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

Figure 4

The linear trend distribution of the SSECE frequency in winter (a, e), December (b, f), January (c, g), and February (d, h) in North China during the periods of 1980–2007 (left) and 2009–2016 (right); unit: number of occurrences/a, areas shaded with black dots represent significance at the 90% confidence level using Student’s t-test. (a) Winter_phase I (1980–2007), (b) Dec_phase I (1980–2007), (c) Jan_phase I (1980–2007), (d) Feb_phase I (1980–2007), (e) Winter_phase II (2009–2016), (f) Dec_phase II (2009–2016), (g) Jan_phase II (2009–2016), and (h) Feb_phase II (2009–2016).

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