Reconstructed Snow Cover Datasets Provide No Evidence of Hemispheric Atmospheric Teleconnections Involving October Eurasian Snow Cover
Abstract
The local and remote impacts of Eurasian autumn snow cover on atmospheric circulation have been extensively studied, in particular, how Eurasian fall snow cover can influence the Northern Hemisphere atmospheric circulation via the generation of planetary scale Rossby waves that influence the Arctic Oscillation in a manner involving interactions with the wintertime Arctic stratosphere's circulation.
In this study, we revisit snow-atmosphere linkages with an updated snow dataset by exploring the impact of the October Eurasian snow cover extent (SCE) on different parameters. This was done by choosing high and low SCE years and making composites of other meteorological variables using those years. We used snow depth data reconstructed by a simple temperature index model based on Brown et al. (2003), using forcing data from the ECMWF Reanalysis, Version 5 (ERA5). The results are robust to the choice of other SCE datasets such as the NOAA-Rutgers Climate Data Record. In line with previous findings, we find that high SCE is associated with anomalously high SWE in the western Siberian sector. This SWE anomaly persists through November and is coincident with a negative temperature anomaly over the same region. There are also regional circulation anomalies that lead the onset of snow (anomalous cyclonic circulation in high vs. low snow years) and suggest a driving mechanism for snow anomalies involving advection of cold polar air. Even using various thresholds of SWE to define a minimum threshold for snow cover, there is no clear evidence of previously proposed teleconnections between October Eurasian snow cover and hemispheric scale wave anomalies, nor of circulation anomalies linking October Eurasian snow cover with the boreal winter Arctic Oscillation. However, the suggested regional atmospheric circulation anomalies that precede snow cover anomalies, and which link SWE and snow cover to Eurasian coastal regions, merit further investigation.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.A52L1123R