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Coastal Atmosphere & Sea Time Series (CoASTS) and Bio-Optical mapping of Marine optical Properties (BiOMaP): the near- surface marine bio-optical data

The CoASTS-BiOMaP data set comprises in situ near-surface inherent (e.g., absorption, scattering and backscattering coefficient s) and apparent (e.g., normalized-water leaving radiance and the corresponding remote sensing reflectance) optical properties of relevance for satellite ocean colour applications. The data were produced through the Coastal Atmosphere & Sea Time Series (CoASTS) and the Bio-Optical mapping of Marine optical Properties (BiOMaP) measurement programs implemented by the Marine Optical Laboratory of the Joint Research Center (JRC) in collaboration with a number of European institutions. Common to both CoASTS and BiOMaP is the standardization of instruments, measurement methods, quality control schemes and processing codes to enforce temporal and spatial consistency to data products. CoASTS measurements comprise 125 field campaigns and 637 stations performed from December 1998 up to March 2016 benefitting of the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea to generate time series data at a fixed coastal site. CoASTS data exhibit occurrence of waters with optical properties largely determined by phytoplankton, as well as diverse concentrations of suspended particulate matter (SPM) and of coloured organic matter (CDOM). BiOMaP measurements comprise 36 bio-optical oceanographic campaigns and 1915 stations performed between July 2000 and May 2022 using a variety of oceanographic vessels to produce spatially distributed data across various European Seas. BiOMaP measurement regions include: the Baltic Sea exhibiting waters dominated by a high concentration of CDOM; the Adriatic Sea, Black Sea, North Sea (comprising the English Channel), Ligurian Sea, Iberian Shelf and the Greenland Sea, characterized by a variety of optically complex waters determined by diverse concentrations of CDOM and SPM; the Eastern and Western Mediterranean oligotrophic and mesotrophic Seas.

Nitrous oxide in the sea surface microlayer and underlying water during a phytoplankton bloom: a mesocosm study (2023)

Dissolved nitrous oxide (N₂O) concentrations were measured in the sea surface microlayer (SML, upper 1 mm) and the underlying water (ULW) during the BASS mesocosm study conducted with Jade Bay (southern North Sea) water from 16 May to 16 June 2023. The dataset contains N₂O concentrations from both water layers throughout the experimental period. Sampling of the SML was carried out using the glass plate method. The measurements cover conditions before, during and after a phytoplankton bloom.

Dissolved organic matter composition in the sea surface microlayer during a Mesocosm study in Wilhelmshaven, Germany (FT-ICR-MS and ATR-FTIR), spring 2023

We studied dissolved organic matter (DOM) dynamics in the sea surface microlayer (SML) during a mesocosm study at the Sea sURface Facility (SURF) of the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany (53.5148 °N, 8.1463 °E). The study was conducted from 18 May to 16 June 2023 as part of the multidisciplinary BASS research unit (Biogeochemical processes and Air-sea exchange in the Sea-Surface microlayer). SURF was filled with pretreated natural seawater from the nearby Jade Bay (53° 28' 42'' N, 8° 12' 15'' E) to replicate natural conditions. We selected this approach to examine the regrowth of surviving phytoplankton cells after the initial water treatments, simulating a native microbial community starting with almost no bioproduction or pre-existing bioproduction products. To induce and maintain the phytoplankton bloom, inorganic nitrogen, phosphorus, and silicate were added on May 26, May 31, and June 01, 2023. By that, we induced an algal bloom of Emiliania huxleyi and Cylindrotheca closterium. Water samples were collected using a glass plate for the SML and a tube at 40 cm depth for the underlying water (ULW). This dataset contains DOM molecular data from ultrahigh-resolution mass spectrometry (Fourier-transform ion cyclotron resonance mass spectrometer, FT-ICR-MS), molecular indices calculated from FT-ICR-MS data (Ibio, Iphoto, IDEG) and environmental data, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). Furthermore, it contains attenuated total reflectance Fourier Transform Infrared (ATR-FTIR) data from representative samples for each bloom phase. By combining molecular analyses with nutrient and bloom-phase data, we highlight the in situ production of carbohydrate-like and laminarin-derived DOM as a significant contributor to SML composition. General metadata from the multidisciplinary mesocosm study, including temperature, salinity and chlorophyll a, are provided in Bibi et al. on PANGAEA at the following link: doi:10.1594/PANGAEA.984101.

Untersuchungen des Tagesgangs verschiedener Spurengase mit Hilfe der solaren Absorptionsspektroskopie im infraroten Spektralbereich im tropischen Westpazifik (TROPAC)

Der Ozean im Westpazifik ist mit Temperaturen von ganzjährig 30°C der wärmste Ozean der Welt. Im tropischen Westpazifik ist die Lufttemperatur der Grenzschicht weltweit am höchsten und die Ozonkonzentration am niedrigsten. Aufgrund der allgemeinen Advektion der Luftmassen in der unteren und mittleren Troposphäre aus dem Osten durch die Walker-Zirkulation über den Pazifik befindet sich die Luft über dem tropischen Westpazifik für längere Zeit in einer sauberen, warmen und feuchten Umgebung. Der Abbau von reaktiven Sauerstoff- und Ozonvorläufern wie NOx findet daher länger als anderswo in den Tropen, was zu sehr niedrigen Ozonkonzentrationen führte. Dies erhöht die Lebensdauer von kurzlebigen biogenen und anthropogenen Spurengasen. Darüber hinaus begünstigen hohe Meeresoberflächentemperaturen eine starke Konvektion im tropischen Westpazifik, was zu niedrigen Ozonmischungsverhältnissen in den konvektiven Ausflussgebieten in der oberen Troposphäre führen kann. Der Warmpool im Westpazifik ist auch eine wichtige Quellregion für stratosphärische Luft. Daher fallen die Region, in der die Lebensdauer kurzlebiger Spurengase erhöht ist, und die Quellregion der stratosphärischen Luft zusammen. Somit bestimmt die Zusammensetzung der troposphärischen Atmosphäre in dieser Region in hohem Maße auch die globale stratosphärische Zusammensetzung.Ozon ist aufgrund von Rückkopplungsprozessen zwischen Temperatur, Dynamik und Ozon ein wichtiges Spurengas in der Klimaforschung. Da der Warmpool im Westpazifik die Hauptquellenregion für stratosphärische Luft ist, ist die Kenntnis von Ozon und anderen kurzlebigen Spurengasen auch wichtig, um den Transport von Spurengasen in die Stratosphäre zu verstehen.Ziel unseres Projektes ist die Messung des Tagesgangs von Ozon und anderen Spurengasen mit Hilfe der hochauflösenden solaren Absorptions-FTIR-Spektroskopie. Die Messungen liefern die Gesamtsäulendichten von bis zu 20 Spurengasen. Für einige Spurengase erlaubt die Analyse der Spektrallinienform die Ableitung der Konzentrationsprofile in bis zu etwa vier atmosphärischen Höhenschichten. Ergänzt werden die Beobachtungen durch Ozonballonsondierungen, kontinuierliche Messungen der UV-Strahlung, und Modellrechnungen mit einem Chemie-Transport-Modell. Die Messungen sind für den Zeitraum August bis Oktober 2022 geplant, die Auswertung und Interpretation von November 2022 bis Januar 2023.

Evolutionsökologie und Biogeographie der Gastropoden des Kaspischen Meeres

Das Kaspische Meer repräsentiert ein Relikt der östlichen Paratethys und das, sowohl nach Oberfläche als auch nach Volumen, weltweit größte lakustrine Gewässer. Die Einzigartigkeit des Sees für evolutionsökologische und biogeographische Forschung ist insbesondere auch im Kontext starker hydrologischer Differenzierungen und einer wechselhaften neogenen und quartären Paläogeographie zu sehen. Die Kaspis scheint biogeographisch zwischen den europäischen und den zentralasiatischen Faunen zu vermitteln. Die Organismen des Sees sind jedoch größtenteils nicht modern, d.h. nicht falsifizierbar systematisch bearbeitet, so dass über stammesgeschichtliche und (paläo-) biogeographische Zusammenhänge weitgehend nur spekuliert werden kann. Im Zuge einer detaillierten, analytischen Bearbeitung der rezenten kaspischen Gastropoden, unter Einbeziehung ausgewählter Begleitfauna, soll deren evolutionsökologischer Kontext aufgeklärt und damit Bezüge zu den fossilen Faunen der westlichen Paratethys einerseits und zu den (Paläo-) Seen Zentralasiens andererseits, abgeklärt werden.

Schwerpunktprogramm (SPP) 527: Bereich Infrastruktur - International Ocean Discovery Program, Teilprojekt: Entwicklung eines 3,5 Millionen Jahre langen Index der Dipolvariabilität im Indischen Ozean

Der Indische Ozean Dipol (IOD) ist der bestimmende Modus der jährlichen Variabilität der Meeresoberflächentemperaturen (SST) im tropischen Indischen Ozean. Der IOD repräsentiert warme (positive) und kalte (negative) SST-Schwankungen zwischen dem westlichen und östlichen Teil des Indischen Ozeans. Vom IOD verursachte extreme Klimaereignisse (z.B: Dürren in Australien, Überschwemmungen in Ostafrika) werden, angetrieben durch die Zunahme von Treibhausgasen, voraussichtlich in Zukunft häufiger auftreten. Trotz potentiell tiefgreifender Auswirkungen auf die angrenzenden Regionen mit mehr als 2 Milliarden Einwohnern ist die die postulierte Sensitivität des IOD gegenüber CO2 Variationen unzureichend erforscht. Hier könnte die Erforschung der IOD-Variabilität während geologischer Zeitintervalle mit höheren CO2-Gehalten einen wichtigen Beitrag leisten. Bisher fehlen jedoch geeignete paläoklimatologische Datensätze aus der Kernregion des IOD im Indischen Ozean weitgehend.Das vorgeschlagene Projekt zielt darauf ab, IOD-Veränderungen während der letzten 3,5 Millionen Jahre mittels eines neuen IOD-Proxies zu entschlüsseln. Dieser Zeitraum war durch erhebliche Schwankungen im globalen CO2-Gehalt gekennzeichnet und umfasst die Spät-Pliozäne Warmphase, die als Analogon für den künftigen Klimawandel gilt. Im Zentrum dieses Projekts steht die Hypothese, dass IOD-bedingte Schwankungen der Oberflächenwinde die tiefe meridionale Umwälzungszirkulation im Indischen Ozean beeinflussen. Basierend auf rezenten Beobachtungsdaten verursacht die Schwächung (Verstärkung) des Ekman-Transports während positiver (negativer) IOD-Phasen eine geringere (verstärkte) Belüftung des Tiefwasserregimes und folglich ein Aufsteigen (Absinken) der Lysokline. Diese neuen hydrografischen Erkenntnisse eröffnen somit einen völlig neuen Weg für die Erforschung vergangener IOD-Veränderungen. Daher zielt dieses Projekt darauf ab, Änderungen der Tiefenwasserbelüftung im westlichen Indischen Ozean als Index für die IOD-Variabilität heranzuziehen. In diesem Projekt sollen daher speziell zwei Hypothesen getestet werden:1) Karbonatlösungsszyklen sind Indikatoren für Veränderungen der Tiefenwasserbelüftung im westlichen Indischen Ozean und repräsentieren ein Maß für die Intensität des IOD,2) Die Amplitude des IOD ist linear korreliert mit Änderungen des globalen CO2-Gehalts.Um die Variabilität der Tiefwasserventilation in hoher zeitlicher Auflösung zu entschlüsseln, wird der Sedimentkern ODP 709 aus dem westlichen äquatorialen Indischen Ozean, einer Schlüsselregion des IOD, untersucht. Dabei werden Daten aus zeitlich hochaufgelösten XRF-Messungen mit stabilen Isotopen und Mg/Ca-basierend Meeresoberflächentemperaturen anhand von benthischen und planktischen Foraminiferen kombiniert. Die Synthese der gesammelten Daten erlaubt die Entwicklung deines Vergleichsindex der IOD-Variabilität für die letzten 3,5 Millionen Jahre.

PARAFAC components and fluorescent dissolved organic matter (FDOM) indices on organic matter transformation processes in the sea-surface microlayer and the underlying water during a mesocosm phytoplankton bloom in 2023

The effects of a phytoplankton bloom and photobleaching on colored dissolved organic matter (CDOM) in the sea-surface microlayer (SML) and the underlying water (ULW) were studied in a month-long mesocosm study, in May and June of 2023, at the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany. The mesocosm study was conducted by the DFG research group BASS (Biogeochemical processes and Air–sea exchange in the Sea-Surface microlayer, Bibi et al., 2025) in the Sea Surface Facility (SURF) of the ICBM. The facility contains an 8 m × 1.5 m × 0.8 m large outdoor basin with a retractable roof, which was closed at night and during rain events. The basin was filled with North Sea water from the adjacent Jade Bay. Homogeneity of the ULW in the basin was achieved by constant mixing of the water column. The daily SML and ULW samples were collected alternating in the morning, about 1 h after sunrise, and in the afternoon, about 10 h after sunrise. The alternation of sampling times intended to capture a potential effect of sun-exposure duration on DOM transformations and elucidated the day and night variability of the layers. The SML was collected via glass plate sampling (Cunliffe and Wurl, 2014). The ULW was sampled via a submerged tube and a connected syringe suction system in 0.4 m depth. The removed sample volume was refilled with Jade Bay water every day. SML and ULW samples were filtered through pre-flushed 0.7 µm Whatman GF/F and 0.2 nucleopore filters into clear 40 ml SUPELCO bottles. These bottles were acid-washed twice and combusted at 500 °C for 5 h. The samples were stored dark and at 4 °C and measured within a few days of the study. FDOM was measured using a Aqualog fluorescence spectrometer (Horiba Scientific, Japan) with 10 seconds integration time and high gain of the CCD (charge-coupled device) sensor within an excitation range from 240 to 500 nm, and an emission range from 209.15 to 618.53 nm. The Aqualog measures fluorescence as well as absorption. The resulting data includes an excitation-emission-matrix (EEM) of the blank (MilliQ Starna cuvette), an EEM of the sample, and the absorption values of the sample. The raw exported Aqualog data was corrected for errors and lamp shifts. The corrected EEM data is then decomposed by PARAFAC (Murphy et al., 2013) for its underlying fluorophore components. Before running the PARAFAC routine, the corrected data needed to undergo a correction process by subtracting the blank from the sample EEM and canceling the influences of the inner-filter effect (IFE, Parker & Rees, 1962; Kothawala et al., 2013). The fluorescence intensity of the IFE-corrected EEM is calibrated by using the Raman scatter peak of water (Lawaetz & Stedmon, 2009). For PARAFAC the corrected data was processed using the drEEM and NWAY toolbox (version 0.6.5; Murphy et al., 2013) in MATLAB (R2020b). A 4-component model was validated with the validation style S4C6T3 for the split half analysis with nonnegativity constraints and 1-8e as the convergence criteria with 50 random starts and a maximum number of 2500 iterations. The resulting final model had a core consistency of 88.11 and the explained percentage was 99.55%. Furthermore, four fluorescence indices were calculated from the corrected EEM data (HIX – Humification index, Zsolnay et al., 1999; BIX – Biological index, Huguet et al., 2009; REPIX – Recently produced index, Parlanti et al., 2000, Drozdowska et al., 2015; ARIX, Murphy, 2025).

Surface seawater carbonate chemistry, nutrients and phytoplankton community composition on a transect between North Sea and Arctic Ocean, 2008

This data was collected during the 'ICE CHASER' cruise from the southern North Sea to the Arctic (Svalbard) in July-Aug 2008. This data consists of coccolithophore abundance, calcification and primary production rates, carbonate chemistry parameters and ancillary data of macronutrients, chlorophyll-a, average mixed layer irradiance, daily irradiance above the sea surface, euphotic and mixed layer depth, temperature and salinity.

Microscale profiles of oxygen, pH and temperature through the sea surface microlayer in a mesocosm experiment during an algal bloom

The sea surface microlayer (SML) is the boundary layer on top of all oceans and is crucial for all exchange processes between the ocean and atmosphere. This less than 1 mm thick layer is heavily influenced by biological processes and events like algal blooms. To quantify the influence of an algal bloom in a controlled environment, we conducted a mesocosm study at the Sea sURface Facility (SURF) of the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany (53.5148 °N, 8.1463°E). SURF is an 8.5 m long, 2 m wide and 1 m deep water basin, which can directly be filled with seawater from the Jade Bay, North Sea. The facility is equipped with a retractable roof, pumps for water circulation and dedicated mounts for multiple sensor systems. The mesocosm experiment was conducted from 18 May to 16 June 2023 as part of the project BASS (Biogeochemical processes and Air-sea exchange in the Sea-Surface microlayer). SURF was filled with seawater a few days before the start of the experiment (water depth 0.7 m). The water was then filtered and the surface skimmed to remove initial pollution. To prevent particle and microbial sedimentation during the experiment, the pumps operated at low speed to maintain gentle mixing of the water column. The roof of SURF was closed during the night, while it was open during the day except when it rained. To induce an algal bloom, a mix of nutrients (nitrogen, phosphorus and silicate) was added on 26 May, 30 May and 01 June. Based on the chlorophyll measurements which show the development of the bloom, three phases of the experiment were determined: the pre-bloom phase (18 May to 26 May), the bloom phase (27 May to 04 June) and the post-bloom phase (05 June to 16 June). Several physical, chemical and biological parameters were measured, which will be published in other datasets. To evaluate the impact of the algal bloom within the SML, oxygen concentration, pH, and temperature were measured in situ using microsensors (UNISENSE, Denmark) mounted on a MicroProfiling System (UNISENSE, Denmark). With this setup, direct in situ measurements inside both the thermal boundary layer and diffusion boundary layer at the sea surface can be made. One oxygen microsensor, two pH microsensors and three temperature microsensors were mounted on the microprofiler with their tips pointing upward to avoid disturbance in the SML. They were positioned a few centimeters apart. The microprofiler was used to automatically move the sensors down, from the air through the SML and into the underlying water over a total distance of 10 000 µm in steps of 125 µm (250 µm at the start of the experiment). At each depth, the sensors stayed for about 10 s, giving a mean value and a standard deviation over that time. Three of these measurements were taken at every depth before the sensor moved down to the next step. After completing a profile, the microprofiler returned to its initial position with the tips in the air to start the next profile. The resulting profiles mostly took between 40 to 50 minutes. These profiles were conducted continuously during day and night, except for small breaks to clean and if needed replace or readjust the sensors and recalibrate the pH sensors. The sensors' height required manual adjustment to position the tip precisely at the water surface (0 µm). Through this manual adjustment, small inaccuracies may occur. As a result, the sensor depth readings form the microprofiler system may not reflect the true sensor position, which can also vary between the sensors. The true sensor positions can later be obtained by analysing the measured profiles.

Clay and heavy minerals and total organic carbon in Arctic Ocean surface sediments – Data tables to distribution maps of Stein (2008)

Total organic carbon (TOC) and mineral assemblages are key data sets determined to characterize marine sediments in terms of sediment provenances, processes, and depositional environments. In a comprehensive review and synthesis (Stein, 2008), such data were compiled for Arctic Ocean surface sediments and shown in nine selected distribution maps: four maps of clay minerals (illite, smectite, chlorite, and kaolinite), four maps of heavy minerals (amphibole, clinopyroxene, epidote, and garnet), and one TOC map. The data used to produce these maps, are represented in the three tables of this data report. For details in background information and methodology see primary source literature cited here as well as the Stein (2008) synthesis.

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