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Layout. Introduction General remarks Model development and validation The surface energy budget The surface water budget The surface CO2 budget Soil heat transfer Soil water transfer Snow Initial conditions Conclusions and a look ahead. H. LE. Day. D. Night. G.

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  1. PA Surface II of IV - training course 2012 Layout • Introduction • General remarks • Model development and validation • The surface energy budget • The surface water budget • The surface CO2 budget • Soil heat transfer • Soil water transfer • Snow • Initial conditions • Conclusions and a look ahead

  2. PA Surface II of IV - training course 2012 H LE Day D Night G Thermal budget of a ground layer at the surface

  3. PA Surface II of IV - training course 2012 Dry Fir canopy Barley field Energy budget: Summer examples Arya, 1988

  4. PA Surface II of IV - training course 2012 Surface albedo Surface emissivity Skin temperature The surface radiation • In some cases (snow, sea ice, dense canopies) the impinging solar radiations penetrates the “ground” layer and is absorbed at a variable depth. In those cases, an extinction coefficient is needed. Arya, 1988

  5. PA Surface II of IV - training course 2012 Sensible heat flux specify the surface Evaporation Ground heat flux The other terms

  6. PA Surface II of IV - training course 2012 Recap: The surface energy equation • Equation for • For: • a thin soil layer at the top • G (Ts,Tsk) is known, or parameterized or G << Rn we have a non-linear equation defining the skin temperature

  7. PA Surface II of IV - training course 2012 Land Sea and ice High vegetation Open sea / unfrozen lakes Low vegetation Sea ice / frozen lakes High vegetation with snow beneath Snow on low vegetation Bare ground Interception layer Tiles

  8. PA Surface II of IV - training course 2012 Fields ERA15 TESSEL Vegetation Fraction Fraction of low Fraction of high Vegetation type Global constant (grass)‏ Dominant low type Dominant high type Albedo Annual Monthly LAI rsmin Global constants Annual, Dependent on vegetation type Root depth Root profile 1 m Global constant Annual, Dependent on vegetation type TESSEL geographic characteristics

  9. PA Surface II of IV - training course 2012 High vegetation fraction at T511 (now at T1279)‏ Aggregated from GLCC 1km

  10. PA Surface II of IV - training course 2012 Low vegetation fraction at T511 (now at T1279)‏ Aggregated from GLCC 1km

  11. PA Surface II of IV - training course 2012 High vegetation type at T511 (now at T1279)‏ Aggregated from GLCC 1km

  12. PA Surface II of IV - training course 2012 Low vegetation type at T511 (now at T1279)‏ Aggregated from GLCC 1km

  13. PA Surface II of IV - training course 2012 Layout • Introduction • General remarks • Model development and validation • The surface energy budget • The surface water budget • The surface CO2 budget • Soil heat transfer • Soil water transfer • Snow • Initial conditions • Conclusions and a look ahead

  14. PA Surface II of IV - training course 2012 Snow Lake Dry vegetation Wet vegetation Bare ground Evaporation: Idealized surfaces

  15. PA Surface II of IV - training course 2012 • Evaporation efficiency • Ratio of evaporation to potential evaporation • Bucket model Budyko 1963, 1974 Manabe 1969 1 0 Potential evaporation, bucket model • Potential evaporation • The evaporation of a large uniform surface, sufficiently moist or wet (the air in contact to it is fully saturated)‏

  16. PA Surface II of IV - training course 2012 A general, algebraic formulation • Two limit behaviours • Bare soil: Evaporation dependent on soil water (and trapped water vapor) in a top shallow layer of soil (~ 20 mm). • Vegetated surfaces: Evaporation controlled by a canopy resistance, dependent on shortwave radiation, water on the root zone (~ 1-5 m deep) and other physical/physiological effects.

  17. PA Surface II of IV - training course 2012 Transpiration: The big leaf approximation • Sensible heat (H), the resistance formulation • Evaporation (E), the resistance formulation (the big leaf approximation, Deardorff 1978, Monteith 1965)‏

  18. PA Surface II of IV - training course 2012 Some plant science • rs, the stomatal resistance of a single leaf. Physiological control of water loss by the vegetation. Stomata (valve-like openings) regulate the outflow of water vapour (assumed to be saturated in the stomata cells) and the intake of CO2 from photosynthesis. The energy required for the opening is provided by radiation (Photosynthetically Active Radiation, PAR). In many environments the system appears to be operate in such a way to maximize the CO2 intake for a minimum water vapour loss. When soil moisture is scarce the stomatal apertures close to prevent wilt and dessication of the plant.

  19. PA Surface II of IV - training course 2012 Jarvis approach(1)‏ Dickinson et al 1991

  20. PA Surface II of IV - training course 2012 Jarvis approach(2)‏ Shuttleworth 1993

  21. PA Surface II of IV - training course 2012 Bare ground evaporation • Soil (bare ground) evaporation is due to: • Molecular diffusion from the water in the pores of the soil matrix up to the interface soil atmosphere (z0q)‏ • Laminar and turbulent diffusion in the air between z0q and screen level height • All methods are sensitive to the water in the first few cm of the soil (where the water vapour gradient is large). In very dry conditions, water vapour inside the soil becomes dominant

  22. PA Surface II of IV - training course 2012 TESSEL transpiration

  23. PA Surface II of IV - training course 2012 TESSEL root profile

  24. PA Surface II of IV - training course 2012 TESSEL evaporation: shaded snow • Evaporation is the sum of the contribution of the snow underneath (with an additional resistance, ra,s ,to simulate the lower within canopy wind speed) and the exposed canopy. The former is dominant in early spring (frozen soils) and the latter is dominant in late spring.

  25. PA Surface II of IV - training course 2012 TESSEL bare ground evaporation

  26. New bare soil evaporation(Balsamo et al. 2011, Albergel et al. 2012) • SOIL EvaporationBalsamo et al. (2011) based on Mahfoufand Noilhan (1991) ut_2129 ####2010### R = 0.583 Bias = 0.005 RMSD= 0.068 ####2011### R = 0.906 Bias = 0.033 RMSD= 0.056 ut_2130 ####2010### R = 0.685 Bias = -0.036 RMSD= 0.064 ####2011### R = 0.812 Bias = -0.037 RMSD= 0.052 f2(w1) The introduction of bare groundevaporation revision (green-line) is quiteeffectivein reducing the soil moisture below the wilting point in non-vegetated area (upper panel of figure above, at79% bare ground, SCAN site in Utah). Rc=Rsoil f2(w1) ICOS Annual meeting, Bruxelles 1/6/2011 - G. Balsamo

  27. PA Surface II of IV - training course 2012 Land Sea and ice High vegetation Open sea / unfrozen lakes Low vegetation Sea ice / frozen lakes High vegetation with snow beneath Snow on low vegetation Bare ground Interception layer Tiles

  28. PA Surface II of IV - training course 2012 Interception (1)‏ • Interception layer represents the water collected by interception of precipitation and dew deposition on the canopy leaves (and stems) • Interception (I) is the amount of precipitation (P) collected by the interception layer and available for “direct” (potential) evaporation. I/P ranges over 0.15-0.30 in the tropics and 0.25-0.50 in mid-latitudes. • Leaf Area Index (LAI) is (projected area of leaf surface)/(surface area) 0.1 < LAI < 6 • Two issues • Size of the reservoir • Cl, fraction of a gridbox covered by the interception layer • T=P-I; Throughfall (T) is precipitation minus interception

  29. PA Surface II of IV - training course 2012 Interception: Canopy water budget

  30. PA Surface II of IV - training course 2012 TESSEL: interception • Interception layer for rainfall and dew deposition

  31. PA Surface II of IV - training course 2012 Example: Deep tropics interception ARME, 1983-1985, Amazon forest Accumulated water fluxes Interception Evaporation Interception Viterbo and Beljaars 1995

  32. PA Surface II of IV - training course 2012 Case study: Aerodynamic resistance (1)‏ • Cabauw (Netherlands), is a grass covered area, where multi-year detailed boundary layer measurements have been taken • Observations were used to force a stand-alone version of the surface model for 1987 • The first model configuration tried had z0h=z0m

  33. PA Surface II of IV - training course 2012 Case study: Aerodynamic resistance (2)‏ Beljaars and Viterbo 1994

  34. PA Surface II of IV - training course 2012 Case study: Aerodynamic resistance (3)‏

  35. PA Surface II of IV - training course 2012 Layout • Introduction • General remarks • Model development and validation • The surface energy budget • The surface water budget • The surface CO2 budget • Soil heat transfer • Soil water transfer • Snow • Initial conditions • Conclusions and a look ahead

  36. PA Surface II of IV - training course 2012 (Calvet et al. 2005) Towards an increased vegetation complexity “old/standard” LSMs “new/photosynthesis- based” LSMs Slide 36

  37. PA Surface II of IV - training course 2012 Jarvis-type Based parameterisation and LAI impact on screen level temperature For vegetated area the evapotranspiration is parameterized as: Where the canopy resistance rc is defined following Jarvis(1976) as: Where rs,min is the minimum stomatal resistance, LAI is the leaf area index and f1 , f2 , f3 are respectively function of the downward shortwave radiation Rs, soil moisture  and vapour deficit Da If LAI then rc and E so T2m If LAI then rc and E so T2m

  38. PA Surface II of IV - training course 2012 Previous Operational Yearly LAI map MODIS LAI (Myneni et al., 2002) Obtained by the inversion of a 3D radiative transfer model which compute the LAI and FPAR based on the biome type and an atmospherically corrected surface reflectance thanks to a look-up-table Slide 38 derived 8years (2000-2008) climatological time serie (Jarlan et al. 2008)

  39. PA Surface II of IV - training course 2012 Impact of the usage of the MODIS based monthly LAI climatology on the 2m Temperature Sensitivity (warming) Impact (error reduction) Results from forecast experiments using MODIS LAI relative to the fixed LAI case for MAM at FC+36 (valid 12UTC), 2m temperature [K]

  40. PA Surface II of IV - training course 2012 Land carbon/photosynthesis-based parameterisation (CTESSEL) RMetS National meeting 18 Jan 2012. S. Boussetta

  41. PA Surface II of IV - training course 2012 Q10 T [oC] Soil Respiration parameterization(1) The Berry and Raison (1982) Q10 approach) Q10 represents the proportional increase of a parameter for a 10 degree increase in temperature (Berry and Raison, 1982) Including a temeperature dependency on the Q10 parameter (McGuire et al., 1992) Including a snow attenuation effect on the soil CO2 emission

  42. PA Surface II of IV - training course 2012 Soil Respiration parametrization (2) Example of NEE (micro moles /m2/s) predicted over the site Fi-Hyy taking the cold process into account (right) and previous simulation (left) by CTESSEL (black line) and observed (red dots) Feedback from the atmosphere can contribute to improve the physical understanding and adjust the contribution from the surface

  43. Jarvis Vs photosynthesis-based evapotranspiration PA Surface II of IV - training course 2012 CTESSEL HTESSEL H Surface sensible heat flux (W/m2) compared with flux-tower observations over Fr-LBr for HTESSEL (left panel) and CTESSEL (right panel) LE Surface laten heat flux (W/m2) compared with flux-tower observations over Fr-LBr for HTESSEL (left panel) and CTESSEL (right panel). • CTESSEL improves the LE/H simulations (Photosynthesis-based vs Jarvis approach).

  44. PA Surface II of IV - training course 2012 CO2 exchanges as part of the daily forecasts Example of Average 10 days forecasted NEE from the 1st of June 2011 extracted from the pre-operational run (e-suites) [micromoles/m2/s] – Operational from November 2011

  45. Impact of climate anomalies on CO2 flux: The summer 2003 2m temp precipitation Observedanomaly NEE July 2004 shown for comparison CTESSELmodelanomaly • Summer 2003 heat-wave/drought hitting western Europe. The effect on NEE was to turn land into a CO2 source due to vegetation stress conditions, consistently with findings of P. Ciais et al. (2005, Nature)

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