Reprocessing of XBT profiles from the Ligurian and Tyrrhenian seas over the time period 1999–2019 with full metadata upgrade

Abstract

Abstract. The advent of open science and the United Nations Decade of Ocean Science for Sustainable Development are revolutionizing the ocean data sharing landscape for an efficient and transparent ocean information and knowledge generation. This blue revolution raised awareness on the importance of metadata and community standards to actionate interoperability of the digital assets (data and services) and guarantee that data driven science preserve provenance, lineage and quality information for its replicability. Historical data are frequently not compliant with these criteria, lacking metadata information that was not retained crucial at the time of the data generation and further ingestion into marine data infrastructures. The present data review is an example attempt to fill this gap through a thorough data reprocessing starting from the original raw data and operational log sheets. The data gathered using XBT (eXpendable BathyThermograph) probes during several monitoring activities in the Tyrrhenian and Ligurian Seas between 1999 and 2019 have been first formatted and standardized according to the latest community best practices and all available metadata have been inserted, including calibration information never applied. Secondly, a new automatic Quality Control (QC) procedure has been developed and a new interpolation scheme applied. The reprocessed (REP) dataset has been compared to the present data version, available from SeaDataNet data access portal through the saved query Url https://cdi.seadatanet.org/search/welcome.php?query=1866&query_code={4E510DE6-CB22-47D5-B221-7275100CAB7F}, processed according to the pioneering work of Manzella et al. (2003) conducted in the framework of the EU Mediterranean Forecasting System Pilot Project (Pinardi et al., 2003). The maximum discrepancy among the REP and SDN data versions resides always within the surface layer (REP profiles are warmer than SDN ones) until 150 m depth, generally when the thermocline settles (from May to November). The overall bias and root mean square difference are equal to 0.002 °C and 0.041 °C, respectively. Such differences are mainly due to the new interpolation technique (Barker and McDougall, 2020), the lack of filtering and the application of the calibration correction in the REP dataset. The REP dataset (Reseghetti et al., 2023; https://doi.org/10.13127/rep_xbt_1999_2019) is available and accessible through the INGV ERDDAP server (http://oceano.bo.ingv.it/erddap/index.html), which allows machine to machine data access in compliance with the FAIR (Findable, Interoperable, Accessible, Reusable) principles (Wilkinson et al., 2016).