Drs. J. (Jorn) Bruggeman

Room: T541
Phone: 020-5986959
Email: bruggemn@bio.vu.nl
Project: Organic carbon pump in meso-scale ocean flows

Organic carbon pump in meso-scale ocean flows

The big picture

Atmospheric carbon-dioxide (CO2) is generally thought to be the dominant greenhouse gas: it absorbs infrared radiation emitted by the earth's surface, thus increasing the average air temperature, and ultimately, the temperature of the earth as a whole. Mainly due to industrial activities, the atmospheric level of CO2 in the air has risen considerably over the past century. This trend may well continue, causing substantial heating of the earth, and potentially severe - even disastrous - climate change. However, human industrial activity is far from the only process contributing to the level of atmospheric CO2. Many sinks and sources of carbon-dioxide exist. For instance: biota (primary producers, i.e. plants) both consume CO2, and produce it. To adequately predict future CO2 levels, one requires a complete, quantitatively correct overview of all carbon-dioxide sinks and sources.

The role of oceans

Oceans may substantially affect the level of atmospheric CO2. The theoretical buffering capacity of oceans is enormous, especially because deep water rarely comes into contact with the atmosphere, and therefore could accumulate carbon-dioxide above atmospheric concentrations. Of course, for this accumulation to occur, some process should transport CO2 from the atmosphere to deeper water. Such a process exists: marine phytoplankton inhabits the upper water layer, consumes CO2, and forms aggregates that sink into deeper water ('marine snow'). This transport process is called the 'organic carbon pump'. So far, little is know about the rate at which the organic carbon pump removes CO2 from the atmosphere. This is not difficult to understand: a quantitative estimate of the carbon pump involves numerous factors, among which a thorough understanding of both phytoplankton physiology and ocean water flow (the latter determining upper- and lower layer separation, and nutrient flows).

Project C-pump

In this project we aim to combine a biologically realistic model of phytoplankton with a three-dimensional geophysical model of ocean water flow. This will combine biological expertise, geophysical expertise (Anne-Willem Omta), and mathematical expertise (CWI) for large-scale simulation. Initially, we will restrict model simulations to an idealized eddy; ultimately, we aim to describe a complete basin such as the (North) Atlantic Ocean.

Initially, I will concern myself with the construction of a mechanistic model of generalized (mixotrophic) phytoplankton. This model should be sufficiently simple to allow for incorporation in 3D models of ocean water flow, yet be detailed enough to give a realistic description of the organic carbon pump. To obtain this balance between simplicity and realism, I will evaluate the impact of various factors that potentially affect the carbon pump, such as self-shading and coagulation of phytoplankton cells, nitrogen fixation, diurnal patterns of light intensity, and seasonal changes in turbulence.

Jorn acquired the prestigious Rubicon grant from the National Science Foundation (NWO) and a junior fellowship from St Johns College for his postdoc work at the Dept Earth Sciences at Oxford University.

2009/09/10:45 Jorn Bruggeman: defense thesis in the Aula

10:45 welcome by Prof. Dr. Maurits van Tulder
(Rector Magnificus)
promotor Prof. Dr. Bas Kooijman;
copromotor Dr. Bob Kooi
10:45 Introduction by Jorn Bruggeman
10:55 Dr. Kai Wirtz Professor at the Department of Ecosystem Modelling, GKSS Forschungszentrum, Geesthacht, Germany
11:05 Dr. Andreas Oschlies Professor of Biochemical Modelling, University of Kiel
11:15 Dr. Hans Metz Emeritus Professor of Mathematical Biology, Leiden University
11:25 Dr. Tieneke Troost Delft Hydraulics, Delft
11:35 Dr. Jaap van der Meer Professor Population dynamics, VU University Amsterdam
11:45 end of defence; start of closed meeting
12:10 ceremony
12:20 end of ceremony; lunch in the Basket

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