Long wave radiation parameterisations
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This document summarizes research testing site-specific parameterizations of longwave radiation integrated into a GIS-based hydrological model. The researchers developed the NewAge-LWRB package to model downwelling and upwelling longwave radiation within the NewAge-JGrass hydrological system. They tested various clear sky emissivity formulations and developed a multistep calibration approach. Model results showed improved performance when using an optimized formulation compared to classic formulations. The researchers also coupled the NewAge-LWRB package with NewAge-SWE models and applied them at both daily and hourly time steps to simulate snow water equivalent in the Cache la Poudre basin in Colorado.
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Long wave radiation parameterisations
- 1. Testing site-specific parameterizations of longwave radiation integrated in a GIS-based hydrological model Giuseppe Formetta1, Marialaura Bancheri2, Olaf David3 and Riccardo Rigon2 !! !1Dept. of Civil and Environmental Engineering, University of Calabria,Rende (CS),Italy 2Dept. of Civil and Environmental Engineering, University of Trento, 77 Mesiano St., 38123 Trento, Italy 3Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, Colorado, USA
- 2. Outline • NewAge-JGrass hydrological system • NewAge-LWRB package • Models Applications (LWRB; SWRB+LWRB+SWE)
- 8. Longwave Radiation: why is important? LW is vitally important in determining the radiation budget, which, in turn, modulates the magnitude of the terms in the surface energy budget (e.g., evaporation, evapotransiration) (Todd and Duchon, 1998, J.A.M. ) ! Solar radiation is an important input for hydrological models e.g., Sinokrot and Stefan, 1993; Wigmosta et al., 1994; Kustas et al. ,1994; Cline et al., 1998; Pomeroy et al. , 2003 While shortwave radiation has often been considered the dominant energy source for snow melting, LW can match, or exceed, incoming shortwave radiation during cloudy periods (Müller 1985; Granger and Gray 1990; Duguay 1993; Ohmura, 2001; Sedlar and Hock, 2006) http://www.wunderground.com/blog/RickyRood Expensive to measure, and LW radiation measurement stations density is at least one of two order of magnitude lower that SW radiation
- 10. NewAge-LWRB package Downwelling Upwelling NewAge-LWRB Model ParametersInputData Raster Maps (dem, sky view factor) Meteorological Forcing data !!!!!!!!!! Time Series or Raster Maps of LWRB (total, in and out) OutputData
- 11. NewAge-LWRB package Downwelling Depends on Atmospheric emissivity L↓ =εa ⋅σ ⋅Ta 4 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Upwelling Depends on Soil emissivity L↑ =εs ⋅σ ⋅Ts 4
- 12. NewAge-LWRB package: model formulation Downwelling Depends on Atmospheric emissivity L↓ =εa ⋅σ ⋅Ta 4 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) 10 clear sky emissivity formulations
- 13. Downwelling Depends on Atmospheric emissivity L↓ =εa ⋅σ ⋅Ta 4 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Correction due to the elevation Swinbank (1963): the air column above the site decreases with elevation NewAge-LWRB package: model formulation
- 14. Downwelling Depends on Atmospheric emissivity L↓ =εa ⋅σ ⋅Ta 4 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Could correction NewAge-LWRB package: model formulation
- 15. NewAge-LWRB package: Multistep Luca Calibration
- 16. NewAge-LWRB package: Multistep Luca Calibration Step0 Separate Clear and cloud periods TA!Shortwave! Measured!Shortwave! CI=MEAS/TA!
- 17. NewAge-LWRB package: Multistep Luca Calibration Step1 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Step0 Separate Clear and cloud periods Estimate Clear LW parameters using clear periods
- 18. NewAge-LWRB package: Multistep Luca Calibration Step1Step2 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Step0 εa = εcls − 0.035⋅ z 1000 # $ % & ' ( ) * + , - .⋅ 1+ a⋅cb ( ) Separate Clear and cloud periods Estimate Clear LW parameters using clear periods Estimate Clouds LW parameters using cloud periods
- 19. Study Area: 6 Ameriflux stations
- 20. NewAge-LWRB package: Model Results in station 101
- 21. 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$11$ 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$24$ 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$62$ 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$75$ 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$101$ 0! 0.2! 0.4! 0.6! 0.8! 1! 1! 2! 3! 4! 5! 6! 7! 8! 9! 10! KGE$ Models$ Sta.on$129$ Classic!formula+on! Op+mized!formula+on! NewAge-LWRB package: Clear-sky model results
- 22. Mass!Balance! Precipita+on!form! Mel+ng! Freezing! DegreeUDay!(C1)! CazorziUDella!Fontana!(C2)! Hock!Model!(C3)! NewAge-LWRB package coupled with NewAge-SWE models
- 23. SWE Model simulation with daily and hourly time step Application on the Cache la Poudre basin (CO, USA)
- 24. SWE Model simulation with daily and hourly time step Application on the Cache la Poudre basin (CO, USA)
- 25. SWE Model simulation in distributed mode for model C2 Application on the Cache la Poudre basin (CO, USA)
- 26. We are not providing “The Hydrological Model”, we are offering a strategy to choose, link and test different hydrological models built by components • Compare, on the same platform different model structures to simulate the same physical process (LWRB, SWE) • Investigate the model structure error using different model for a given calibration algorithm • Parameter optimization, using the same platform, for different hydrological processes Conclusions