After leaving the Cape Verde Islands, the next days were rather quiet. We had regular stations every morning with XBT mesurements and bucket samples from the slow-moving ship. As time for stations is very short on transect cruises we have to use underway measurements as much as possible. Additional measurements are obtained using instrumentse comprising of the ship’s thermosalinograph, the Ferry Box and satellite images.
The students are very busy analyzing all samples and processing the data. Every evening the students give talks about their own work and also the scientists and lecturers on board present their research topics.
On this cruise leg seven scientists from the Leibniz Institute for Tropospheric Research (TROPOS, Leipzig) participate who regularly collect on the transects important samples for climate research as part of the OCEANET project (Fig. 1). The research focusses on interaction between aerosols and clouds that can influence the radiation balance of Earth. The crossing of the Atlantic from North to South helps the scientists to record with their instruments the contrast between the anthropogenic influenced northern hemisphere and the distinctly cleaner southern hemisphere. From a container a green laser radar (LIDAR) beams straight up into the sky to characterize the atmospheric layers above the ocean (Fig. 2). In another container, air is filtered for obtaining detailed microphysical and chemical properties of cloud condensation and ice nuclei. Therefore, eleven measuring instruments are on board for the analysis of the aerosols.
The weather was very calm and even in the Inner Tropical Convergence Zone we did not encounter the usual heavy showers and thunderstorms. It was oppressively hot and the sea surface temperature reached 28 - 29°C. Between 7°N and 5°N we encountered large patches of the floating algae Sargassum drifting past (Fig. 3). At Cape Verde we took some insect stowaways on board. Apparently a swarm of crickets landed on the ship and now we hear their chirping everywhere.
In the night from 18 to 19 November we crossed the Equator. Exactly on the Equator we conducted a full sampling station with CTD down to the bottom and plankton nets. All students were excited about taking samples at this special station. Interestingly at this equatorial station many dinoflagellates were found which contained symbiotic blue-green algae.
On the ship there were many people (47) who had not undergone the equatorial “crossing-the-line baptism”. After many threatening announcements from Neptune and hefty resistance from the ocean novices, an equatorial “baptizing” ceremony was announced for Saturday, 22nd November. On this day all novices were woken up very early and the lengthy procedure of the baptismal ceremony was accomplished by all, with courage and stoicism (Fig.4). Since even the cruise leaders had to pass the ceremony they could not ask Neptune or his wife Thetis to be merciful to the novices. Also the mischievous rumours spread earlier by the novices about Neptune’s crew on board the RV Polarstern were proven to be completely unfounded. Now peace has returned to the ship and everyone got over the turmoil of the ceremony in good shape.
All the best wishes from everybody on board
Karin Lochte
