There is a nervous energy onboard the RV Sonne today, as we approach the “40 hour station”. The idea is that we will place ourselves in a certain location, bring the engines of the Sonne to a stop, and then perform repeated sampling of the same water mass over almost two full days. In this way we hope to learn more about the daily cycles and variability of the water biochemistry in the Indian Ocean.
The planned schedule calls for radiosonde launches every 6 hours, CTDs approximately every 6 hours, and lots of lab work to analyze the samples taken by the CTD as well as by the underway measurement systems.  This morning at 8:30 local time, the students learned what measurement duties the scientists would need help with, and students were able to choose which measurement stations they would like to work at. Each measurement team will organize shifts for the students and scientists, and work will go on all through the night.

Preparing for the “40 hours station”. Photo: Serge Kenny Rakotonjanahary

Not only are the students expected to play a major role in the measurements during the 40-hour station, but they will also be responsible for “working up” the data, i.e., putting data from the 40-hour station together with data from the cruise so far, making plots with the data, and interpreting the data with the help of the cruise scientists. Student pairs will prepare a short presentation to be given later this week, and will also produce a short report.
Today, the Sonne has been steaming at full speed to reach the location of the 40-hour station. With the help of satellite data, the lead scientists are trying choose a good location to make sure we sample an “interesting” water mass! Shift schedules are being made, responsibilities distributed and last minute lab or instrument preparations made. For some with night shifts, afternoon naps may be advisable. The laundry machines are busy as people get ready for a busy next couple of days!

by Matt Toohey