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Title: Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1

Abstract

Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. Wemore » show that ILSS-simulated isotopic equilibrium is independent of the total water and energy budget (with respect to both equilibration time and state), but interestingly the partitioning of available energy and water is a function of the models' complexity.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - Collaboration with ANSTO,Institute for Nuclear Geophysiology; NASA Goddard Institte for SpaceSciences and Columbia University; University of Technology at Sydney,Australia; Universi
OSTI Identifier:
901054
Report Number(s):
LBNL-60932
Journal ID: ISSN 0921-8181; GPCHE4; TRN: US200711%%777
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Global and Planetary Change; Journal Volume: 51; Journal Issue: 1-2 (Special Issue); Related Information: Journal Publication Date: May 2006
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; CLIMATES; ECOSYSTEMS; ENERGY BALANCE; EVAPORATION; FORESTS; FRACTIONATION; QUALITY CONTROL; SIMULATION; TRANSFER FUNCTIONS; VALIDATION; WATER; WOOD

Citation Formats

Henderson-Sellers, A., Fischer, M., Aleinov, I., McGuffie, K., Riley, W.J., Schmidt, G.A., Sturm, K., Yoshimura, K., and Irannejad, P.. Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1. United States: N. p., 2005. Web.
Henderson-Sellers, A., Fischer, M., Aleinov, I., McGuffie, K., Riley, W.J., Schmidt, G.A., Sturm, K., Yoshimura, K., & Irannejad, P.. Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1. United States.
Henderson-Sellers, A., Fischer, M., Aleinov, I., McGuffie, K., Riley, W.J., Schmidt, G.A., Sturm, K., Yoshimura, K., and Irannejad, P.. Mon . "Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1". United States. doi:. https://www.osti.gov/servlets/purl/901054.
@article{osti_901054,
title = {Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1},
author = {Henderson-Sellers, A. and Fischer, M. and Aleinov, I. and McGuffie, K. and Riley, W.J. and Schmidt, G.A. and Sturm, K. and Yoshimura, K. and Irannejad, P.},
abstractNote = {Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. We show that ILSS-simulated isotopic equilibrium is independent of the total water and energy budget (with respect to both equilibration time and state), but interestingly the partitioning of available energy and water is a function of the models' complexity.},
doi = {},
journal = {Global and Planetary Change},
number = 1-2 (Special Issue),
volume = 51,
place = {United States},
year = {Mon Oct 31 00:00:00 EST 2005},
month = {Mon Oct 31 00:00:00 EST 2005}
}
  • Day-to-day and within-day (diel) variations in {delta}D and {delta}{sup 18}O of the body water of the land snail, Theba pisana, were studied at a site in the southern coastal plain of Israel. Three phases of variation, which relate to isotopic changes in atmospheric water vapor, were distinguished. The isotopic variations can be explained by isotopic equilibration with atmospheric water vapor and/or uptake of dew derived therefrom. During the winter, when the snails are active, there is only very minor enrichment in {sup 18}O relative to equilibrium with water vapor or dew, apparently as a result of metabolic activity. But thismore » enrichment becomes pronounced after long periods of inactivity. Within-day variation in body water isotopic composition is minor on non-rain days. Shell carbonate is enriched in {sup 18}O by ca. 1-2% relative to equilibrium with body water. In most regions, the isotopic composition of atmospheric water vapor (or dew) is a direct function of that of rain. Because the isotopic composition of snail body water is related to that of atmospheric water vapor and the isotopic composition of shell carbonate in turn is related to that of body water, land snail shell carbonate {sup 18}O should provide a reliable indication of rainfall {sup 18}O. However, local environmental conditions and the ecological properties of the snail species must be taken into account.« less
  • The system effect of tritium arises from the interaction of tritium in the gas phase with water on the surface of piping materials. It has been reported that the system effect can be quantified by applying the serial reactor model to the piping system and that adsorption and isotope exchange reactions play the main roles in the trapping of tritium. The isotope exchange reaction that occurs when the chemical form of tritium in the gas phase is in the molecular form, i.e., HT or T{sub 2}, has been named isotope exchange reaction 1, and that which occurs when tritium inmore » the gas phase is in water form, i.e., HTO or T{sub 2}O, has been named isotope exchange reaction 2.The rate of isotope exchange reaction 2 is experimentally quantified, and the rate is observed to be about one-third of the rate of adsorption. The trapping and release behavior of tritium from the piping surface due to isotope exchange reaction 2 is also discussed. It is certified that swamping of water vapor to process gas is effective to release tritium from the surface contaminated with tritium.« less
  • A modified soil-canopy-boundary layer model based on Ek and Mahrt is presented to simulate surface heat fluxes on a daily basis. The model is validated against independent published bare soil data from Agassiz, Canada, and observations taken over sparse and dense vegetation as part of the HAPEX-MOBILHY (Hydrological Atmospheric Pilot Experiment-Modelisation du Bain Hydrique) experiment. Simulated surface energy components are shown to be in close agreement with the observations, and the sensitivity of the parameterization is evaluated.