Correlation between Solar Activity and Winter/Spring Snow over the Tibetan Plateau on Multi-timescale and Atmospheric Circulation in East Asia

Abstract:

Detecting the influence of solar activity on snow is of very meaningful for understanding global change. However, the previous studies in this field were quite limited. Using statistical tools, this paper tries to detect correlation between solar activity (including Solar Radiation Flux SRF, Total Solar Irradiance TSI and Solar Sunspot Number SSN) and winter/spring snow (including winter/spring snow depth and snow day number) over the Tibetan Plateau with gauge data for 1961-2011. This paper also detects the connection between solar activity and East Asian atmospheric circulation. We studied the correlation between solar activity and Arctic Oscillation and the East Asian winter monsoon, which are typical winter modes of the atmospheric circulation in East Asian. The result shows that on interdecadal time scale the correlation between solar activity and snow is more significant than raw data, especially after removing 11-yr solar cycle. It indicates that the sun leads and modulates interdecadal change of winter/spring snow over the Tibetan Plateau and East Asian atmospheric circulation. We find that comparing to winter snow, spring snow has closer relationship to solar activity, especially spring snow day number has significant simultaneous and lag time correlation with three parameters of solar activity no matter on short or long time scales. At the first (third) 11-yr lag years, the correlation coefficients between spring snow day number and SRF, SSN (TSI) have passed 0.01 significance level using Monte-Carlo test method. Our study exposes that winter/spring snow over the Tibetan Plateau has significant simultaneous and lag time correlation with Arctic Oscillation and the East Asian winter monsoon on interdecadal time scale. With more snow, the Arctic Oscillation is in positive phase, and East Asian winter monsoon is weak; vice versa. In 2012/2013 winter, the fact of less snow over the Tibetan Plateau, negative phase of Arctic Oscillation and strong East Asian winter monsoon is an example. Finally, we try to explore the physical mechanism of connecting solar activity to snow over the Tibetan Plateau, and give some reasonable explanation for the results obtained above.

Keywords: solar activity； correlation analysis； snow over the Tibetan Plateau； Arctic Oscillation；East Asian winter monsoon