Tropical forcing of the circumglobal teleconnection pattern in boreal winter

Recently there has been an increase in interest in hemispheric-scale teleconnections. The circumglobal teleconnection pattern (CGT) is a special zonal phase of the jet whereby disturbances originating near the South Asian jet entrance, or within the jet, remain trapped and can propagate around the globe. Recent studies have shown that this CGT pattern affects climatic conditions across the entire hemisphere, from North America to Europe to South Asia. The CGT is generally thought of as an internal mode of atmospheric variability, but this study aims to examine whether the CGT can be forced during the boreal winter when the jet is at its peak amplitude. To accomplish this, we make use of a simple general circulation model to test whether an imposed diabatic heating anomaly in the tropics can force the CGT. Results from the simple model show that heating over the equatorial Indian Ocean and cooling over the western Tropical Pacific Ocean can drive a CGT-like pattern. Lagged regression using pentad reanalysis data supports these results, showing that a dipole convection pattern in these same regions precede the CGT.

Automated summary

Recent studies have shown that the South Asian jet can affect climatic conditions across the entire hemisphere. The study found that during the boreal winter in the Northern Hemisphere, imposing a diabatic heating anomaly in the tropics can force a CGT pattern.