliquity, in agreement with a simple Rayleigh distillation model, and moreover seem to be influenced by Northern Hemisphere ice sheet volume.
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Risi, C., A. Landais, R. Winkler, and F. Vimeux. "Can we determine what controls the spatio-temporal distribution of d-excess and <sup>17</sup>O-excess in precipitation using the LMDZ general circulation model?" Climate of the Past 9, no. 5 (September 16, 2013): 2173–93. http://dx.doi.org/10.5194/cp-9-2173-2013.
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Abstract. Combined measurements of the H218O and HDO isotopic ratios in precipitation, leading to second-order parameter D-excess, have provided additional constraints on past climates compared to the H218O isotopic ratio alone. More recently, measurements of H217O have led to another second-order parameter: 17O-excess. Recent studies suggest that 17O-excess in polar ice may provide information on evaporative conditions at the moisture source. However, the processes controlling the spatio-temporal distribution of 17O-excess are still far from being fully understood. We use the isotopic general circulation model (GCM) LMDZ to better understand what controls d-excess and 17O-excess in precipitation at present-day (PD) and during the last glacial maximum (LGM). The simulation of D-excess and 17O-excess is evaluated against measurements in meteoric water, water vapor and polar ice cores. A set of sensitivity tests and diagnostics are used to quantify the relative effects of evaporative conditions (sea surface temperature and relative humidity), Rayleigh distillation, mixing between vapors from different origins, precipitation re-evaporation and supersaturation during condensation at low temperature. In LMDZ, simulations suggest that in the tropics convective processes and rain re-evaporation are important controls on precipitation D-excess and 17O-excess. In higher latitudes, the effect of distillation, mixing between vapors from different origins and supersaturation are the most important controls. For example, the lower d-excess and 17O-excess at LGM simulated at LGM are mainly due to the supersaturation effect. The effect of supersaturation is however very sensitive to a parameter whose tuning would require more measurements and laboratory experiments. Evaporative conditions had previously been suggested to be key controlling factors of d-excess and 17O-excess, but LMDZ underestimates their role. More generally, some shortcomings in the simulation of 17O-excess by LMDZ suggest that general circulation models are not yet the perfect tool to quantify with confidence all processes controlling 17O-excess.
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Risi, C., A. Landais, R. Winkler, and F. Vimeux. "What controls the spatio-temporal distribution of D-excess and <sup>17</sup>O-excess in precipitation? A general circulation model study." Climate of the Past Discussions 8, no. 6 (November 8, 2012): 5493–543. http://dx.doi.org/10.5194/cpd-8-5493-2012.
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Abstract. Combined measurements of the H218O and HDO isotopic ratios in precipitation, leading to second-order parameter D-excess, have provided additional constraints on past climates compared to the H218O isotopic ratio alone. More recently, measurements of H217O have led to another second-order parameter: 17O-excess. Recent studies suggest that 17O-excess in polar ice may provide information on evaporative conditions at the moisture source. However, the processes controlling the spatio-temporal distribution of 17O-excess are still far from being fully understood. We use the isotopic general circulation model LMDZ to better understand what controls D-excess and 17O-excess in precipitation at present-day (PD) and during the last glacial maximum (LGM). The simulation of D-excess and 17O-excess is evaluated against measurements in meteoric water, water vapor and polar ice cores. A set of sensitivity tests and diagnostics are used to quantify the relative effects of evaporative conditions (sea surface temperature and relative humidity), Rayleigh distillation, precipitation re-evaporation and supersaturation during condensation at low temperature. Simulations suggest that in the tropics convective processes and rain re-evaporation are important controls on D-excess and 17O-excess. In higher latitudes, the effect of distillation, transport and mixing balance the effect of supersaturation. Since these terms are very large and near cancellation, results for both PD and LGM are very sensitive to the supersaturation function. The lower D-excess and 17O-excess at LGM simulated at LGM are dominated by the supersaturation effect. Evaporative conditions had previously been suggested to be key controling factors of D-excess and 17O-excess. In LMDZ, evaporative conditions are key in explaining the PD latitudinal and seasonal distributions, but play little role for 17O-excess and for LGM variations. However, the LMDZ may underestimate this role. More generally, some shortcomings in the simulation of 17O-excess by LMDZ suggest that GCMs are not yet the perfect tool to quantify with confidence all processes controlling 17O-excess.
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Botsyun, Svetlana, Pierre Sepulchre, Camille Risi, and Yannick Donnadieu. "Impacts of Tibetan Plateau uplift on atmospheric dynamics and associated precipitation <i>δ</i><sup>18</sup>O." Climate of the Past 12, no. 6 (June 28, 2016): 1401–20. http://dx.doi.org/10.5194/cp-12-1401-2016.
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Abstract. Palaeoelevation reconstructions of mountain belts have become a focus of modern science since surface elevation provides crucial information for understanding both geodynamic mechanisms of Earth's interior and the influence of mountain growth on climate. Stable oxygen isotopes palaeoaltimetry is one of the most popular techniques nowadays, and relies on the difference between δ18O of palaeo-precipitation reconstructed using the natural archives, and modern measured values for the point of interest. Our goal is to understand where and how complex climatic changes linked with the growth of mountains affect δ18O in precipitation. For this purpose, we develop a theoretical expression for the precipitation composition based on the Rayleigh distillation and the isotope-equipped atmospheric general circulation model LMDZ-iso outputs. Experiments with reduced height over the Tibetan Plateau and the Himalayas have been designed. Our results show that the isotopic composition of precipitation is very sensitive to climate changes related to the growth of the Himalayas and Tibetan Plateau. Specifically our simulations suggest that only 40 % of sampled sites for palaeoaltimetry depict a full topographic signal, and that uplift-related changes in relative humidity (northern region) and precipitation amount (southern region) could explain absolute deviations of up to 2.5 ‰ of the isotopic signal, thereby creating biases in palaeoelevation reconstructions.
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Wen, Xue-Fa, Xuhui Lee, Xiao-Min Sun, Jian-Lin Wang, Ya-Kun Tang, Sheng-Gong Li, and Gui-Rui Yu. "Intercomparison of Four Commercial Analyzers for Water Vapor Isotope Measurement." Journal of Atmospheric and Oceanic Technology 29, no. 2 (February 1, 2012): 235–47. http://dx.doi.org/10.1175/jtech-d-10-05037.1.
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Abstract The δ18O and δD of atmospheric water vapor are important tracers in hydrological and ecological studies. Isotope ratio infrared spectroscopy (IRIS) provides an in situ technology for measuring δ18O and δD in ambient conditions. An intercomparison experiment was carried out with four commercial IRIS analyzers to characterize their performance and transferability of calibration methods. Over a 15-day atmospheric measurement, during which the water vapor concentration ranged from 14 to 27 mol mol−1 and the isotopic ratios spanned about 90‰ and 13‰ for δD and δ18O, respectively, these analyzers tracked the natural variability in ambient conditions very well and achieved an average difference between one another within 2‰ for δD and within 0.1‰ for δ18O after calibration at appropriate frequencies. Two of the calibration methods (discrete liquid water injection and continuous dripping) agreed with each other within the tolerance thresholds of 2‰ for δD and 0.1‰ for δ18O. The Rayleigh distillation technique appeared to be acceptable as a calibration standard for δD but not for δ18O. The δD measurements were less prone to concentration dependence errors than the δ18O measurements. The concentration dependence underscores the importance of using a calibration procedure at multiple mixing ratios to bracket the range of natural variability.
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Fripiat, F., A. J. Cavagna, F. Dehairs, A. de Brauwere, L. André, and D. Cardinal. "Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography." Biogeosciences 9, no. 7 (July 6, 2012): 2443–57. http://dx.doi.org/10.5194/bg-9-2443-2012.
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Abstract. Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition (δ30Si) of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (Bonus-GoodHope) which includes for the first time summer δ30Si signatures of suspended biogenic silica (i) for the whole water column at three stations and (ii) in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation) should satisfactorily describe the δ30Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ30Si. The failures of previous models (Rayleigh and steady state) become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1) a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2) a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large vertical silicic acid gradient, e.g. in the Polar Front Zone and at the Polar Front.
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Kindler, P., M. Guillevic, M. Baumgartner, J. Schwander, A. Landais, and M. Leuenberger. "Temperature reconstruction from 10 to 120 kyr b2k from the NGRIP ice core." Climate of the Past 10, no. 2 (April 30, 2014): 887–902. http://dx.doi.org/10.5194/cp-10-887-2014.
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Abstract. In order to reconstruct the temperature of the North Greenland Ice Core Project (NGRIP) site, new measurements of δ15N have been performed covering the time period from the beginning of the Holocene to Dansgaard–Oeschger (DO) event 8. Together with previously measured and mostly published δ15N data, we present for the first time a NGRIP temperature reconstruction for the whole last glacial period from 10 to 120 kyr b2k (thousand years before 2000 AD) including every DO event based on δ15N isotope measurements combined with a firn densification and heat diffusion model. The detected temperature rises at the onset of DO events range from 5 °C (DO 25) up to 16.5 °C (DO 11) with an uncertainty of ±3 °C. To bring measured and modelled data into agreement, we had to reduce the accumulation rate given by the NGRIP ss09sea06bm timescale in some periods by 30 to 35%, especially during the last glacial maximum. A comparison between reconstructed temperature and δ18Oice data confirms that the isotopic composition of the stadial was strongly influenced by seasonality. We evidence an anticorrelation between the variations of the δ18Oice sensitivity to temperature (referred to as α) and obliquity in agreement with a simple Rayleigh distillation model. Finally, we suggest that α might be influenced by the Northern Hemisphere ice sheet volume.
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Hercman, Helena, Michał Gąsiorowski, Jacek Pawlak, Marcin Błaszczyk, Michał Gradziński, Šárka Matoušková, Paweł Zawidzki, and Pavel Bella. "Atmospheric circulation and the differentiation of precipitation sources during the Holocene inferred from five stalagmite records from Demänová Cave System (Central Europe)." Holocene 30, no. 6 (February 12, 2020): 834–46. http://dx.doi.org/10.1177/0959683620902224.
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Five stalagmites from the Demänová Cave System (DCS, Western Carpathians, Slovakia), spanning the period from 13,000 to 500 a BP, were analyzed for their oxygen and carbon stable isotopic composition of the calcite. The isotopic data obtained from several stalagmites located in one cave system allow us to separate the changes of regional/global importance from the local changes. Oxygen isotope ratios point to dynamic changes in the environment at the onset of the Holocene. Despite the local differences, carbon isotope data express the gradual and steady development of vegetation on the surface above the cave from the beginning of the Holocene until 6,000 a BP. The oxygen isotope values in the DCS stalagmites are higher than that derived from the Rayleigh distillation model until approximately 9,000 a BP, suggesting (1) an increase in the isotopic gradient to the east of Europe, probably caused by a different seasonality in precipitation amount or (2) different sources of meteoric water, transported from the Mediterranean and Black Sea region, in Central and Eastern Europe compared to the Western, circum-Atlantic part of the continent. The younger part of the DCS records falls in the range described by the model and points to the increasing role of the westerlies in the determination of the climatic conditions of Central Europe during middle- and late-Holocene.
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Guo, Jing-Liang, Zaicong Wang, Wen Zhang, Frédéric Moynier, Dandan Cui, Zhaochu Hu, and Mihai N. Ducea. "Significant Zr isotope variations in single zircon grains recording magma evolution history." Proceedings of the National Academy of Sciences 117, no. 35 (August 18, 2020): 21125–31. http://dx.doi.org/10.1073/pnas.2002053117.
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Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ94Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon–melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation.
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Wynn, Jonathan G., Michael I. Bird, and Vanessa N. L. Wong. "Rayleigh distillation and the depth profile of 13C/12C ratios of soil organic carbon from soils of disparate texture in Iron Range National Park, Far North Queensland, Australia." Geochimica et Cosmochimica Acta 69, no. 8 (April 2005): 1961–73. http://dx.doi.org/10.1016/j.gca.2004.09.003.
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Scheepmaker, R. A., C. Frankenberg, A. Galli, A. Butz, H. Schrijver, N. M. Deutscher, D. Wunch, T. Warneke, S. Fally, and I. Aben. "Improved water vapour spectroscopy in the 4174–4300 cm<sup>−1</sup> region and its impact on SCIAMACHY HDO/H<sub>2</sub>O measurements." Atmospheric Measurement Techniques 6, no. 4 (April 8, 2013): 879–94. http://dx.doi.org/10.5194/amt-6-879-2013.
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Abstract. The relative abundance of the heavy water isotopologue HDO provides a deeper insight into the atmospheric hydrological cycle. The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) allows for global retrievals of the ratio HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range 4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O. We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra compared to HITRAN 2008 and Jenouvrier et al. (2007) spectroscopy, and the retrievals become more robust against changes in the retrieval window. For both the FTS and SCIAMACHY measurements, the retrieved total H2O columns decrease by 2–4% and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio.
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Scheepmaker, R. A., C. Frankenberg, A. Galli, A. Butz, H. Schrijver, N. M. Deutscher, D. Wunch, T. Warneke, S. Fally, and I. Aben. "Improved water vapour spectroscopy in the 4174–4300 cm<sup>−1</sup> region and its impact on SCIAMACHY HDO/H<sub>2</sub>O measurements." Atmospheric Measurement Techniques Discussions 5, no. 6 (November 29, 2012): 8539–78. http://dx.doi.org/10.5194/amtd-5-8539-2012.
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Abstract. The relative abundance of the heavy water isotopologue HDO provides a deeper insight in the atmospheric hydrological cycle. The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) allows global retrievals of the ratio HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range 4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O. We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra compared to HITRAN 2008 and Jenouvrier et al. (2007) spectroscopy and the retrievals become more robust against changes in retrieval window. For both the FTS and SCIAMACHY measurements the retrieved total columns H2O decrease by 2–4 % and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio.
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Casado, Mathieu, Amaelle Landais, Ghislain Picard, Thomas Münch, Thomas Laepple, Barbara Stenni, Giuliano Dreossi, et al. "Archival processes of the water stable isotope signal in East Antarctic ice cores." Cryosphere 12, no. 5 (May 24, 2018): 1745–66. http://dx.doi.org/10.5194/tc-12-1745-2018.
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Abstract. The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation–condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.
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Casola, Valentin, Lydéric France, Albert Galy, Nordine Bouden, and Johan Villeneuve. "No evidence for carbon enrichment in the mantle source of carbonatites in eastern Africa." Geology 48, no. 10 (June 25, 2020): 971–75. http://dx.doi.org/10.1130/g47629.1.
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Abstract Carbonatites are unusual, carbon-rich magmas thought to form either by the melting of a carbon-rich mantle source or by low-degree partial melting of a carbon-poor (<80 ppm C) mantle followed by protracted differentiation and/or immiscibility. Carbonate-bearing mantle xenoliths from Oldoinyo Lengai (East African Rift), the only active volcano erupting carbonatites, have provided key support for a C-rich mantle source. Here, we report unique microscale O and C isotopic analyses of those carbonates, which are present as interstitial grains in the silicate host lava, veins in the xenoliths, and pseudo-inclusions in olivine xenoliths. The δ18O values vary little, from 19‰ to 29‰, whereas δ13C values are more variable, ranging from –23‰ to +0.5‰. We show that such carbonate δ18O values result from the low-temperature precipitation of carbonate in equilibrium with meteoric water, rather than under mantle conditions. In this framework, the observed δ13C values can be reproduced by Rayleigh distillation driven by carbonate precipitation and associated degassing. Together with petrological evidence of a physical connection between the three types of carbonates, our isotopic data support the pedogenic formation of carbonates in the studied xenoliths by soil-water percolation and protracted crystallization along xenolith cracks. Our results refute a mechanism of C enrichment in the form of mantle carbonates in the mantle beneath the Natron Lake magmatic province and instead support carbonatite formation by low-degree partial melting of a C-poor mantle and subsequent protracted differentiation of alkaline magmas.
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Noone, David. "Pairing Measurements of the Water Vapor Isotope Ratio with Humidity to Deduce Atmospheric Moistening and Dehydration in the Tropical Midtroposphere." Journal of Climate 25, no. 13 (July 1, 2012): 4476–94. http://dx.doi.org/10.1175/jcli-d-11-00582.1.
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Abstract Measurements of the isotope ratio of water vapor (expressed as the δ value) allow processes that control the humidity in the tropics to be identified. Isotopic information is useful because the change in δ relative to the water vapor mixing ratio (q) is different for different processes. The theoretical framework for interpreting paired q–δ data is established and based on a set of simple models that account for mixing and a range of condensation conditions. A general condensation model is derived that accounts for cloud precipitation efficiency and postcondensation exchange. Using data from the Tropospheric Emission Spectrometer (TES), aspects of subtropical hydrology are characterized by the match between theoretical curves and observed displacement in q–δ space. The subtropics are best described as the balance between drying associated with (mostly horizontal) transport of dry air from high latitudes and moistening by clouds with low precipitation efficiency. In the western Pacific moistening involves the import of air into which raindrops have evaporated and is identified by “super-Rayleigh” isotopic distillation. In the dry subtropics, the observations are consistent with the condensation–advection explanation for the humidity minimum but also reflect details of the cloud processes and moistening by high humidity filaments of tropical origin. In spite of limitations of the TES data, the success of the analysis highlights the value of using isotopic data in analysis of tropospheric moisture budgets and the role water isotopic ratio measurements can play in identifying mechanisms associated with large-scale changes in atmospheric humidity.
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Weng, Yongbiao, Aina Johannessen, and Harald Sodemann. "High-resolution stable isotope signature of a land-falling atmospheric river in southern Norway." Weather and Climate Dynamics 2, no. 3 (August 5, 2021): 713–37. http://dx.doi.org/10.5194/wcd-2-713-2021.
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Abstract. Heavy precipitation at the west coast of Norway is often connected to elongated meridional structures of high integrated water vapour transport known as atmospheric rivers (ARs). Here we present high-resolution measurements of stable isotopes in near-surface water vapour and precipitation during a land-falling AR in southwestern Norway on 7 December 2016. In our analysis, we aim to identify the influences of moisture source conditions, weather system characteristics, and post-condensation processes on the isotope signal in near-surface water vapour and precipitation. A total of 71 precipitation samples were collected during the 24 h sampling period, mostly taken at sampling intervals of 10–20 min. The isotope composition of near-surface vapour was continuously monitored in situ with a cavity ring-down spectrometer. Local meteorological conditions were in addition observed from a vertical pointing rain radar, a laser disdrometer, and automatic weather stations. We observe a stretched, “W”-shaped evolution of isotope composition during the event. Combining paired precipitation and vapour isotopes with meteorological observations, we define four different stages of the event. The two most depleted periods in the isotope δ values are associated with frontal transitions, namely a combination of two warm fronts that follow each other within a few hours and an upper-level cold front. The d-excess shows a single maximum and a step-wise decline in precipitation and a gradual decrease in near-surface vapour. Thereby, the isotopic evolution of the near-surface vapour closely follows that of the precipitation with a time delay of about 30 min, except for the first stage of the event. Analysis using an isotopic below-cloud exchange framework shows that the initial period of low and even negative d-excess in precipitation was caused by evaporation below cloud base. The isotope signal from the cloud level became apparent at ground level after a transition period that lasted up to several hours. Moisture source diagnostics for the periods when the cloud signal dominates show that the moisture source conditions are then partly reflected in surface precipitation and water vapour isotopes. In our study, the isotope signal in surface precipitation during the AR event reflects the combined influence of atmospheric dynamics, moisture sources, and atmospheric distillation, as well as cloud microphysics and below-cloud processes. Based on this finding, we recommend careful interpretation of results obtained from Rayleigh distillation models in such events, in particular for the interpretation of surface vapour and precipitation from stratiform clouds.
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Bonne, J. L., V. Masson-Delmotte, O. Cattani, M. Delmotte, C. Risi, H. Sodemann, and H. C. Steen-Larsen. "The isotopic composition of water vapour and precipitation in Ivittuut, Southern Greenland." Atmospheric Chemistry and Physics Discussions 13, no. 11 (November 21, 2013): 30521–74. http://dx.doi.org/10.5194/acpd-13-30521-2013.
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Abstract. Since September 2011, a Wavelength-Scanned Cavity Ringdown Spectroscopy analyzer has been remotely operated in Ivittuut, southern Greenland, providing the first continuous record of surface water vapour isotopic composition (δ18O, δD) in South Greenland and the first record including the winter season in Greenland. This record depicts small summer diurnal variations. Measurements of precipitation isotopic composition suggest equilibrium between surface vapour and precipitation. The vapour data show large synoptic and seasonal variations corresponding to shifts in moisture sources estimated using a quantitative moisture source diagnostic. The arrival of low pressure systems towards south Greenland leads to δ18O enrichment (+5‰) and deuterium excess depletion (−15‰), coupled with moisture sources shifts. Monthly δ18O is minimum in November–December and maximum in June–July, with a seasonal amplitude of ~10‰. The strong correlation between δ18O and the logarithm of local surface humidity is consistent with Rayleigh distillation processes. The relationship with local surface air temperature is associated with a slope of ~0.4‰ °C−1. During the summer 2012 heat waves, the observations display a divergence between δ18O and local climate variables, probably due to the isotopic depletion associated with long distance transport from subtropical moisture sources. Monthly deuterium excess is minimum in May–June and maximum in November, with a seasonal amplitude of 20‰. It is anti-correlated with δ18O, and correlated with local surface relative humidity (at the station) as well as surface relative humidity in a North Atlantic sector, south of Greenland and Iceland. While synoptic and seasonal variations are well represented by the Atmospheric General Circulation Model LMDZiso for Ivittuut δ18O, the model does not capture the magnitude of these variations for deuterium excess.
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Ghalambaz, Mohammad, S. A. M. Mehryan, Muneer A. Ismael, Ali Chamkha, and D. Wen. "Fluid–structure interaction of free convection in a square cavity divided by a flexible membrane and subjected to sinusoidal temperature heating." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 6 (June 6, 2019): 2883–911. http://dx.doi.org/10.1108/hff-12-2018-0826.
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Purpose The purpose of the present paper is to model a cavity, which is equally divided vertically by a thin, flexible membrane. The membranes are inevitable components of many engineering devices such as distillation systems and fuel cells. In the present study, a cavity which is equally divided vertically by a thin, flexible membrane is model using the fluid–structure interaction (FSI) associated with a moving grid approach. Design/methodology/approach The cavity is differentially heated by a sinusoidal time-varying temperature on the left vertical wall, while the right vertical wall is cooled isothermally. There is no thermal diffusion from the upper and lower boundaries. The finite-element Galerkin technique with the aid of an arbitrary Lagrangian–Eulerian procedure is followed in the numerical procedure. The governing equations are transformed into non-dimensional forms to generalize the solution. Findings The effects of four pertinent parameters are investigated, i.e., Rayleigh number (104 = Ra = 107), elasticity modulus (5 × 1012 = ET = 1016), Prandtl number (0.7 = Pr = 200) and temperature oscillation frequency (2p = f = 240p). The outcomes show that the temperature frequency does not induce a notable effect on the mean values of the Nusselt number and the deformation of the flexible membrane. The convective heat transfer and the stretching of the thin, flexible membrane become higher with a fluid of a higher Prandtl number or with a partition of a lower elasticity modulus. Originality/value The authors believe that the modeling of natural convection and heat transfer in a cavity with the deformable membrane and oscillating wall heating is a new subject and the results have not been published elsewhere.
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Bonne, J. L., V. Masson-Delmotte, O. Cattani, M. Delmotte, C. Risi, H. Sodemann, and H. C. Steen-Larsen. "The isotopic composition of water vapour and precipitation in Ivittuut, southern Greenland." Atmospheric Chemistry and Physics 14, no. 9 (May 7, 2014): 4419–39. http://dx.doi.org/10.5194/acp-14-4419-2014.
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Abstract. Since September 2011, a wavelength-scanned cavity ring-down spectroscopy analyser has been remotely operated in Ivittuut, southern Greenland, providing the first record of surface water vapour isotopic composition based on continuous measurements in South Greenland and the first record including the winter season in Greenland. The comparison of vapour data with measurements of precipitation isotopic composition suggest an equilibrium between surface vapour and precipitation. δ18O and deuterium excess are generally anti-correlated and show important seasonal variations, with respective amplitudes of ~10 and ~20‰, as well as large synoptic variations. The data depict small summer diurnal variations. At the seasonal scale, δ18O has a minimum in November–December and a maximum in June–July, while deuterium excess has a minimum in May–June and a maximum in November. The approach of low-pressure systems towards South Greenland leads to δ18O increase (typically +5‰) and deuterium excess decrease (typically −15‰). Seasonal and synoptic variations coincide with shifts in the moisture sources, estimated using a quantitative moisture source diagnostic based on a Lagrangian back-trajectory model. The atmospheric general circulation model LMDZiso correctly captures the seasonal and synoptic variability of δ18O, but does not capture the observed magnitude of deuterium excess variability. Covariations of water vapour isotopic composition with local and moisture source meteorological parameters have been evaluated. δ18O is strongly correlated with the logarithm of local surface humidity, consistent with Rayleigh distillation processes, and with local surface air temperature, associated with a slope of ~0.4‰ °C−1. Deuterium excess correlates with local surface relative humidity as well as surface relative humidity from the dominant moisture source area located in the North Atlantic, south of Greenland and Iceland.
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AL-Jawary, Majeed Ahmed, Ghassan Hasan Radhi, and Jure Ravnik. "Two efficient methods for solving Schlömilch’s integral equation." International Journal of Intelligent Computing and Cybernetics 10, no. 3 (August 14, 2017): 287–309. http://dx.doi.org/10.1108/ijicc-11-2016-0042.
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Purpose In this paper, the exact solutions of the Schlömilch’s integral equation and its linear and non-linear generalized formulas with application are solved by using two efficient iterative methods. The Schlömilch’s integral equations have many applications in atmospheric, terrestrial physics and ionospheric problems. They describe the density profile of electrons from the ionospheric for awry occurrence of the quasi-transverse approximations. The paper aims to discuss these issues. Design/methodology/approach First, the authors apply a regularization method combined with the standard homotopy analysis method to find the exact solutions for all forms of the Schlömilch’s integral equation. Second, the authors implement the regularization method with the variational iteration method for the same purpose. The effectiveness of the regularization-Homotopy method and the regularization-variational method is shown by using them for several illustrative examples, which have been solved by other authors using the so-called regularization-Adomian method. Findings The implementation of the two methods demonstrates the usefulness in finding exact solutions. Practical implications The authors have applied the developed methodology to the solution of the Rayleigh equation, which is an important equation in fluid dynamics and has a variety of applications in different fields of science and engineering. These include the analysis of batch distillation in chemistry, scattering of electromagnetic waves in physics, isotopic data in contaminant hydrogeology and others. Originality/value In this paper, two reliable methods have been implemented to solve several examples, where those examples represent the main types of the Schlömilch’s integral models. Each method has been accompanied with the use of the regularization method. This process constructs an efficient dealing to get the exact solutions of the linear and non-linear Schlömilch’s integral equation which is easy to implement. In addition to that, the accompanied regularization method with each of the two used methods proved its efficiency in handling many problems especially ill-posed problems, such as the Fredholm integral equation of the first kind.
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Kurita, Naoyuki, and Hiroyuki Yamada. "The Role of Local Moisture Recycling Evaluated Using Stable Isotope Data from over the Middle of the Tibetan Plateau during the Monsoon Season." Journal of Hydrometeorology 9, no. 4 (August 1, 2008): 760–75. http://dx.doi.org/10.1175/2007jhm945.1.
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Abstract Both meteorological data and stable isotope data were used to investigate the role that local moisture recycling plays in maintaining moist land surface conditions over the middle of the Tibetan Plateau during the summer monsoon season. Past studies have shown that precipitation events of the summer monsoon season can be categorized according to synoptic conditions as east-migrating trough types, heat low types, and regional circulation types. Precipitation events during an intensive observation period from 13 to 27 August 2004 were therefore classified into these three types. The contributions of locally recycled moisture in each precipitation type were investigated using isotopic features. The isotope data include precipitation, near-surface atmospheric moisture, and evapotranspiration. First, using a simple Rayleigh distillation model, the isotopic content of the moisture source of the rainfall was estimated from observed precipitation isotope data. The contribution of lower-atmospheric moisture to the precipitation was then evaluated by comparing isotopic values. Next, when rainfall was mainly fed by lower-atmosperic moisture, the contribution of evapotranspirated water in the lower atmosphere was assessed by considering the factors controlling the isotopic variability of lower-atmospheric moisture. The results show that, in the case of trough-type rainfall, moisture flux convergence occurred in this area and a remarkable increase in precipitable water was observed when a trough approached the site. Thus, observed large isotopic variation associated with the passage of a trough reflects the isotopic content of moisture advected from the surrounding areas. With the exception of trough-type rainfall, the simulated isotopic values agreed well with the isotopic value of lower-atmospheric moisture. This finding indicates that lower-atmospheric moisture is the dominant source of such rainfall. In these periods, temporal isotopic variation in lower-atmospheric moisture showed gradual increases accompanied by an increased contribution of evapotranspirated water that had relatively heavy isotopic values. In particular, when the regional circulation type of rainfall was observed, the local recycling ratio, which is the contribution of locally evapotranspirated water in the boundary layer, increased from 30% to 80%. Locally recycled moisture thus plays an important role in precipitation associated with regional circulation. Active moisture recycling contributes to a high frequency of precipitation events so that the moist land surface is maintained during the summer monsoon period in this region.
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Liu, Sean X., and Ming Peng. "The simulation of the simple batch distillation of multiple-component mixtures via Rayleigh's equation." Computer Applications in Engineering Education 15, no. 2 (2007): 198–204. http://dx.doi.org/10.1002/cae.20098.
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Cavazzini, Giancarlo. "Rayleigh's distillation law and linear hypothesis of isotope fractionation in thermal ionization mass spectrometry." International Journal of Mass Spectrometry 288, no. 1-3 (November 2009): 84–91. http://dx.doi.org/10.1016/j.ijms.2009.09.002.
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Dreybrodt, Wolfgang. "Problems in using the approach of Rayleigh distillation to interpret the 13C and 18O isotope compositions in stalagmite calcite." Acta Carsologica 45, no. 3 (December 21, 2016). http://dx.doi.org/10.3986/ac.v45i3.4698.
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Sabat, Pablo, Seth D. Newsome, Stephanie Pinochet, Roberto Nespolo, Juan Carlos Sanchez-Hernandez, Karin Maldonado, Alexander R. Gerson, Zachary D. Sharp, and John P. Whiteman. "Triple Oxygen Isotope Measurements (Δ'17O) of Body Water Reflect Water Intake, Metabolism, and δ18O of Ingested Water in Passerines." Frontiers in Physiology 12 (September 6, 2021). http://dx.doi.org/10.3389/fphys.2021.710026.
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Understanding physiological traits and ecological conditions that influence a species reliance on metabolic water is critical to creating accurate physiological models that can assess their ability to adapt to environmental perturbations (e.g., drought) that impact water availability. However, relatively few studies have examined variation in the sources of water animals use to maintain water balance, and even fewer have focused on the role of metabolic water. A key reason is methodological limitations. Here, we applied a new method that measures the triple oxygen isotopic composition of a single blood sample to estimate the contribution of metabolic water to the body water pool of three passerine species. This approach relies on Δ'17O, defined as the residual from the tight linear correlation that naturally exists between δ17O and δ18O values. Importantly, Δ'17O is relatively insensitive to key fractionation processes, such as Rayleigh distillation in the water cycle that have hindered previous isotope-based assessments of animal water balance. We evaluated the effects of changes in metabolic rate and water intake on Δ'17O values of captive rufous-collared sparrows (Zonotrichia capensis) and two invertivorous passerine species in the genus Cinclodes from the field. As predicted, colder acclimation temperatures induced increases in metabolic rate, decreases in water intake, and increases in the contribution of metabolic water to the body water pool of Z. capensis, causing a consistent change in Δ'17O. Measurement of Δ'17O also provides an estimate of the δ18O composition of ingested pre-formed (drinking/food) water. Estimated δ18O values of drinking/food water for captive Z. capensis were ~ −11‰, which is consistent with that of tap water in Santiago, Chile. In contrast, δ18O values of drinking/food water ingested by wild-caught Cinclodes were similar to that of seawater, which is consistent with their reliance on marine resources. Our results confirm the utility of this method for quantifying the relative contribution of metabolic versus pre-formed drinking/food water to the body water pool in birds.