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Time series of 12 months running window averaged SWE for ERA5 (blue) and ERA5Snow (cyan) and ERAland (pink). Also included offline ERA5-Land re-run at the ERA5 resolution with single layer (black) and ERA5Snow multi-layer snow model (red).
Global and North America: Clear stepwise negative trend in 2004 in ERA5 due to absence/activation of IMS assimilation before/from 2004. ERA5snow and ERA5;and have similar trend but with no data assimilation ERA5land has more snow than ERA5snow which assimilates in situ observations
Europe: not strong impact of IMS activation in 2004, due to well constrained snow analysis by dense in situ observations. Similar trend the three products
References:
Arduini G., G. Balsamo, E. Dutra, J. Day, I. Sandu, S. Boussetta, T. Haiden Impact of a Multi‐Layer Snow Scheme on Near‐Surface Weather Forecasts, Journal of Advances in Modeling Earth Systems n. 12, pp. 4687–4710.
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Fairbairn, D., P. de Rosnay, and P. Browne: "The new stand-alone surface analysis at ECMWF: Implications for land-atmosphere DA coupling", Journal of Hydrometeorology 20, 2023-2042, 2019 https://doi.org/10.1175/JHM-D-19-0074.1
Mortimer, C., Mudryk, L., Derksen, C., ...Kelly, R., Tedesco, M. Evaluation of long-term Northern Hemisphere snow water equivalent products, Cryosphere, , ,
Zsoter, E., H. Cloke, E. Stephens, P. de Rosnay, J. Muñoz-Sabater, C. Prudhomme and F. Pappenberger: "How well do operational Numerical Weather Prediction setups represent hydrology?", in press Journal of Hydrometeorology, 2019, 20, 1533-1552, https://doi.org/10.1175/JHM-D-18-0086.1
Zsótér, E., C. Prudhomme, S. Harrigan, P. de Rosnay, J. Muñoz-Sabater, E. Stephens, "Trends in the GloFAS-ERA5 river discharge reanalysis", , ECMWF Technical Memorandum, TM-871, 2020, doi: 10.21957/p9jrh0xp