ANALYTIC STUDY ON THE MECHANISM FOR LOW FREQUENCY TELECONNECTION AND HORIZONTAL PROPAGATION IN THE ATMOSPHERE

Abstract:

(1) Assuming that there is a zero-divergent layer in mid-troposphere, a diabatic and quasi-geostrophic equation set (bearing the format of that for barotropic vorticity) is derived by vertical integration of the thermodynamics equation and approximate description of anomalous tropospheric heating field in a simultaneous equation.(2) Discussing the spectral mean and group velocities, it is proved that the enclosed centers of the climatically mean geopotential field are no other than the atmospheric low-frequency oscillators ill the mid-and higher-latitudes. They have reversed variation of phase on two sides, with the energy supplied by the positive feedback of condensation by CISK or the sensible heat of sea temperature. (3) A formula is derived for low-frequency teleconnecting rays, which are shown to cross the streamlines southward in the northerly or northward in the southerly and to change direction of movement at the bottom of troughs or the top of ridges. Comparing to the great circle argument. the theoretic results above are more reasonable in explaining the observed low-frequency teleconnection in the Northern Hemisphere.