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Incorporating Stable Water Isotopes in the Community Land Model. Xinping Zhang 1 Guoyue Niu 2 Zongliang Yang 2 1 College of Resources and Environmental Sciences Hunan Normal University, Changsha, China 2 Department of Geological Sciences, the University of Texas at Austin, Texas, USA.
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Xinping Zhang 1 Guoyue Niu 2 Zongliang Yang 2
1 College of Resources and Environmental Sciences Hunan Normal University, Changsha, China
2 Department of Geological Sciences, the University of Texas at Austin, Texas, USA
☞ Determination of the atmospheric circulation patterns
and global or local water cycle mechanisms
☞ Recovery of paleoclimatic records
in mid-high latitudes: the index as temperature
in monsoon regions: the index as strength of monsoon or
☞ Investigations for water or vapor resources inventory
iPILPS is a new type of PILPS experiment in which the process of international intercomparison will inform, illuminate and educate the land-surface scheme (LSS) parameterization community while new aspects of LSS are being developed.
1. identify and test ILSSs (isotopically enabled land-surface schemes) which incorporate SWIs (stable water isotope)
2. appraise SWI data applicable to hydro-climatic and water resource aspects of ILSSs;
3. identify observational data gaps required for evaluating ILSSs;
4. apply SWI data to specific predictions of well-understood locations simulated by available ILSSs.
On the monthly time scale:
water mass balance: Prj－Evapj－Roj－ΔSj=0
isotope mass balance:
δPrj monthly isotopic δ value of precipitation Prj
δEvapj monthly isotopic δ value of evaporation Evapj
δRoj monthly isotopic δ value of surface plus subsurface runoff Roj
δΔSj monthly isotopic δ value of the change in the total storage water Evapj
1. Rayleigh evaporation fractionation equation:
Rl: stable isotopic ratio in water;
f: residual proportion of evaporating water body
α: α=Rl/Rv（＞1) stable isotopic fractionation factor between liquid and vapor.
α= α(T) on the equilibrium fractionation
α = αk(T, h, V, D) on the kinetic fractionation
Rv: stable isotopic ratio in vapor;
f: residual proportion of condensing vapor
3.1 Seasonal variations of daily-averaged 18O and precipitation
on month time scale at Manaus
The diurnal variation of 18O in canopy dew, canopy reservoir and canopy evaporation for January (a) and July (b) at Manaus
The diurnal variation of 18O in surface dew and surface runoff for January (a) and July (b) at Manaus
Comparisons between actual and simulated MWLs in precipitation
scheme 1:fpi = 1. - exp(-0.5*(clm%elai + clm%esai))
scheme 2:fpi = min(0.1,1. - exp(-0.5*(clm%elai + clm%esai)))
scheme 3:fpi = min(0.2,1. - exp(-0.5*(clm%elai + clm%esai)))
1. Simulations show reasonable features in the seasonal and diurnal variations of δ18O in canopy and surface reservoirs;
2. Owing to originating mainly from atmospheric precipitation, the stable water isotopes in these reservoirs change as the stable isotopes in precipitation;
3. On the diurnally time scale, the stable isotopes in precipitation display the typical isotopic signature in evergreen tropical forest: the heavy rains are usually depleted in stable isotopes, but the light ones are usually enriched;
4. On the monthly time scale, δ18O in reservoirs have distinct seasonal variation with two peaks. The feature called as amount effect is consistent with the actual survey at Manaus, from 1965 to 1990, set up by IAEA/WMO;
5. Different hydrological process cause very different isotopic responses.
End of Presentation