[email protected]
The lower trophic level model hindcast
ensemble
EURO-BASIN annual meeting, Copenhagen – 02/09/2014
J.I. Allen (PML), T. Anderson (NOC), M. Butenschön (PML), L. Memery
(LEMAR), C. Stegert (LEMAR), A. Yool (NOC)
[email protected]
The Models
Ocean Physics
•NEMO ¼ dgr
•Rigid lid
•Z-coordinate
•DSF5
reanalysis
•MEDUSA: subsampled
•ERSEM,
PISCSES:
dedicated setup
•Ensemble
Coverage 19882006
MEDUSA
•A modestly complex
ecosystem model
•includes two
phytoplankton, two
zooplankton and three
nutrients
•specifically designed
for open ocean
applications.
PISCES
•Considers
two
phytoplankton
and
two zooplankton
•explicit semi labile
DOM and two particle
sizes
•Using N as the main
currency, as well as P,
Si and Fe.
•Also simulates the C
(DIC and alkalinity)
and O cycles.
ERSEM
•developed as a
generic lower-trophic
level/biogeochemical
cycling model.
•intermediate
complexity
•originally designed
for shelf seas
•pelagic and benthic
component
•P, B, Z, DOM, POM
•cycles of C, N, P, Si.
[email protected]
Ensemble Results – Nitrate [mmol/m3]
Season
Spring
Min
Mean
Max
Summer
Autumn
Winter
[email protected]
Ensemble Results – Non Diatom Chlorophyll-a [mg/m3]
Season
Spring
Min
Mean
Max
Summer
Autumn
Winter
[email protected]
Ensemble Results – Diatom Chlorophyll-a [mg/m3]
Season
Spring
Min
Mean
Max
Summer
Autumn
Winter
[email protected]
Ensemble Results – Zooplankton [mg/m3]
Season
Spring
Min
Mean
Max
Summer
Autumn
Winter
[email protected]
Variabilities
Season
Spring
MEDUSA
PISCES
omplexity
ERSEM
Summer
Autumn
Winter
[email protected]
Model Performance - Nitrate
Comparison
against WOA
surface data
[email protected]
Model Performance – Chlorophyll-a
Comparison
against CCI ocean
colour monthly
composites
[email protected]
Model Performance – Chlorophyll-a Spatial Structures
Chlorophyll mean state
Blue: Low Quartile
Red: High Quartile
Green: IQR
MEDUSA
PISCES
ERSEM
CCI
[email protected]
Model Performance – Chlorophyll-a Spatial Structures
Get average skill sc
MEDUSA
PISCES
ERSEM
CCI
[email protected]
Model Performance – Community Structure
MEDUSA
PISCES
Comparison
against data
derived
relationships to
total chlorophyll-a
Red: Hirata 2011
Blue: Brewin 2010
ERSEM
CCI
[email protected]
Time Series
NO3 [mmol/m3]
OWS M
PAP
atitude
BATS
Trophic Level
Non-Diatoms Diatoms [mg Chl/m3] Zooplankton [mg C/m3
[email protected]
ERSEM hindcast
First hindcast (from D6.3) showed significant overestimation of
surface Nitrogen.
-> traced to a dubious nitrogen to phosphorus ration in
mesozooplankton
In addition a new parametrisation was developed related to the
ERSEM release to the public within the UK-SSB program based on
calibrations against time series data at BATS and L4
-> final hindcast, base for RCP8.5 projection
[email protected]
ERSEM parametrisations
Nitrate
Comparison
against WOA
surface data
[email protected]
ERSEM parametrisations
Chlorophyll-a
Comparison
against CCI ocean
colour monthly
composites
[email protected]
Community Structure - Phytoplankton
N2P fix
[email protected]
Community Structure - Phytoplankton
Final
[email protected]
Community Structure - Zooplankton
N2P fix
Heterotrophic Flag.
Microzoo
Mesozoo
[email protected]
Community Structure - Zooplankton
Final
Heterotrophic Flag.
Microzoo
Mesozoo
[email protected]
Time Series
NO3 [mmol/m3]
OWS M
PAP
atitude
BATS
Trophic Level
Non-Diatoms Diatoms [mg Chl/m3] Zooplankton [mg C/m3]
[email protected]
Summary
Quantitatively and qualitatively comparable results across the
three ensemble members.
Good Performance against ocean colour and World Ocean Atlas
nutrients.
Sensible representation of diatom/non-diatom community.
Strongly improved hindcast for ERSEM with respect to D6.3
results.
Variability within the simulation appears to scale with model
complexity.