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This study has discovered a significant linear relationship between the Southern Hemisphere (SH) annular mode (SAM) and the mid‐latitude Northern Hemisphere (NH) circulation in February using two reanalysis data sets. Significant positive height anomalies corresponding to the positive SAM appear over the mid‐latitude region of the NH, and significant positive surface air temperature anomalies prevail over Western Europe and Northeast Asia. The realistic vorticity forcing associated with the SAM is applied in a dry linear baroclinic model, and the results demonstrate that the SAM in February can induce height anomalies with the same sign at 300 hPa over the mid‐latitudes of the NH and that these anomalies have amplitudes as large as 22% of their counterparts in the SH. Further numerical experiments show that the positive height response over the mid‐latitudes of the NH mainly comes from the influence of the realistic positive vorticity over the mid‐latitudes of the SH and that the vorticity forcing over the southern Indian Ocean seems to be the most effective at exciting the NH circulation anomalies. The numerical experiments also demonstrate that the transient eddy feedback forcing contributes to the formation of mid‐latitude NH circulation anomalies, especially over Northeast Asia. The maintenance of the negative vorticity anomalies over Europe is further diagnosed through vorticity budget analysis. In December, however, the significant vorticity anomalies associated with the SAM are not limited to the middle and high latitudes of the SH but also appear over the subtropics of the SH (approximately 30°S). The numerical experiments show that cancellation occurs between the responses to the subtropical vorticity forcing and the mid‐latitude vorticity forcing, thereby accounting for the independence of the NH circulation from the December SAM variability. Simultaneous regression coefficients of the geopotential height at 300 hPa (a) and the surface air temperature (b) at 2 m on the Southern Hemisphere annular mode index in February. The contour intervals are 15 gpm for h300. For T2m, contours are drawn at every −2.5, −1.5, −0.5, 0.5, 1.5 and 2.5°C. In all of the panels, the red solid contours and the blue dashed contours denote positive and negative values, respectively. The zero lines are omitted. Shading denotes the statistically significant region at the 0.05 significance level. [ABSTRACT FROM AUTHOR]

• Two daily patterns of winter circulation responses to aerosols are identified. • Daily patterns are linked to tropical rainfall and extratropical transient eddies. • Seasonal mean changes can arise from certain daily response patterns. Anthropogenic aerosols (AA) have significantly caused anomalous winter mean atmospheric circulation over the Northern Hemisphere, but the main daily patterns of winter large-scale circulation change are not well understood. Here a self-organizing map analysis is applied to identify the leading patterns in AA-induced winter daily geopotential height (Z) anomaly fields simulated by three atmospheric general circulation models, with a focus on fast adjustments. Two winter daily circulation response patterns with a synoptic time scale are found: one pattern shows concurring Z anomalies over North America and North Asia with the same sign and the Bering Sea seeing the opposite, resembling the Asia–Bering–North American teleconnection; while the other is the Arctic Oscillation-like pattern with similar Z anomalies over North Pacific and North Atlantic and the opposite over the Arctic region. The AA-induced anomalous precipitation over the tropics and anomalous synoptic eddy activities over the extratropical oceans concur to support and maintain these circulation anomaly patterns. The winter-mean climate responses to AA can be understood as a result of these daily anomaly patterns, especially over the higher latitudes. Specifically, the associated changes in surface air temperature (SAT) over the mid-high latitudes are caused by the AA-driven meridional movements of polar (cold and dry) airmass and midlatitude (warm and moist) airmass in the regions, mainly through the relevant surface downward longwave radiation. This study highlights the role of AA in altering daily weather patterns, which is not sufficiently captured by seasonal mean responses. [ABSTRACT FROM AUTHOR]