Abstract
Distributed temperature data are used as input and as calibration data for an energy based temperature model of a first order stream in Luxembourg. A DTS (Distributed Temperature Sensing) system with a fiber optic cable of 1500m was used to measure stream water temperature with 1m resolution each 2 min. Four groundwater inflows were identified and quantified (both temperature and relative discharge). The temperature model calculates the total energy balance including solar radiation (with shading effects), longwave radiation, latent heat, sensible heat and river bed conduction. The simulated temperature is compared with the observed temperature at all points along the stream. Knowledge of the lateral inflow appears to be crucial to simulate the temperature distribution and conversely, that stream temperature can be used successfully to identify sources of lateral inflow. The DTS fiber optic is an excellent tool to provide this knowledge.
Highlights
The total incoming longwave radiation is computed to be the weighted average of atmospheric longwave radiation and land cover radiation (Eq 19 of Westhoff et al, 2007), where θVTS determines their weights
The only difference between the Eqs. (14) and (19) is the emissivity, ε, which has a value of 0.96 for land cover longwave radiation and has a value
In the original formulation, there was a double counting of incoming longwave radiation, which resulted in a large value for θVTS to achieve land cover longwave radiation within the correct range
Summary
The total incoming longwave radiation is computed to be the weighted average of atmospheric longwave radiation and land cover radiation (Eq 19 of Westhoff et al, 2007), where θVTS determines their weights.
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