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Dr. Martina Hollstein

Postdocs

Group: 

Marine Sedimentology

Phone: 

+49 421 218-65687

Email:

Room: 

MARUM II, 3290

Martina Hollstein

PhD project

Hydrology of the Western Pacific Warm Pool and its impact on the IndonesianThroughflow

The Western Pacific Warm Pool (WPWP) encompasses the equatorial western Pacific Ocean and the Indonesian Seas, where sea surface temperatures exceed 28°C. Due to these high temperatures, the WPWP is a main source area of heat and water vapour to the global atmosphere with potentially far reaching climate impacts. Furthermore, the Indonesian seas provide pathways for the transport of near-surface (surface and thermocline) water masses from the Pacific to the Indian Ocean via the Indonesian Throughflow (ITF). As the ITF is the only tropical interoceanic conduit it is of major importance for the regulation of salinity and heat budgets of the Pacific and Indian oceans and is thought to play a major role in the return branch of the global overturning circulation.

Despite its importance for the global atmospheric and ocean circulation systems, there is still discussion about past WPWP climate and ocean dynamics. Especially, records from sites located east of Indonesia and Papua New Guinea are sparse although the area is crucial for our understanding of WPWP climate and ITF source water masses of South Pacific origin.

The aim of my study is to improve our understanding about the relative influence of several forcing factors on the WPWP hydroclimate as well as to decipher how water masses from southern Pacific influenced the ITF in the past. For this purpose I will primarily measure Mg/Ca ratios and the stable isotope compositions in shells of shallow dwelling planktic foraminifera from sediment cores retrieved northeast of Papua New Guinea. In combination, these proxies can be used to reconstruct near-surface temperature and salinity variations (two key components to assess past climate and ocean dynamics) on different timescales.

 

Academic CV

03.2018

PhD: "Variations in surface and thermocline conditions of the Western Pacific Warm Pool - Insights from Mg/Ca and stable isotopes in foraminifera tests"

11.2014-10.2017 Research associate at MARUM - University of Bremen
06.2015-09.2015 Research Stay at the Institute of Marine and Coastal Sciences (IMCS) - Rutgers University (New Brunswick, USA)
2010-2013 MSc Marine Geosciences at the University of Bremen
2007-2010 BSc Geosciences at the University of Bremen

 

 

Publications

Hollstein, M., Mohtadi, M., Rosenthal, Y., Prange, M., Oppo, D., Martínez Méndez, G., Tachikawa, K., Moffa Sanchez, P., Steinke, S., Hebbeln, D.. Variations in Western Pacific Warm Pool surface and thermocline conditions over the past 110,000 years: Forcing mechanisms and implications for the glacial Walker circulation. In review for Quaternary Science Reviews.

Hollstein, M., Mohtadi, M., Rosenthal, Y., Moffa Sanchez, P., Oppo, D., Martínez Méndez, G., Steinke, S., Hebbeln, D. (2017). Stable oxygen isotopes and Mg/Ca in planktic foraminifera from modern surface sediments of the Western Pacific Warm Pool: Implications for thermocline reconstructions. Paleoceanography, 32, doi:10.1002/2017PA003122.

 

Conference contributions (First author only)

  • Hollstein, M., Mohtadi, M., Rosenthal, Y., Prange, M., Oppo, D., Martínez Méndez, G., Tachikawa, K., Moffa Sanchez, P., Steinke, S., Groeneveld, J., Kienast, M., Hebbeln, D., 2018. Forcing mechanisms of Western Pacific Warm Pool surface and thermocline conditions over the last glacial-interglacial cycle. Oral presentation at AOGS annual Meeting 2018, Honolulu, Hawaii, USA.
  • Hollstein, M., Mohtadi, M., Rosenthal, Y., Moffa-Sanchez, P., Martínéz-Méndez, Oppo, D., Steinke, S., Hebbeln, D., 2016. Western Pacific near surface conditions reflected in shells of planktic foraminifera. Poster presentation at the 12th International Conference on Paleoceanography, Utrecht, the Netherlands.
  • Hollstein, M., Mohtadi, M., Rosenthal., Y., Oppo, D., Martínez-Méndez, G., Steinke, S., Moffa-Sanchez, P., Hebbeln, D., 2016. Millennial-scale variations in Western Pacific Warm Pool (sub)surface conditions over the past 110,000 years. Poster presentation at the 12th International Conference on Paleoceanography, Utrecht, the Netherlands.

 

Expeditions

  •  SO-256 (TACTEAC), SW Pacific, Auckland (NZ) - Darwin (AUS), 17.04.-09.05.2017, Chief scientist: Mahyar Mohtadi

 

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