Guidance on measuring, modelling and monitoring the Canopy Layer Urban Heat Island (CL‑UHI)

The guidance provides an overview of and recommendations for measuring, modelling and monitoring the Canopy Layer urban heat island, which is based on temperature information at about 1.5 m above ground. Canopy Layer urban heat island information is one component of the integrated urban hydro-meteorological, climate and environmental services for citizens. The urban heat island (UHI) is one of the earliest documented effects on air temperature observed in urban areas.

According to this guidance, measurements can support CL-UHI assessments and enable robust evaluations of model outputs. Models performing satisfactorily for their intended applications can be used for simulating CL-UHIs for current and future scenarios such as city development and climate change. Monitoring the CL-UHI requires both observations and modelling. Key to monitoring are long-term maintenance and documentation of changes, for example, of site and instruments (that is, metadata). Mitigation and adaptation efforts to reduce the effects of CL-UHIs are discussed, such as efforts to reduce heat stress, air pollutant concentrations and energy use.