Longyearbyen UHI experiment, 31 January 2008

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Longyearbyen 31 January 2008 02:55 PM, looking WNW from the northern end of the lake Isdammen (see map below). The weather is almost overcast, but dry. The wind was weak from mainly easterly direction, 0.5-1 m/s. 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 air temperature was about -14.5^oC, and the wind weak from mainly easterly direction, 0.5-1 m/s, but with local deviations (see map below). The sky was almost overcast, but no snow was falling. The ground surface was covered by snow. The nearby fjord was ice free. 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 31 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 wind was weak, 0.5-1 m/s, from a mainly easterly direction, but with local deviations (blue arrows). The fjord was ice free. The map section measures c. 11 km west to east.

Results

Result of temperature measurements along the route Svalbard Airport - Longyearbyen -Adventdalen, 31 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. 

The registered air temperatures show an overall 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 -13.0^oC), which is interpreted as being the result of the weak onshore airflow from NE across the ice free fjord. Further towards SE, this local warming effect diminishes, and colder air (about -16.3^oC) slowly draining out of the valley Adventdalen dominates. The temperature difference between the Airport and Adventdalen is about 3.3^oC, representing the open water effect (OWE). In between, the local heat island effect of the town Longyearbyen is only weakly developed. The maximum UHI effect appears to be about +0.5^oC at the time of the experiment. The local cold trough recorded within Longyearbyen (14:41) 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.