A 500,000 year record of Indian summer monsoon dynamics recorded by eastern equatorial Indian Ocean upper water-column structure

LA‐ICPMS Ba/Ca analyses of planktic foraminifera from the Bay of Bengal: Implications for late Pleistocene orbital control on monsoon freshwater flux

“…On orbital timescales, monsoon proxy records are forced in part by low‐latitude northern hemisphere summer insolation [e.g., Wang et al ., ]. However, different proxies lag insolation maxima by differing amounts, particularly within the precession band [e.g., Bolton et al ., ]. In order to address current uncertainties regarding the potentially indirect relationship between existing palaeomonsoon indices and precipitation amount/source (as opposed to wind stress), we have produced the first direct reconstructions of central Bay of Bengal (proportionally related to salinity), based on planktic foraminifera Ba/Ca measurements.…”

Orbital Asian summer monsoon dynamics revealed using an isotope-enabled global climate model

“…These deposits have been widely interpreted as records of changing intensity of the summer monsoon precipitation at orbital scales. However, interpretation of the speleothem d 18 O record is complex and is a subject of considerable debate [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] . Studies point to the potential control of seasonality, as well as large-scale atmospheric circulation effects in addition to the amount of Asian summer monsoonal rainfall on the d 18 O signal 11,12,17,18 .…”

“…The speleothem d 18 O records over Asia seem to be forced mainly and directly by local orbitally forced insolation [3][4][5]9,20,21 . On the contrary, a large variety of other Indo-Asian summer monsoonal records (marine and continental records documenting winds and precipitation) suggest a sensitivity to northern hemisphere summer sensible heating (insolation), the timing of energy release from the southern hemisphere Indian Ocean and the timing of global ice-volume minima 6,7,[11][12][13][14]16 .…”

“…8). Similarly, the monsoon winds could be affected by such ocean internal feedback not only from the Pacific 15 , but also from the southern Indian Ocean 6,7,[11][12][13][14]16,29 and lead to different timing. Our study therefore highlights a complex Asian monsoon dynamic with distinct response inside the monsoon system.…”

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“…Parts of the uppermost sections are almost entirely depleted, and sampling has moved to the archive half. Recent research using Site 758 sediments include high-resolution (suborbital) late Pleistocene reconstruction of changes in upper water column structure based on multispecies planktonic foraminifer records (Bolton et al, 2013), reconstruction of the Li isotope composition of seawater over the past 70 My (Misra and Froelich, 2012), Late Cretaceous to early Eocene reconstruction of seawater neodymium (Le Houedec et al, 2012), and glacial-interglacial scale reconstruction of Os isotopic composition of seawater (Burton et al, 2010). Drilling Site U1443 had the following main objectives:…”