ECOSMO II(CHL): a marine biogeochemical model for the North Atlantic and the Arctic

• Main Authors: Yumruktepe, Veli Çağlar, Samuelsen, Annette, Daewel, Ute
• Format: Text
• Language: English
• Published: 2021
• Subjects: Arctic; Barents Sea; Norwegian Sea; Nordic Seas; North Atlantic; Phytoplankton; Zooplankton
• Online Access: https://doi.org/10.5194/gmd-2021-279; https://gmd.copernicus.org/preprints/gmd-2021-279/

ECOSMO II is a fully coupled bio-physical model of 3d-hydrodynamics with an intermediate complexity N(utrient) P(hytoplankton) Z(ooplankton) D(etritus) type biology including sediment-water column exchange processes originally formulated for the North Sea and Baltic Sea. Here we present an updated version of the model incorporating chlorophyll a as a prognostic state variable: ECOSMO II(CHL). The version presented here is online coupled to the HYCOM ocean model. The model is intended to be used for regional configurations for the North Atlantic and the Arctic incorporating coarse to high spatial resolutions for hind-casting and operational purposes. We provide the full descriptions of the changes in ECOSMO II(CHL) from ECOSMO II and provide the evaluation for the inorganic nutrients and chlorophyll variables, present the modeled biogeochemistry of the Nordic Seas and the Artic and experiments on various parameterization sets as use cases targeting chlorophyll a dynamics. The model evaluations demonstrated that the simulations are consistent with the large-scale climatological nutrient settings, and are capable of representing regional and seasonal changes. The Norwegian and Barents Seas primary production show distinct seasonal patterns with a pronounced spring bloom dominated by diatoms and low biomass during winter months. The Norwegian Sea annual primary production is around double that of the Barents Sea while also having an earlier spring bloom. The parameterization experiments showed that the representation of open ocean chlorophyll a benefits from using higher phytoplankton growth and zooplankton grazing rates with less photosynthesis efficiency compared to the original implementation of ECOSMO II, which was valid for the North Sea and the Baltic Sea representing coastal domains. Thus, for open ocean modeling studies, we suggest the use of the parameterization sets presented in this study.