Monopol (Indian MONsOon PaleO-variabiLity) (2012-2016) & DIPOMOUSS (2019-2020)
ANR (2012-2016) / IFREMER (2019-2020)
F. Bassinot (LSCE)
GEOPS (Univ. Paris Saclay, campus Paris Sud Orsay)
CEREGE (CNRS-Univ. Aix-Marseille)
EPOC (CNRS – Univ. Bordeaux I)
IPGP (Univ. Paris-Diderot)
Tongji University (Shanghai)
China University of Geosciences (Pékin)
Peking University (Pékin)
The Indo-Asiatic monsoon is a major climatic phenomenon due to its economic and social impacts on one of the most densely populated regions of the world, and because of the scale of the heat and humidity transfers involved; in short, it is an essential element of the planet’s climate. The natural variability of the Indo-Asiatic monsoon, is however, not fully understood and its future evolution is difficult to model because of the complexity of the processes and the interactions involved (i.e. ocean dynamics, vegetation response, teleconnections with middle and high latitudes, monsoon/ENSO/IOD/ITF coupling).
The MONOPOL and DIPOMOUSS projects aim to study the water and sediments of the Tropical Indian Ocean (East and Central) in order to reconstruct the past variability of the Indo-Asiatic monsoon and its sensitivity to various types of forcing over the course of the Quaternary. They are based on the study of water samples and sedimentary cores taken in 2012 during the MONOPOL oceanographic expedition (on board the N/O Marion Dufresne II) and on further samples that will be taken in 2020 during the DIPOMOUSS campaign; the latter will employ rosettes, CASQ and CALYPSO corers and an interface (multi-tube) corer. The projects involve six laboratories – CEREGE, EPOC, GEOPS, IPGP, LSCE and MNHN- and are part of an international collaboration undertaken within the IGBP/PAGES – IMAGES programme (International Marine Global Changes Study).
Photograph of the Marion Dufresne taken during the MONOPOL oceanographic mission (Gulf of Bengal). Photo credit: Stéphanie Duchamp-Alphonse
In concrete terms, the paleooceanographic and paleoclimatic reconstructions are based on a multi-tracer approach which includes biological tracers (e.g. studies of calcareous nanofossil and pollen assemblages), sedimentary tracers and geochemical tracers (e.g. Ti/Al, δ18O, Mg/Ca). Past changes in alteration in the Himalayas linked to variations in the monsoon are identified on the basis of analysis of sedimentary tracers (clays, laser granulometry) and geochemical tracers (major and trace elements combined with Nd, Sr and Pb isotopes).
Our team focuses in particular on the Indian monsoon and its impact on the following dynamics: (i) Himalayan erosion and the transfer of sediments to the ocean as well as the distribution of Nd isotopes in the Bay of Bengal and their past evolution (the impact of erosion); (ii) Surface waters and thermocline/nutricline depth, which have a considerable impact on primary producers (particularly coccolithophores); and iii) the hydrology of subsurface and intermediate waters at the scale of glacial-interglacial cycles.
Photograph of the multi-corer used on board the Marion Dufresne, during the MONOPOL oceanographic mission: it allows samples to be taken from the water-sediment interface in the Gulf of Bengal. Photo credit: Stéphanie Duchamp-Alphonse