The marine biogeochemical model ERGOM
ERGOM was originally developed
by Neumann et al. (2002)
to feature the Baltic Sea Ecosystem.
The model provides a full mathematical description of the behavior of
marine ecology state variables due to these
ERGOM has nine state variables:
- dissolved nutrients
- phytoplankton (primary production)
- diatoms (grow in nutrient-rich conditions)
- flagellates (grow in nutrient-poor conditions)
- blue-green algae (cyanobacteria, fix atmospheric nitrogen)
- zooplankton (graze on phytoplankton)
- detritus (dead plankton, some of which enter the sediment)
- dissolved oxygen
ERGOM is nitrogen-based, and the balance of phosphorus/oxygen is based on
nitrogen using stoichiometric
The concentration of dissolved oxygen controls processes as denitrification
and nitrification. Hydrogen sulfate is included as a deficit in the oxygen balance.
Detritus in the sediment is either buried, mineralised
or resuspended into the water column, depending on
the velocity of near-bottom currents.
DMI/ERGOM model set-up
DMI/ERGOM is coupled with a version the DMI North Sea - Baltic Sea ocean circulation model
HBM in high spatial resolution. DMI/ERGOM
runs twice daily for a 60 hour marine ecology forecast.
DMI/ERGOM is initialized
using marine ecology data from the ICES
(International Council for the Exploration of the Sea)
Oceanographic Data Centre. For time progression, DMI/ERGOM is forced with nutrient loadings
from the following sources:
- North Sea riverine nutrient loadings as climatological monthly means
- Baltic river loadings, derived from the daily
operational output of the hydrological HBV model
run at the Swedish Meteorological Hydrological Institute (SMHI)
for 43 Baltic catchment areas.
- atmospheric dry precipitation of nitrogen and phosphorus is neglected, as we focus on
the annual cycle in the euphotic layers.
- open boundary conditions towards the Atlantic are configured using the climatology of ICES data.
DMI/ERGOM gives full 3-d information about nine state variables
(see below), in a time resolution of one hour.
The forecast page
presents some of this output:
- near-bottom dissolved oxygen
- surface total chlorophyll-a
- surface Nitrate
for the upcoming two days.
Neumann, T., Towards a 3-D ecosystem model of the Baltic Sea, J. Mar.
Syst., 25, 405-419, 2000.
Neumann, T., W. Fennel, and C. Kremp, Experimental simulations with an ecosystem model of the Baltic Sea: A nutrient load reduction experiment, Global Biogeochemical Cycles, 16, 10.1029/2001GB001,450, 2002.
Wan, Z., Jonasson, L., Bi, H., 2011. N/ P ratio of nutrient uptake in the Baltic Sea. Ocean Sci. 7, 693â€“704.
Wan, Z., She, J., Maar, M., Jonasson, L., Baasch-Larsen, J., 2012. Assessment of a physical-biogeochemical coupled model system for operational service in the Baltic Sea. Ocean Sci. 8, 683-701.