Preprints
https://doi.org/10.5194/egusphere-2022-939
https://doi.org/10.5194/egusphere-2022-939
15 Nov 2022
 | 15 Nov 2022

Forcing and impact of the Northern Hemisphere continental snow cover in 1979–2014

Guillaume Gastineau, Claude Frankignoul, Yongqi Gao, Yu-Chiao Liang, Young-Oh Kwon, Annalisa Cherchi, Rohit Ghosh, Eliza Manzini, Daniela Matei, Jennifer Mecking, Lingling Suo, Tian Tian, Shuting Yang, and Ying Zhang

Abstract. The role of surface ocean anomalies for the continental Northern Hemisphere snow cover is investigated, together with the interactions between snow cover and atmosphere. Four observational datasets and two large multi-model ensembles of atmosphere-only simulations are used, with prescribed sea surface temperature (SST) and sea ice concentration (SIC). A first ensemble uses observed interannually varying SST and SIC conditions for 1979–2014, while a second ensemble is identical except for SIC where a repeated climatological cycle is used.

SST and external forcing typically explain 10 to 25 % of the snow cover variance in model simulations, with a dominant forcing from the tropical and North Pacific SST, while no robust influence of the SIC is found. In observations, the Ural blocking is the main driver of the November and April snow cover over Eastern Eurasia, while the North Atlantic Oscillation (NAO) dominates the snow cover forcing in January. In November and more robustly in January, dipolar anomalies of snow cover over Eurasia, with positive anomalies over Europe and negative anomalies over Southern Siberia, also precede the Arctic Oscillation (AO) by one month. In models, snow cover over western Eurasia in January also precedes by one or two months a negative AO phase. The detailed outputs from one of the models suggest that both the western Eurasia snow cover and polar vortex are generated by Ural blocking, and that both snow cover and polar vortex anomalies act to generate the AO one or two months later.

Guillaume Gastineau et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2022-939', Joaquin Munoz-Sabater, 23 Nov 2022
    • CC2: 'Reply on CC1', Guillaume Gastineau, 05 Jan 2023
  • RC1: 'Comment on egusphere-2022-939', Anonymous Referee #1, 14 Dec 2022
  • RC2: 'Comment on egusphere-2022-939', Anonymous Referee #2, 06 Jan 2023
  • RC3: 'Comment on egusphere-2022-939', Anonymous Referee #3, 10 Jan 2023

Guillaume Gastineau et al.

Guillaume Gastineau et al.

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Short summary
Snow cover variability is important for many human activities. This study aims to understand the main drivers of snow cover in observations and models, in order to better understand it and guide the improvement of forecasting systems. Analyses reveal a dominant role for sea surface temperature in the Pacific. Winter snow cover is also found to have important two-way interactions with the troposphere and stratosphere.