Ocean Net Heat Flux Influences Seasonal to Interannual Patterns of Plankton Abundance

Changes in the net heat flux (NHF) into the ocean have profound impacts on global climate. We analyse a long-term plankton time-series and show that the NHF is a critical indicator of ecosystem dynamics. We show that phytoplankton abundance and diversity patterns are tightly bounded by the switches between negative and positive NHF over an annual cycle. Zooplankton increase before the transition to positive NHF in the spring but are constrained by the negative NHF switch in autumn. By contrast bacterial diversity is decoupled from either NHF switch, but is inversely correlated (r=-0.920) with the magnitude of the NHF. We show that the NHF is a robust mechanistic tool for predicting climate change indicators such as spring phytoplankton bloom timing and length of the growing season.

Validation of the NEMO-ERSEM operational ecosystem model for the North West European Continental Shelf

This paper details updates to the Met Office's operational coupled hydrodynamic-ecosystem model from the 7 km Medium-Resolution Continental Shelf – POLCOMS-ERSEM (MRCS-PE) system (Siddorn et al., 2007) to the 7 km Atlantic Margin Model NEMO-ERSEM (AMM7-NE) system. We also provide a validation of the ecosystem component of the new operational system. Comparisons have been made between the model variables and available in situ, satellite and climatological data. The AMM7-NE system has also been benchmarked against the MRCS-PE system. The transition to the new AMM7-NE system was successful and it has been running operationally since March 2012 and has been providing products through MyOcean (http://www.myocean.eu.org) since that time. The results presented herein show the AMM7-NE system performs better than the MRCS-PE system with the most improvement in the model nutrient fields. The problem of nutrient accumulation in the MRCS-PE system appears to be solved in the new AMM7-NE system with nutrient fields improved throughout the domain as discussed in Sect. 4. Improvements in model chlorophyll are also seen but are more modest.