Could we explain the solar-QBO influence on the troposphere-stratosphere system?

Measurements and models' results show that solar and QBO signals found in many atmospheric parameters are comprehensively mixed. This makes a separation and explanation of the mechanisms of such an influence extremely difficult. A brief resume of the most known mechanisms, presented here, shows that neither of the existent hypotheses are able to explain the great variety of features and exceptions observed in Solar-QBO interrelations and their effect on the troposphere-stratosphere system. Unlike the traditional pathway for solar signal transition - from the upper stratosphere poleward and downward to the troposphere - we supposed that tropical UTLS region may be 'arena' for solar-QBO interactions. The main reason for this is a statistical result reported from many authors that the tropical UTLS is warmer: a) at solar maxima than at solar minima; and b) during west QBO phase than during east one. Moreover, the QBO amplitude is strongest in the lower stratosphere and the experimental evidence for its influence on the atmospheric parameters is remarkable. We recognized four main channels of this coupling: 1) Redistribution of the additional solar heating away from the tropical UTLS through the QBO induced secondary meridional circulation; 2) Feedback up effect of redirected solar signal on: i) circulation and, ii) planetary wave propagation conditions into the lower stratosphere; 3) Solar control over the wave propagation and Brewer-Dobson circulation in the middle and upper stratosphere; 4) Solar modulation of the QBO duration. (authors)