Estimation of optical turbulence with standard weather-station observations
The model was tested for two crop types and two climates through three datasets (daytime data only); over a grass field in the Netherlands (Haarweg, Wageningen; one year), over a grass field in southern France (BLLAST experiment, Lannemezan; a summer period), and over a wheat field in western Germany (Transregio experiment, Merken; a growing season).
We validated the modelled sensible and latent heat fluxes and the modelled Cn2 for the various fields with values derived from 30-minute high-frequency wind, temperature and humidity data from sonic anemometers and gas analysers. Despite many underlying assumptions regarding field conditions, the model performs well for both grass fields. The model is also able to represent the fluxes and Cn2 over the wheat field, albeit with some more deviations from the observed fluxes and Cn2. These deviations are mainly caused by the uncertainty in the approximation of the canopy resistance of the growing wheat, which in our model only depends on leaf area index and water vapour deficit.
Estimates for Cn2 that are derived from our model could for example be used in the planning phase of microwave-link networks for communicational purposes or campaigns using imaging systems, since the propagation of electromagnetic radiation suffers from strong atmospheric turbulence. Furthermore, the derived Cn2 from our model could be tested in equations that specify the image quality achieved by a ground-based telescope. The robust estimates of evaporation could for instance be used in crop studies if direct flux measurements are not available.
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