On Wintertime Low Temperature of Jieyang and Its Extreme Events and Their Relationship with Low-frequency Oscillations
Based on the daily minimum temperature data from a national station in Jieyang and the NCEP/NCAR reanalysis from 1981 to 2020,this paper studied the minimum temperature and persistent ex-treme cold events(PECEs)in winter and their relationship with low-frequency oscillations in the city using the methods of relative thresholds and power spectra.The results are shown as follows.For Jieyang,the minimum temperature of winter had significant oscillations at 10 to 30 d(quasi-biweekly oscillation)and at 30 to 90 d(intraseasonal oscillation),being an important modulator for the genesis of PECEs.It was shown that 60％of the PECEs are affected by coupled variability of both the 10 to 30 d and 30 to 90 d oscillations,30％by the variability of the 10 to 30 d oscillation only and 10％by the variability of the 30 to 90 d oscilla-tion only.Low-frequency circulation wavetrains at the mid-and higher-latitudes play a role in the southward movement of low-frequency cold air by modulating the changes in intraseasonal location and intensity of a major high in Siberia and a main trough in East Asia,causing persistent drop in the low-frequency compo-nent of the city's minimum temperature that favors the occurrence of PECEs.
万方数据
维普
