DOI: 10.5281/zenodo.17215066
title: Multi-Depth Velocity, Direction, Pressure, and Temperature Measurements in Heraklion Port

description: Experiment overviewData start: 08.05.2025 (Uploaded data start: 08.05.2025 00:00)Data end: 31.08.2025 (Uploaded data end: 31.08.2025 23:59)Location: Heraklion Port, Heraklion, GreeceInstallation location: 35°20'54.8"N 25°09'09.3"E

This experiment was conducted as part of the European Union’s Horizon 2020-funded ILIAD project (Grant Agreement No. 101037643). The deployment aimed to support the development and operationalization of digital twin technologies for the marine environment. Specifically, the experiment's objectives were:1. To construct high-resolution datasets for machine learning training and forecasting of current trends.2. To provide in-situ validation data for hydrodynamic simulation models operating at very fine spatial resolutions.3. To contribute to the implementation of an operational alerting system, designed to detect extreme current events and issue alerts to vessels. These alerts may trigger more accurate, near-real-time simulations focused on the evolving wave–current–weather extreme scenarios.

During the campaign, continuous measurements of current velocity, flow direction, and dynamic pressure were obtained using an array of Hydromast sensors deployed at three distinct vertical levels within the water column. The dataset is time-synchronized and fully aligned across depths, covering an uninterrupted period from 8 May to 31 August 2025.Measurements were acquired at a sampling frequency of 2 Hz and capture the full range of tidal cycles and weather conditions during the deployment.The data is space-time aligned. It consists of continuous measurements between 8.May 2025 and 31. August 2025. The measurements were made using Hydromasts (Parasyris et al., 2025, Egerer et al., 2024; Ristolainen et al., 2016).This dataset provides all measurements with frequency 2Hz.

 

DevicesHydromastLong-term continuous Hydromast current measurement logger technical details are given below.LoggerAdafruit Adalogger M0Velocity range0.12 – 1.2m/s (300mm mast1) 0.65 - 1.7 m/s (100mm mast2)Mast sensorTLV493DCompassLIS3MDLSampling rate50 Hz

The Hydromast system has been previously validated and documented in Egerer et al. (2024) and Ristolainen et al. (2016). This dataset contributes directly to the operationalization of high-resolution marine digital twins, supporting safety and sustainability in port operations through predictive modeling and real-time response mechanisms.

 

The data is saved into NetCDF (Network Common Data Form). The data is organised into datafiles with Dataset name “HeraklionYYYYMMDDHHmm.nc”, where YYYY is the year, MM is the month, DD os the day, HH is the hour, mm is the minute of the data inside the file. Each file starts at time HH:mm:00:00 and contains data from full hour. The experiment was set up at 07.05.2025, the data is provided from the first full day 08.05.2025 00:00. The experiment ended 31.08.2025.The velocity and direction are valid when the water velocity is over 0.12m/s. If the velocity is below 0.12m/s, there is no reading in the Dataset. The velocity and direction data are recorded as NaN.The sensor names denote the three different sensors. N26 (top), N28 (middle), N27 (bottom)For example, the data with velocity and direction below the measurement threshold:Time:1500, Lat: 35.348554, Lon: 25.152601, sen:N26 -> Velocity: --, Dir: --, Depth: 2.524An example of data with velocity and direction over the measurement threshold:Time:1500, Lat: 35.348554, Lon: 25.152601, sen:N26 -> Velocity: 0.169, Dir: -36.593, Depth: 2.571Note: Direction is more accurate with higher velocities.

 

ReferencesEgerer, M., Ristolainen, A., Piho, L., Vihman, L., & Kruusmaa, M. (2024). Hall Effect Sensor-Based Low-Cost Flow Monitoring Device: Design and Validation. IEEE Sensors Journal, 24(5), 5986–5997. https://doi.org/10.1109/JSEN.2024.3354194Ristolainen, A., Tuhtan, J. A., Kuusik, A., & Kruusmaa, M. (2016). Hydromast: A Bioinspired Flow Sensor with Accelerometers. 510–517. https://doi.org/10.1007/978-3-319-42417-0_55

Parasyris A. et al., "Coastal Crete: The Ship Routing/Harbor Safety Digital Twin of the Ocean," OCEANS 2025 Brest, BREST, France, 2025, pp. 1-6, doi: 10.1109/OCEANS58557.2025.11104645.