Towards a Multi‐Platform Assimilative System for North Sea Biogeochemistry. Issue 4 (25th March 2021)

• Record Type: Journal Article
• Authors: Skákala, Jozef; Ford, David; Bruggeman, Jorn; Hull, Tom; Kaiser, Jan; King, Robert R.; Loveday, Benjamin; Palmer, Matthew R.; Smyth, Tim; Williams, Charlotte A. J.; Ciavatta, Stefano
• Is Part Of: Journal of geophysical research. Volume 126:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-25
• Subjects: glider observations -- marine ecosystems -- multi‐platform data assimilation -- Shelf seas; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2020JC016649
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Oceanography has entered an era of new observing platforms, such as biogeochemical‐Argo floats and gliders, some of which will provide three‐dimensional maps of essential ecosystem variables on the North‐West European (NWE) Shelf. In a foreseeable future operational centers will use multi‐platform assimilation to integrate those valuable data into ecosystem reanalysis and forecast systems. Here we address some important questions related to glider biogeochemical data assimilation (DA) and introduce multi‐platform DA in a preoperational model of the NWE Shelf sea ecosystem. We test the impact of the different multi‐platform system components (glider vs. satellite, physical vs. biogeochemical) on the simulated biogeochemical variables. To characterize the model performance, we focus on the period around the phytoplankton spring bloom, since the bloom is a major ecosystem driver on the NWE Shelf. We found that the timing and magnitude of the phytoplankton bloom is insensitive to the physical DA, which is explained in the study. To correct the simulated phytoplankton bloom one needs to assimilate chlorophyll observations from glider or satellite Ocean Color (OC) into the model. Although outperformed by the glider chlorophyll assimilation, we show that OC assimilation has mostly desirable impact on the sub‐surface chlorophyll. Since the OC assimilation updates chlorophyll only in the mixed layer, the impact on the sub‐surface chlorophyll is the result of the model dynamical response to the assimilation. We demonstrate that the multi‐platform assimilation combines the advantages of its components and always performs comparably to its best performing component. Plain Language Summary: North‐West European (NWE) Shelf is a region of major importance for both European economy and climate. Observational oceanography has entered an important era of new observing biogeochemical platforms, such as Biogeochemical‐Argos and gliders. Gliders are being currently deployed to measure three‐dimensional distributions of some essential biogeochemical variables on the NWE Shelf. This work establishes a multi‐platform assimilative system on the NWE Shelf which will be used to combine multiple different types of observing platforms (e.g., satellite, gliders) with our up to date models in order to optimize our estimate and forecast of the NWE Shelf ecosystem state. We provide an understanding for how the different components of the system interact. We demonstrate that the assimilative system is skilled to combine physical data with satellite and glider data for chlorophyll, as well as the glider data for oxygen. The work establishes the foundations of a system that is planned to be used in the future operational oceanography on the NWE Shelf. Key Points: We successfully developed a multi‐platform assimilative system for biogeochemistry in the North Sea We tested the impact of the different assimilative system components on the ecosystem reanalysis The multi‐platform assimilation will become an essential part of future operational research