by Marta Mrozowska, Niels Bohr Institute, UCPH

The tropical mixed layer – real and simulated

Under the cloudy skies of the Swedish summer, the members of the WP6 group gathered on a beautiful remote island on the Gullmarsfjorden – Stora Bornö. The long hours of intensive work and discussion during the day were rewarded by scenic starry nights, both above and below, thanks to the local bioluminescent algae. This environment motivated an inspired and thorough evaluation of the two ocean mixing schemes, a turbulent kinetic energy (TKE) and an empirical K-profile (KPP) based scheme. Using sensitivity experiments of the uncoupled ICON and FESOM runs, we have discovered that biases in the model output cannot be attributed to a single mixing scheme. While TKE was slightly better on large scales, KPP was better at reproducing some local processes such as near-inertial wave induced mixing.

Group photo of the participants for the Bornö Summer School 2022.

We also uncovered biases in the ERA5 forcing, and an interesting trend of the mixed layer becoming shallower with increasing model resolution. Aside from the analysis, we shared expert knowledge through lectures given by the professors in the group, and project presentations by the early career scientists. On the final days of the workshop, we also received two guest lectures: a master’s student from AWI, Jan Gärtner, explained how he coupled a sea ice component to the python-based ocean model Veros; and dr. James Avery gave a talk about the future of programming languages tailored for constructing comprehensive and transparent climate model code.

For more insights of the summer slackathon have a look here.


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