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The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface to bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2023 is an update of the previous version, GLODAPv2.2022 (Lauvset et al., 2022). The major changes are as follows: data from 23 new cruises were added. In addition, a number of changes were made to the data included in GLODAPv2.2022. GLODAPv2.2023 includes measurements from more than 1.4 million water samples from the global oceans collected on 1108 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, chlorofluorocarbon-11 (CFC-11), CFC-12, CFC-113, CCl 4 , and SF 6) have undergone extensive quality control with a focus on the systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 23 new cruises were derived by comparing those data with the data from the 1085 quality-controlled cruises in the GLODAPv2.2022 data product using crossover analysis. SF 6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO 2), chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data-handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µ mol kg -1 in dissolved inorganic carbon, 4 µ mol kg -1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO 2 fugacity (f CO 2), were not subjected to bias comparison or adjustments. The original data, their documentation, and DOI codes are available at the Ocean Carbon and Acidification Data System of NOAA National Centers for Environmental Information (NCEI), which also provides access to the merged data product. This is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/zyrq-ht66 (Lauvset et al., 2023). These bias-adjusted product files also include significant ancillary and approximated data, which were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2023 methods and provides a broad overview of the secondary quality control procedures and results. [ABSTRACT FROM AUTHOR]

Having descended through the water column, microplankton in ocean sediments is representative of the ocean surface environment, where it originated. Sedimentary microplankton is therefore used as an archive of past and present surface oceanographic conditions. However, these particles are advected by turbulent ocean currents during their sinking journey. So far, it is unknown to what extent this particle advection shapes the microplankton composition in sediments. Here we use global simulations of sinking particles in a strongly eddying global ocean model, and define ocean bottom provinces based on the particle surface origin locations. We find that these provinces can be detected in global datasets of sedimentary microplankton assemblages, demonstrating the effect provincialism has on the composition of sedimentary remains of surface plankton. These provinces explain the microplankton composition, in addition to, e.g., the ocean surface environment. Connected provinces have implications for the optimal spatial extent of microplankton sediment sample datasets that are used for palaeoceanographic reconstruction, and for the optimal spatial averaging of sediment samples over global datasets. [ABSTRACT FROM AUTHOR]

EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of 17 tidal constituents are provided on a global 0.125 ∘ grid based on empirical analysis of seven satellite altimetry missions and four extended missions. The EOT20 model shows significant improvements compared to the previous iteration of the global model (EOT11a) throughout the ocean, particularly in the coastal and shelf regions, due to the inclusion of more recent satellite altimetry data as well as more missions, the use of the updated FES2014 tidal model as a reference to estimated residual signals, the inclusion of the ALES retracker and improved coastal representation. In the validation of EOT20 using tide gauges and ocean bottom pressure data, these improvements in the model compared to EOT11a are highlighted with the root sum square (RSS) of the eight major tidal constituents improving by ∼ 1.4 cm for the entire global ocean with the major improvement in RSS (∼ 2.2 cm) occurring in the coastal region. Concerning the other global ocean tidal models, EOT20 shows an improvement of ∼ 0.2 cm in RSS compared to the closest model (FES2014) in the global ocean. Variance reduction analysis was conducted comparing the results of EOT20 with FES2014 and EOT11a using the Jason-2, Jason-3 and SARAL satellite altimetry missions. From this analysis, EOT20 showed a variance reduction for all three satellite altimetry missions with the biggest improvement in variance occurring in the coastal region. These significant improvements, particularly in the coastal region, provide encouragement for the use of the EOT20 model as a tidal correction for satellite altimetry in sea-level research. All ocean and load tide data from the model can be freely accessed at 10.17882/79489. The tide gauges from the TICON dataset used in the validation of the tide model, are available at 10.1594/PANGAEA.896587. [ABSTRACT FROM AUTHOR]

In recent decades the decline of the Arctic sea ice has modified vertical momentum fluxes from the atmosphere to the ice and the ocean, thereby affecting the surface circulation. In the past ten years satellite altimetry has contributed to understand these changes. However, data from ice-covered regions require dedicated processing, originating inconsistency between ice-covered and open ocean regions in terms of biases, corrections and data coverage. Thus, efforts to generate consistent Arctic-wide datasets are still required to enable the study of the Arctic Ocean surface circulation at basin-wide scales. Here we provide and assess a monthly gridded dataset of sea surface height anomaly and geostrophic velocity. This dataset is based on Cryosat-2 observations over ice-covered and open ocean areas of the Arctic up to 88° N for the period 2011 to 2018, interpolated using the Data-Interpolating Variational Analysis (DIVA) method. Geostrophic velocity was not available north of 82° N before this study. To examine the robustness of our results, we compare the generated fields to one independent altimetry dataset and independent data of ocean bottom pressure, steric height and near-surface ocean velocity from moorings. Results from the comparison to near-surface ocean velocity show that our geostrophic velocity fields can resolve seasonal to interannual variability of boundary currents wider than about 50 km. We further discuss the seasonal cycle of sea surface height and geostrophic velocity in the context of previous literature. Large scale features emerge, i.e. Arctic-wide maximum sea surface height between October and January, with the highest amplitude over the shelves, and basin wide seasonal acceleration of Arctic slope currents in winter. We suggest that this dataset can be used to study not only the large scale sea surface height and circulation but also the regionally confined boundary currents. The dataset is available in netCDF format from PANGAEA at [data currently under review]. [ABSTRACT FROM AUTHOR]

Sedimentary 231Pa / 230Th ratios provide clues to estimate the strength of past ocean circulation. For its estimation, understanding the processes controlling the distributions of dissolved 231Pa and 230Th in the ocean is important. However, simulations of dissolved and particulate 231Pa and 230Th in the modern ocean, recently obtained from the GEOTRACES project, remain challenging. Here we show an improved model simulation of 231Pa and 230Th in the global ocean by introducing bottom scavenging and the dependence of scavenging efficiency on particle concentration with water-column reversible scavenging. The incorporation of bottom scavenging improves the simulated distribution of dissolved 231Pa and 230Th in the deep ocean, which has been overestimated in models not considering the bottom scavenging. We further demonstrate that introducing the dependence of scavenging efficiency on particle concentration results in a high concentration of dissolved 230Th in the Southern Ocean. Our best simulation can well reproduce not only the oceanic distribution of 231Pa and 230Th but also the sedimentary 231Pa / 230Th ratios. Sensitivity analysis reveals that oceanic advection of 231Pa primarily determines sedimentary 231Pa / 230Th ratios. On the other hand, 230Th advection and bottom scavenging have an opposite effect to 231Pa advection on the sedimentary 231Pa / 230Th ratios, reducing their latitudinal contrast. Our model realistically simulates the residence times of 231Pa and 230Th, whereas previous models that reported the similar distribution of sedimentary 231Pa / 230Th ratios significantly overestimate the residence times for both 231Pa and 230Th. [ABSTRACT FROM AUTHOR]

EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of seventeen tidal constituents are provided on a global 0.125-degree grid based on empirical analysis of seven satellite altimetry missions and four extended missions. The EOT20 model shows significant improvements compared to the previous iteration of the global model (EOT11a) throughout the ocean, particularly in the coastal and shelf regions, due to the inclusion of more recent satellite altimetry data as well as more missions, the use of the updated FES2014 tidal model as a reference to estimated residual signals, the inclusion of the ALES retracker and improved coastal representation. In the validation of EOT20 using tide gauges and ocean bottom pressure data, these improvements in the model compared to EOT11a are highlighted with the root-square sum (RSS) of the eight major tidal constituents improving by ~3 cm for the entire global ocean with the major improvement in RSS (~3.5 cm) occurring in the coastal region. Concerning the other global ocean tidal models, EOT20 shows an improvement of ~0.2 cm in RSS compared to the closest model (FES2014) in the global ocean. Variance reduction analysis was conducted comparing the results of EOT20 with FES2014 and EOT11a using the Jason-2, Jason-3 and SARAL satellite altimetry missions. From this analysis, EOT20 showed a variance reduction for all three satellite altimetry missions with the biggest improvement in variance occurring in the coastal region. These significant improvements, particularly in the coastal region, provides encouragement for the use of the EOT20 model as a tidal correction for satellite altimetry in sea-level research. All ocean and load tide data from the model can be freely accessed at https://doi.org/10.17882/79489 (Hart-Davis et al., 2021). [ABSTRACT FROM AUTHOR]

Mineral dust plays an important role in the ocean's carbon cycle through the input of nutrients and metals which potentially fertilise phytoplankton, and by ballasting organic matter from the surface ocean to the sea floor. However, time series and records of open-ocean dust deposition fluxes are sparse. Here, we present a two-year time series of the spatial and temporal evolution of dust-deposition fluxes from a trans-Atlantic array of dust-collecting instruments (surface dust collectors and moored submarine traps) directly below the core of the Saharan dust plume along 12°N. By combining observational data of actually deposited dust with model simulations and satellite observations, we argue that dust deposition in the Atlantic is strongly influenced by summer rains. Using in-situ incubation experiments we demonstrate that such wet deposition increases the release of nutrients up to an order-of-magnitude relative to dry deposition. As a result, we hypothesise that rain-amplified bioavailability of these nutrients may well be the key to increased surface-ocean productivity in remote and oligotrophic parts of the oceans and, potentially, continental ecosystems. [ABSTRACT FROM AUTHOR]

Ocean bottom pressure signals surrounding major bathymetric features along the Antarctic Circumpolar Current (ACC) are caused by topographic form stress balancing the zonal wind stress being applied to the Southern Ocean. Variability in this pressure field can be attributed to changes in the ACC. However, Antarctic Bottom Water (AABW), which is formed locally, flows northward into the basin. This flow is geostrophic and has an altering effect on the bottom pressure observed along the bathymetry. This signal can be observed in the remotely-sensed ocean bottom pressure data from the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Followon satellites and can be used as a tool for better understanding the variability of this system in a changing climate. In this experiment, we use GRACE bottom pressure data from the Center for Space Research at the University of Texas to examine both the upstream and downstream sides of two significant bathymetric features along the path of the ACC: the Drake Passage and the Kerguelen Plateau. We show the variability of the bottom pressure signal in these locations and analyze their relationship with each other as well with regional zonal wind stress and AABW formation over time. [ABSTRACT FROM AUTHOR]

Sea Level Rise (SLR) is both an indicator and a serious consequence of climate change. To estimate the impact of SLR in the future, it is necessary that we monitor and understand the contemporary SLR. Partitioning SLR into its contributors, conventionally understood to be mass change and steric change, is known as Sea Level Budget (SLB). In the last few decades, we have been able to monitor changes in sea surface height, ocean mass, and steric heights with unprecedented accuracy. However, we are able to close the SLB only within most pessimistic uncertainties of its components. The SLB equation assumes the ocean bottom to be static, which is likely not the case in recent past because the ocean mass is increasing rapidly, and it invites an elastic solid Earth response. Therefore, we revisit the SLB with a mass-volume model that allows ocean bottom to deform. We find that the SLB equation requires additional solid Earth term: Ocean Bottom Deformation (OBD). The mathematical derivation illustrates that OBD will be picked up by global observations of sea surface heights and ocean mass change from GRACE. We use global observations of sea surface height anomaly, ocean mass anomaly and steric changes to obtain a first observation driven estimate of OBD: $\unit[-0.12 \pm 0.01]{mm/yr}$, which is very close to that obtained by another study using an Earth-system model. [ABSTRACT FROM AUTHOR]

The International Ocean Discovery Program (IODP) is supported by multiple Funding Agencies from around the world, and delivered by 3 Platform Providers; the US National Science Foundation provides the JOIDES Resolution, Japan's Ministry of Education, Culture, Sports, Science, and Technology provides the D/V Chikyu, and the European Consortium for Ocean Research Drilling (ECORD) provides mission-specific platforms (MSPs) which are contracted on a case-by-case basis. Each IODP platform provides specialist capability. However, as capable as the two dedicated IODP platforms are, they are unable to reach all geological targets, such as those located under ice-covered seas, in shallow water, in environmentally sensitive areas or in certain hard-to-drill lithologies. To date, ECORD has implemented eight MSP expeditions in a wide range of challenging environments. Whilst these projects had multiple objectives, including the recovery of records of climate and sea level change, and previously unknown buried microbiological communities, all of them were driven by scientific demands. As the IODP evolves, so do the methods used to collect cores from below the seabed. From utilisation of In-Kind Contributions of vessels through to development of new tools with industry, ECORD aim to realise the call from the scientific community to continually push the scientific boundaries. ECORD is driving an initiative to use alternative coring technologies in addition to the wireline coring that is traditionally used for scientific drilling. This includes development of remotely operated seabed rockdrills and associated battery triggered wireline logging tools, to borehole plugs and water sampling and analysis whilst drilling capability. [ABSTRACT FROM AUTHOR]

The Arctic is warming twice as fast as other parts of the globe. The loss of Arctic ice and changes in the Arctic environment are dramatic – but year-round in situ observations of this harsh, remote, and hardly accessible environment, are still scarce.To overcome this lack of data and improve scientific insight, the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) started to build up the Arctic Observatory FRAM (FRontiers in Arctic Marine Monitoring). Scientifically, FRAM grounds on more than fifteen years of AWI time-series observations in the Fram Strait and the central Arctic, including the LTER Observatory HAUSGARTEN. FRAM provides various sensor platforms to improve multidisciplinary year-round observations of the Arctic Ocean system in Fram Strait and the central Arctic, covering the entire water column, the sea ice, and the sea floor: Moorings, ice-tethered and mobile sensor platforms, fixed-point benthic installations as well as ship-based instrumentation and regular sampling campaigns allow a wide range of physical, biogeochemical, and biological measurements of Essential Ocean Variables (EOV). Field data are being cross validated by satellite observations and used to improve model simulations. FRAM is planned as a sustained observatory infrastructure for long-term operation to sustain multidisciplinary time-series. Large parts of FRAM are now operational, with ongoing and future extensions and further technical developments. The full set of physical, biogeochemical, and biological observations will be made freely available via the AWI data portal (https://data.awi.de).This talk provides a) background information on FRAM infrastructure and b) present new mooring strategies in combination with FRAM's latest technical developments on sensors, samplers, observation platforms for autonomous year-round deployments and ship-based observations carried out during annual expeditions. Novel technologies include profiling winches, ice-tethered platforms, automated filtration systems, imaging systems for marine snow aggregates and zooplankton, as well as benthic crawlers for biogeochemical observations. These new technologies allow improved spatiotemporal coverage of observations in these remote areas and provide a comprehensive insight into dynamics in nutrient availability and primary productivity, particulate organic matter export, and its fate below the mixed surface layer and at the deep seafloor. [ABSTRACT FROM AUTHOR]