Chaos in the Canopy
Understanding the Uses of Fiber Optics in the Forest
A.L. Vroom (TU Delft - Civil Engineering & Geosciences)
Miriam Gerrits – Mentor (TU Delft - Water Resources)
L.D. van der Valk – Graduation committee member (TU Delft - Water Resources)
Bas van de Wiel – Graduation committee member (TU Delft - Atmospheric Remote Sensing)
Michiel van der Molen – Coach (Wageningen University & Research)
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Abstract
This thesis explores the application of Distributed Temperature Sensing (DTS) technology to observe temperature gradients and turbulent eddies within and above a forest vegetation layer. Atmospheric temperature gradients tie directly to heat transfer, a primary mode of which are turbulent eddies. The goal in studying these elements is to enhance the understanding of land-atmosphere coupling, which plays a role in climate and weather modelling. The data collection took place in the first two weeks of November 2022 at a meteorology study site in Loobos, the Veluwe. A fiber optic cable was installed, running from the forest floor to 1.5 times the canopy height along a tower. The DTS technology provided high-resolution temperature measurements at one-second intervals. Fluctuations in these profiles could potentially be associated with turbulent eddies. By analyzing temperature profiles over time and integrating meteorological data, the study provided insights into the temporal evolution of vertical temperature distribution at the test site and its sensitivity to weather conditions. Phenomena such as direct sunlight, rainfall, canopy effects, and inversion layers were identified in the DTS data and validated with other meteorological measurements. Notably, sharp temperature inversions observed on two nights exhibited strong correlations with wind speed and its variation. Increases in wind speed and variability were associated with lower inversion heights.