7B.5 WRF for winter roads

Hartmann, Hugo, Jelle Wisse, Daniël van Dijke, Meteogroup

Accurate and detailed road surface temperature forecasts are essential for winter road safety. During winter, these forecasts are used to decide when and where to grit resulting in more public safety and less unnecessary gritting actions.

Measurements of air temperature along routes (i.e. an air temperature fingerprint) in complex terrain have revealed significant air temperature variations, especially during stable atmospheric conditions. These air temperature variations have a substantial impact on the local road surface temperature and road conditions. To be able to determine when and where to grit is therefore highly depending on accurate local forecasts of the air temperature.

Forecasts of road surface temperature and road conditions along single routes or road networks are based on the network model, which is an in-house developed land surface model. This presentation discusses the capabilities of the high resolution meso-scale WRF model in resolving the local air temperature variations. If successful, the simulated WRF air temperature fingerprints can be used as input to the network model.

Two case studies will be presented for a route in Wales (UK) under clear and calm nocturnal conditions. The main results will be highlighted for horizontal resolutions between 7.5 km and 500 m.