Longyearbyen UHI experiment, 30 January 2008

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Longyearbyen 30 January 2008 11:13 AM, looking WNW from the northern end of the lake Isdammen (see map below). The weather is almost overcast with light snow and blowing snow on the ground. The wind is from SE, 8-10 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 -9oC, and the wind medium strong from SE, 8-10 m/s. The sky was almost overcast and it was snowing lightly. The ground surface was covered by blowing 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 78o17'N 11o20'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 30 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 8-10 m/s from SE (blue arrows), but with a local deviation in Longyearvalley. The fjord was ice free. The map section measures c. 11 km west to east.



Result of temperature measurements along the route Svalbard Airport - Longyearbyen -Adventdalen, 30 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 -8.7oC), which is interpreted as being the result of the onshore airflow from ESE across the ice free fjord. Further towards SE, this local warming effect diminishes, and colder air (about -10.3oC) draining out of the valley Adventdalen dominates. The temperature difference between the Airport and Adventdalen is about 1.6oC, which presumably represents the open water effect (OWE). In between, the local heat island effect of the town Longyearbyen is only weakly developed, probably because of the rather high wind speed. The maximum UHI effect appears to be about +0.2oC at the time of the experiment. The local cold trough recorded within Longyearbyen (10:59) 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.