Research Article

Impacts of Sea Surface Temperature and Atmospheric Teleconnection Patterns in the Northern Mid-Latitudes on Winter Extremely Cold Events in North China

Figure 3

The regional average series of the SSECE frequency (solid line) and its linear trend (dotted line) in North China in winter (a), December (b), January (c), and February (d) from 1980 to 2016 (unit: number of occurrences). One asterisk represents significance at the 95% confidence level using Student’s t-test.
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