Towards a high‐resolution regional reanalysis for the European CORDEX domain

Abstract

Atmospheric reanalyses covering the European region are mainly available as part of relatively coarse global reanalyses. The aim of this article is to present the development and evaluation of a next generation regional reanalysis for the European CORDEX EUR-11 domain with a horizontal grid spacing of approximately 6 km. In this context, a reanalysis is understood to be an assimilation of heterogeneous observations with a physical model such as a numerical weather prediction (NWP) model. The reanalysis system presented here is based on the NWP model COSMO by the German Meteorological Service (Deutscher Wetterdienst) using a continuous nudging scheme. In order to assess the added value of data assimilation, a dynamical downscaling experiment has been conducted, i.e. an identical model set-up but without data assimilation. Both systems have been evaluated for a 1 year test period, employing standard measures such as analysis increments, biases, or log-odds ratios, as well as tests for distributional characteristics. An important aspect is the evaluation from different perspectives and with independent measurements such as satellite infrared brightness temperatures using forward operators, integrated water vapour from GPS stations, and ceilometer cloud cover. It can be shown that the reanalysis better resolves local extreme events; this is basically an effect of the higher spatio-temporal resolution, as known from dynamical downscaling approaches. However, an important criterion for regional reanalyses is the coherence with independent observations of high temporal and spatial resolution, resulting in significant improvement over dynamical downscaling. The system is intended to become operational within a year, continuously reprocessing and evaluating longer time periods. The reanalysis data are planned to become available to the research community within a year.

Improving soil moisture and runoff simulations over Europe using a high-resolution data-assimilation modeling framework

“…The high-resolution reanalysis COSMO-REA6 dataset (Bollmeyer et al, 2015) from the Hans-Ertel Centre for Weather 15 Research (HErZ; Simmer et al, 2016) for the time period of 2000-2006 was used as the atmospheric forcing for CLM3.5.…”

Towards a probabilistic regional reanalysis system for Europe: evaluation of precipitation from experiments

“…The reanalysis system to be introduced has been advanced from a deterministic nudging regional reanalysis system that employs the limited-area model COSMO (Bollmeyer et al, 2015).…”

“…This service will provide consistent estimates of essential climate variables (Bojinski et al, 2014) to support policy and decision makers and different sectors of public. The regional reanalysis systems currently available for the EuropeanAtlantic region include a Met Office system (Jermey and Renshaw, 2016) at 12 -km grid spacing, a system of the Swedish Hydrological and Meteorological Institute at 22-km resolution Landelius et al, 2016) and a high-resolution system of the German Hans-Ertel Centre for Weather Research (Simmer et al, 2016) at a 6-km grid spacing (Bollmeyer et al, 2015).…”

Met Éireann high resolution reanalysis for Ireland

“…Over sea grid-points the geopotential fields used to plot the model orographies show "spectral ripples", which are a reflection of the fact that the ERA-Interim and HARMONIE models are defined in spectral space. Several regional reanalyses have already been produced including, for example, the Arctic Reanalysis ASR (Bromwich et al, 2010(Bromwich et al, , 2000(Bromwich et al, -2010, the Baltic Sea reanalysis (Luhamaa et al, 2011(Luhamaa et al, , 1965(Luhamaa et al, -2005, COSMO-REA6 (Bollmeyer et al, 2015(Bollmeyer et al, , 1997(Bollmeyer et al, -2004, the HIRLAM reanalysis (Dahlgren et al, 2016(Dahlgren et al, , 1979(Dahlgren et al, -2014, the North American Regional Reanalysis (Mesinger et al, 2006(Mesinger et al, , 1979(Mesinger et al, -2003 and the South Asian Regional Reanalysis (Kar et al, 2016(Kar et al, , 1998(Kar et al, -2002 dress this, we have run the HARMONIE-AROME canonical configuration of the ALADIN-HIRLAM system on a 2.5 km horizontal grid for the 35-year period 1981-2015 forced by ERA-Interim lateral boundary conditions, with the aim of improving our knowledge of surface parameters and extremes. Inspiration for this project came from KNMI's production of a 35-year wind atlas for the North Sea (KNWatlas;1997-2013Stepek et al, 2015) which was also produced using the ALADIN-HIRLAM system.…”