Monsoon

South Asian summer monsoon variations during interglacials (2 years)

Rapidly accumulating sediments from the Indus slope in the northeastern Arabian Sea are ideal for reconstructing the history of the South Asian summer monsoon (SASM) rainfall. By using the MARUM drill-rig MeBo200 to sample two sites off the Indus River mouth, it is planned to reconstruct temperature and rainfall changes during Marine Isotope Stages (MIS) 5, 11 and 21. Reliable SASM rainfall reconstructions from these interglacials do not exist so far, although MIS 11 around 400,000 years ago represents the best analog for present climate with similar sea level, greenhouse gas concentrations, and insolation forcing. This comparative analysis of interglacial SASM rainfall variability improves our understanding of the response and sensitivity of the SASM to different forcing mechanisms under different interglacial boundary conditions, as well as its connection to the other monsoon systems.

MARUM-Excellence cluster “The ocean floor”, RECORDER 1 "Perturbations" (2022-2025)

Sea surface tem­per­at­ure (SST) sim­u­la­tion is one of the main sources of er­ror for pro­ject­ing fu­ture rain­fall. De­ci­pher­ing the coup­ling between SST and mon­soonal rain­fall is thus cru­cial to bet­ter un­der­stand mon­soon dy­nam­ics and pro­ject the fu­ture de­vel­op­ment of mon­soon sys­tems. However, the con­nec­tion between SST and mon­soon rain­fall in the past has yet to be stud­ied in a sys­tem­atic ap­proach.

In this pro­ject, we will com­pile avail­able and newly gen­er­ated SST and rain­fall re­cords from the Aus­tralasian mon­soon realms to ana­lyze ex­ist­ing trends and vari­ab­il­ity across the Holo­cene and pre­vi­ous in­ter­gla­cial peri­ods as “warmer-than-present world” ana­logues. The proxy data basis will be com­bined with nu­mer­ical model sim­u­la­tions that ad­dress the SST in­flu­ence on mon­soon rain­fall.

Cental Asian Holocene Climate (2016-2019)

Modern observations and model simulations show that the position of the westerly winds is controlled by climate changes in the North Atlantic, confining the Asian monsoon range to the north. This correlation between the regional monsoon strength and the position of the westerly winds in Asia is of crucial importance for the precipitation regime in large parts of Asia. However, the brevity of the instrumental data series does not allow reliable conclusions on the periods and interactions of these climate phenomena.

This project tests the hypothesis that prolonged phases of the Atlantic Multidecadal Oscillation (AMO) or the North Atlantic Oscillation (NAO) can cause tipping points in the Asian monsoon climate due to a longterm shift in the westerly wind systems. For this purpose, new sediment archives in the westerly wind system (Kyrgyzstan), the Indian monsoon (northern Arabian Sea) and the East Asian monsoon (South China Sea) will be examined in order to improve our understanding about phase shifts and teleconnections between North Atlantic, westerly winds, and monsoon systems.

Natural versus anthropogenic controls of past monsoon variability in Central Asiarecorded in marine archives (2012-2014)

This project aims at a better understanding of monsoon dynamics at timescales of societal relevance. We employ high-resolution marine climate archives and novel proxies in combination with climate modeling in order to disentangle natural from human-induced variations in the South and East Asian monsoon systems, by using proxies that reflect environmental conditions on land, specifically, changes in vegetation, hydrological and carbon cycles.