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How heat in the upper ocean can influence large-scale weather features in the tropics 

Ashneel Chandra will defend his PhD thesis at the University of Bergen on 19 March 2024 at 10:15 with the thesis “The Role of Ocean Heat Content on the Madden-Julian Oscillation”.


In the tropical atmosphere, there is a planetary-scale (~10 000 km) pattern of clouds and rain that moves eastward along the equator with a cycle repeating about every 60 days. This phenomenon is known as the Madden-Julian Oscillation (MJO). Accurate forecasting of the MJO is important for the predictability of weather in the coming weeks. In my dissertation, I try to understand the influence of heat in the upper ocean on this important tropical phenomenon known as the MJO.

As heat energy stored in the ocean moves from the ocean to the atmosphere, this heat can cause changes to the large-scale weather features that manifest in the atmosphere such as the MJO. I find that heat changes in the equatorial upper ocean are mainly caused by currents moving in the east-west direction along the equator which are linked to planetary-scale oceanic waves.

I then test an idea about the importance of these planetary-scale oceanic waves on the MJO in the Norwegian Earth System Model (NorESM). NorESM is a state-of-the-art climate model developed by climate scientists in Norway. From the model experiments, I find that the planetary-scale oceanic waves do not drastically influence the MJO in the model. However, climate models such as NorESM often struggle to produce a realistic MJO. Thus, my research offers insight into how improving the interaction between planetary-scale oceanic waves and the atmosphere in the model could potentially help the models produce a more realistic simulation of the MJO.

Time: 10:15

Venue: Rom BCCR4020, Bjerknessenteret, Jahnebakken 5

Personal information

Ashneel Chandra holds a Bachelor of Science degree in Mathematics and Physics and a Masters degree in Physics both from The University of the South Pacific, Suva, Fiji. Ashneel was affiliated with the Bjerknes Centre for Climate Research and the Island Lives Ocean States project during his PhD. This dissertation was supervised by Professor Noel Keenlyside and Dr Lea Svendsen at the Geophysical Institute, University of Bergen as well as Dr Awnesh Singh at The University of the South Pacific.

Contact information

Email: Ashneel.Chandra@uib.no