The London Heat Island – surface and air temperature measurements in a park and street gorges

This paper reports results from short-term tests carried

out as part of a project to characterize the urban heat island

in London. The investigations looked at air temperatures

upstream and downstream of a park and the surface and air

temperatures within street gorges. It was found that the air in

the park was associated with lower mean (0.6°C [1.1°F] less)

and peak temperatures (1.1°C [2.0°F] less) compared to residential

or shopping streets on either side. The apparent cooling

influence of the park extended downstream between 200 and

400 meters (200 to 400 yards). Measurements in four street

gorges showed a wide variation in surface temperatures—up

to 22°C (40°F)—although 5ºC to 10°C (9ºF to 18°F) was more

typical. For a given façade, lighter surfaces were associated

with lower temperatures, between 6ºC and 10°C (11ºF and

18°F) cooler. A strong relationship was found between mean

gorge surface temperature and the gorge air temperature

measured at 6 m (20 ft) (half-gorge height). This was true for

both a sunny day and a cloudy day. The results suggest that

significant reductions in air temperature may be possible by

adjusting the albedo of urban surfaces.