Abstract
SUMMARY AND ITINERARYBuilding on our cruises and experiences in 2019, we wanted to continue and expand the trips in 2020 (cf. BzPM_0741_2020). In discussion with colleagues from Modular Observation Solutions for Earth Systems (MOSES) and Program-oriented Funding (PoF) IV of the Helmholtz Association, the planned cruise in 2020 served as a joint test case for MOSES instrumentation, as well as the further establishment of the communication between the groups concerning preparation of common campaigns, planning of available equipment, determination of responsibilities and building collaborating teams to investigate processes across the compartments. A special focus was set on the intercalibration of sensors and parameters, by insisting on several inter-calibration times for most sensors, measuring at the same time and location.The data management will be challenging as data from marine institutes / sensors will have to be combined with terrestrial institutes / sensors. All sensors were registered in MOSES data management tool (https://moses-dmp.gfz-potsdam.de/) beforehand. The registration procedure had been considerably improved, now the applicability in practice was to be checked. All sensors and data are now linked in the new MOSES data discovery portal (https://moses-data.gfz-potsdam.de). The decisive factor for the southern North Sea (or German Bight) is which water body and with which constituents it arrives in the Tide-Elbe area and how it is further modified in this area. Thus, the idea arose to continuously trace a group of parameters from the beginnings of the Elbe to the North Sea. What are the main impact factors for terrestrial and coastal water quality during floods and low water periods? Data for a better understanding of the different branches of the relevant event chain were provided by investigations within the Elbe river catchment (starting at the Czech/German border), along the middle course, Tide-Elbe und Elbe estuary (German Bight). To follow the water from the Elbe our campaign started with the Albis (research vessel from the UFZ), travelling with the water velocity of the Elbe; from 4 to 12 August. As the water takes about 2 weeks to travel from Geesthacht to Cuxhaven at the river mouth, the next campaign started on 25 and 26 August 2020. The Ludwig Prandtl (HZG) started at ebb tide near Cuxhaven, thus reducing the marine influence and focusing on the Elbe water. The estuarine cruise was followed by the marine cruise, from 31 August to 3 September 2020 5Summary and Itinerarywith three coastal research vessels, covering a broad area within the German Bight. Different thematic teams were covering the various processes across the considered compartments: terrestrial waters, coastal and marine zones. The basic hydrographic parameters (temperature and conductivity or salinity) were measured by FerryBoxes and probes on the ships, with some instruments actually being passed from ship to ship. Similarly, atmospheric and dissolved greenhouse gases (CH4 and CO2) were measured throughout. To learn more about the phytoplankton or productivity of the water, chlorophyll a, turbidity and nutrients were also determined. The carbon cycle was continuously described with the parameters TA, DOC, POC and DIC (total alkalinity, dissolved and particulate organic carbon, and dissolved inorganic carbon).As improvement from the previous cruises, we extended the duration of our cruises. Thus, for Sternfahrt_5 we could cover a wide area for four days with three ships, even though Corona restrictions allowed only 4 scientists on board and partly restricted access to the vessels.Also, the problem of switching from “on the way” modus to vertical sampling has been solved as now all vessels have d-ship installed which provides exact timing of the stations and switches. This information is now incorporated into the O2A as actions, consequently the data can be easily separated.In the following chapters and the tables in the annex, we explain in more detail the set-up of the cruises and our experiences. All of our data are now deposited in the database athttps://sensor.awi.de and https://www.ufz.de/record/dmp. However, such complex set-up as in our combined Elbe-2020 cruises are not easily mirrored in the database, thus this cruise report should also help to use the obtained data and their meta data along the river Elbe and its estuary as well as in the southern North Sea.
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