Speaker
Description
The Citizen Science project Delft Measures in Delft (The Netherlands) engages residents in monitoring their local microclimate using low-cost weather stations installed in their gardens. The network currently consists of ~50 stations distributed across diverse neighbourhoods, capturing fine-scale variability in urban microclimates, with particular emphasis on rainfall. Unlike typical Private Weather Station networks, Delft Measures operates as a structured, long-term collaboration: regular meetings and workshops provide insight into site-specific conditions, installation choices, and maintenance practices. This contextual knowledge is crucial for interpreting opportunistic precipitation data.
To assess data quality, eight stations were co-located at The Green Village, the outdoor urban climate field lab of TU Delft. Installations deliberately replicated realistic citizen setups: slightly tilted sensors, placement near walls, on roofs, and free-standing configurations. Three properly installed stations served as reference. This design enabled quantification of biases arising from non-ideal exposure, tipping-bucket mechanics, and sensor drift.
Results indicate a systematic overestimation of rainfall by the raingauges relative to reference instrumentation and radar products, alongside a discernible negative bias associated with sheltering by vegetation and, to a lesser extent, walls. These findings highlight the dual challenge of instrumental and siting errors in opportunistic sensing.
Crucially, the sustained two-way engagement with citizen scientists proved essential for identifying faulty data, understanding maintenance constraints, and contextualizing anomalies. The project demonstrates that structured Citizen Science (combining experiments with local knowledge) can substantially enhance the reliability and interpretability of crowdsourced precipitation observations for urban hydrometeorological applications.