 |
| Titel |
Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980-2000 |
| VerfasserIn |
M. Vichi, S. Masina |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 11 ; Nr. 6, no. 11 (2009-11-02), S.2333-2353 |
| Datensatznummer |
250004078
|
| Publikation (Nr.) |
 copernicus.org/bg-6-2333-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| Global Ocean Biogeochemistry General Circulation Models are useful
tools to study biogeochemical processes at global and large scales
under current climate and future scenario conditions. The credibility
of future estimates is however dependent on the model skill in capturing
the observed multi-annual variability of firstly the mean bulk biogeochemical
properties, and secondly the rates at which organic matter is processed
within the food web. For this double purpose, the results of a multi-annual
simulation of the global ocean biogeochemical model PELAGOS have been
objectively compared with multi-variate observations from the last
20 years of the 20th century, both considering bulk variables and
carbon production/consumption rates. Simulated net primary production
(NPP) is comparable with satellite-derived estimates at the global
scale and when compared with an independent data-set of in situ observations
in the equatorial Pacific. The usage of objective skill indicators
allowed us to demonstrate the importance of comparing like with like
when considering carbon transformation processes. NPP scores improve
substantially when in situ data are compared with modeled NPP which
takes into account the excretion of freshly-produced dissolved organic
carbon (DOC). It is thus recommended that DOC measurements be performed
during in situ NPP measurements to quantify the actual production
of organic carbon in the surface ocean. The chlorophyll bias in the
Southern Ocean that affects this model as well as several others is
linked to the inadequate representation of the mixed layer seasonal
cycle in the region. A sensitivity experiment confirms that the artificial
increase of mixed layer depths towards the observed values substantially
reduces the bias. Our assessment results qualify the model for studies
of carbon transformation in the surface ocean and metabolic balances.
Within the limits of the model assumption and known biases, PELAGOS
indicates a net heterotrophic balance especially in the more oligotrophic
regions of the Atlantic during the boreal winter period. However,
at the annual time scale and over the global ocean, the model suggests
that the surface ocean is close to a weakly positive autotrophic balance
in accordance with recent experimental findings and geochemical considerations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|