Nearing the Cape and Preparing for Inspection
So it has been a hectic month, but Silbo and our team are making final preparations for an inspection that will take in the early hours of the morning.
First let us back track a bit and catch up on what has happened in recent weeks. Since Antonio and I did the barnacle analysis back in June after recovery, we started making projections for potential growth on the next journey.
From our findings, we saw that due to the temperature variations in the water column of the North Atlantic, it would be more likely that we saw substantial barnacle growth between the Canaries and Cape Verde than Cape Verde to Brazil due to the temperatures at depth (seen in the temperature map above). Another point supporting our hypothesis was that we were flying Silbo through some of the most productive waters in the world, thus why the islands have been called Cape Verde. This year has also been a very productive year as there have been a number of strong wind events over the Sahara that have deposited iron rich dust into the waters off the African coast which have sparked some large blooms. So as we flew Silbo through these productive waters, we began to worry that we may start picking up some hitch hikers.
To try and monitor if we were picking anything up, I began looking at Silbo's velocity with the help of Dave Aragon. We initially looked at the raw vertical velocity Silbo reported at each surfacing.
As the weeks went on, we saw some slight indications that we were going slower, but we couldn't be completely sure of what was going on. We then started filtering data, taking out times that we were at the surface, and then correcting the data for changes in pitch and ballast to try and get a better estimate on what the velocities were.
We also added a 10 day average to see any trends in the data, and we saw that there was a definite slowing occurring over the course of the last three weeks.
We had previously discussed a collaborative 48 hour station keep in the vicinity of the Geomar mooring site just north of the islands of Cape Verde and we proposed the plan for an inspection. This would be our last opportunity for contact before Silbo would leave the coast and set sail to cross the Atlantic with Rio De Janeiro as our finish line.
After coordinating with our team, PLOCAN was able to secure a boat and a crew of scientists and technicians to go out on a boat, while our friends Ben and Lauren at Webb provided ground support for an inspection. The tricky part it seems will be communication as the boat does not have internet and our team is without a satellite phone. So what we plan to do, is to use Silbo's iridium and freewave connection as a sort of instant messaging service, with Ben and Lauren leaving messages for Alvaro via iridium and Alvaro responding through the freewave.
Alvaro and our friends have left harbor a few hours ago now, and plan on being on site by 8am gmt, so as they near the area, Ben and Lauren back in the US will be ready to catch Silbo and stop his mission so that the ship can find him. While Silbo waits for the boat, he will drift with the currents it looks to the west (red is surface whiel orange and blue are 250m and 500m respectively).
News of the inspection will be relayed back throughout the morning, so over the next couple of days we will make sure to update everyone and release the pictures!
Good luck to our team!
Force Wind Sea & Honor
Nilsen & Antonio
Tags: Nilsen Strandskov