Abstract
Abstract. Temperature in northeast Greenland is expected to rise at a faster rate than the global average as a consequence of anthropogenic climate change. Associated with this temperature rise, precipitation is also expected to increase as a result of increased evaporation from a warmer and ice-free Arctic Ocean. In recent years, numerous palaeoclimate projects have begun working in the region with the aim of improving our understanding of how this highly sensitive region responds to a warmer world. However, a lack of meteorological stations within the area makes it difficult to place the palaeoclimate records in the context of present-day climate. This study aims to improve our understanding of precipitation and moisture source dynamics over a small arid region located at 80∘ N in northeast Greenland. The origin of water vapour for precipitation over the study region is detected by a Lagrangian moisture source diagnostic, which is applied to reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA-Interim) from 1979 to 2017. While precipitation amounts are relatively constant during the year, the regional moisture sources display a strong seasonality. The most dominant winter moisture sources are the North Atlantic above 45∘ N and the ice-free Atlantic sector of the Arctic Ocean, while in summer the patterns shift towards local and north Eurasian continental sources. During the positive phases of the North Atlantic Oscillation (NAO), evaporation and moisture transport from the Norwegian Sea are stronger, resulting in larger and more variable precipitation amounts. Testing the hypothesis that retreating sea ice will lead to an increase in moisture supply remains challenging based on our data. However, we found that moisture sources are increasing in the case of retreating sea ice for some regions, in particular in October to December. Although the annual mean surface temperature in the study region has increased by 0.7 ∘C per decade (95 % confidence interval [0.4, 1.0] ∘C per decade) according to ERA-Interim data, we do not detect any change in the amount of precipitation with the exception of autumn where precipitation increases by 8.2 [0.8, 15.5] mm per decade over the period. This increase is consistent with future predicted Arctic precipitation change. Moisture source trends for other months and regions were non-existent or small.
Highlights
The Arctic is known to be highly sensitive to changes in climate as a result of Arctic amplification, a process in which positive feedbacks act to amplify changes compared to the rest of the Northern Hemisphere (e.g. Dahl-Jensen et al, 1998; Miller et al, 2010)
Between 1875 and 2008, surface air temperature north of 60◦ N increased at twice the pace of the Northern Hemisphere average (e.g. Bekryaev et al, 2010), with the winter season being the most affected because of the delayed onset of sea ice resulting in a loss of heat from the open ocean to the atmosphere (e.g. Screen and Simmonds, 2010; Bintanja and Van der Linden, 2013)
For North Atlantic Oscillation (NAO)+ winter months, Sodemann et al (2008a) found that moisture sources for the northern and east-central Greenland Ice Sheet are larger over the Norwegian Sea, which is qualitatively similar to our findings
Summary
The Arctic is known to be highly sensitive to changes in climate as a result of Arctic amplification, a process in which positive feedbacks act to amplify changes compared to the rest of the Northern Hemisphere (e.g. Dahl-Jensen et al, 1998; Miller et al, 2010). Screen and Simmonds, 2010; Bintanja and Van der Linden, 2013) These temperature changes are expected to be accompanied by precipitation changes Within the Arctic, the greatest increases in precipitation are simulated over the Arctic Ocean and northeast Greenland by the end of this century, with up to 50 % increase in an RCP8.5 scenario (Bintanja and Selten, 2014). Enhanced precipitation predictions in the Arctic may be explained by the increase in surface temperature (Collins et al, 2013), which is accompanied by a predicted increase in moisture transport towards the Arctic that reaches a maximum during summer months, when meridional temperature and moisture gradients are at their maximum Whilst the absolute values of moisture transported to the Arctic are expected to increase, the relative contribution of remote sources will diminish in comparison to locally sourced moisture, which will be enhanced due to increased surface evaporation from open ice-free Arctic waters in late autumn–winter (e.g. Bintanja and Selten, 2014)
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