Abstract
An observational study illustrates that three distinct modes of winter Siberian high variability exist in observations at the inter-annual time scale. In this paper, we compare the connection between these diverse Siberian high variation modes with pre-autumn and simultaneous Eurasian snow cover in an observation and BCC-CSM2-MR coupled climate model run under pre-industrial conditions from the CMIP6 project. Our analyses indicate that the inter-annual variation of observed Siberian high modes do have a connection with pre-autumn and simultaneous Eurasian snow cover anomalies, but the BCC-CSM2-MR coupled climate model does not capture the observed diverse Eurasian snow–Siberian high relationships well. The BCC-CSM2-MR coupled climate model can partly reproduce the observed Siberian high variation modes, but fail to capture the spatial distribution and statistics of boreal fall and winter Eurasian snowpack, which is a key facet of simulated diverse Siberian high variability irrespective of the influence of Eurasian snow cover.
Highlights
The Siberian high (SH) is the most conspicuous pressure system found in the Northern Hemisphere during wintertime (Lydolf, 1977)
The BCC-CSM2-MR model cannot reproduce the observed diverse connections between the winter SH and preceding autumn Eurasian snow variations, which is possibly related to the poor ability of the model in simulating the Eurasian snow cover fraction and snow depth
The original contributions presented in the study are included in the article/Supplementary Material
Summary
The Siberian high (SH) is the most conspicuous pressure system found in the Northern Hemisphere during wintertime (Lydolf, 1977). With the influence of the SVD-SC3 mode (Figures 6H,I), the enhanced snow cover over the northeastern Siberian Plateau and less snow cover over the Ural region persists from later autumn into winter (Figures 9A,B), and it modulates the mid-latitude circulation resembling the POLEUR teleconnection pattern through synoptic eddy-vorticity forcing response (Figure 9C), which further impacts the occurrence of SH-EOF 3 mode as in Figures 3E,F; Table 1. Associated with variation in the simulated EOF2 mode, a similar east–west dipole pattern is observed in the SLP and 500-hPa geopotential height anomaly fields over the Eurasian continent (Figures 11C,D). The SLP and 500-hPa geopotential height anomalies associated with the simulated EOF3 mode both show a wavy pattern over the Eurasian mid–high latitudes (Figure 11E), with alternating positive and negative anomalies over southeastern Europe, the northern Siberian plateau–Arctic Ocean, and northeastern Asia. Future modeling studies should focus on assessing this snow cover/snowfall issue
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