Snow modeling in ORCHIDEE

1. Snow modeling in ORCHIDEE Tao Wang, Catherine Ottlé, Philippe Ciais, Gerhard Krinner, Shilong Piao

2. Importance of snow (I) Less snow, warmer air temperatures 3/32

3. Importance of snow (I) Less snow, warmer air temperatures Thicker snow, warmer soil temp. 3/32

4. Importance of snow (I) Less snow, warmer air temperatures Thicker snow, warmer soil temp. earlier snowmelt, earlier spring runoff 3/32

5. Importance of snow (I) Less snow, warmer air temperatures Thicker snow, warmer soil temp. Prolonged snow, later vegetation greening earlier snowmelt, earlier spring runoff 3/32

6. Importance of snow (II) Recent Eurasia winter cooling More Open water in the arctic ocean increased Autumn snow cover Strengthened siberia high Winter cooling (Cohen et al., 2012)

7. Importance of snow (III) Soil carbon sensitivity to snow insulation effect Gouttevin et al. (2012)

8. Snow model development in ORCHIDEE Old ORCHIDEE (1-layer) Heat Water Kin Lin H LE En P Tsurf Skin layer J Tsurf > 0, snow melt occurs; Ws, D, ρ T, D, ρ composite composite Top soil layer Top soil layer Kin (short wave radiation), Lin (longwave radiation), H (sensible heat flux), LE(latent heat flux), J (conduction heat flux), Ws (Snow layer water equivalent ), Wl(Snow layer liquid water content),D (snow depth), ρ (snow density, constant in ORC-O) , P (precipitation), En (evaporation), T(snow temperature), Tsurf (skin layer temperature), Q (snow layer heat content), Qp(advective heat from rain and snow) 22/32

9. Snow model development in ORCHIDEE Old ORCHIDEE (1-layer) ORCHIDEE-ES (3-layers) Heat Water Heat Water Kin Lin H LE Kin Lin En Qp P En H LE P Tsurf Skin layer J J1 K1 Q1, T1, D1, ρ1 P1 Ws1, Wl1, D1, ρ1 Q2, T2, D2, ρ2 Ws2, Wl2, D2, ρ2 J2 Tsurf > 0, snow melt occurs; K2 P2 Ws, D, ρ T, D, ρ Q3, T3, D3, ρ3 Ws3, Wl3, D3, ρ3 J3 K3 P3 Separate Separate composite composite Top soil layer Top soil layer Top soil layer Top soil layer Modified from ISBA-ES (Boone et al., 2004) Kin (short wave radiation), Lin (longwave radiation), H (sensible heat flux), LE(latent heat flux), J (conduction heat flux), Ws (Snow layer water equivalent ), Wl(Snow layer liquid water content),D (snow depth), ρ (snow density, constant in ORC-O) , P (precipitation), En (evaporation), T(snow temperature), Tsurf (skin layer temperature), Q (snow layer heat content), Qp(advective heat from rain and snow) 22/32

10. Model evaluation SWE comparison Wang et al. (2013)

11. Model evaluation Soil temperature comparison Wang et al. (2013)

12. Model evaluation Improvements can also be found over stations over Eurasia Wang et al. (2013)

13. Parameter sensitivity analysis Albedo-related Thermal conductivity-related Snow compaction factors

14. Soil freezing/thawing Old feature Gouttevin et al. (2012)

15. Soil freezing/thawing New feature Old feature Gouttevin et al. (2012)

16. More recently, … New feature Old feature Gouttevin et al. (2012)

17. More recently, … New feature Old feature > soil freezing Snow Gouttevin et al. (2012)

18. Thanks a lot for your attention!