Investigating the dynamical behavior of the Intertropical Convergence Zone since the last glacial maximum based on terrestrial and marine sedimentary records

The Intertropical Convergence Zone (ITCZ) is an integral component of the earth's climate system. It plays important roles in monsoon precipitation, transport of chemical tracers between the hemispheres, ENSO variability etc. The ITCZ is characterized by seasonal movement that stays several degrees north of the equator during the boreal summer and a few degrees south of the equator during the boreal winter. The seasonal movement across the hemisphere is driven by seasonal changes in insolation. Apart from seasonal migration ITCZ also moves in longer timescales that is governed by the orbital motion of the earth as well as by the internal dynamics of the earth's ocean-atmospheric variability. Proxy records indicate the mean position of the ITCZ of the Indian Ocean sector was somewhat different relative to its estimated position considering solar insolation variability in orbital time scale. In this paper we investigate the movement of the ITCZ that occurred in millennium time scales and discuss its implications mainly on South Asian monsoon variabilities. The study relies on proxy data; the isotopic analysis of foraminifera and speleothem. One of the important implications of this study is that the Indian summer monsoon rainfall which is undergoing a slow decreasing trend for the last several decades is expected to experience a reverse trend in a few decades.