Interannual Variability Of Indian Summer Monsoon: Role Of Tbo: Tropospheric Biennial Oscillation And Indian Summer Monsoon In Presence And Absence Of Enso And Iod

The socio-economic progress of a country like India strongly depends on agricultural sector and related industries and thereby to the timely and sufficient summer monsoon rainfall. So understanding of the variabilities of the summer monsoon is very important. The interannual variability of summer monsoon corresponds to biennial scale (TBO) and multi-year scale variability (ENSO). The relationship of interannual variability of monsoon to ENSO is established earlier, though the reverse relationship is weakening in recent decades. Different mechanisms involving coupled ocean-atmosphere processes in the Indo-Pacific regions are proposed to explain the mechanism of TBO. But the monsoon-TBO interaction, effect of Pacific and Indian Ocean dynamics on TBO, relationship with stratospheric QBO and boreal summer ISO like factors are not studied in detail. The present work analyses the above factors of TBO with the help of NCEP/NCAR reanalysis data sets, ISMR index, Indian monsoon rainfall and zonal wind and temperature of ECMWF.