Beschreibung: Particle fluxes at the Cape Verde Ocean Observatory (CVOO) in the eastern tropical North Atlantic for the period December 2009 until May 2011 are discussed based on bathypelagic sediment trap time-series data collected at 1290 and 3439m water depth. The typically oligotrophic particle flux pattern with weak seasonality is modified by the appearance of a highly productive and low oxygen (minimum concentration below 2 μmol kg-1 at 40m depth) anticyclonic modewater eddy (ACME) in winter 2010. The eddy passage was accompanied by unusually high mass fluxes of up to 151 mgm-2 d-1, lasting from December 2009 to May 2010. Distinct biogenic silica (BSi) and organic carbon flux peaks of ~15 and 13.3 mgm-2 d-1, respectively, were observed in February–March 2010 when the eddy approached the CVOO. The flux of the lithogenic component, mostly mineral dust, was well correlated with that of organic carbon, in particular in the deep trap samples, suggesting a tight coupling. The lithogenic ballasting obviously resulted in high particle settling rates and, thus, a fast transfer of epi-/mesopelagic signatures to the bathypelagic traps. We suspect that the two- to three-fold increase in particle fluxes with depth as well as the tight coupling of mineral dust and organic carbon in the deep trap samples might be explained by particle focusing processes within the deeper part of the eddy. Molar C :N ratios of organic matter during the ACME passage were around 18 and 25 for the upper and lower trap samples, respectively. This suggests that some productivity under nutrient (nitrate) limitation occurred in the euphotic zone of the eddy in the beginning of 2010 or that a local nitrogen recycling took place. The d15N record showed a decrease from 5.21 to 3.11‰ from January to March 2010, while the organic carbon and nitrogen fluxes increased. The causes of enhanced sedimentation from the eddy in February/March 2010 remain elusive, but nutrient depletion and/or an increased availability of dust as a ballast mineral for organic-rich aggregates might have contributed. Rapid remineralisation of sinking organic-rich particles could have contributed to oxygen depletion at shallow depth. Although the eddy formed in the West African coastal area in summer 2009, no indications of coastal flux signatures (e.g. from diatoms) were found in the sediment trap samples, confirming the assumption that the suboxia developed within the eddy en route. However, we could not detect biomarkers indicative of the presence of anammox (anaerobic ammonia oxidation) bacteria or green sulfur bacteria thriving in photic zone suboxia/hypoxia, i.e. ladderane fatty acids and isorenieratene derivatives, respectively. This could indicate that suboxic conditions in the eddy had recently developed and/or the respective bacterial stocks had not yet reached detection thresholds. Another explanation is that the fast-sinking organic-rich particles produced in the surface layer did not interact with bacteria from the suboxic zone below. Carbonate fluxes dropped from ~52 to 21.4 mgm-2 d-1 from January to February 2010, respectively, mainly due to reduced contribution of shallow-dwelling planktonic foraminifera and pteropods. The deep-dwelling foraminifera Globorotalia menardii, however, showed a major flux peak in February 2010, most probably due to the suboxia/hypoxia. The low oxygen conditions forced at least some zooplankton to reduce diel vertical migration. Reduced “flux feeding” by zooplankton in the epipelagic could have contributed to the enhanced fluxes of organic materials to the bathypelagic traps during the eddy passage. Further studies are required on eddy-induced particle production and preservation processes and particle focusing.

Beschreibung: The need to cover established and emerging Essential Ocean Variables (EOVs) as defined by the Global Ocean Observing System (GOOS) calls for the development and refinement of the available sensors and samplers, specifically for biogeochemical and biology/ecosystem observations. For several of these EOVs as well as for microplastics as a relatively novel variable of particular societal concern, technological progress has been made as part of AtlantOS. This involves the samplers and sensors and the platforms to use them from as such as well as the required methodologies for obtaining relevant and well-validated results and disseminate data according to the FAIR principles. For biological observations, a main focus was on automated sampling of particles and water samples. While active, pump-based samplers for particles in the water column have been available for many years, it turned out that they were not yet fully mature for operational sampling of zooplankton, microorganisms (e.g., bacteria, archaea, phytoplankton and other eukaryotic unicellular organisms), and microplastics. AtlantOS partners joined forces with manufacturers to overcome limitations with respect to quantitative filtering without leakage, avoidance of plastic contamination and the option for preservation with appropriate agents. Technical solutions were identified and partly tested but could not in all cases be fully implemented in the time frame of the project. Technologies for automated water sampling proved to be more mature and samplers could already be successfully included in observation programs. For both water and particle samples only very few manufacturers offer off-the-shelf solutions which slows down innovation and adaption to user’s needs and may impede successful implementation of appropriate instruments on a larger scale. Particle traps are well-established and operational passive samplers of sinking particles that are widely used for phytoplankton and particulate matter observations based on microscopic sorting and chemical analyses. Using legacy samples collected in the Arctic it could be demonstrated that the same samples can also be used for omics-based observations allowing to address the emerging EOV ‘Microbe biomass and diversity’ and also contributing to the ‘Phytoplankton biomass and diversity’ EOV. Applied to legacy samples also from other sites, this holds the potential to assess past microbial communities of the Atlantic that could serve as a baseline for comparisons to recent communities that are subject to global change. Significant progress was achieved in building capacities for the implementation of omics-based observations of marine organisms into recent and future observation programs. The feasibility of samplers and different preservation agents was tested and a comparison of different methods for omics-based investigations of microbial communities was conducted. The Global Omics Observatory Network (GLOMICON) was established to better connect the institutes and initiatives that are active in the field. As part of GLOMICON, solutions were implemented that allow for a registration of omics observatories and for the sharing of protocols and bioinformatics code. Irrespective of these achievements, major steps still need to be taken to consolidate and standardize approaches in this rapidly evolving field and to establish operational and well-integrated omics-observations as part of an Atlantic Ocean Observation System. For biogeochemical observations, the focus was placed on sensors for oxygen and marine CO2 system parameters (pCO2, total alkalinity) and their readiness for integration into classical as well as emerging biogeochemical observation platforms. For oxygen, the situation is very favourable as the oxygen optode technology and the best practices routines developed around it can be considered fully operational. There are no obstacles for the D3.17 „OceanSITES Innovation Report“ 5 integration of oxygen optodes into the full range of autonomous ocean observation platforms (mooring, drifter, glider, wave gliders, floats, voluntary observing ship etc.). For marine CO2 system parameters, work carried out in AtlantOS focussed the CO2 partial pressure (pCO2) and total alkalinity (TA). With respect to pCO2 it can be stated, that the membraneequilibration sensors with NDIR detection have clearly matured to a level that they can be used routinely on a range of platforms (mooring, wave glider, voluntary observing ship) with an accuracy of ~1% under well-constrained operation conditions and with rigorous data processing routines. Major limitations still exist, however, for this sensor technology on moving platforms (long sensor response time) and platforms with stringent payload and energy limitations (float, glider etc.). In contrast, the pCO2 (as well as pH) optode technology, in which significant hopes lie, has not been forthcoming and existing products still do not meet the quality requirements for open ocean applications. For TA, our intensive testing both in the laboratory and in the field has led to significant improvement of the commercially available system, which now can be considered operational. It allows high-quality autonomous bench-top measurements (e.g., on voluntary observing ships). Ideas for a submersible version of the system are in early stages and would need significant design and testing efforts. With respect to the possibilities of oxygen and carbon measurements from novel autonomous observation platforms, our work in AltantOS has shown very promising applications on profiling Argo floats, submersible winch systems with upper ocean profilers as well as wave gliders. On all these platforms, we were able to successfully implement oxygen and carbon measurements for high-quality observations.

Beschreibung: The European Research Infrastructure Consortium “Integrated Carbon Observation System” (ICOS) aims at delivering high quality greenhouse gas (GHG) observations and derived data products (e.g., regional GHG-flux maps) for constraining the GHG balance on a European level, on a sustained long-term basis. The marine domain (ICOS-Oceans) currently consists of 11 Ship of Opportunity lines (SOOP – Ship of Opportunity Program) and 10 Fixed Ocean Stations (FOSs) spread across European waters, including the North Atlantic and Arctic Oceans and the Barents, North, Baltic, and Mediterranean Seas. The stations operate in a harmonized and standardized way based on communityproven protocols and methods for ocean GHG observations, improving operational conformity as well as quality control and assurance of the data. This enables the network to focus on long term research into the marine carbon cycle and the anthropogenic carbon sink, while preparing the network to include other GHG fluxes. ICOS data are processed on a near real-time basis and will be published on the ICOS Carbon Portal (CP), allowing monthly estimates of CO2 air-sea exchange to be quantified for European waters. ICOS establishes transparent operational data management routines following the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles allowing amongst others reproducibility, interoperability, and traceability. The ICOSOceans network is actively integrating with the atmospheric (e.g., improved atmospheric measurements onboard SOOP lines) and ecosystem (e.g., oceanic direct gas flux measurements) domains of ICOS, and utilizes techniques developed by the ICOS Central Facilities and the CP. There is a strong interaction with the international ocean carbon cycle community to enhance interoperability and harmonize data flow. The future vision of ICOS-Oceans includes ship-based ocean survey sections to obtain a threedimensional understanding of marine carbon cycle processes and optimize the existing network design.

Beschreibung: The project MarParCloud (Marine biological production, organic aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine organic matter (OM) from its biological production, to its export to marine aerosol particles and, finally, to its ability to act as ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the tropics in September–October 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atmospheric Science Unravelled). A suite of chemical, physical, biological and meteorological techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground-based and a mountain station took place. Key variables comprised the chemical characterization of the atmospherically relevant OM components in the ocean and the atmosphere as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modeling studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle number size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concentrations of marine background conditions. Accumulation- and coarse-mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean-derived compounds, such as sea salt and sugar-like compounds, to the cloud level, as derived from chemical analysis and atmospheric transfer modeling results, denotes an influence of marine emissions on cloud formation. Organic nitrogen compounds (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non-marine sources to the local INP concentration, as (biologically active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean–atmosphere transfer. In addition, the number of CCN at the supersaturation of 0.30 % was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar-like compounds, UV-absorbing (UV: ultraviolet) humic-like substances and low-molecular-weight neutral components were important organic compounds in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific organic compounds in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atmosphere and the role of additional sources. In summary, when looking at particulate mass, we see oceanic compounds transferred to the atmospheric aerosol and to the cloud level, while from a perspective of particle number concentrations, sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited.

Beschreibung: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Benway, H. M., Lorenzoni, L., White, A. E., Fiedler, B., Levine, N. M., Nicholson, D. P., DeGrandpre, M. D., Sosik, H. M., Church, M. J., O'Brien, T. D., Leinen, M., Weller, R. A., Karl, D. M., Henson, S. A., & Letelier, R. M. Ocean time series observations of changing marine ecosystems: An era of integration, synthesis, and societal applications. Frontiers in Marine Science, 6, (2019): 393, doi:10.3389/fmars.2019.00393.

Beschreibung: Sustained ocean time series are critical for characterizing marine ecosystem shifts in a time of accelerating, and at times unpredictable, changes. They represent the only means to distinguish between natural and anthropogenic forcings, and are the best tools to explore causal links and implications for human communities that depend on ocean resources. Since the inception of sustained ocean observations, ocean time series have withstood many challenges, most prominently availability of uninterrupted funding and retention of trained personnel. This OceanObs’19 review article provides an overarching vision for sustained ocean time series observations for the next decade, focusing on the growing challenges of maintaining sustained ocean time series, including ship-based and autonomous coastal and open-ocean platforms, as well as remote sensing. In addition to increased diversification of funding sources to include the private sector, NGOs, and other groups, more effective engagement of stakeholders and other end-users will be critical to ensure the sustainability of ocean time series programs. Building a cohesive international time series network will require dedicated capacity to coordinate across observing programs and leverage existing infrastructure and platforms of opportunity. This review article outlines near-term observing priorities and technology needs; explores potential mechanisms to broaden ocean time series data applications and end-user communities; and describes current tools and future requirements for managing increasingly complex multi-platform data streams and developing synthesis products that support science and society. The actionable recommendations outlined herein ultimately form the basis for a robust, sustainable, fit-for-purpose time series network that will foster a predictive understanding of changing ocean systems for the benefit of society.

Beschreibung: This work was led by HB in the Ocean Carbon and Biogeochemistry (OCB) Project Office, which is supported by the NSF OCE (1558412) and the NASA (NNX17AB17G).

Beschreibung: Modern digital scientific workflows - often implying Big Data challenges - require data infrastructures and innovative data science methods across disciplines and technologies. Diverse activities within and outside HGF deal with these challenges, on all levels. The series of Data Science Symposia fosters knowledge exchange and collaboration in the Earth and Environment research community. We invited contributions to the overarching topics of data management, data science and data infrastructures. The series of Data Science Symposia is a joint initiative by the three Helmholtz Centers HZG, AWI and GEOMAR Organization: Hela Mehrtens and Daniela Henkel (GEOMAR)