SLIDE 1 1/16
Haruyasu Nagai Research Group for Environmental Science, Japan Atomic Energy Agency
System for Prediction of Environmental Emergency Dose Information Multi-model Package
Incorporation of Tritium Transport Processes into Incorporation of Tritium Transport Processes into Atmosphere Atmosphere-
soil-
vegetation Model: SOLVEG ~HTO transport from atmosphere to bare soil~ ~HTO transport from atmosphere to bare soil~
SLIDE 2
Land surface model SOLVEG2 Outline of Study
Objectives
Development of sophisticated land surface model
including radionuclide (Tritium) transport processes
Understand and predict behavior of radionuclide at land-surface
by numerical experiment
Model development
Step 1: Heat and water exchange processes Step 2: Canopy radiation and stomatal resistance SOLVEG Step 3: CO2 exchange processes
SOLVEG2
EMRAS-II: Radionuclide transport processes (THO)
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SLIDE 3
Land surface model SOLVEG2 Description of model
Function One-dimensional multi-layer sub-models for atmosphere, soil, and vegetation. Scheme for radiation transmission in the canopy and CO2 exchange processes. Diurnal variation and seasonal change. Atmospheric surface layer, root zone soil, and vegetation canopy. Structure Simulation of water, heat, and CO2 exchanges in the atmosphere-soil-vegetation system. Objectives Overview Overview Temperature Volumetric water content Specific humidity of soil air CO2 concentration Vegetation Down/upward solar radiation (direct and diffuse, visible and near-infrared) Down/upward long-wave radiation Horizontal wind components (u, v) Potential temperature Specific humidity Fog water CO2 concentration Turbulence kinetic energy, length scale Soil Leaf surface temperature Leaf surface liquid water Vertical liquid water flux in canopy Leaf CO2 concentration Radiation Atmosphere Variables Variables
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SLIDE 4 Diffusion Fog water Water vapor Phase change Latent heat Temperature Wind, Turbulence CO2 concentration Surface exchange: Momentum, Heat, Water, CO2 Rain CO2 assimilation, Transpiration Heat exchange, Evaporation/condensation Absorption, Emission Temperature, water Heat/water budget Drip Interception Photosynthesis Short wave Long wave Scattering Surface water Advection & Diffusion Surface budget: Heat, Water, CO2 Uptake: Water & CO2 Water vapor Liquid water Phase change Latent heat Temperature CO2 conc. Root/soil respiration
Soil Vegetation Atmosphere
Physical processes are calculated at each layer of vertical multi-layer model Bold: main var., Underlined: processes, Red: heat/rad., Blue: water, Green: CO2
Land surface model SOLVEG2 Physical processes
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SLIDE 5 Atmosphere
Diffusion:
Soil
Heat: Liquid water: Water vapor:
Vegetation
Heat budget: Leaf water: Water flux:
Radiation
Short wave: Downward and upward transfer (Next slide) Direct (visible + near-infrared) + Diffuse (visible + near-infrared) Long wave: Downward and upward transfer
φ
∂ ∂φ ∂ ∂ ∂ ∂φ F z K z t
z
+ = z T C E C C H z T K z t T
s s s w w s s b s T s
∂ ∂ ρ ρ ∂ ∂ ∂ ∂ ∂ ∂ − + = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + − =
b t w w w
E E z E t ∂ ∂ ρ ∂ η ∂ 1
[ ]
ρ ∂ ∂ η ∂ ∂ ∂ η η ∂
b s w a w s w ws
E z q f D z t q + = − ) ( ) (
p c c c
H lE H R + + =
d cap d d
P E E E dt dw − + − =
int
( )
col pr d r
E E P E a dz dP − + − =
int b b
lE H − =
f a
w e e q v u , , , , , , λ θ φ =
s d c
E E E + =
Transpiration Evaporation/ condensation Boundary condition Source term Net radiation
Land surface model SOLVEG2 Basic equations (1): heat, water, momentum
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SLIDE 6 Radiation scheme (coefficients based on Verstraete 1987, 1988)
Short: (direct) (diffuse) (visible) (near-IR) Long wave:
( )
,
↓ ↓
′ + ′ + =
d w w rd d
S A a aF dz dS
( ) [ ]
( )
, 1
↓ ↑ ↓ ↓
− ′ + − ′ + ′ + − =
d df rd s w sb rs s w w sf rs s
S f aF S A f aF S A a f aF dz dS
( ) [ ]
( )
. 1
↓ ↓ ↑ ↑
+ ′ + + ′ + ′ + − − =
d db rd s w sb rs s w w sf rs s
S f aF S A f aF S A a f aF dz dS
( )
[ ] ( ),
1
4 4 a l l c c sb sf rs
T L w k T L f L f aF dz dL σ σ ε − + − − − =
↓ ↑ ↓ ↓
( )
[ ] ( ).
1
4 4 a l l c c sb sf rs
T L w k T L f L f aF dz dL σ σ ε − − − − − − =
↑ ↓ ↑ ↑
Scattering Leaf projection cf.: Frd Scattering cf.: fdf (forward), fdb (backward) Depend on solar angle and leaf surface angle Forward scattering cf.: fsf Back scattering cf.: fsb └Depend on leaf surface angle┘ Leaf projection cf.: Frs Depend on leaf area density
Land surface model SOLVEG2 Basic equations (2): radiation
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SLIDE 7 Stomatal resistance (Jarvis scheme): BATS (Dickinson et al. 1993) rs,min ⇒ measured parameter fr, fs, fm, ft : Functions of PAR, soil water, humidity, temperature CO2 assimilation (An): Farquhar et al. (1980) wc, we, ws, Rd : Depend on PAR, leaf CO2 conc., temperature Stomatal resistance (rs): Collatz et al. (1991, 1992) m (constant), b (minimum conductance) ⇒ measured parameter cs CO2 partial pressure at leaf surface es/esat(Tv) Relative humidity at leaf surface pa Atmospheric pressure
( )
d s e c n
R w w w A − = , , min
( )
b p T e e c A m g r
a v sat s s n s s
+ = = 1
1 1 1 min , − − −
=
t m s r s s
f f f f r r
CO CO2
2
No CO No CO2
2
Land surface model SOLVEG2 Basic equations (3): CO2, stomata resistance 2 options
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SLIDE 8 Soil CO2 conservation: Simunek and Suarez (1993) Volume: Diffusion: Advection: ⇒ Treatment of CO2 in gas and aqueous phase together by Henry’s Law: cw = KHRTca ca CO2 conc. in soil air ηw Volumetric water content Et
*
Root uptake (transpiration) S CO2 source term (＝ soil: Ss ＋ root: Sr)
S RTc K E c E z z c D z c V t
a H t a E a E a E
+ − ∂ ∂ − ∂ ∂ ∂ ∂ = ∂ ∂
* *
( )
,
w H w ws E
RT K V η η η + − =
( )
,
w w H a w ws E
D RT K D D η η η + − = ,
* * * w H a E
RTE K E E + =
( ) ( ) ( ) ( ) ( )
t f c f T f f z f S S
s a s s w s s s s
η =
( ) ( ) ( ) ( ) ( )
t f c f T f f z f S S
r a r r w r r r r
η = Land surface model SOLVEG2 Basic equations (4): soil CO2
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SLIDE 9
2 0 0 4 0 0 6 0 0 9 7 1 2 7 1 5 7 1 8 7 2 1 7 2 4 7 2 7 7 3 0 7 J u l i a n d a y s (L S T ) LH ( W m
2 0 9 7 1 2 7 1 5 7 1 8 7 2 1 7 2 4 7 2 7 7 3 0 7 J u l i a n d a y s (L S T ) FC ( μm ol m
s
APR MAY JUN JUL AUG SEP OCT NOV Observation ○: daily mean ◇: daily max ＋: daily min Calculation ―: daily mean ―: daily max ―: daily min Upward positive
Latent heat (water vapor) flux CO2 flux Good performance for water and CO2 exchanges at grassland (AmeriFlux data) Diurnal variation and seasonal change are well reproduced. It can be applied for detailed simulation of 3H and 14C transport.
Land surface model SOLVEG2 Water and CO2 fluxes at grassland
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SLIDE 10 Land surface model SOLVEG2 Incorporation of HTO transport processes
Concept
Process based HTO transport model to simulate dynamic behavior
- f HTO in air-soil-plant system
Explicit calculation of HTO transport in a similar way as water and
vapor transport
Model development
Step 1: transport in the atmosphere and bare soil (no decay)
- In-soil transport by Yamazawa (2001) applied for BIOMASS
Theme 3-F (rise of HTO from contaminated groundwater)
- Atmospheric transport for HTO vapor (1-D diffusion eq.)
- Test calculation using met. data of AmeriFlux (previous slide)
Step 2: inclusion of plant uptake processes Step 3: OBT production and translocation
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SLIDE 11 external input: precipitation stomata Fog water Diffusion equation Precipitation Conservation equation
Water vapor in air Diffusion equation Ground surface water budget eq. Water vapor in soil Diffusion eq. Liquid water in soil Transport equation Leaf surface water Water budget eq. accretion accretion condensation evaporation interception drip evaporation/ condensation transpi- ration evaporation/ condensation evaporation/ condensation evaporation/ condensation drip run-off uptake by root
Land surface model SOLVEG2 Incorporation of HTO transport processes
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Water and vapor exchange processes Water and vapor exchange processes Step 1
HTO transport process Calculate HTO conc. for each variable of water
Step 2
New variable: Plant water Water budget eq.
(root uptake - transpiration)
Step 3
OBT formation and translocation
SLIDE 12 Soil HTO transport: Yamazawa (2001) applied for BIOMASS theme 3 Liquid phase: Gas phase: Surface B.C.: χw, χsa , χr HTO conc. in soil water (Bq/m3-water), soil air and air (Bq/m3-air) ηw, ηsw Volumetric soil water content and saturated value (m3/m3) ρw Density of soil water (kg/m3) Ew Vertical liquid water flux (kg/m2/s) DTw, Dta Effective diffusivities of HTO in water and HTO vapor in air (m2/s) fsa(ηw) Tortuosity for diffusion in soil air eb HTO conc. in soil air (Bq/m3-air) cE0, |ur| Bulk transfer coefficient for evaporation, wind speed (m/s)
b w Tw w w w w w
e z D z E z t − ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ∂ ∂ ∂ ∂ + ∂ ∂ − = ∂ ∂ χ χ ρ χ η 1 Land surface model SOLVEG2 In-soil HTO transport processes
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( )
[ ]
( )
b sa w sa Ta sa w ws
e z f D z t + ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ∂ ∂ ∂ ∂ = − ∂ ∂ χ η χ η η
+: evaporation
( ) ( )
r sa r E b z sa w sa Ta
c e z f D χ χ χ η − = + ∂ ∂ −
=
u
Atmosphere- land exchange
SLIDE 13
Land surface model SOLVEG2 Test calculation
13/16 [Calculation condition] Bare soil (7 layers: boundary depth = 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0 m) First 10 days of AmeriFlux data with hypothetical no rain condition
SLIDE 14
Land surface model SOLVEG2 Test calculation
14/16 [Case 1] Constant HTO concentration in air humidity (1Bq/l) No HTO in soil at the calculation start time
SLIDE 15
Land surface model SOLVEG2 Test calculation
15/16 [Case 2] Constant HTO concentration in air humidity (1Bq/l) during the first 24 hour No HTO in soil at the calculation start time
HTO exposure
SLIDE 16 Land surface model SOLVEG2 Summary
Incorporation of HTO transport into SOLVEG
Process based HTO transport model to simulate dynamic behavior
- f HTO in air-soil-plant system
Explicit calculation of HTO transport in a similar way as water and
vapor transport
Coding for transport in the atmosphere and bare soil (no decay) Test calculation using met. data of AmeriFlux
Calculated results seem to be reasonable. Farther tests using experimental data (EMRAS or BIOMASS) are necessary.
Next step
Step 2: inclusion of plant uptake processes (under construction) Step 3: OBT production and translocation (need suggestions)
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