In December 1958, the subtropical jet stream displaced, on a large-scale, into North America and then towards the end of the month, also into Western Europe. The largescale displacement of the subtropical jet stream and the related behavior are described in relation to the general circulation of middle- and higher-latitudes.
The interaction between the mid-latitude circulation and the tropical one is important for thedisplacement', but the manner in which the former acts upon the latter is different for different places. Over the eastern Pacific, it was done through the formation of an extended and sharp trough of the mid-latitude westerlies. While, over the Atlantic it was performed by the amalgamation of the migrating anticyclone with the subtropical high.
Due to the outbursts of cold air in front of the ridge, the subtropical jet stream which had meandered strongly into mid-latitudes was broken-off from the southern part, and was left behind in mid-latitudes, and then disappeared as the subtropical high on its south side declined.
The large-scale displacement of the subtropical jet stream acts as a trigger of the change of circulation features, and has a remarkable influence upon the general circulation of the middle- and higher-latitudes.
On the south side of the ‘normal’ subtropical jet stream, another core of strong wind is sometimes observed over Cuba and the neighbourhood, near Japan and northern Africa in winter, which seems to be related to the deeply penetrating cold outbreaks over the relatively warm sea surfaces.
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