Abstract
Recent studies of correlations between solar flux and Northern Hemisphere wintertime tropospheric fields have suggested that sun-weather effects at the solar-cycle time scale may exist and be mediated by the phase of the quasi-biennial oscillation (QBO). In this study similar correlations are calculated for all warns at five levels in the troposphere in order to further define the nature of the possible QBO effect. Sets of 38-year monthly mean radiosonde and NMC winds and temperatures at 176 Northern Hemisphere locations are compared with a composite 10.7 cm solar flux-QBO wind index.
When the correlation analyses are judged on the basis of an expected winter effect as reported in other investigations, they are found to be significant. As there is at present no well-developed hypothesis for a sun-weather effect, however, the significances must also be viewed from the standpoint of no a priori knowledge. In this case their significance is questionable at best.
The results corroborate the complex correlation patterns of past studies. At 10 kPa the winter temperature fields show a large degree of zonal symmetry and appear centered on or near the pole. The 10- and 70-kPa level temperature patterns are of opposite phase. The winter correlations between the composite index and temperature are positive during the westerly phase of the QBO and negative during the easterly phase. Winds attributable to the observed correlations support the contention that storm tracks in the North Atlantic may vary in latitude with the changes in solar flux and QBD phase, A summer correlation is observed in temperature and winds that shows only modest change with phase of the QBO. This correlation is largely positive during both phases and also shows the vertical phase shift men in the winter patterns.
