Drs. J. (Jorn) Bruggeman
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.
| 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 |
Go to projects' entry