Evaluating the land-surface energy partitioning in ERA5

• Published in: Geoscientific Model Development Vol. 13; no. 9; pp. 4159 - 4181
• Main Authors: Martens, Brecht, Schumacher, Dominik L, Wouters, Hendrik, Muñoz-Sabater, Joaquín, Verhoest, Niko E. C, Miralles, Diego G
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 09-09-2020; Copernicus Publications
• Subjects: Analysis; Atmosphere; Atmospheric boundary layer; Atmospheric models; Bowen ratio; Climate; Data assimilation; Datasets; Energy; Enthalpy; Evaluation; Experiments; Fields; Fluctuations; Heat; Heat flux; Heat transfer; Hydrology; Latent heat; Latent heat flux; Partitioning; Precipitation; Quality; Sensible heat; Sensible heat flux; Sensible heat transfer; Surface energy; Surface properties; Surface science; Turbulent fluxes; Weather; Weather forecasting
• ISSN: 1991-9603; 1991-959X; 1991-962X; 1991-9603; 1991-962X
• DOI: 10.5194/gmd-13-4159-2020

Climate reanalyses provide a plethora of global atmospheric and surface parameters in a consistent
manner over multi-decadal timescales. Hence, they are widely used in many fields, and an in-depth
evaluation of the different variables provided by reanalyses is a necessary means to provide
feedback on the quality to their users and the operational centres producing these data sets, and
to help guide their development. Recently, the European Centre for Medium-Range Weather Forecasts
(ECMWF) released the new state-of-the-art climate reanalysis ERA5, following up on its popular
predecessor ERA-Interim. Different sets of variables from ERA5 were already evaluated in a handful
of studies, but so far, the quality of land-surface energy partitioning has not been assessed.
Here, we evaluate the surface energy partitioning over land in ERA5 and concentrate on the
appraisal of the surface latent heat flux, surface sensible heat flux, and Bowen ratio against
different reference data sets and using different modelling tools. Most of our analyses point
towards a better quality of surface energy partitioning in ERA5 than in ERA-Interim, which may be
attributed to a better representation of land-surface processes in ERA5 and certainly to the
better quality of near-surface meteorological variables. One of the key shortcomings of the
reanalyses identified in our study is the overestimation of the surface latent heat flux over
land, which – although substantially lower than in ERA-Interim – still remains in ERA5. Overall,
our results indicate the high quality of the surface turbulent fluxes from ERA5 and the general
improvement upon ERA-Interim, thereby endorsing the efforts of ECMWF to improve their climate
reanalysis and to provide useful data to many scientific and operational fields.