start:hype_model_description:processes_above_ground
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start:hype_model_description:processes_above_ground [2019/03/19 16:08] cpers [Alternative potential evaporation models] |
start:hype_model_description:processes_above_ground [2019/08/27 15:34] cpers [Alternative potential evaporation models] |
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| |Figure 3 Soil temperature factor for reduction of soil evapotranspiration. Parameter values: //ttrip//=1, //tredA//=0.5, //tredB//=1.| | |Figure 3 Soil temperature factor for reduction of soil evapotranspiration. Parameter values: //ttrip//=1, //tredA//=0.5, //tredB//=1.| | ||
| - | The actual evaporation is set to zero for temperatures below the threshold temperature and for negative potential evaporation estimates (condensation). The soil evapotranspiration reduction is calculated as: | + | The soil temperature evapotranspiration reduction is calculated as: |
| <m> factor = 1-e^( - tredA*(soiltemp-ttrig)^tredB) </m> | <m> factor = 1-e^( - tredA*(soiltemp-ttrig)^tredB) </m> | ||
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| <m> evapp = evapp*factor </m> | <m> evapp = evapp*factor </m> | ||
| - | A river with an area (is a class), flooded floodplains and lakes are assumed to evaporate at the potential rate, when the air temperature is above the threshold temperature (//ttmp//). Evaporation is limited by the water body's volume. | + | The actual soil evaporation is set to zero for temperatures below the threshold temperature and for negative potential evaporation estimates (condensation). |
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| + | A river with an area (i.e. is a class), flooded floodplains and lakes are assumed to evaporate at the potential rate, when the air temperature is above the threshold temperature (//ttmp//). Evaporation is limited by the water body's volume. | ||
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| === Model 4 - Priestly-Taylor === | === Model 4 - Priestly-Taylor === | ||
| - | The Priestly-taylor potential evaporation depends on net downward radiation (//netrad//), slope of saturated vapour pressure curve (//dsatvap//), latent heat of vaporization (<m>lambda</m>) and a psychrometric constant (<m>gamma</m>). One general parameter (//alfapt//) are used and one land use dependent (crop coefficient //kc4// or //kc//). | + | The Priestly-Taylor potential evaporation depends on net downward radiation (//netrad//), slope of saturated vapour pressure curve (//dsatvap//), latent heat of vaporization (<m>lambda</m>) and a psychrometric constant (<m>gamma</m>). One general parameter (//alfapt//) are used and one land use dependent (crop coefficient //kc4// or //kc//). |
| <m> epot_{base} = MAX(0,kc*alfapt * {dsatvap*netrad/lambda*(dsatvap+gamma)}) </m> | <m> epot_{base} = MAX(0,kc*alfapt * {dsatvap*netrad/lambda*(dsatvap+gamma)}) </m> | ||
start/hype_model_description/processes_above_ground.txt · Last modified: 2024/02/21 08:54 by cpers
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