Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

Transcript of Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

Page 1: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

Snow processes in ORCHIDEE

Tao Wang, C. Ottlé, P. Ciais, etc..

Page 2: 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)

Page 3: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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)

Page 4: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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

Page 5: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

Evaluation results (CDP-snow depth)

Page 6: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

Evaluation results (Albedo and soil temperature), Col de Porte, mean seasonal cycle (1993-2011)

Page 7: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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)

Page 8: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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)

Page 9: Snow processes in ORCHIDEE Tao Wang, C. Ottlé, P. Ciais, etc..

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)