Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM114-2	23.01.2023 - 22.02.2023		South Atlantic Ocean Equatorial East Atlantic Equatorial West Atlantic North Atlantic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Nitsche Frank	Die Universitat zu Koln	Mindelo	Punta Arenas

Ziel der Reise / Objectives of Cruise:

The MSM114/2 cruise served three major goals. As the topic "Atlantic References and Convection" (ARC) already suggests, the main activities centered around (1) to collection of atmospheric and oceanic references across the Atlantic, (2) the investigation of tropical convection near the equator and (3) the protist diversity along this transect The ship's regular underway measurements of wind speed and direction, humidity, temperature, pressure and radiative fluxes were enhanced by additional instruments. On the atmospheric side, these were (1) a microwave radiometer (to capture vertically the integrated condensed water and water vapor), (2) a ceilometer (to capture cloud-base altitude and aerosol vertical distributions in the lower atmosphere), (3) a cloud camera (for regular images of the sky and cloud base altitude distributions), (4) several sun-photometers and (5) an in-situ size-stratified particle samples (to capture the properties of atmospheric aerosol). On the oceanic side an extra effort involved the analysis oy automatically recorded bathymetry data for a subsequent delivery into the SEABED 2030 database. This analysis also included the detailed investigation of a volcanic seamount in the southern Atlantic. With a side focus on air-sea interactions, these underway measurements were interrupted twice daily (usually at 9am and 2pm) to simultaneously sample profiles of the upper ocean and the lower atmosphere. During more than 40 station stops, CTD casts down to 500m explored upper ocean properties and protist diversity, and more than 110 drone flights up to 500m in altitude with different instrumentations (i.e. to address particle size or atmospheric state) sampled the upper atmosphere. The CTD casts automatically provided water samples from different depths which were analyzed to inform on the biodiversity and biogeography of protists (single celled organisms). Despite the importance of protists in the microbial food web, little is known about the biodiversity and biogeography of protists, single celled eukaryotes. Applying high-throughput sequencing, we want to answer the question, if certain species, found only in surface waters of the South Atlantic during one of the last cruises, are also present in the North Atlantic or if the equatorial counter current is forming a physical barrier. The South Atlantic is still an understudied region regarding protist diversity. The aim of this project is to enhance the dataset for protist from understudied areas and to contribute to The meteorological program during MSM114-2 focused on the thermodynamic and dynamic state of the Atlantic Intertropical Convergence Zone (ITCZ) in boreal winter. The measurement program complements measurements of the boreal summer Atlantic ITCZ taken during SO284. The key question addressed is how convective scale processes in the atmosphere, and their coupling to the ocean, shape the large-scale structure of the ITCZ and the regions of low wind speed therein. To this end, the ITCZ was crossed three times along 23?W longitude. During these crossings the ITCZ was sampled using continuous underway measurements and regular radiosonde launches. The underway measurements were used to obtain detailed measurements at the surface of key atmospheric parameters such as wind speed and direction, humidity, temperature, pressure as well as vertically integrated quantities of condensed water and water vapor. All underway measurements ran from the time we left the Cape Verde Islands EEZ until we re-entered the Argentine EEZ. In addition to the underway measurements, 92 radiosondes were launched to obtain vertical profiles extending from the surface to the lower stratosphere with high vertical resolution. Radiosonde launches were mostly limited to the deep tropics and were conducted at a frequency of about every 3 hours.

Messungen / Measurements