In November of last year, I had the opportunity to visit Southampton, UK, and spent a month at the National Oceanographic Center (NOC). Upon my arrival, I found myself in the midst of a literal and metaphorical storm. Shortly after reaching Southampton, a severe storm hit the area. My landlord advised me to stay indoors, and my host had to cancel our initial meeting due to closed bridges preventing access to the institute. While the physical storm passed after a few days, I still had to “weather the storm” of proposal writing. With the deadline for the third phase of the TRR approaching in mid-November, I dedicated a significant amount of my time to the proposal writing.

My main host, Alberto Naveira Garabato, a distinguished expert on submesoscales processes and mixing, proved to be not only a brilliant scientist (recently awarded the Fridtjof Nansen Medal) but also a warm and welcoming person. Bieito Fernandez Castro was also a great host, so I really enjoyed working at NOC. We had several meetings to discuss my results, and Alberto was very enthusiastic about my Baltic Sea simulations, saying he now understands why the Baltic is considered an ideal natural laboratory. We plan to write two joint papers: one focusing on the submesoscale instabilities and the vorticity generation above sloping topography, and another one (hopefully) focusing on the generation of submesoscale eddies in the oceanic interior and the lateral exchange of properties between the boundaries and the interior of the ocean. During my research stay, I also had the opportunity to present my work at the physical oceanography seminar at NOC, attend various seminars, and meet and discuss with many people. Exploring Southampton and its surroundings, I visited the local pubs with different groups of colleagues, further enriching my experience.

As the saying goes, “After every storm, the sun always shines”, and indeed, my experience in Southampton was a testament to this. I would therefore like to thank TRR for funding my research visit. It was a unique experience and I would strongly recommend and encourage everyone to seize the opportunity to visit other institutes and universities.

Hi, my name is Tridib and this is a short report on my 2 months research stay at Massachusetts Institute of Technology, Boston, United States.

There is no way to begin this report without first thanking everyone involved in making it happen. I would like to express how grateful I am to everyone from TRR who helped me through the entire research stay. From planning to securing of funds. To the organizers and the Vorstand, thank you so much. I would also like to thank the responsible people from Constructor university for expediting the fund disbursement so that I could pursue the research at my desired dates. I would also like to thank my supervisor of the research stay Prof. Raffaele Ferrari, for being a terrific mentor (alongside postdoc Simone Silvestri) and sponsoring the discretionary funding to Massachusetts Institute of Technology. I would further like to thank Massachusetts Institute of Technology for making my immigration to US very easy. I would like to thank also my supervisor at TRR – Prof Sergey Danilov for always being available for consultations and helpful discussions and finally, also my current collaborators who kindly shared my workload so that I could focus on the research stay. Thank you all.

I joined the Climate Modelling Alliance to work in collaboration with California Institute of Technology and NASA, Jet Propulsion Laboratory. My role was to join the ocean modelling team at Massachusetts Institute of Technology and help them diagnose their new advection scheme using a diagnostic technique Me, Sergey Danilov, and Knut Klingbeil developed during my PhD. It was a great experience and I learned a lot during the process. Unlike the ocean model that I had worked with in Alfred Wegener Institute, the one I had to use during my research stay ran on GPUs instead of CPUs. This shift of compute architecture meant rethinking of even the fundamental mathematical operations. The work was initially planned to be concise but later, we realized it to be bigger and more important than expected. We ran several interesting experiments and, in the end, we began writing a new manuscript together. Currently, we are running more experiments and working towards finishing our manuscript. In summary, the stay in Boston impacted my career way more than I thought.

While I had my fair share of work to do in Boston, I also enjoyed my time there a lot. I fell in love with their research culture and found a family in my land-lady who was so generous and kind to me during my whole stay. I also went to Michigan to visit my actual family, watch my very first American Football, that too a classic Ohio versus Michigan which Michigan surprisingly won (it was a total pandemonium), and also have my very first American thanksgiving. I was extremely scared going to US but I had nothing but only fun during my entire stay. I would definitely do it again.

Exploring Atmospheric Dynamics

From the 1st of October and until the 14th, I had the opportunity to embark on a short research stay in Lyon, France, funded by the project TRR181 at École Centrale de Lyon. This period was not just a chance to collaborate and learn but also a stepping stone in my understanding of atmospheric dynamics, particularly regarding gravity wave (GW) spectra.

My time in Lyon was spent working alongside Raffaele Marino (scientist at CNRS, France) and the team at the Laboratory Mechanical Des Fluides Et D'acoustique (LMFA). The environment at LMFA was not only academically stimulating but also warmly welcoming, fostering both professional growth and personal connections.

One of the most enlightening aspects of this visit was the shift in my perspective on the processes which contribute to the canonical GW spectra. Discussions about turbulence and the scaling of gravity wave spectra opened my eyes to the broader physics underlying these phenomena. It was a transition from focusing merely on the slope of gravity wave spectra to understanding the vast, open-ended field of their scaling.

A highlight of my stay was exploring the relationship between the Froude number and statistics (kurtosis) of velocity and temperature fields. Although time constraints didn’t allow for its application on lidar data, the concepts presented were inspiring and thought-provoking.

Our work concentrated on validation of spectra from direct numerical simulations (DNS) against lidar data, scrutinizing how different wind regimes affect GW spectra. This involved a detailed comparison of integrated kinetic energy/scalar spectra with lidar data.

Leaving Lyon, I am armed with an array of studies and topics to delve into, especially regarding the comparison with DNS regimes. These studies are pivotal in enhancing our interpretation of GW data from lidar measurements. I am optimistic about the continuation of this collaboration in the future and the potential for significant findings.

Beyond the academic realm, Lyon itself proved to be a delightful experience. The city's transportation system was notably efficient which made commuting a breeze. The streets of Lyon are filled with friendly faces, many of them young students, also the 2023 Rugby World Cup was taking place there which added a lively and diverse vibe to the city. École Centrale de Lyon, nestled in this vibrant environment, struck me as an exceptional place for study and research, providing many chances to do sports as well.

I extend my deepest gratitude to the entire team at LMFA for their hospitality and support. Special thanks go to Rafaello Foldes and Fabio Feraco (IAP) for their invaluable help in answering my questions and assistance with data provision.

My research stay in Lyon was not only productive but also immensely rewarding. It has broadened my understanding and has surely impacted my approach to atmospheric science. I am grateful for this experience and hopeful that my contributions, though a fraction, have added value to our collective research endeavors.

At the end of last year, I spent two months in Perth, Western Australia, to work on a collaborative project with Jen-Ping Peng, who was a PhD in TRR181’s first phase and is now a PostDoc in the working group of Nicole Jones at the Indian Ocean Marine Research Centre of the University of Western Australia. For the most part, my stay in Perth was covered by the Australia–Germany Joint Research Cooperation Scheme, with the TRR kindly providing some additional financial support. The above scheme is an initiative of Universities Australia and the German Academic Exchange Service (DAAD) for the support of international academic cooperation. Early-career researchers from Australia and Germany are encouraged to hand in proposals for a joint research topic, and, if approved, the grant covers the expenses for a research stay at the partner institute. For our project, Jen-Ping and I decided that we want to combine our two fields of research and investigate the interactions of diurnal warm layers, submesoscale fronts and other turbulent processes in the surface mixed layer. For this, we firstly extended the 1D turbulence model GOTM to include 3D frontal effects and validated our model results by comparing them to published LES studies. Then, we used our model to recreate measurements taken previously during two campaigns in the Baltic Sea and the Indian Ocean and use the results to understand the governing processes involved. We found nice agreements between the measurements and our simple model and are planning on publishing two joint papers on these topics.

But besides the work aspect, Western Australia was also a great place to explore and spend time. Jen-Ping was an excellent host (I think we went to every great Asian restaurant in all of Perth) and the weather was pleasant from beginning to end (basically nothing but sunshine for two months). I stayed in a researcher accommodation on campus, which is located a few kilometres away from the city centre directly at the Swan river estuary with lots of green areas and beautiful old trees. Moreover, I got to go on two nice road trips up and down the coast, explore the Margaret River wine region, see quokkas on Rottnest Island and snorkel in the beautiful Ningaloo Reeve national reserve with an infinite amount of fish, stingrays and even a big sea turtle. I also got to see a living colony of stromatolites, microorganisms that are believed to be the oldest form of life on earth dating back 3 billion years, and that can only survive in hypersaline estuaries like Shark Bay in Western Australia. And while there were a few snake and spider sightings, I didn’t have the heart to look up their level of toxicity, so I like to believe it was all safe and sound.

I can definitely recommend looking into the Joint Research Cooperation Scheme (it exists not only between Germany and Australia, but also other countries) and would strongly encourage others to take the opportunity to extend their network and travel, maybe to Perth, it’s a lovely corner of the world. I would like to thank Jen-Ping, Nicole Jones and all other members of this working group for hosting me, showing interest in my research and teaching me about their fields of research.

My name is Nicolas Dettling, I am a PhD student in subproject T3 „Energy Transfers in Gravity Currents“. So far I have worked on applying and improving eddy parameterizations in the presence of gravity currents, such as the ones exporting dense water from the Antarctic continental shelves. Now, it is time to apply what we have found in idealised models to regional models of the Antarctic marginal seas.

For this purpose, I visited Prof. Yoshihiro Nakayama and his research group at the Institute for Low Temperature Science at Hokkaido University, Japan in November. Over the last years, Prof. Nakayama and his group have set up a number of regional ocean model simulations targeting key questions concerning the dynamics of the ocean around the Antarctic continental shelf and slope. Over the course of three weeks, I was introduced to a model of the Cape Darnley region, where dense water flows down the continental slope into the abyssal ocean, providing a nice test case for my previous parameterization work. I learned how to set up, run and interpret the model at different resolutions and we discussed the steps towards applying an eddy parameterization in the model. I am very grateful for the support and the fruitful discussions during my time at the institute.

The Hokkaido University campus is centred around a park and every morning I would walk along the Ginkgo Avenue enjoying the autumn colours on my way to work. Fortunately, there was also time to explore the City of Sapporo and the beautiful nature of Hokkaido, where the first snow of the season had already arrived. Luckily, the next Hokkaido Soup Curry or a bunch of Gyozas (fried dumplings) were never far away to recover after working or travelling.

I genuinely enjoyed to work in Japan and to engage in this cultural exchange. I would like to thank Prof. Nakayama and his group for their hospitality and I am very much looking forward to working together again in the future. Finally I want to thank the TRR 181 for funding the research visit.

After completing a 1-month research stay at the Centre for Materials & Processes (CERI MP)- IMT Nord Europe in Douai, I feel it is an important moment to reflect on how the stay has informed my work, including key research findings, implications and emerging questions.
My intention in working in Douai as a visiting researcher was to experience another academic reality, build a professional network and identify possibilities for future research collaborations.

From October 2nd to October 31st, I had the great opportunity to visit Prof. Modesar shakoor at the IMT Nord Europe’s Centre for Education, Research and Innovation in Materials and Processes. The IMT (Institut Mines Télécom) Nord Europe is a French graduate school of engineering. It is located in the Hauts-de-France region, shared between 2 campuses: the science campus of the University of Lille (Villeneuve-d'Ascq, European Metropolis of Lille); and the city of Douai. The school trains high-level engineers and scientists (Master and PhD level) in various technological fields including Digital Sciences, Energy and Environment Eco-Materials, Industry and Civil Engineering.

The working environment in the research center was very vivid and enabled a productive exchange of knowledge. I received a lot of useful input regarding my PhD topic and was supported in any possible way. This leads me to clarify some doubts related to my current work. I have been able to further develop and improve a big part of my PhD.

I shared the office with Sarabilou, a Phd Student who is working in the same field of interest. This provided me an opportunity to have some interesting discussions with him on various topics.

During my research stay, Prof. Modesar recommended that I learn and experience some deep learning tools and for this, he proposed some online tutorials related to specific class of artificial recurrent neural network (RNN) architecture called the Long Short-Term Memory (LSTM) neural networks implemented in Python with the TensorFlow library. I used the LSTM to solve the 1D wave equation and 2D heat equation. Our regular meeting and discussions  lead to a possibility for future research collaborations in this direction.

Although my stay abroad was shortened, the experience was still great and the journey was worthwhile. I got to know interesting personalities. The people I met in the Student Residence were extremely welcoming, supportive and easy to talk with.

Lastly, I believe the networking I have done throughout this experience will become valuable in the future and am very grateful to have made so many valuable contacts.

I would like to thank the TRR181 for enabling and financially supporting this research stay abroad.