water vapor isotope measurements above the greenland ice ... · water vapor isotope measurements...
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Water vapor isotope measurements above the Greenland Ice Sheet and importance for interpretation of surface-atmosphere interactions
H. C. Steen-Larsen1 , V. Masson-Delmotte1, E. Brun2,
R. Winkler1, F. Prie1, A. Landais1, C. Risi3, B. Stenni4
1 Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS/IPSL Gif-Sur-Yvette2 Meteo-France/CNRM, Toulouse3 Laboratoire Meteorolgie Dynamic, Paris4 Department of Mathematics and Geosciences, University of Trieste
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Water vapor isotope measurements above the Greenland Ice Sheet and importance for interpretation of surface-atmosphere interactions
H. C. Steen-Larsen1 , V. Masson-Delmotte1, E. Brun2,
R. Winkler1, F. Prie1, A. Landais1, C. Risi3, B. Stenni4
- Introduction to stable water isotopes
1 Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS/IPSL Gif-Sur-Yvette2 Meteo-France/CNRM, Toulouse3 Laboratoire Meteorolgie Dynamic, Paris4 Department of Mathematics and Geosciences, University of Trieste
- Introduction to stable water isotopes
- The diurnal water vapor cycle above the
Greenland Ice Sheet
- Tracing Arctic moisture using isotopes
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Isotope hydrology
Isotopologues are molecules with an isotope exchanged in
Nomenclature:
1H
16O
1H 2H
16O
1H 1H
18O
1H
Regular water Heavy water Even heavier water
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FRACTIONATION is temperature-dependent-Larger at low temperature
Water Vapor Liquid Water
Hot
Heavy
Regular
Cold
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Setup of the NEEM isotopic surface
campaign 2009 - 2012
Subsurface temperature
Measurements 0-150cm
With 10 mK resolution
Precipitation samples
Collected as often as
possible
Air temperatures
1, 3, 7, 10, 13 m
above snow surface
d18O and dD of vapor
Continuously from
1, 3, 7, 10, 13 m
above snow surface
Surface snow
samples every
12 hours
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Water vapor isotopes on top of the
Greenland Ice Sheet
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Water vapor isotopes on top of the
Greenland Ice Sheet
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Vertical diurnal structure of the
atmospheric water vapor close to the
surfaceHourly time slices of diurnal cycle
~2h
local~6h ~10h
local~6h
local
~10h
local
~14h
local
~18h
local
~22h
local
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The structure of the isotopic profile
with height
-290-12
-10
-8
-6
empe
ratu
re [º
C]
Humidity at ~1 meter Humidity at ~13 meter δD at ~1 meter δD at ~13 meter Temperature at ~1meter
Free troposphere
and boundary
layer interaction
Snow-Air
interaction
4000
3500
3000
2500
2000
Hum
idity
[ppm
]
2015105Time [UTC]
-330
-320
-310
-300
δD [‰
]-16
-14
Te
Snow-pack fluxes
- Humidity and isotopes are linked
- Gradient with height in both humidity and isotopes
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Still work in progressModel output (Mass flux and snow
surface temperature) from
CROCUS
4000
3500
3000
2500
2000
Hum
idity
[pp
m]
2015105Time [UTC]
-330
-320
-310
-300
-290
δD [‰
]-16
-14
-12
-10
-8
-6
Tem
pera
ture
[ºC
]
Humidity at ~1 meter Humidity at ~13 meter δD at ~1 meter δD at ~13 meter Temperature at ~1meter
ERA-40 re-
analysis
CROCUS
Snow pack scheme
Boundary layer
model
Free Free
troposphere
isotopes
Interstitial fluxes
Snow-air fluxes
Validate against
observation
Snow surface Snow surface
isotopes
Compare with
atmospheric water
vapor isotopes
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δD =8•δ18O+10
αEqδD /αδ18O
Eq ~ 8
d − excess= δD −8•δ18O
Water vapor isotopes as means of
tracking origin of the vapor
Introducing the second order parameter:
Captures kinetic fractionation occurring when a humidity gradient is
present because of different molecular diffusivity of the isotopes.
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Introducing the second order parameter:
Captures kinetic fractionation occurring when a humidity gradient is
present because of different molecular diffusivity of the isotopes.
δD =8•δ18O+10
αEqδD /αδ18O
Eq ~ 8
d − excess= δD −8•δ18O
Water vapor isotopes as means of
tracking origin of the vapor
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Using back trajectories to find the
moisture source
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Using back trajectories to find the
moisture source
Sea Ice
Very dry air
Vapor with
excess
Vapor with
high d-excess
Strong
evaporation
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Comparing the observations with
isotope enabled GCM
50
40
30
20
10
Ob
serve
d d-exess [‰
]
20
16
12
MD
Z d
-exc
ess
40x10-3
20
0Frac
Arc
tic m
oist
ure
Bad agreement between
observed and modeled d-
excess
-320
-300
-280
-260
-240
-220
-200
LMD
Z d
D [
‰]
210200190180170160150140Day of 2010
4000
3000
2000
1000
0LM
DZ
Hum
idity
[PP
M]
-360
-320
-280
-240
Observe
d dD[‰
]
6000
4000
2000
0
Observerd H
umdity [P
PM]
8
LM
Good agreement between
observed and modeled
humidity.
OK agreement between
observed and modeled dD
isotopic composition
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Water vapor isotopic measurements above the Greenland Ice Sheet and importance for interpretation of surface-atmosphere interactions.
H. C. Steen-Larsen1 , V. Masson-Delmotte1, E. Brun2,
R. Winkler1, F. Prie1, A. Landais1,C. risi3, B. Stenni4
1 Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS/IPSL Gif-Sur-Yvette2 Meteo-France/CNRM, Toulouse3 Laboratoire Meteorolgie Dynamic, Paris4 Department of Mathematics and Geosciences, University of Trieste