Previous studies showed that Antarctic ozone could modulate the Hadley circulation (HC) and precipitation in the Southern Hemisphere. However, whether and how, if any, Arctic stratospheric ozone (ASO) modulates the northern HC and subtropical precipitation remains unclear. We found an out‐of‐phase relationship between the northern HC extent (HCE) and ASO during boreal spring on interannual timescales during 1979–2014. Decreased (increased) ASO tends to result in an equatorward (poleward) shift of HCE by +0.67° (−0.45°) latitude per one standard deviation of decreased (increased) ASO year. Observational analysis and model simulations show that increased ASO leads to an equatorward shift of HCE and subtropical moistening via weakened eddy momentum flux and decreased subtropical static stability, accompanied with negative eddy momentum flux divergence anomalies and northward meridional wind anomalies over the subtropics. Our results may help to understand the linkage between the Arctic and midlatitudes, especially important for the subtropical precipitation and hydrological cycle.

Previous studies have reported that the tropospheric climate shifted around the 2000s, but the recent trend in the stratospheric wave intensity (SWI) is still unclear. The results in this study show that the SWI in December during 2001–2015 weakens, which is opposite to that during 1979–2000, implying a shift around the 2000s. The weakened SWI is dominated by its wave number‐1 component, which is related to the wave propagation impeded by the decreased refractive index at high latitudes and the weakened wave activity in the troposphere. Changes in refractive index are mainly contributed by changes in the meridional potential vorticity gradient via the barotropic term. This shift in the wave number‐1 waves leads to a shift in the stratospheric Arctic temperature, that is, warming (cooling) during 1979–2000 (2001–2015), implying that similar shifting phenomena may appear regardless of the continued greenhouse gas emissions.

The connections between the stratosphere and troposphere, for example, the stratospheric Arctic vortex (SAV) and Arctic Oscillation (AO), have been paid attention by scientists and the public in recent years. Previous studies suggested that the coupling between the stratosphere and troposphere is the strongest in winter. However, whether the link between SAV and AO during boreal winter on interannual timescales is steady is still unknown. Our results show that the interannual relationship between the SAV in early winter and AO in late winter during 1958–2018 is unsteady and has experienced a remarkable interdecadal change around the 2000s, with large and statistically significant positive correlations before the 2000s but small and insignificant correlations after the 2000s. The weakened linkage between the SAV and AO after the 2000s is possibly caused by (a) the weakened downward effect of SAV on the North Atlantic and polar sectors of AO, and (b) the opposite signs of sea level pressure (SLP) in the North Pacific and North Atlantic. The links of SAV‐AO are enforced (weakened) when AO‐related SLP anomalies over the North Pacific are the same (opposite) signs of those over the North Atlantic before (after) the 2000s. Differences in the tropospheric state over the North Pacific during two periods might be jointly contributed by the SAV and the SAV‐related significant (insignificant) sea surface temperature anomalies over central North Pacific in the earlier (latter) period. Our results may provide evidences to improve the predictability in seasonal or interannual timescales forecasts of weather and climate at mid‐latitudes.

Previous studies have paid much attention to the impact of major sudden stratospheric warming (SSW) events on the tropospheric circulation. However, the attention to the modulation of minor SSW events on the extreme cold events is limited. In this study, the extreme cold event in Siberia in the winter of 2000/2001, the longest-lasting one from 1980/1981 to 2019/2020, and its linkages to the minor SSW event have been examined. Our results show that the largest cooling occurred in Siberia during 30 December 2000 − 10 January 2001, and then the cooling weakened and migrated to Northeast China from 11 to 18 January 2001. During the recovery stage of this minor SSW event, the stratospheric polar vortex gradually strengthened, along with strengthening of the zonal winds over the Ural region. The vertical distribution of positive zonal wind anomalies in the Ural region favored the reflection of stratospheric planetary wave in the Atlantic-Euro and Siberia region. The changes of planetary wave propagation were beneficial to the strengthening of the trough in the Atlantic-Euro and Siberia region during 26 December − 10 January, which facilitated the growth and maintenance of the Ural ridge in the same period by strengthening the meridional flow. The strengthened Ural ridge resulted in the extreme cold event breaking out and lasting from 30 December to 10 January. Because the stratospheric polar vortex did not continue to strengthen and a new ridge generated in the Atlantic region during 11 − 18 January, the Ural ridge decayed and the cold air moved to Northeast China.