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Ilmar Leimann

Tel: +49 (0)421 218-62163
Fax: +49 (0)421 218-62165
Email: ileimann [at] uni-bremen.de

PhD Project
Internal Wave Energy Dissipation and Wavenumber Spectra: Adaptive Sampling in the Ocean Interior Ocean mixing is an important process for sustaining ocean stratification and circulation. Breaking of internal waves creates conditions in which turbulent mixing is enhanced. Still, mixing is yet poorly represented in ocean models and needs to be parameterized, and these parameterizations (e.g. IDEMIX) rely on the spectral properties of internal wave energy. Observational data of internal wave energy spectra and the distribution of mixing are, however, sparse - particularly in the deep ocean. My project aims to reduce this gap, which is a small yet crucial step towards energy consistent climate modeling. Specifically, I target three main goals: (i) Observing and describing the internal wave energy spectrum in the interior ocean (with a focus on the Eastern South Atlantic), (ii) charting and analyzing the spatial distribution of energy dissipation in the deep ocean, also in reference to (i), and (iii) exploring and co-developing new (adaptive) techniques to obtain microstructure observations in the deep ocean using autonomous vehicles. The project is part of the Collaborative Research Centre 181 "Energy Transfers in Atmosphere and Ocean" (TRR181). Learn more about the sub-projects I'm involved in here (W5) and here (L3).

PhD Project

Internal Wave Energy Dissipation and Wavenumber Spectra: Adaptive Sampling in the Ocean Interior
Ocean mixing is an important process for sustaining ocean stratification and circulation. Breaking of internal waves creates conditions in which turbulent mixing is enhanced. Still, mixing is yet poorly represented in ocean models and needs to be parameterized, and these parameterizations (e.g. IDEMIX) rely on the spectral properties of internal wave energy. Observational data of internal wave energy spectra and the distribution of mixing are, however, sparse - particularly in the deep ocean. My project aims to reduce this gap, which is a small yet crucial step towards energy consistent climate modeling.
Specifically, I target three main goals:
(i) Observing and describing the internal wave energy spectrum in the interior ocean (with a focus on the Eastern South Atlantic),
(ii) charting and analyzing the spatial distribution of energy dissipation in the deep ocean, also in reference to (i), and
(iii) exploring and co-developing new (adaptive) techniques to obtain microstructure observations
in the deep ocean using autonomous vehicles.
The project is part of the Collaborative Research Centre 181 "Energy Transfers in Atmosphere and Ocean" (TRR181). Learn more about the sub-projects I'm involved in here (W5) and here (L3).

Curriculum Vitae
since 09/2022	PhD student at Center for Marine Environmental Sciences (MARUM) and Institute for Environmental Physics (IUP), University of Bremen, Germany
2022	M.Sc. in Climate Physics, Christian-Albrechts-Universität zu Kiel
2019	B.Sc. in Physik des Erdsystems, Christian-Albrechts-Universität zu Kiel

Projects
since 09/2022	Internal Wave Energy Dissipation and Wavenumber Spectra: Adaptive Sampling in the Ocean Interior (sub-project W5 & L3 in TRR181)

Publications
Leimann, I., 2022. Temporal and spatial variability of the Deep Western Boundary Current. Master’s Thesis, Christian Albrechts University Kiel.
Kieke, D., K. Bulsiewicz, C. Gapp, Y. Hinse, O. Huhn, B. Holanda, A. Hunkemöller, S. Kinne, M. Köllner, L. Krisztian, O. Krüger, I. Leimann, M. Pöhlker, A. Schneehorst, A. Smirnov, R. Steinfeldt, M. Stelzner, J. Stiehler, T. Svensson, S. Wett, and K. N. Wiegand (2021), AMOC Components at 47°N, Cruise No. M164 (GPF-19-1-105), June 23 - July 31, 2020, Emden (Germany) - Emden (Germany), METEOR-Berichte, Gutachterpanel Forschungsschiffe, doi:10.48433/cr_m164.
Visbeck. M, A. Lopes Brum, J. Carbajal, O. Dada, J. Galetti, E. Gonzales, P. Handmann, J. Herrford, M. Hundsdörfer, C. Jahr, G. Krahmann, I. Leimann, R. Link, P. Michaelis, N. Niebaum, U. Papenburg, L. Sarmiento Trujillo, C. Schmidt, M. Stelzner, L. Stramma, C. Trahms, R. Witt (2019), Circulation off Brazil, Cruise No. M159, October 29 - November 20, 2019, Recife (Brazil) - Mindelo (Cape Verde), METEOR-Berichte, Gutachterpanel Forschungsschiffe, doi: 10.2312/cr_m159.
Kieke, D., K. Bulsiewicz, I. Deschepper, O. Huhn, M. Kastens, A. Kersting, M. Köllner, L. Krisztian, I. Leimann, B. Mirau, M. Moritz, N. Rohlfs, A. Schneehorst, R. Steinfeldt, I. Stendardo, J. Stiehler, and R. Tao (2020), Long-term observations of the Atlantic Meridional Overturning Circulation, Cruise No. MSM83, May 17 - June 15, 2019, Las Palmas (Spain) - St. John's (Canada). MARIA S. MERIAN- Berichte, Gutachterpanel Forschungsschiffe, doi:10.2312/cr_msm83.
Leimann, I., 2019. Mesoscale eddies on the Labrador Sea and their particle distribution. Bachelor’s Thesis, Christian Albrechts University Kiel.
Karstensen J., D. Atamanchuk, A. Barboni, A. Bendinger, D. Fonseca, N. Fried, P. Holliday, M. Hundsdörfer, L. Kerrigan, I. Leimann, C. Normandeau, M. Oltmanns, N. v. Oppeln-Bronikowski, J. Ribbe, S. Schmidtko, T. Suits, C. Willis (2019), Water mass transport and transformation in the western SPNA, Cruise No. MSM74, May 25 - June 26, 2018, St. John's (Canada) - Reykjavik (Iceland), Western SPNA transport.). MARIA S. MERIAN-Berichte, Gutachterpanel Forschungsschiffe, doi:10.2312/cr_msm74.

Participation in Scientific Cruises

RV Maria S. Merian, MSM121	Subpolar North Atlantic	Sep - Oct 2023	Nuuk, Greenland - Ponta Delgada, Portugal
RV Meteor, M188	South Atlantic	Mar - Apr 2023	Walvis Bay, Namibia - Wavis Bay, Namibia
RV Meteor, M164	Subpolar North Atlantik	Jun - Jul 2020	Emden, Germany - Emden, Germany
RV Meteor, M159	South Atlantic	Oct - Nov 2019	Recife, Brazil - Mindelo, Cape Verde
RV Maria S. Merian, MSM83	Subpolar North Atlantic	Mar - Jun 2019	Las Palmas, Spain - St. John's, Canada
RV Poseidon, POS530	Baltic Sea	Oct 2018	Kiel, Germany - Kiel, Germany
RV Maria S. Merian, MSM74	Subpolar North Atlantic	Mar - Jun 2018	ST. John's, Canada - Reykjavik, Iceland

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