Greenland monthly precipitation analysis from the Arctic System Reanalysis (ASR): 2000–2012

Tomoko Koyama,Julienne Stroeve

doi:10.1016/j.polar.2018.09.001

Abstract

Arctic System Reanalysis version 1 (ASRv1) forecasts of monthly precipitation over Greenland are compared with gauge-based precipitation measured by the Danish Meteorological Institute (DMI) and precipitation retrieved from the Precipitation Occurrence Sensor System (POSS) at Summit. The ASRv1 precipitation generally agrees with the corrected DMI gauge-based precipitation measured at coastal or near-coastal stations in Greenland, but the corresponding data at Ikerasassuaq and Nuuk are not the case. ASRv1 precipitation at Summit, i.e., in a higher continental environment, is overestimated compared with the POSS observations. The North Atlantic Oscillation (NAO index and ASRv1 precipitation are moderately correlated over northern Greenland, the North Atlantic, and the Greenland Sea regions (0.32–0.49). It is presumed that local wind events have a larger influence on precipitation where smaller correlations occur. Suggested future work to understand discrepancies between ASRv1 and DMI precipitation fields in Greenland coastal regions is to include case studies of local wind events and corresponding precipitation variations utilizing in-situ measurements during both strong positive and negative NAO phases. At high-altitude and inland areas, further observations are needed to confirm the ASRv1 overestimation.

Highlights

The Greenland ice sheet (GrIS) has been losing mass in recent decades (1992–2011) at an estimated rate of 142 ± 49 Gt per year, with an increase in mass loss rate from 51 ± 65 Gt per year (1992–2000) to 263 ± 30 Gt per year (2005–2010) (Shepherd et al, 2012)
Correlation coefficients for the 3 × 3 and 5 × 5 patches generally only differ by ± 0.04, suggesting precipitation at the nearest ASRv1 grid point is representative of the corresponding Danish Meteorological Institute (DMI) station
Monthly ASRv1 precipitation was compared with biascorrected DMI precipitation around coastal Greenland and precipitation retrieved from Precipitation Occurrence Sensor System (POSS) at Summit

Summary

Introduction

The Greenland ice sheet (GrIS) has been losing mass in recent decades (1992–2011) at an estimated rate of 142 ± 49 Gt per year, with an increase in mass loss rate from 51 ± 65 Gt per year (1992–2000) to 263 ± 30 Gt per year (2005–2010) (Shepherd et al, 2012) Another estimate based on measurements by NASA's Gravity Recovery and Climate Experiment (GRACE) showed similar mass loss rate, 265 ± 25 Gt per year (2002–2015), corresponding to 0.72 mm per year average global sea level rise (Forsberg et al, 2017). The impact of sea ice loss on Greenland accumulation, remains less clear

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