St. Andrews UHI experiment, February 25, 2008

St. Andrews seen from southeast February 25, 2008 10:43 AM.

The general weather situation, measurement equipment and measurement route

The weather was dry and overcast, with a warm front approaching from west. The wind was strong from SSW, about 14-16 m/s. The ambient air temperature was about 6.5^oC. 

A thermistor mounted inside a radiation shield was attached to the roof of a car (c. 1.5 m above terrain), and temperatures were logged at 2 sec. intervals. The time given in the diagrams below is according to normal winter zonal time. The measurements were carried out for a route passing through the city from west to southeast, as shown by the map below.

St. Andrews is located at 56^o20'N 2^o50'W, on the east coast of Scotland. The present number of inhabitants is about 14,000 (2007). There is no official meteorological station located in St. Andrews; neither are there any major factories or heat generating industries located in St. Andrews. St. Andrews is on the other hand famous for the invention of golf and for having the famous University of St. Andrews, the oldest university in Scotland, third oldest in UK.

Map showing location of the measurement route (yellow). The map measures 12 km from west to east. The altitude ranges from 5 to 60 m asl., highest at the endpoints of the traverse.

Results

Result of temperature traverse 25 February 2008: Starting in rural landscape west of St. Andrews, passing through St. Andrews , and ending in rural landscape southeast of the town (see map above). Winds were strong from SSW, wherefore there is no temperature influence from the nearby sea (see map above). The weather was overcast, and there was no direct solar radiation on the buildings. The maximum urban heat island effect of St. Andrews was about 0.9^oC. 

Interpretation

According to conventional wisdom the UHI effect should disappear as wind speeds goes up, mixing the lowermost part of the atmosphere more efficiently. However, the above graph shows that this is not always the case. The interpretation is that the strong SSW winds (14-16 m/s) introduced a forced ventilation of the heated buildings, whereby enough warm air escaped to the exterior to sustain a clear UHI effect in St. Andrews.