36 Cruise Report, RV ATAIR, Cruise 067I033-1, Bremerhaven – Thybor?n – Aberdeen, 23 Jul – 15 Aug 2024 7. Underway Measurements A variety of routine underway measurements were carried out during cruise 067I033-1. The acquired data of interest included navigational information and near-surface hydrography (tem- perature, conductivity, and thus salinity), which was measured by the vessel's thermosalino- graph (TSG). Other data included near-surface fluorescence and turbidity, both obtained from a dual-wavelength ECO sensor attached to the TSG system. Meteorological parameters and water temperature were also recorded by the weather station, operated by the German Weather Service (DWD) under the identifier CVTKCAL. Navigational and meteorological data was recorded from the beginning of the cruise onwards. Recording of additional underway data was interrupted during the port stay in Thybor?n, Denmark, and resumed afterwards. Data was logged in time intervals of 1 or 10 sec by the vessel’s DSHIP system with time intervals depending on measurement intervals of the respective devices. All underway data relevant to this cruise were exported from the DSHIP database daily. Water depths were measured by a single-beam echo-sounder along the cruise track and at hydrographic stations. Depths pro- vided by the vessel’s echo-sounding device result in water depths when the vessels’s draft of 5 m is added. Any further processing or quality control of water depth data was not carried out. Filtering of surface water to determine the size and abundance of microplastics was conducted on various transects (see Section 5.10). A Vessel-Mounted Acoustic Doppler Current Profiler (VMADCP) provided information on the speed and direction of the oceanic current field. Addi- tionally, eight lightweight surface drifters were deployed in different regions of the North Sea. These were exposed to tides and the oceanic current field, which revealed major spreading pathways. 7.1 Ship’s Meteorological Station The autonomous weather station installed aboard RV ATAIR and operated by the DWD auto- matically records every second all meteorological standard parameters like wind speed and direction, air temperature and air pressure, relative humidity, surface water temperature, global radation and others. While corresponding data is sent directly to the Global Telecommunication System (GTS), it is also fed into the DSHIP database. Figure 7.1 provides an overview on the meteorological conditions encountered during cruise 067I033-1. Raw data was taken from the DSHIP database and smoothed by applying a moving median filter. The radiometer delivering global radiation data was not properly working during many days of the cruise due to unknown reasons, see Figure 7.1. The average air temperature throughout the cruise was 16.7°C, but temperatures ranged from 12.8°C to 28.2°C while at sea. Maximum water temperatures exceeded 21.8°C right at the start of the cruise, minum water temperatures were 11.5°C, the average was 16.9°C. Average air pressure was 1012.6 hPa, and pressures ranged from 996.2 hPa to 1026.3 hPa. Notable periods of absolute wind speeds exceeding 7 Bf were observed on 9/10 August, on 12 August, on 13/14 August, and 14/15 August 2024. The average wind speed throughout the cruise was 7.45 m/s, which corresponds to a wind strength of 4 Bf. The maximum wind speed was 22.65