Svalbard meteorological observations since 1912

Svalbard meteorological observations since 1912. The thin lines indicate the annual values, while the thick line is the simple running 5-yr mean. The diagram has been prepared using the composite monthly meteorological series homogenised by the Norwegian Meteorological Institute. The data may be downloaded from their official data access website, or from the Rimfrost.no website.

Comments

Summer (JJA) surface air temperature is relatively constant, while all other seasons show large interannual variations, and control variations shown by the annual temperature. Especially the temperature relation between mid winter (DJF) and late winter and spring (MAM) has changed considerably over the observational period. Until 1926 MAM was clearly warmer than DJF, but in the following period, until 1944, these two seasons were almost equal as to air temperature. Since 1945, however, MAM again has been clearly warmer than DJF, especially during the two relatively cold periods 1958-1971 and 1976-1996. During the general temperature increase since 1997, the temperature difference between DJF and MAM has again decreased somewhat. The difference between DJF and MAM is seen to be controlled mainly by variations in the DJF air temperature. This varying relation between DJF and MAM therefore suggests that a change in sea ice conditions may be reflected in the temperature data. The Svalbard meteorological series consists of data obtained at four different measurement sites. These data series have subsequently been homogenised and stiched together (Førland et al. 1997). All meteorological stations, however, have been located near the coast, where modern observations suggest that variations in sea ice cover during the winter influence significantly on the air temperature recorded. Warm winter periods thereby partly may be the result of less sea ice than during cold winter periods. Had the meteorological stations instead being located inland, the warm winter periods would presumably have been recorded as somewhat colder.

The annual precipitation has typically varied between 120 and 230 mm w.e., but the relation between air temperature and precipitation is complex. In contrast to simple physical expectations and the output from global and regional climate models, the relatively cold period 1955-1995 was characterised by a relatively high annual precipitation, and the warming period since 1996 has been characterised by decreasing annual precipitation. Presumably orographic effects derived from variations in the prevailing wind direction and wind speed may cause variations in the precipitation recorded. In addition, precipitation in windy Arctic areas like Svalbard is notorious difficult to measure and precipitation values are exposed to a high degree of uncertaincy.