Longyearbyen UHI experiment, 2 February 2007

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Longyearbyen looking east, 16. July 2007. Winter darkness still prevails in early February when the experiment was carried out, but this summer picture provides an impression of the general topographic setting. In the lower part of the picture the valley Longyeardalen extends to the right (SW), and most of the buildings in the town is located shortly SE of the valley axis as seen in this picture. At the extreme left-hand edge of the picture part of UNIS, the northernmost university in the world, is seen.

The general weather situation, measurement equipment and measurement route

The weather was relatively mild, around -5^oC, and the sky almost overcast. Winds were from north, about 11 m/s. The nearby fjord was without ice cover. A thermistor mounted inside a radiation shield was attached to a 1 m rod, mounted on a snowmachine (thermistor 1.5 m above terrain). Within a two hour period, the snowmachine was driven in a dense network across the area shown in the diagram below, while air temperatures were logged at 5 sec. intervals. 

Longyearbyen is the worlds northernmost town and is located at 78^o17'N 11^o20'E, in central Spitsbergen . The present number of inhabitants is 2,001 (January 1, 2007). There is no official meteorological station located in Longyearbyen at the moment. The official meteorological station is located at the airport, about 4 km northwest of Longyearbyen, close to the coast.

Aerial photo showing Longyearbyen located in the valley Longyeardalen. Note that shades are falling toward north (up) in this photo. Source: Google Earth. The photo measures c. 6 km across from west to east.

Results

Result of temperature measurements in Longyeardalen 2. February 2007. UTM coordinates are given along the axes. The red dots indicate the position of roads within Longyearbyen. Most buildings are located along the roads in the northern, central part of the area shown (compare with the two photos above).

Interpretation of results

The whole area was snowcovered. The sun was below the horizon at the time of measurement, and albedo effects caused by buildings and roads for that reason not important. The local heat islands seen in the diagram above are therefore interpreted as representing heat escaping from buildings. The nearby fjord was ice free at the time of measurement, and heat from the relatively warm sea water may have caused the high temperatures in the north-western part of the study area, especially as the wind was from northerly direction. 

The temperature pattern shown above does not represent a real snapshot of the temperature conditions, at the whole measuring scheme took almost two hours. As mentioned, the measurements were carried out using a snowmachine, and it can not be excluded that a number of the measurements may have been affected by heat release from the snowmachine itself. In addition, some of the temperature details in the diagram represent artefacts of interpolation, only. The overall temperature pattern, however, presumably is correct.

The existence of an urban heat island effect in a relatively small settlement as Longyearbyen may come as a surprise. This is, however, not the first time this has been observed in the Arctic; see, e.g., Hinkel et al. 2003.