ALBERT

Description: Varved lake sediments provide climatic records with seasonal to annual resolution and low associated age uncertainty. Robust and detailed comparison of well-dated and annually laminated sediment records is crucial for reconstructing abrupt and regionally time-transgressive changes as well as validation of spatial and temporal trajectories of past climatic changes. The VARved sediments DAtabase (VARDA) presented here is the first data compilation for varve chronologies and associated palaeoclimatic proxy records. The current version 1.0 allows detailed comparison of published varve records from 95 lakes. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. VARDA additionally provides a technical environment that enables us to explore the database of varved lake sediments using a connected data model and can generate a state-of-the-art graphic representation of a multisite comparison. This allows the reassessment of existing chronologies and tephra events to synchronize and compare even distant varved lake records. Furthermore, the present version of VARDA permits the exploration of varve thickness data. In this paper, we report in detail on the data-mining and compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies, as well as the technical infrastructure of the database. Additional palaeoclimatic proxy data will be provided in forthcoming updates. The VARDA graph database and user interface can be accessed online at https://varve.gfz-potsdam.de (last access: 15 September 2020), all datasets of version 1.0 are available at https://doi.org/10.5880/GFZ.4.3.2019.003 (Ramisch et al., 2019).

Description: The International Generic Sample Number (IGSN) is a unique and persistent identifier for physical objects that was originally developed in the Geosciences. In 2022, after 10 years of service operation and more than 10 million registered samples worldwide, IGSN e.V. and DataCite have agreed on a strategic partnership. As a result, all IGSNs are now registered as DataCite DOIs and the IGSN metadata schema will be mapped to the DataCite Metadata Schema according to agreed guidelines. This will, on the one hand, enrich the very limited mandatory information shared by IGSN allocating agents so far. On the other hand, the DataCite metadata schema is not designed for the comprehensive description of physical objects and their provenance. The IGSN Metadata Schema is modular: the mandatory Registration Schema only included information on the IGSN identifier, the minting agent and a date - complemented by the IGSN Description Schema (for data discovery) and additional extensions by the allocating agents to customise the sample description according to their sample’s subdomain. Within the project “FAIR Workflows to establish IGSN for Samples in the Helmholtz Association (FAIR WISH)”, funded by the Helmholtz Metadata Collaboration Platform (HMC), we (1) customised the GFZ-specific schema to describe water, soil and vegetation samples and (2) support the metadata collection by the individual researcher with a user-friendly, easy-to-use batch registration template in MS Excel. The information collected with the template can directly be converted to XML files (or JSON in the future) following the IGSN Metadata schema that is required to generate IGSN landing pages. The template is also the source for the generation of DataCite metadata. The integration of linked data vocabularies (RDF, SKOS) in the metadata is an essential step in harmonising information across different research groups and institutions and important for the implementation of the FAIR Principles (Findable, Accessible, Interoperable, Reusable) for sample descriptions. More information on these controlled vocabularies can be found in the FAIR WISH D1 List of identified linked open data vocabularies to be included in IGSN metadata (https://doi.org/10.5281/zenodo.6787200). The template to register IGSNs for samples should ideally fit to various sample types. In a first step, we created templates for samples from surface water and vegetation from AWI polar expeditions on land (AWI Use Case) and incorporated the two other FAIR WISH use cases with core material from the Ketzin coring site (Ketzin Use Case) and for a wide range of marine biogeochemical samples (Hereon Use Case). The template comprises few mandatory and many optional variables to describe a sample, the sampling activity, location and so on. Users can easily create their Excel-template, including only the variables needed to describe a sample. A tutorial on how to use the FAIR WISH: Sample description template (https://doi.org/10.5281/zenodo.7520016) can be found in the FAIR WISH D3 Video Tutorial for the FAIR SAMPLES Template (https://doi.org/10.5281/zenodo.7381390). As our registration template is still a work in progress, we are furthermore happy for user feedback (https://doi.org/10.5281/zenodo.7377904). Here we will present the template and discuss its applicability for sample registration.

Description: This database contains major and trace element compositions of European tephra and metadata for the datasets and lakes they were found in. It was created by collecting data from scientific literature to support the synchronisation of annually-resolved lake sediment records during the Last Glacial Interglacial Transition (25 ka BP to 8 ka BP). 49 individual tephra layers across 19 varved lake records have been included, with Lago di Grande Monticchio being the largest contributor of geochemical data with 28 layers. The Vedde Ash and Laacher See tephra are the most common layers, being found in 6 different varved records, and highlight the potential of refining the absolute age estimates for these tephra layers using varve chronologies and for synchronising regional paleoclimate archives. This project is the first stage in a 5-years plan funded by the Past Global Changes (PAGES) Data Stewardship Scholarship to incorporate a global dataset of tephra geochemical data in varved sediment records. Further stages of this project will focus on different regions and timescales.

Description: The Varved Sediments Database (VARDA) was launched in 2020 and aimed to establish a community database for annually resolved chronological archives with their associated high-resolution proxy records. This resource would support reproducibility through accessible data for the paleoclimate and modelling communities. In this paper, VARDA has been extended by a dataset of European tephra geochemical data and metadata to enable the synchronisation of varve records during the Last Glacial–Interglacial Transition (LGIT; here defined as 25 to 8 ka; Beckett et al., 2022). Geochemical data from 49 known individual tephra layers across 19 lake records have been included, with Lago di Grande Monticchio being the single biggest contributor of geochemical data with 28 tephra layers. The Vedde Ash and Laacher See tephra are the most common layers found in six different records. This highlights the potential of refining the absolute age estimates for these tephra layers using varve chronologies and for synchronising regional paleoclimate archives. This is the first stage in a 5-year plan funded by the Past Global Changes (PAGES) Data Stewardship Scholarship to incorporate a global dataset of tephra geochemical data into varve records. Further stages of this project will focus on different regions and timescales. Data collated for this project are available open access at https://doi.org/10.5880/fidgeo.2023.015 (Beckett et al., 2022).