Historic temperature observations on Nordaustlandet, north-east Svalbard

Long-term meteorological data for the Arctic are sparse. One of the longest quasi-continuous temperature time series in the High Arctic is the extended Svalbard Airport series, providing daily temperature data from 1898 until the present. Here, I derive an adjustment to historic temperature observations on the island of Nordaustlandet, north-east Svalbard, in order to link these to the extended Svalbard Airport series. This includes the Haudegen observations at Rijpfjorden during 1944/45 and a previously unrecognized data set obtained by the Norwegian hunters and trappers Gunnar Knoph and Henry Rudi during their wintering at Rijpfjorden in 1934/35. The adjustment is based on data from an automatic weather station at Rijpfjorden during 2014-16 and verified with other independent historic temperature observations on Nordaustlandet. An analysis of the Haudegen radiosonde data indicates that the surface tempera-ture observations at Rijpfjorden are generally well correlated with the free tro-pospheric temperatures at 850 hPa, but occasionally show the occurrence of boundary-layer inversions during winter, where local temperatures fall sub-stantially below what is expected from the regression. The adjusted historic observations from Nordaustlandet can, therefore, be used to fill remaining gaps in the extended Svalbard Airport series.