Longyearbyen UHI experiment, 20 January 2008

Longyearbyen 20 January 2008 4:27 PM, looking WNW from the SE end of the red measurement route shown in the map below. The weather is clear, with only little clouds, and the wind is light from SE. The smaller group of lights to the right in the picture is Svalbard Ariport. Compare with map below.

The general weather situation, measurement equipment and measurement route

The weather was cold, about -15^oC, clear and dry with only little clouds. The wind was light, 0.5-1 m/s from SE. The nearby fjord was ice free, with the exception of a 15-20 m band of thin, unstable ice along the coast. A thermistor 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 are according to normal winter zonal time. The measurements were carried starting at Svalbard Airport in the upper left of the map below, driving SE along the coast to the town, making a roundtour here, before proceding SE into the lower part of the major valley Adventdalen. 

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 (see map below).  

Topographic map showing Longyearbyen and Svalbard Airport (Svalbard Lufthavn). The red line shows the measurement route 20 January 2008, starting at the Airport and ending in the lower part of the valley Adventdalen to the SE. In between, a detour was made in the central part of the town as shown. The blue arrows indicates the direction of the weak wind (0.5-1 m/s) during the measurement. The fjord was ice free, with the exception of a 15-20 m band of thin, unstable ice along the coast. The map section measures c. 11 km west to east.

Results

Result of temperature measurements along the route Svalbard Airport - Longyearbyen -Adventdalen, 20 January 2008. The official Svalbard meteorological station is located at the airport. Se map above for reference. Time is given in hh:min:ss format along the x-axis.

Interpretation of results

The whole area was snowcovered. The sun was below the horizon, and albedo effects caused by buildings and roads for that reason not important. It was a busy time in Longyearbyen, with much activity on the roads and in the shops. 

The registered air temperatures, in general, show a falling trend towards SE along the main measurement route. Near the airport, where the official Svalbard meteorological station is located, air temperatures are relatively high (about -11^oC), which is interpreted as being the result of the light omshore airflow from SE across the ice free fjord. Further towards SE, this local warming effect diminishes, and the cold air (about -16^oC) draining out of the valley Adventdalen dominates. The temperature difference between the Airport and Adventdalen is about 5.5^oC, representing the open water effect (OWE). In between, the local heat island effect of the town Longyearbyen is clearly seen. The maximum UHI effect appears to be about +3.5^oC at the time of the experiment. The local cold trough recorded within Longyearbyen (16:18) corresponds to the main valley axis, where cold air masses is draining NNE from the glacier at the valley head.

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.