Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL597	05.07.2023 - 25.07.2023		Baltic Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Hieronymi Martin	Helmholtz-Zentrum Hereon GmbH	Kiel	Kiel

Ziel der Reise / Objectives of Cruise:

Ocean Colour satellite remote sensing enables continuous and global monitoring of phytoplankton biomass and other water constituents in the upper layer of the ocean as well as of coastal and inland waters. The Baltic Sea is a particularly difficult water body to interpret from a remote sensing perspective; compared to other sea areas, it is very dark due to the high concentration of coloured dissolved organic matter brought in by many rivers and due to the limited water exchange with the North Sea. It also has intense cyanobacterial blooms in the summer months, which is not usual for temperate seas. This leads to large uncertainties in satellite products and limited usability of observational data. The measurement of specific optical properties in the field, especially of cyanobacteria, and the determination of biogeochemical properties are essential for the evaluation and further development of satellite products, e.g., with regard to phytoplankton diversity or the marine carbon cycle. During the ALKOR cruise, relevant bio-geo-optical and -chemical parameters were determined in the upper water layer and at the sea surface. High concentrations of cyanobacteria were detected and sampled. The cruising area could be flexibly optimised for match-ups with satellite data (with Copernicus satellites, but also with the German EnMAP mission), which resulted in an exceptionally large number of inter-comparison measurements for validation. The medium-term goal of this research is the development of novel Earth observation products to quantify biodiversity, detect environmental risks and better characterise the carbon cycle in the ocean.

Messungen / Measurements