A high‐resolution regional reanalysis for Europe. Part 1: Three‐dimensional reanalysis with the regional HIgh‐Resolution Limited‐Area Model (HIRLAM)

A regional reanalysis covering the years 1989–2010 has been produced with the HIgh Resolution Limited‐Area Model (HIRLAM) forecast model and data assimilation system. Surface and upper‐air variables were analysed at 0000, 0600, 1200 and 1800 UTC on a three‐dimensional grid‐mesh with 22 km spacing covering Europe using conventional insitu observations. Information from the global reanalysis ERA‐Interim has been used as a large‐scale constraint in the data assimilation and as lateral boundaries in the forecast model integrations. Comparison to the global forcing reanalysis shows good agreement in the large‐scale structures, as expected given the forcing from the boundaries and in the analysis. Comparison to the observed climatological distribution and a skill score evaluation showed that the HIRLAM reanalysis is better than ERA‐Interim at describing extreme values of 2 m temperature and 24 h accumulated precipitation. However, no added value in the HIRLAM reanalysis could be quantified for the wind speed at 10 m over land. The first production run covered the years 1989–2010 and the statistics presented in this paper are based on that dataset. This reanalysis has also been used as input to a two‐dimensional surface analysis using the MESoscale ANalysis (MESAN) system which is presented in Part 2. Since then both the two‐ and three dimensional reanalyses have been extended to cover the years 1979–2014.