Article
Solar influences on spatial patterns of Eurasian winter temperature and atmospheric
Journal of Geophysical Research
Haishan Chen, Hedi Ma, Xing Li, Shanlei Sun
Abstract
Solar influences on spatial patterns of Eurasian winter climate and possible mechanisms are investigated based on a multiple linear regression method and multisource observational and reanalysis data. Robust and significant solar signals are detected in Eurasian surface air temperature (SAT), and strong solar activity evidently warms most area of the continent. The spatial pattern of sea level pressure (SLP) responses to solar activity is similar but not identical to that of the North Atlantic Oscillation (NAO). Compared to the NAO, geographic distribution of solar-induced SLP anomalies shifts eastward, with significantly enhanced influences over northern Eurasia. Relatively weaker solar signals were also found in mid-to-upper troposphere. The spatial pattern of 500?hPa geopotential anomalies resembles a negative Scandinavia teleconnection pattern, and the 200?hPa subtropical jet is weakened, while zonal wind at high latitudes is enhanced due to strong solar activity. The anomalous zonal circulations can be attributed to the “top-down” mechanism. During high solar activity winters, an enhanced stratospheric zonal wind anomaly propagates downward, causing zonal wind anomalies in the troposphere. However, the “bottom-up” mechanisms may provide more reasonable explanations of the distinct solar influences on Eurasian climate. Solar-induced strong warm advection in lower atmosphere tends to increase SAT but decrease SLP, resulting in enhanced solar influences over northern Eurasia. Meanwhile, change in the land-ocean thermal contrast (LOTC) could also amplify the circulation anomaly. Inhomogeneous surface heating caused by anomalous solar activity modifies LOTC, which probably enhances the solar-induced circulation patterns. Such a positive feedback may potentially strengthen the solar influences.
http://onlinelibrary.wiley.com/doi/10.1002/2015JD023415/full
