• Energy Research

Using five ice core data sets combined into a single time series, we provide for the first time strong observational evidence for two distinct time scales of Arctic temperature fluctuation that are interpreted as variability associated with the Atlantic Multidecadal Oscillation (AMO). The dominant and the only statistically significant multidecadal signal has a time scale of about 20 years. The longer multidecadal variability of 45–85 years is not well defined and none of the time scales in this band is statistically significant. We compare these observed temperature fluctuations with results of coupled climate model simulations (HadCM3 and GFDL CM2.1). Both the 20–25 year and a variable longer AMO time scale are prominent in the models' long control runs. This periodicity supports our conjecture that the observed ice core fluctuations are a signature of the AMO. The robustness of this short time scale period in both observations and model simulations has implications for understanding the dominant AMO mechanisms in climate.

Hourly automatic weather station (AWS) data collected at two sites on the Zachariae Isstrøm between 2016 an 2020 (S22, S23), and at a Firn Aquifer site West from Helheim glacier between 2014 and 2017 (S21). S23 was installed at approx. 145 m a.s.l and 13km from the Zachariae Isstrøm glacier front, and S22 was installed at 535 m a.s.l and 35km from the Zachariae Isstrøm glacier front. S21 was installed at 1660m elevation and c.a. 50km from the Helheim glacier front. The data contains air temperature, humidity, wind speed/direction corrected at standard heights of 2 m and 10 m, all four radiation components, atmospheric pressure, snow accumulation by a sonic ranger, ice ablation by a draw wire (S23 only), and glacier surface velocity (GPS).

Daily averaged surface energy balance (SEB) components and meteorological quantities at 19 locations on the Greenland ice sheet. Three stations are located in the accumulation zone (S10, KAN_U and S21), while the other locations are in the ablation zone. Seven stations are part of the IMAU network , while the other stations are from the PROMICE network. The longest time series span between 2003 and 2023 (S5, S6 and S9, all located along the K-transect in West Greenland). The data contains modelled and measured turbulent heat fluxes, all four radiation components, daily melt energy, subsurface heat flux, air temperature, wind and humidity corrected at standard heights above the surface, height of the sensor, snow accumulation measured by a sonic height ranger, ice/snow ablation measured by a draw-wire, a pressure transducer depth assembly, or acoustic ranger mounted on a separate stake. Days with at least one missing sample are removed from the dataset.

Daily averaged surface energy balance (SEB) components and meteorological quantities at 19 locations on the Greenland ice sheet. Three stations are located in the accumulation zone (S10, KAN_U and S21), while the other locations are in the ablation zone. Seven stations are part of the IMAU network , while the other stations are from the PROMICE network. The longest time series span between 2003 and 2023 (S5, S6 and S9, all located along the K-transect in West Greenland). The data contains modelled and measured turbulent heat fluxes, all four radiation components, daily melt energy, subsurface heat flux, air temperature, wind and humidity corrected at standard heights above the surface, height of the sensor, snow accumulation measured by a sonic height ranger, ice/snow ablation measured by a draw-wire, a pressure transducer depth assembly, or acoustic ranger mounted on a separate stake. Days with at least one missing sample are removed from the dataset.

Daily averaged surface energy balance (SEB) components and meteorological quantities at 19 locations on the Greenland ice sheet. Three stations are located in the accumulation zone (S10, KAN_U and S21), while the other locations are in the ablation zone. Seven stations are part of the IMAU network , while the other stations are from the PROMICE network. The longest time series span between 2003 and 2023 (S5, S6 and S9, all located along the K-transect in West Greenland). The data contains modelled and measured turbulent heat fluxes, all four radiation components, daily melt energy, subsurface heat flux, air temperature, wind and humidity corrected at standard heights above the surface, height of the sensor, snow accumulation measured by a sonic height ranger, ice/snow ablation measured by a draw-wire, a pressure transducer depth assembly, or acoustic ranger mounted on a separate stake. Days with at least one missing sample are removed from the dataset.