The Copernicus Climate Change Service of the European Commission aims to produce and deliver a land regional reanalysis for Europe covering the period from 1984 to the present at a horizontal resolution of 5.5 km.
The need for precipitation and surface variables at an ever-increasing spatial and temporal resolution is a recurrent demand. These variables allow, among other things, to address water resource management issues and to conduct climate change impact studies. Regional surface reanalyses are a way to reconstruct these variables for past periods covering several years using state-of-the-art models.
CERRA-Land (Copernicus European Regional Re-Analysis) is a regional land surface reanalysis dataset that describes the evolution of soil moisture, soil temperature and the snowpack. CERRA-Land is the result of a single stand alone integration of the SURFEX V8.1 land surface model driven by meteorological forcing from the CERRA atmospheric reanalysis and an offline analysis of daily accumulated surface precipitation using an optimal interpolation between an initial estimate (first guess) based on CERRA predicted precipitation and in situ rain gauges. The 2-meter temperature and relative humidity forcing data come from the CERRA surface analysis and the shortwave and longwave downwelling radiation, the 10-meter wind speed, and surface pressure come from the CERRA forecast outputs.
The CERRA-Land system uses the tiling approach where each grid-box of the model is divided into three different fractions: urban, lake and natural. For the nature fraction, the soil is discretized into 14 layers to accurately describe the water and energy transfers between the surface and the deep soil.
The quality of CERRA-Land is assessed by comparisons to ground-based observations, such as snow depth, 2-meter temperature, downwelling shortwave radiation and independent rainfall stations. A comparison with ERA5-Land will be done and the added value of the regional dataset will be discussed. The entire CERRA-Land dataset from 1984 to present is now available in the MARS database at ECMWF and will be available through the Copernicus Climate Data Store.
How to cite: Verrelle, A., Michael, G., Eric, B., and Le Moigne, P.: Strengths and weaknesses of the new CERRA-Land surface reanalysis at 5.5 km resolution over Europe, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-279, https://doi.org/10.5194/ems2022-279, 2022.
