A model parameter is a value that is included in the model equations. Often, this quantifies a physical, biogeochemical or biological feature of the ecosystem (e.g., a mortality rate of phytoplankton, a feeding preference of zooplankton, a sinking rate of particulate matter). Typically, this value is a constant, but it can be assumed to be variable (e.g. stocastically) in the framework assimilation approaches, to represent uncertainties in the model.
A model parameter is a variable that is internal to the model and whose value can be estimated from data. It is important to determine the top parameters for a given model system so as to:
-
Reduce the uncertainty on the model output indicators, by improving the estimates of the parameters;
-
Generate biogeochemical model ensembles, by perturbing the reference values of the parameters;
-
Improve understanding of biogeochemical processes and fluxes, by assimilating observations in a state-parameter estimation framework.
We ranked the biogeochemical parameters of all the Copernicus Marine Service models investigated in SEAMLESS. This was achieved by using the one-dimensional configurations of the models available to users in the SEAMLESS modelling prototype EAT (https://github.com/BoldingBruggeman/eat). The configurations were chosen to simulate different trophic regimes (oligotrophic deep-ocean station “BATS” in the Sargasso Sea and mesotrophic coastal station “L4” in the English Channel) in contrasting physical conditions (mixed and stratified water column). A Monte-Carlo based sensitivity of the parameters was then run to rank the most important (see the details in the deliverable D3.2 of SEAMLESS: doi: 10.5281/zenodo.6580236). The following tables list the 10 most important parameters for each biogeochemical model.
PISCES (Pelagic Interactions Scheme for Carbon and Ecosystem Studies; doi.org/10.5194/gmd-8-2465-2015)
PISCES
|
Rank
|
Notation
|
Description
|
Score
|
Group
|
1
|
dom_rem/xremik
|
DOM remineralization rate
|
100%
|
[10]
|
2
|
dom_rem/xkdoc
|
DOC half-saturation constant in limiting bacterial DOM degradation activity (Aumont et al, Eq 34)
|
99%
|
[12]
|
3
|
Optics/parlux
|
PAR : SWR ratio
|
93%
|
[6]
|
4
|
zoo/xprefn
|
Microzooplankton preference for nanophyto
|
91%
|
[17]
|
5
|
Dia/mumax0
|
Diatoms Max Growth
|
90%
|
[1]
|
6
|
Phy/logbp
|
Nanophyto temperature sensitivity for growth
|
88%
|
[5]
|
7
|
zoo/grazrat
|
MicroZoo maximum grazing rate
|
85%
|
[13]
|
8
|
phy/mumax0
|
Nanophyto Max Growth
|
83%
|
[1]
|
9
|
dia/logbp
|
Diatoms Temperature sensitivity for growth
|
81%
|
[5]
|
10
|
phy/padlopers
|
Nanophyto P-I slope
|
67%
|
[1]
|
ECOSMO II (ECOSystem Model; doi.org/10.1016/j.jmarsys.2013.03.008)
ECOSMO
|
Rank
|
Notation
|
Description
|
Score
|
Group
|
1
|
g2
|
E-folding depth of visible fraction (m)
|
100%
|
[6]
|
2
|
muPs
|
Maximum growth rate of small Phytoplankton
|
83%
|
[1]
|
3
|
mPs
|
Small Phytoplankton mortality rate
|
69%
|
[3]
|
4
|
A
|
non-visible fraction of shortwave radiation
|
66%
|
[6]
|
5
|
GrZsP
|
Grazing rate of small Zooplankton on Phytoplankton
|
64%
|
[13]
|
6
|
gammaZsp
|
Small Zooplankton assimilation efficiency on Phytoplankton
|
52%
|
[13]
|
7
|
reminD
|
Detritus remineralization rate
|
42%
|
[10,18]
|
8
|
alfaPs
|
Initial slope of P-I curve for small Phytoplankton
|
41%
|
[1]
|
9
|
rPO4
|
PO4 half saturation
|
38%
|
[10]
|
10
|
Rg
|
Half saturation rate for Zooplankton
|
37%
|
[13,16]
|
ERGOM (Ecological Regional Ocean Model; doi.org/10.1016/S0924-7963(00)00030-0)
ERGOM
|
Rank
|
Notation
|
Description
|
Score
|
Group
|
1
|
rp0
|
Diatoms uptake rate
|
100%
|
[17]
|
2
|
q10_rec
|
sediment recycling q10 rule factor
|
98%
|
[5]
|
3
|
rfr
|
Redfield ratio P/N
|
79%
|
[1]
|
4
|
imin_di
|
minimal optimal light radiation, diatoms
|
66%
|
[21]
|
5
|
graz
|
Zooplankton grazing rate
|
55%
|
[13]
|
6
|
deltao
|
Phytoplankton mortality rate (pl -> dd)
|
49%
|
[10]
|
7
|
dn
|
Detritus mineralization rate (dd -> aa)
|
45%
|
[17 or 11]
|
8
|
rf0
|
Flagellates uptake rate
|
44%
|
[12]
|
9
|
iv
|
Ivlev constant, quadratic
|
42%
|
[11]
|
10
|
zcl1
|
Zooplankton closure parameter
|
40%
|
[14]
|
BFM (Biogeochemical Flux Model; doi.org/10.1016/j.jmarsys.2006.03.006)
BFM
|
Rank
|
Notation
|
Description
|
Score
|
Group
|
1
|
light/EPS0r
|
Background shortwave attenuation
|
100%
|
[21]
|
2
|
light/pEIR_eow
|
Photosynthetically active fraction of shortwave radiation
|
57%
|
[6]
|
3
|
B1/p_pu_ra
|
Activity respiration fraction, bacteria
|
55%
|
[9]
|
4
|
Z5/p_pu
|
Assimilation efficiency, microzooplankton
|
44%
|
[13]
|
5
|
P3/p_q10
|
Q10 coefficient, picophytoplankton
|
40%
|
[5]
|
6
|
Z4/p_sds
|
Exponent of density-dependent mortality, omnivorous mesozooplankton
|
38%
|
[14]
|
7
|
P3/p_qlcPPY
|
Reference Chla:C quotum, picophytoplankton
|
35%
|
[1]
|
8
|
P3/p_qplc
|
Minimum phosphorus to carbon ratio, picophytoplankton
|
33%
|
[4]
|
9
|
P3/p_temp
|
Cut-off threshold for temperature factor, picophytoplankton
|
32%
|
[5]
|
10
|
P2/p_qlcPPY
|
Reference Chla:C quotum, nanophytoplankton
|
32%
|
[1]
|
ERSEM (European Regional Seas Ecosystem Model; doi.org/10.5194/gmd-9-1293-2016, 2016)
ERSEM
|
Rank
|
Notation
|
Description
|
Score
|
Group
|
1
|
light/PEIR_eow,
|
photosynthetically active fraction of shortwave radiation,
|
100%
|
[6]
|
2
|
B1/pu
|
efficiency at high oxygen levels (bacteria)
|
92%
|
[9]
|
3
|
B1/sR1
|
maximum turn-over rate of DOM
|
83%
|
[12]
|
4
|
light/a0w
|
absorption coefficient of clear water
|
74%
|
[21]
|
5
|
B1/rR2
|
fraction of semi-labile DOC available to bacteria
|
69%
|
[12]
|
6
|
P2/xqcn
|
threshold for nitrogen limitation (relative to Redfield ratio) in nanophytoplankton
|
61%
|
[20]
|
7
|
P1/xqn
|
maximum nitrogen to carbon ratio (relative to Redfield ratio) for diatoms
|
58%
|
[20]
|
8
|
P1/xqcn
|
threshold for nitrogen limitation (relative to Redfield ratio) in diatoms
|
57%
|
[20]
|
9
|
P2/xqn
|
maximum nitrogen to carbon ratio (relative to Redfield ratio) for nanophytoplankton
|
57%
|
[20]
|
10
|
P1/sum,
|
maximum specific productivity at reference temperature for diatoms,
|
52%
|
[7]
|
Assessment of observability/controllability levels of ecosystem indicators in the 5 CMEMS regions.
Indicator
|
ARC
|
BAL
|
NWES
|
MED
|
GLO/IBI
|
Phenology
|
High
|
TBD
|
High
|
Medium
|
High
|
PP
|
n/a
|
TBD
|
High
|
Medium
|
Medium
|
POC flux
|
n/a
|
TBD
|
High
|
Low
|
Medium
|
PFT
|
Medium
|
TBD
|
Medium
|
Medium
|
n/a
|
Trophic efficiency
|
Medium
|
TBD
|
High
|
Low
|
Low
|