Reports

The use of a new technology combined with new sampling algorithms potentially offers unprecedented insights into deep ocean mixing and internal wave climate.

Hi! My name is Ilmar and I work as a PhD student at the MARUM/University of Bremen. I am supervised by Dr. Maren Walter (MARUM/University of Bremen) and Dr. Alexa Griesel (Universität Hamburg) and am part of the TRR subprojects L3
entitled “Meso- to Submesoscale Turbulence in the Ocean” and W5 „Internal Wave Energy Dissipation and Wavenumber Spectra: Adaptive Sampling in the Ocean Interior “.

Before I joined TRR, I lived in Kiel, where I got a bachelor degree in Physics of Earth and master degree in Climate Physics: Meteorology and Physical Oceanography at Christian Albrechts University Kiel & GEOMAR. I started my work as a part of TRR in September 2022.

In the first phase of L3, we assessed turbulence regimes with a focus on the Benguela upwelling region. Using a new scaling method and with adequate subsampling of the deployed surface drifters, we estimated a consistent energy transfer rate and identified an inverse cascade for scales 30-500 km close to the upwelling current. Now Our aim in the second phase is to extend the Lagrangian analyses and apply the structure-function diagnostic (in addition to the classical Lagrangian dispersion estimates) in an area offshore from the Benguela region that is characterized by high internal tide and eddy activity but without a deep baroclinic current. In a concerted effort (targeted measurements with gliders, ship ADCP, drifters) we will quantify horizontal wavenumber spectra for the upper ocean in the Walvis Ridge Region in close collaboration with W5 and W2. The subsampling methods developed from the analyses in the Benguela and Walvis Ridge regions, together with high-resolution modelling, will be used to extrapolate to the global ocean using the global drifter program.

The W5 Project is concerned with the shape of the internal wave energy spectrum, where our aim is to simultaneously observe the oceanic energy spectrum below the submesoscale range and the spatial distribution of energy dissipation, using adaptive/reactive sampling to guide the observations. For this purpose, we will deploy a new hybrid pelagic glider (developed by Prof. Ralf Bachmayer) using an innovative approach of combining advanced numerical model informed sampling techniques in real-time to observe internal wave spectra and turbulence in the ocean interior. As a key sensor, a pressure rated microstructure probe will be integrated into the pelagic glider system; this use of a new technology combined with new sampling algorithms potentially offers unprecedented insights into deep ocean mixing and internal wave climate. Obtained observational data will be contextualized by idealized and regional numerical modelling studies carried out in L3 and L2 and the results of this project will complement the observations, that will be jointly used to construct the upper- and pelagic oceanic energy spectrum within L3, and the observations towards obtaining a local energy budget.