Climate Extremes across the North American Arctic in Modern Reanalyses

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  • 1 Department of Agricultural Engineering, Universidade Federal de Viçosa, Viçosa, MG, Brazil
  • 2 Polar Meteorology Group, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH, USA
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Abstract

Atmospheric reanalyses are a valuable climate-related resource where in-situ data are sparse. However, few studies have investigated the skill of reanalyses to represent extreme climate indices over the North American Arctic, where changes have been rapid and indigenous responses to change are critical. This study investigates temperature and precipitation extremes as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) over a 17 year period (2000-2016) for regional and global reanalyses, namely the Arctic System Reanalysis version 2 (ASRv2), North American Regional Reanalysis (NARR), European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 Reanalysis, Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA2), and Global Meteorological Forcing Dataset for Land Surface Modeling (GMFD). Results indicate that the best performances are demonstrated by ASRv2 and ERA5. Compared to observations, reanalyses show the weakest performance over far northern basins (e.g., Arctic and Hudson) where observing networks are less dense. Observations and reanalyses show consistent warming with decreased frequency and intensity of cold extremes. Cold days, cold nights, frost days, and ice days have decreased dramatically over the last two decades. Warming can be linked to a simultaneous increase in daily precipitation intensity over several basins in the domain. Moreover, the North Atlantic and the Arctic Oscillations (NAO, AO) distinctly influence extreme climate indices. Thus, these findings detail the complexity of how the climate of the Arctic is changing, not just in an average sense, but in extreme events that have significant impacts on people and place.

Corresponding author address: Aaron B. Wilson, Byrd Polar and Climate Research Center, The Ohio State University, 1090 Carmack Rd., Columbus, OH 43210 E-mail: wilson.1010@osu.edu

Abstract

Atmospheric reanalyses are a valuable climate-related resource where in-situ data are sparse. However, few studies have investigated the skill of reanalyses to represent extreme climate indices over the North American Arctic, where changes have been rapid and indigenous responses to change are critical. This study investigates temperature and precipitation extremes as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) over a 17 year period (2000-2016) for regional and global reanalyses, namely the Arctic System Reanalysis version 2 (ASRv2), North American Regional Reanalysis (NARR), European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 Reanalysis, Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA2), and Global Meteorological Forcing Dataset for Land Surface Modeling (GMFD). Results indicate that the best performances are demonstrated by ASRv2 and ERA5. Compared to observations, reanalyses show the weakest performance over far northern basins (e.g., Arctic and Hudson) where observing networks are less dense. Observations and reanalyses show consistent warming with decreased frequency and intensity of cold extremes. Cold days, cold nights, frost days, and ice days have decreased dramatically over the last two decades. Warming can be linked to a simultaneous increase in daily precipitation intensity over several basins in the domain. Moreover, the North Atlantic and the Arctic Oscillations (NAO, AO) distinctly influence extreme climate indices. Thus, these findings detail the complexity of how the climate of the Arctic is changing, not just in an average sense, but in extreme events that have significant impacts on people and place.

Corresponding author address: Aaron B. Wilson, Byrd Polar and Climate Research Center, The Ohio State University, 1090 Carmack Rd., Columbus, OH 43210 E-mail: wilson.1010@osu.edu
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