Abstract
Arctic Fennoscandia has undergone significant climate change over recent decades. Reanalysis data sets allow us to understand the atmospheric processes driving such changes. Here we evaluate four reanalyses against observations of near‐surface air temperature (SAT) and precipitation (PPN) from 35 meteorological stations across the region for the 35‐year period from 1979 to 2013. The reanalyses compared are the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), the European Centre for Medium‐Range Weather Forecast (ECMWF) Interim reanalysis (ERA‐Interim), the Japanese Meteorological Agency (JMA) 55‐year reanalysis (JRA‐55) and National Aeronautics and Space Administration (NASA)’s Modern‐Era Retrospective Analysis for Research and Applications (MERRA).All four reanalyses have an overall small cool bias across Arctic Fennoscandia, with MERRA typically ~1 °C cooler than the others. They generally reproduce the broad spatial patterns of mean SAT across the region, although less well in areas of complex orography. Observations reveal a statistically significant warming across Arctic Fennoscandia, with the majority of trends significant at p < .01. Three reanalyses show similar regional warming but of smaller magnitude while CFSR is anomalous, even having a slight cooling in some areas. In general, the other reanalyses are sufficiently accurate to reproduce the varying significance of observed seasonal trends.There are much greater differences between the reanalyses when comparing PPN to observations. MERRA‐Land, which merges a gauge‐based data set, is clearly the best: CFSR is the least successful, with a significant wet bias. The smoothed reanalysis orography means that the high PPN associated with the western side of the Scandinavian Mountains extends too far inland. Spatial patterns of PPN trends across the region differ markedly between the reanalyses, which have varying success at matching observations and generally fail to replicate sites with significant observed trends. Therefore, using reanalyses to analyse PPN changes in Arctic Fennoscandia should be undertaken with caution.
Highlights
Recent increases in near-surface Arctic temperatures are significantly greater than the global average (e.g., Bindoff et al, 2013) and, since 1980, are more than twice that of the Northern Hemisphere average (Overland et al, 2016)
Our motivation for this paper is to provide the first detailed validation of reanalyses across the region of Arctic Fennoscandia: while the aforementioned studies analysed the entire Arctic, they were unable to provide the detailed regional information on surface air temperature (SAT) and PPN we do here
We compare the reanalyses in terms of the four types of error statistics calculated as mean values of all the stations for all months: these data are provided as summary tables
Summary
Recent increases in near-surface Arctic temperatures are significantly greater than the global average (e.g., Bindoff et al, 2013) and, since 1980, are more than twice that of the Northern Hemisphere average (Overland et al, 2016). Changes in the spatial and temporal distribution of heat and moisture, such as the frequency of temperatures close to zero and strong precipitation events, have the potential to trigger natural hazards in Fennoscandia such as avalanches, rock slides or flooding (e.g., Dyrrdal, Isaksen, Hygen, & Meyer, 2012) These climatic changes have led to major behavioural changes in the region’s vegetation, including a general lengthening of the growing season and both increases and decreases in plant productivity (e.g., Barichivich et al, 2014; Bjerke et al, 2014; Blinova & Chmielewski, 2015; Høgda, Tømmervik, & Karlsen, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
