Vertical extension of the Tibetan high of the Asian summer monsoon


*Corresponding author.


We illustrate the vast expanse and the connection of anticyclonic flows of the Tibetan high (at the 200 hPa level) to the pole centred hemispheric North Polar anticyclone at the 10 hPa level during 1988. This feature of clockwise flows appears in the form of a tilted cone that appears to connect the Asian summer monsoon to the 10 hPa high. The anticyclonic flow tapers down to the vortex of the cone near the 400 hPa level. The tropical easterly jet of the Asian summer season is found near 10°N, at the 200 hPa level. Summer monsoon rainfall resides on the poleward side of this jet where the circulation carries a large negative relative vorticity. Over these precipitating regions, large-scale upward motion contributes to a transport of negative vorticity into the lower stratosphere. We show that this region of the stratosphere carries the kinematics for a large conversion of anticyclonic shear vorticity into anticyclonic curvature vorticity. Four-dimensional parcel trajectories emanating and rising from this region slowly carve out the hemispheric anticyclonic gyre at the 10 hPa level (i.e.) the North Polar anticyclone. This kinematics plays an important role in establishing this tilted system and a connection with the 10 hPa circulation.