Validation of ECMWF (re)analysis surface climate data, 1979–1998, for Greenland and implications for mass balance modelling of the ice sheet

• Published in: International Journal of Climatology
• Main Authors: Hanna, Edward, Valdes, Paul
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2001
• Subjects: Greenland; Ice Sheet
• Online Access: http://dx.doi.org/10.1002/joc.609; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjoc.609; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.609

Abstract Climate (re)analysis products are potentially valuable tools, when properly verified, for helping to constrain the surface mass balance of the Greenland Ice Sheet (GIS). Monthly surface fields from European Centre for Medium‐Range Weather Forecasts (ECMWF) operational‐ and re‐analyses spanning 1979–1998 were validated using in situ data (surface air pressure and temperature, precipitation, cloud cover, short‐/all‐wave radiation, and wind speed/direction). These validation data are from coastal or near‐coastal Danish Meteorological Institute (DMI) synoptic stations, inland Greenland Climate Network (GC‐Net) and University of Wisconsin Automatic Weather Stations (AWSs), and two energy balance stations near the southern ice margin. The ECMWF analyses closely reproduce the seasonal patterns and interannual variations of much of the in situ data. Differences in the mean values of surface air pressure and temperature can mainly be ascribed to orography errors in the analyses' schemes, compared with the latest available accurate digital elevation model. Much of the GIS margin as modelled by ECMWF was too cold, on average by 4°C, and ECMWF precipitation averaged some 136% of the DMI station values. The misrepresentation of the (relatively) steep ice‐sheet margin, which tends to be broadened and systematically over‐elevated by several hundred metres, orographically reduced temperature and enhanced precipitation there in the ECMWF models. The cloud‐cover comparison revealed not dissimilar annual mean cloud covers (ECMWF −8%) but the ECMWF analyses had too little cloud and were too ‘sunny’ during the critical summer melt‐season. ECMWF‐modelled surface albedo in summer was ∼11% lower than GC‐Net values, which was mainly responsible for the disagreement of modelled surface short‐wave radiation fluxes with observations. Model albedo and cloud errors need to be rectified if the analyses are to be used effectively to drive energy balance models of Greenland snowmelt. ECMWF wind speed averaged 66% (62%) of the DMI ...