Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..
Jan 29, 2016
Snow processes in ORCHIDEE
Tao Wang, C. Ottlé, P. Ciais, etc..
Thicker snow, warmer soil temp.
Prolonged snow, later vegetation greening
earlier snowmelt, earlier spring runoff
Less snow, warmer air temperatures
Snow roles in high latitudes:
NDVI (30 May - 5 June)
EnP
H LEKin Lin
T, D, ρ
TsurfJ
Ws, D, ρ
Skin layer
Tsurf > 0, snow melt occurs;
Heat Water
Old ORCHIDEE (ORC-O, 1-layer)
Top soil layer Top soil layercomposite composite
ORCHIDEE Snow developmentsSingle layer vs. Three layers Composite vs. Separate snow structure Snow density and snow thermal conductivity (constant vs. variable)Freezing and refreezing processes (no vs. yes)Water flow between layers (no vs. yes)
3
EnH LEKin Lin
K1
K2
K3
Q1, T1, D1, ρ1
Q2, T2, D2, ρ2
Q3, T3, D3, ρ3
J1
J2
J3
Qp
Heat WaterP
P1
P2
P3
Ws1, Wl1, D1, ρ1
Ws2, Wl2, D2, ρ2
Ws3, Wl3, D3, ρ3
Top soil layer Top soil layerSeparate Separate
New ORCHIDEE (ORC-ES, 3-layers)
Sensitivity tests (Morris method)
Albedo-related
Thermal conductivity-related
Snow compaction factors
ORCHIDEE-ES on Col de Porte
Most important
Very important for soil temperature simulation
Very important for snow depth simulation
Evaluation results (CDP-snow depth)
Evaluation results (Albedo and soil temperature), Col de Porte, mean seasonal cycle (1993-2011)
How to constrain snow albedo feedback in model ?
Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc
Albedo = f(snow grain size, impurity, sun angle, snow depth)
Albedo = f(snow age)
How to constrain snow albedo feedback in model ?
Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc
Option 2: Data assimilation from in-situ or albedo product (GlobAlbedo)
In-situ snow albedo assimilation into ORCHIDEE-ES (alpine site, WFJ)
How to constrain snow albedo feedback in model ?
Wang et al. (in preparation)
Control
Assimil.
April Reflected radiation (albedo x SWdown)
Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc
Option 2: Data assimilation from in-situ or albedo product (GlobAlbedo)