1) Land reanalysis set-up
SnowPEX-2 is the second snow products inter-comparison coordinated by ENVEO and ECCC. It includes snow cover and snow water equivalent products.
...
The full period 1980-2020 is covered with 41 streams experiments initialised on 1st of July of each year. The list of experiment is given below. They are reading in the ERA5 atmospheric anlaysis. The experiments are all conducted at the same resolution than ERA5 (TL639).
| ERA5Snow-SL | ERA5Snow-SL | |||
|---|---|---|---|---|
| January to June | July to December | January to June | July to December | |
| 1980 | hhnb | hhnb | ||
| 1981 | hhnb | hhnc | ||
| 1982 | hhnc | hi43 | ||
| 1983 | hi43 | hhnd | ||
| 1984 | hhnd | hi45 | ||
| 1985 | hi45 | hhne | ||
| 1986 | hhne | hi47 | ||
| 1987 | hi47 | hhnf | ||
| 1988 | hhnf | hi48 | ||
| 1989 | hi48 | hhnh | ||
| 1990 | hhnh | hi49 | ||
| 1991 | hi49 | hhni | ||
| 1992 | hhni | hi4c | ||
| 1993 | hi4c | hhnj | ||
| 1994 | hhnj | hi4g | ||
| 1995 | hi4g | hhnl | ||
| 1996 | hhnl | hi4i | ||
| 1997 | hi4i | hhnm | ||
| 1998 | hhnm | hi4o | ||
| 1999 | hi4o | hhnn | ||
| 2000 | hhnn | hi4s | ||
| 2001 | hi4s | hhno | ||
| 2002 | hhno | hi4t | ||
| 2003 | hi4t | hhnp | ||
| 2004 | hhnp | hi4w | ||
| 2005 | hi4w | hhnq | ||
| 2006 | hhnq | hi4x | ||
| 2007 | hi4x | hhnr | ||
| 2008 | hhnr | hi4z | ||
| 2009 | hi4z | hhqp | ||
| 2010 | hhqp | hi50 | ||
| 2011 | hi50 | hhqq | ||
| 2012 | hhqq | hi51 | ||
| 2013 | hi51 | hhqr | ||
| 2014 | hhqr | hi53 | ||
| 2015 | hi53 | hhqs | ||
| 2016 | hhqs | hi54 | ||
| 2017 | hi54 | hhqt | ||
| 2018 | hhqt | hi55 | ||
| 2019 | hi55 | hhqu | ||
| 2020 | hhqu | hi56 |
SWE and snow density are extracted on a 0.25 regular gid and converted into NetCDF (script to extract SnowPEX data)
2) Example of the results from SnowPex-SL compared to ERA5
3) Trends
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 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.
...
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