Long‐term trends and the effect of solar cycle variations on mesospheric winter temperatures over Longyearbyen, Svalbard (78°N)

This paper gives an update on the long-term trend in hydroxyl (OH*) airglow winter temperatures measured by a 1 m Ebert-Fastie spectrometer in Longyearbyen, Svalbard (78°N, 16°E), from 1983 to 2013. The temperatures are derived through synthetic fits of measured airglow spectra of the OH*(6-2) vibrational state. The data set is corrected for seasonal variations by subtracting the mean climatology. Also, solar cycle dependence is investigated. A solar response coefficient of 3.6 K ± 4.0 K/100 solar flux units (SFU) is calculated from F10.7 cm solar radio flux data. After subtraction of the climatology and solar response, the remaining long-term trend is a near-zero trend, −0.2 K ± 0.5 K/decade. Trend analysis of monthly temperatures indicates positive trends for November, January, and February and a negative trend for December, but the uncertainties are high.