description of a flexible and extendable physical-biogeochemical model system … · 2009. 1....
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Description of a flexible and extendable
physical-biogeochemical model system
for the water column
Hans Burchard 1, Karsten Bolding 2, Wilfried Kuhn 3,
Andreas Meister 4, Thomas Neumann 1, Lars Umlauf 1,
1. Baltic Sea Research Institute Warnemunde, Germany; 2. B olding & Burchard
Hydrodynamics, Asperup, Denmark; 3. Institute of Oceanogr aphy, University of Hamburg,
Germany; 4. Faculty of Mathematics and Informatics, Univer sity of Kassel, Germany
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 1/??
Motivation for GOTM-BIO
Major aim:
Building a framework for coupledphysical-biogeochemical model simulations
Starting from the existing GOTM (see below) model, weintend to
extend the physics towards the needs ofbiogeochemical modelling: wrt. mixing, air-seainteraction, light
set up example biogeochemical models properly linkedto physics
provide documentation and support for use andextention of model
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 2/??
Cooperation, funding
IOW staff involved: Lars Umlauf, Thomas Neumann,Hans Burchard
External scientists involved: 200 registered GOTMusers, plus unknown number of unregistered people
No direct funding. Planned as integrating model forSOPRAN (German SOLAS, FS 1). Used in 3D modelGETM (QuantAS-OFF funding, Küste & Gesellschaft)
Current status: house project, part of IOW modelenvironment, maybe BMBF funding requested
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 3/??
GOTM, http://www.gotm.net
Challenge
Aim
The Idea
Key features
Software
Fortran code
Test cases
Forcing
How to run?
Information
What's
Publications
E-mail list
FAQ
User Group
Hot Links
Who's Who?
Guestbook
PPM:
10/26/00 20:48:54
New
GOTM is a one-dimensional numerical modeldeveloped and supported by a core team ofocean modellers. GOTM aims at simulatingaccurately vertical exchange processes in themarine environment where mixing is known toplay a key role. GOTM is freely available underthe GPL (Gnu Public License).
The interested user can download the sourcecode , a set of test cases (Papa, November, Flex,...) and a comprehensive report .
You are warmly invited to join the GOTM mailinglist and send any comments/questions to theGOTM team or become a GOTM contributor . TheGOTM developers are grateful to their sponsors .
Page "www.gotm.net" maintained by webmaster. Last update: 10/28/00 18:10:02
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 4/??
GOTM
GOTM is a physical model for the water column withstate-of-the-art turbulence parameterisations
GOTM has conventional light and air-sea flux modelsincorporated
GOTM is Public Domain since 1999 (25.000 loginssince then)
Under Google, GOTM turbulence gives 554 hits
Many extentions to GOTM exist. E.g. both ERSEM(European Regional Seas Ecosystem Model) versionsare implemented into GOTM, see e.g. Allen et al. 2004.
GOTM is popular because of its quality turbulencemodels which perform numerically sufficiently stable.
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 5/??
What is it good for ?
Any kind of ecosystem modelling in the water columncan be investigated. Advantage: fast execution, highresolution; disadvantage: neglect or parameterisation oflateral processes
The user has to properly describe the processes ! Oncethis is done, model modification should be easy.
Focus on fast processes such as photochemistry ispossible, see SOPRAN proposal.
In the following, we will show some example results.
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 6/??
Stiff versus explicit solvers
Surface nutrient content in Northern North Sea seen withnumerical different solvers:
-35
-30
-25
-20
-15
-10
-5
0
5
10
0 50 100 150 200 250 300 350
RK4, ∆t = 20 s
nut(z
=0)
[mm
olN
m−
3]
4th-order Runge-Kutta
RK4, ∆t = 2 hRK4, ∆t = 1/2 h
Julian Day 1998
0
2
4
6
8
10
0 50 100 150 200 250 300 350
RK4, ∆t = 20 s
nut(z
=0)
[mm
olN
m−
3]
Julian Day 1998
Modified Patankar-Runge-Kutta
MPRK2, ∆t = 2 hMPRK2, ∆t = 1/2 h
Explicit solver at long time steps (left) does not obey nutrient limitation. Stiff solver (right,
Burchard et al. [2003]) is stable and accurate. Note the different scales.
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 7/??
Neumann et al. 2002 model
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 8/??
Gotland Basin simulations
Basic experiment: model simulations for 1983-1991 atstation 271 in Central Gotland Sea. Forcing by output ofatmospheric model, initialisation by physicalobservations.
Sensitivity studiesExperiment with increased diapycnal mixing(kmin = 4 · 10−6 J kg−1 instead kmin = 1 · 10−6 J kg−1)Experiment with increased wind forcing in Februaryand March (factor 2 applied to wind speed inFebruary and March)
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 9/??
Base run: temperature
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 10/??
Base run: Chl-a
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 11/??
Base run: DIN
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 12/??
Base run: DIP
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 13/??
Base run – Dia run: O2
solid: Base run; dashed: increased diapycnal mixing
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 14/??
Base run – Wind run: Cyanos
solid: Base run; dashed: increased winter storms
FS2 Workshop, Baltic Sea Research Institute Warnemunde, Germany, Mar. 13, 2005. – p. 15/??