Water Isotopes and Hydrology

1
Water Isotopes and Hydrology
Advanced Hydrology on 30 June, 2005

• by
• Kei YOSHIMURA (?? ?)

H
18O
H
H
16O
H
16O
D
H
2
In Nature, June 2004.
740,000-year record of the planets climate in
the deep ice core of European Project for Ice
Coring in Antarctica (EPICA). The isotopic
signals can tell how the climate has been
changing.
From EPICA, Nature, 2004
3
Objective of this lecture
Agekyr BP

• In what reason(s), isotopes can be indicator(s)
  of climate?
• How isotopes have been used in hydrology ?
• What is a latest use of water isotopes ? And how
  is it applicable ?

200
400
600
800
From EPICA, Nature, 2004
4
Outline

1. Introduction (done)
2. What are stable water isotopes?
3. Applications
4. Global and long-term scales
5. Global/Regional and short-term scales
6. Summary

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Stable Isotopes
Isotopes
Stable Isotopes (SI)
Radio(active) Isotopes (RI)
Deuterium(D)
e
2H13C15N18O
3H14C235U
??
P
N
Environmental IsotopesSafety Isotopes
More Neutron
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Terminology for isotopes

• d-value
• For standard, SMOW (standard Mean Ocean Water) is
  used.

Samples isotope existence ratio
Due to small difference, units per thousand ()
is commonly used.
International standard waters isotope existence
ratio is used.
SMOW
fewer isotopes
more isotopes
0

-
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Existence of Isotopes
Element SI Existence () Weighted ()
Hydrogen 1H 99.9851 99.9702
2H(D) 0.0149 0.0298
Oxygen 16O 99.763 99.736
17O 0.037 0.040
18O 0.200 0.225
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Stable Water Isotopes
O 16O, 17O, 18OH 1H, 2H(D), 3H(T)
D
H218O
H
18O
18O
H
H
0.20
H
lt
16O
H
HDO
D
H2O
16O
18O
D
0.015
D
H
Water Isotopes
(Heavy Water)
(Light Water)

• Although their amounts are very small, they exist
  in all water body due to their stability.

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Qualitatively the same,Quantitatively different.
Property H216O D216O H218O
Density(20C, g/cm3) 0.997 1.1051 1.1106
Temp. of greatest density (C) 3.98 11.24 4.30
Melting Point 0.00 3.81 0.28
Boiling Point 100.00 101.42 100.14
Viscosity 1.002 1.247 1.056
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The Largest Difference FRACTIONATION
Vapor
Lower existence ratio Rvap
evaporation
Moreexistence ratio Rliq
Liquid
a Fractionation factorIn above case, alt1
Q What if vapor?liquid?
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What cause fractionation?

• Mainly, difference of intermolecular force
  (hydrogen bond).
• H-18O gt D-16O gt H-16O
• So, More energy to vaporize H218O or HDO.

gt
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Fractionation FactorsMerely function of temp.
For dD
If only by temp.
?10 diff.?
0C
10C
-101.1
-89.1
0
But, in Ice core
?Up to 60?
Vostok Ice, Nature, 1999
Is it because of gt50C diff. in temp??No Way!
Hoefs, 1997
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Sampling Measurement
Equilibrium Equipment
Mass Spectrometer
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Mass Spectrometry
Heavy Ion
Detector
Light Ion
Magnetic Field
Ion source
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Applications for Hydrology

• Global and Long-term Scales
• Global/Regional and Short-term Scales

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Global and Long-term ScalesStudy on Climate
Change

• In what reason, stable water isotopes can be
  indicators of climate?
• Why isotopic fluctuations are far larger than
  theoretical values?

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Greenland Ice Core
For d18O
yr BP
? gt 5 ?
Corresponds to gt50C diff.
18
GCM1 simulation on LGM2
1.General Circulation Model 2.Last Glacial Maximum
For d18O
Hoffmann et al., 2000
Isotopic differences are amplified only in
Antarctica/Greenland

• ? Importance of global hydrology on different
  climate.

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Global/Regional and Short-term Scales

• Study on Hydrologic Mechanism
• How isotopes have been used in hydrology ?

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What water isotopes tell us for hydrology is
Iso.var.
iso.var.
To verify estimation of unknown process by
adding isotopic information of start and
end. Isotopes can add one (or 2) more
simultaneous equations to hydrological eqs.
iso.var.
Known
River flow
Unknown
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Governing PhenomenaFractionation in Time series
d-value / R-value
heavier
Rayleigh Equation
Liquid
Vapor
Q What about in case of vapor?liquid?
evap. process /f remaining ratio
1
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Applications of water isotopes on hydrology

• Evaporation estimation
• Runoff separation
• Atmospheric Hydrologic Cycle
• Classical interpretation of isotopes in
  precipitation
• Up-to-date application of isotopes in
  precipitation

Classical Application
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Evaporation Estimation

• Basic Idea

Hydrologic Eq. PEGIsotopic Eq.
PdpEdeGdg
Unknown
P
dp
E
de
dl (lake water)
G
dg
Unknown
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Runoff Separation
Precip.
River Water
New Water
Old Water
Precip.rate
Discharge
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Atmospheric Hydrologic Cycle

• Precipitation knows where it originated.

Global Network of Isotopes in Precipitation
(GNIP) by IAEA
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d-diagram Meteoric Water Line
Relationship of dD and d18O of various waters
Rain in ThailandMostly good fit ondD
8xd18O10(Meteoric Water Line MWL)
d18O ()
origin SMOW (standard mean ocean water)
dD ()
Water in Antarctica
H-axis d18O (), relative value to SMOWs H218O
V-axis dD (), relative value to SMOWs HDO
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Isotope Hydrological Cycle
Craig and Gordon (1965)
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Latitude-Altitude Effect
Good regression between annual precip isotopes,
latitude, and altitude. Bowen and Wilkinson, 2002
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Weakness of the Classical Interpretation

• Qualitative explanation.
• Only applicable to gtmonthly average.

Precip. Isotope Daily variation in Thailand
(1998)
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New application on Atmospheric Hydrology

• Challenge by GCMs (General Circulation Models)
• As passive tracers, water isotopes are
  incorporated into some GCMs
• More than monthly averages are good fit with
  observations.
• Could not reproduce daily time scales.

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Isotope Circulation Model (ICM) published in
Yoshimura et al. (JGR,2003)

• Realistic hydrological fields are imported.
• Vertical in-cloud micro processes are integrated
  by Rayleigh equation.

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Well-reproduced daily d18O
Cor. RMSE
ChiSukBan 0.800.770.60 2.9 2.8 2.8
Cor. RMSE
ChiSukBan 0.760.740.56 4.2 4.1 3.5
GAMEGPCP
GAMEonly
Yoshimura et al., 2003, JGR
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Global Distribution of d18O is reproduced, too.
Corr.coef. b/w monthly obsdestd prcp iso.
for 1979-93. (blue is good)
Int-ann. variations of prcp iso.
Yoshimura et al., 2004, JGR
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There are other Isotope Models
Coupled simulations GPC (2005) subm.
Atmospheric Isotope Circulation Model(AICM)JGR
(2003)
Water Surface SchemeCG (1965), MJ (1979)
Isotope Land Surface Model(Iso-MATSIRO)GPC
(2005), subm.
Isotope River Routing Scheme(Iso-TRIP)??????
(2004)
Colored Moisture Analysis (CMA)JMSJ (2004)
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Land SurfaceIso-MATSIRO

• Each of water-related variables has its isotopic
  concentration.
• Water Mass and Isotopic Mass are always balanced.
• Kinetic fractionations of
• Soil evap./subl.
• Intercepted water evap./subl.
• Transpiration
• Snow sublimation
• are taken into account.
• No soil diffusion

dEt
dEc
dSs
dEb
Rs
dR
Rb
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Water Surface Kinetic Fractionation

• Assume thin equilibrium layer and lift up by
  molecular diffusion.

Evaporation flux
Rair, qair h01
Isotopic flux
V
Diffusion
Isotopic ratio of evaporation flux
Equilibrium
Req, qeqh1
Ro
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River Flow Iso-TRIP
dsr1
dsr2
dsr3
O2
O1
O3
SR
dsr
Original TRIPOki and Sud (1998)
R
v
dr
O
Observations
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If atmospheric hydrology is validated by
precipitation isotopesOrigin of Rain are also
validated.
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Colored Moisture Analysis
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12 regions simulation
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80 regions simulation- focused on Asian Monsoon
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Focused on Indian Ocean
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Recycling Ratio

• Contribution of land evaporated water to
  precipitation.

Yoshimura et al.,2004, JMSJ
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Chiangmai, Apr.-Oct. 1998
Contents of each origin in water vapor
(precipitable water)
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Bangkok, Apr.-Oct. 1998
Contents of each origin in water vapor
(precipitable water)
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The Objective were

• In what reason(s), isotopes can be indicator(s)
  of climate?
• How isotopes have been used in hydrology ?
• What is a latest use of isotopes ? And how is it
  applicable ?

Have you got any idea ??
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Reference

• Textbook in English
• C. Kendall and J. McDonnell (Eds.), Isotope
  Tracers in Catchment Hydrology, Elsevier, 1998.
• I. Clark and P. Fritz, Environmental Isotopes in
  Hydrogeology, Lewis, 1997.
• J. Hoefs, Stable Isotope Geochemistry, Springer,
  4th Ed., 1997.
• Research paper in English
• K. Yoshimura et al., JGR, 2003.
• ??????
• ???,????,?????????,???????,?2?,1998.
• ?????,?????-????????????????,1996.
• ???????
• ????,???????????-????????-,???????,1986.
• ????,?????????????????????,???????,1993.

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Thank you for your attention
Any question or comment?? If you cannot ask now,
please contact me by email,kei_at_iis.u-tokyo.ac.jp
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Longer simulation period NCEP
Monthly result of a 17-year simulation
(1979-1995) in Bangkok
Observation
Simulation
R0.68,RMSE6 However, discrepancy of
consistent over-depletion
Monthly anomaly
Monthly anomaly R0.61 ?reproduce interannual
variability
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Precipitation Recycling

• Definition Precipitation returns back to
  atmosphere by evaporating from land

Precipitation
Evaporation
Recycle!
Evaporation
Recycle!
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Rain differences

• In Chiangmai, more water from lands and less
  water from Indian Ocean.
• Seasonality is very similar.

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Global monthly validation
ERA-15 simulation reproduced precipitation
isotope better in Europe!!
No Cor.
Sig. Cor.
Bad
Good
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Inter-annual Validation
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Inter-annual Validation (cont.)
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Latitude Effect
Cloud
Lighter Vapor
Light

Cloud
Rain
dDd18O
Rain
Rain
Evap.
Heavier Rain Drop
Latitude
Sea
0
Heavy
Equator
Temperate
Pole
Altitude Effect
Altitude
Cloud
Light
High
Cloud
Heavy
Low
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Other Effects

• Amount Effect
• Continental Effect
• Temperature Effect
• etc.Overall, the basic idea behind them is all
  same, the Rayleigh equation.

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Why Could Not?
According to them, SV occurs in local
scale. Therefore, present GCMs cannot reproduce
it because of their rough spatial resolutions.
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New findings are

• Almost all effects (latitude, amount, continent,
  etc.) are really appeared as aggregation of one
  single isotopic physical process, fractionation.
• However, hydrological situations of each event at
  any place are all different. It causes large
  variability of precip.isotopes.
• These different hydrological situations can be
  described with reliable met. field datasets.
• Their accuracy can be validated with
  precipitation isotopes.

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Reproducing Precip. Isotopes

• Atmospheric circulation are validated with
  inverse theory.
• Moisture origins can be estimated by the same
  scheme.

Iso.var.
Inversely Validated
iso.var.
ReproduceObs.
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The results.
Obs.
New Estimates
Old Estimates (Pink too)
Systematic Discrepancy Dissolved!!
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d18O Distribution, Apr-Oct, 98
Surface Soil Water
Total Runoff
Precipitation
Total Evaporation
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Basic Performance1. Ener./Water/Iso. Ann.Budget
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Basic Performance2. Seasonality (Tumbarumba)
Precipitation
Soil moist. contentsof each soil layer
1st layer
3rd 4th 5th
2nd layer
d18O in soil moist.
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Basic Performance3. Diurnal variations in Transp.
Tumbarumba
Each line shows different season
d18O in leaf water(dashed in stem)
d18O in T-Flux
Transp. Flux (W/m2)
Manaus
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Basic Performance4. d-Diagram at Munich
MWL
Leaf Water
Cnp. reserv.
Runoff
Soil Water (surf.)
Transp
ET
Precip.
Soil Evap.
Cnp. Evap.
Vapor
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Isotopically Atm.-Surf. Coupled Global Simulation
Calculation flow for Each Time step
ERA15
Upper Meteor.Qu, Qv, W, P, E
Surface Meteor.U, V, q, T, p, P
ICM
Iso-MAT
Isotopes in vapor/precip.
Isotopes in Evap.