GEOFRAMECafe Giacomo Bertoldi

GEOtop vegetation description. Current parameterization and proposed improvements. Geotop café 18.12.2008 Giacomo Bertoldi stb_stn ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Equations used in GEOTOP to calculate vegetation ET stb_stn004f ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Fig 1 Environmental dependencies of stomata conductance For daytime conditions of simulation stb_stn004f Stomata close for high vapor pressure deficit Transpiration stop for too high and low Ta Transpiration is decreased below a critical water content Photosynthesis increases with PaR ,[object Object],[object Object], wp  fc

Ground evaporation vs. Transpiration For daytime conditions of simulation stb_stn004f  wp  fc Etc > Eg Eg > Etc Rs min/LAI ,[object Object],[object Object]

Drainage experiment: sensitivity of E TC /E G to soil moisture stb_stn005

Effect of a different vegetation fraction in GEOtop (I) Simulation on Little Washita with GEOtop 0.875 (Rigno et al., JHM, 2006)

Effect of a different vegetation fraction in GEOtop (II) Simulation on Little Washita with GEOtop 0.875 (Rigno et al., JHM, 2006)

Vegetation energy balance in GEOtop. What are the problems ? Stubai Neustift data - Snow-free daily averaged energy and Ts cycle - simulation stb_stn028 G daily cycle over-estimated Ts daily cycle over-estimated It behaves as bare soil (See Best, 1998)

Vegetation energy balance in GEOtop. What is missing ? 2. Radiation adsorption in the canopy (shadow of leaves) Increase Rlw, Decrease Rsw 3. Reduction wind speed in the canopy. Little H, ET from below the canopy. Decrease G. What we can to do to improve vegetation description ? ,[object Object],[object Object],[object Object],[object Object]

Bare soil evaporation. Some improvements. ,[object Object],[object Object]

2. Proposed vegetation layer energy balance scheme

GEOFRAMECafe Giacomo Bertoldi

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GEOFRAMECafe Giacomo Bertoldi