Ghent University studies urban micro-climatic differences within Ghent
Friday 6 January: Urban heat island during a winter night
Last night the meteorological conditions were ideal for strong cooling: a cold air mass, merely wind and clear conditions. The minimal temperatures were indeed quite low this morning: from -3°C in the city center to nearly -6°C in the rural Melle location.
Temperature evolution during the 05/01/17-06/01/17 night. Remark the strong nocturnal cooling.
As in summer we notice that the nighttime temperatures in the city are clearly higher. It is interesting to compare the wintertime urban heat island with the effect in summer. Based on the observations of last night we can expect some differences. Last night the rural-urban temperature difference was limited to 3°C. This considerable temperature contrast is somewhat lower than during clear summer nights (differences up to 6°C sometimes). The nighttime temperature behaviour at some locations seems to depend on the season. As an example the location in the port (Honda) reached during summer minima close to the highest minimal temperatures measured in the city center. But last night the port location registered the lowest temperatures apart from the rural station in Melle.
Map of the temperatures at 8h35 in the morning. Apart from Melle the lowest temperature is reached in the port of Gent.
At the end of June we will have data for a complete year and this will enable a more detailed analysis of the seasonal variations in the heat island of Gent.
Remark concerning precipitation measurements
As some snow (probably going over into rain after some time) is forecast for the coming night it is good to make a short remark concerning the rain gauges used on the weather stations. We use ARG100 rain gauges and these are not meant for measuring snow. Accurate precipitation measurements in case of snow need a heating element to melt precipitation but the ARG100 is not equipped with such a heating element.
