Keywords

Solar radiation balance, Longwave radiation modelling, Object Modelling System.

Location

Session H3: Agro-Ecosystem Modeling for Spatial Solutions to Watershed Conundrums

Start Date

19-6-2014 9:00 AM

End Date

19-6-2014 10:20 AM

Description

Incoming (Rli) and outgoing (Rlo) longwave atmospheric radiation are very important components of the global radiation balance. They influence many hydrological processes such as evapotranspiration, soil-surface temperature, energy balance, and snowmelt. Field measures of Rli and Rlo are extremely rare except for a few sites and experimental watersheds. Many parameterization schemes were proposed in order to model Rli and Rlo by using easily available meteorological observations such as air temperature, relative humidity, incoming solar radiation and cloud cover.

In this work 10 methods of parameterizing clear sky radiation for the estimation of Rli and Rlo were integrated in the GIS based hydrological system NewAge-JGrass and tested against field measurement data at hourly and daily timesteps. Two applications were performed. In the first application the 11 algorithms were applied by using the model parameters as proposed in literature. In the second application we preserved the analytical formulation of the models but site-specific parameters were estimated by using the automatic calibration algorithms available in the NewAge-JGrass system. Model verification was performed computing classical goodness of fit indices such as root mean square error, mean absolute error, percentage bias and Kling-Gupta efficiency. The use of site specific model parameters improves simulation results providing an improvement of all the indices of goodness of fit for all the parameterizations tested in the paper.

 
Jun 19th, 9:00 AM Jun 19th, 10:20 AM

Testing site-specific parameterizations of longwave radiation integrated in a GIS-based hydrological model

Session H3: Agro-Ecosystem Modeling for Spatial Solutions to Watershed Conundrums

Incoming (Rli) and outgoing (Rlo) longwave atmospheric radiation are very important components of the global radiation balance. They influence many hydrological processes such as evapotranspiration, soil-surface temperature, energy balance, and snowmelt. Field measures of Rli and Rlo are extremely rare except for a few sites and experimental watersheds. Many parameterization schemes were proposed in order to model Rli and Rlo by using easily available meteorological observations such as air temperature, relative humidity, incoming solar radiation and cloud cover.

In this work 10 methods of parameterizing clear sky radiation for the estimation of Rli and Rlo were integrated in the GIS based hydrological system NewAge-JGrass and tested against field measurement data at hourly and daily timesteps. Two applications were performed. In the first application the 11 algorithms were applied by using the model parameters as proposed in literature. In the second application we preserved the analytical formulation of the models but site-specific parameters were estimated by using the automatic calibration algorithms available in the NewAge-JGrass system. Model verification was performed computing classical goodness of fit indices such as root mean square error, mean absolute error, percentage bias and Kling-Gupta efficiency. The use of site specific model parameters improves simulation results providing an improvement of all the indices of goodness of fit for all the parameterizations tested in the paper.