EFFECTS OF SOLAR-ACTIVITY AND STRATOSPHERIC QBO ON TROPICAL MONSOON RAINFALL

A study on the influence of solar activity and phases of equatorial qu asi-biennial oscillation (QBO) on tropical rainfall over India has bee n made. The results of the total rainfall I,ver the country indicate t hat during the period of low solar activity, excess/normal rainfall (f requent fl(,ods) are associated with the westerly phase of QBO and def icient/normal rainfall (frequent droughts) cot responded to the easter ly phase. During the period of high solar activity only normal rain is observed when QBO is in its westerly phase. Multiple regression analy sis has employed to estimate the summer monsoon rainfall using sunspot number and equatorial zonal wind at 15-20 hPa during January-February as independent parameters. A study on the spatial variability of mons oon rainfall in response to the solar activity and phases of QBO has a lso been attempted.