Visit from Professor Samar Khatiwala
In May, Samar Prakash Khatiwala visited the Bjerknes Centre for Climate Research with the main objective to enhance the collaboration works initiated under the NFR-ORGANIC project. Professor Khatiwala spent several hours each day during his visit implementing the Transport Matrix Method (TMM) to the offline HAMOCC model with Ingjald Pilskog. This is a critical preliminary step to building the acceleration method proposed in the project. By the end of his visit, we managed to extract the HAMOCC code from NorESM and coupled it with TMM. In the next step, Khatiwala and Pilskog will perform several basic experiments with the TMM-HAMOCC, while Pilskog will continue with implementing the Newton-Krylov method in Bergen.
In connection to this visitation a half-a-day mini-workshop was organized, titled ‘Anthropogenic carbon uptake and storage in the North Atlantic’. The workshop had six short talks presented by Bjerknes scientists from RG3, the Biogeochemistry research group at the Bjerknes Centre. Khatiwala also presented an extra talk for the weekly GFI-colloquium entitled ”Constraining ocean ventilation pathways and time scales with observations and models”.
Tracing deep ocean currents
Radioactive isotopes typically take four years to reach the Norwegian coast from Sellafield on the north-eastern coast of England. Researchers like Yongqi Gao follow the radioactive waste to understand how ocean currents are formed and to see where they flow.
Welcome to Ingjald
At January 1. 2016 Ingjald Pilskog started up his work at Uni Research and the Bjerknes Centre in the Organic project. He will mainly be working on the carbon cycle in the NorESM, with numerical modelling.
”I am a Ph.D in atomic physics and physical chemistry, and had a postdoctoral fellowship in geophysics at VISTA, a collaboration between Statoil and Norwegian Academy of Science and Letters”, Ingjald says.
“I will work on the NorESM. This is a typical spin-up model.” A spin-up model is a model that needs to “get started” before it is ready to be used in theoretical experiments on the climate. The time for the model to get ready is called spin-up time. For ocean tracers, the spin-up time can be equivalent of several thousand years. This means that it is expensive to start the model for running experiments.
”I will use advanced numerical methods to reduce this spin-up time, and therefore reducing the cost of running the model and making it possible for other researchers to run more experiments.” he explains.
”But the challenge is to implement these methods in complex models such as the NorESM, without braking anything”.
Best whishes to Ingjald on his work, and welcome on the team.
The ORGANIC project will enhance our knowledge in climate variability simulatedby the NorESM model and identify uncertainty that comes with its future projections. The focus is to elucidate the linkage between large scale overturning circulation with the biogeochemical cycling in the ocean.
This link is necessary since hydrography tracers such as temperature andsalinity do not give us a comprehensive overview on the overturning circulation.
On the other hand, biogeochemical tracers such as nutrient and CFCs are closely tied to the ocean circulation and can be used as indicators for patterns and ventilation rates of the ocean.
Due to the non linear interactions between climate and ocean carbon cycle, it is vital for an Earth system model to accurately simulate the relevant former and latter processes individually as well as interactively in order for it to produce a sound future climate projections.
The outcome of ORGANIC will be of highly relevant for both global and regional climate studies, particularly in regions where the ocean ventilation will be perturbed by anthropogenic forcing.
The work is divided in three work packages:
WP1: Sensitivity of thermohaline circulation patterns and rates
WP2: Equilibrium states of ocean biogeochemistry
WP3: Marine sediment dynamics
The proposed interdisciplinary work will involve scientists from natural, mathematical and computational scientists. The study utilizes the nationally developed Norwegian Earth system model and observational sets from contemporary and paleo periods.
The methods that will be developed throughout the project, the Matrix Free Newton Krylov, will provide novel and efficient approach to increase our understanding in the sophisticated interactions between the physical and biogeochemical processes in the climate system.