Influence of Atmospheric 10–20 Day Low Frequency Oscillation on Regional Strong Cooling Events in the Winter of Northern China over the Past 40 Years

Using daily minimum temperature data at 2481 stations provided by the National Meteorological Information Center (China) and reanalysis from NCEP/NCAR during period 1980 to 2019, effects of atmospheric low frequency oscillations (LFOs) on regional strong cooling events (RSCEs) in winter northern China are investigated, extended range forecast signals RSCEs extracted. The results show that: (1) is higher before year 2000 then decreases, but its interannual variability increases. There 10–20, 20–30 30–60 d significant periods average China, oscillation with a 10–20 most significant. (2) key systems affecting west, middle, east Ural blocking high trough Lake Balkhash-Baikal (Lake Ba-Bei), northwest southeast Ba-Bei, Ba-Bei East Asian trough, respectively, Siberian High (SH) that expands moves all time. jets upper level weaker north stronger south. (3) potential vorticity (PV) center lower stratosphere eastward southward along 315 K isentropic surface via southern Baikal Northeast Sea Japan, causing 2 PVU line move above-mentioned PV mid-high troposphere extend vertically. Meanwhile, under influence gradually increasing vertical meridional circulation, column continues propagate downward mid-low latitudes 300–315 surfaces, which enhances positive deepens trough. In addition, convergence troposphere, divergence layer, development descending motion behind lead movement SH. (4) At −10 d, negative anomalies 500 hPa geopotential height appearing European Plain Western for respectively.