rv-sonne-lidar-experiment

[rv-sonne-lidar-experiment]

52 days offshore, the final post

Dear readers,

This is the last post of the blog. I hope you enjoyed reading the posts as I did writing them and that I was able to show you (a small part of) how it is to live in a research vessel for more than 50 days.

It has been a unique and wonderful experience, from which I take moments and memories that will last for the rest of my life. I had the chance to see dolphins and whales, feel the real seasickness, cross the Atlantic and the Equator, learn about different scientific fields, and above all, to meet great people and professionals who made this adventure so enjoyable. And this is just a minuscule part of all the lived moments.

I must confess that I have contradictory feelings. On the one hand, I am willing to be back to normal life in Germany. I do miss many things like eating some fresh fruit, lying on the grass, running, or visiting my friends and family. But on the other hand, I am sad to see this adventure come to an end and say goodbye to all the people I have been living with for almost two months.

Before ending the blog, I would like to thank all the people who have made this experience possible in one way or another. To the RV Sonne crew for their work and effort to accomplish this successful cruise. To all the scientific staff for everything I learned from them and the great moments we shared on board, with a particular mention to the cruise leaders Peter Brandt and Julia Windmiller. And finally, to Julia Gottschall, my PhD supervisor, for giving me the opportunity to be part of this exceptional and rewarding experience.

I would be delighted to answer any questions you may have about the campaign or the data, so do not hesitate to contact me by email (hugo.rubio@iwes.fraunhofer.de).

Thank you all for reading and see you soon,

Hugo.

[rv-sonne-lidar-experiment]

51 Days offshore, 16th of August

We are already in Emden. We arrive at the harbor at around noon, and during the afternoon, I have been tidying my cabin up and preparing the lidar to move it out from the ship tomorrow morning. You can see a timelapse of the system dismantling with some help from my colleagues from MPI following the next link:

https://drive.google.com/drive/folders/1F8JJh8kxIt831fS9-qQZ0mg3cHycnonm?usp=sharing

Most of the people have already gone, and just those who leave tomorrow are still on board. This evening, I will try to enjoy the last hours with the very nice people as much as possible.

[rv-sonne-lidar-experiment]

49 Days offshore, 14th of August

Time is running, and we are already on the English Channel. We can feel closer to the mainland because of the intense vessels traffic in this region and because we could see France on the horizon. We are very close to the end of the campaign!

We also had the chance to enjoy several dolphin sightings. I uploaded a nice video of one of these views that you can see using the following link:

https://drive.google.com/drive/folders/1F8JJh8kxIt831fS9-qQZ0mg3cHycnonm?usp=sharing

[rv-sonne-lidar-experiment]

48 Days offshore, 13th of August

This morning we entered the EEZ of France, and it means that I had to switch off the lidar system. It has been continuously measuring from the 7th of July, and overall, the system worked smoothly and without troubles (after solving the issue with the GPS antennas). Although I still need to look more carefully at the data, it seems that we were able to retrieve a nice dataset for further investigations. Actually, the raw lidar data availability of the system is above 98% at every measured height, which is a very positive value. Apart from the lidar, the other parts of the complete system have worked nominally for the entire campaign too.

[rv-sonne-lidar-experiment]

46 Days offshore, 11th of August

There is a slight change in the planned program. We will finally arrive in Emden on Monday, the 16th of August, in the afternoon or evening instead of the 17th. It is good because I will have more time to disassembly the ship lidar system without any hurry. I will travel back home the next day, on the 17th.

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44 Days offshore, 9th of August

The chief engineer has shown us the engine room of the ship. It is very impressive to see how big the engines are and to learn about all the systems involved in keeping the ship running.

[rv-sonne-lidar-experiment]

42 Days offshore, 7th of August

Today we left behind the Tropic of Cancer, and we can already feel it with a decrease in the temperatures that results in a strange feeling during the evenings and nights I forgot about: cold. I am afraid that from now on we will need to wear a pullover or something more than just shorts and t-shirts while being outside.

[rv-sonne-lidar-experiment]

41 Days offshore, 6th of August

Most of the scientific duties have already been accomplished. For instance, people from GEOMEAR have already deployed and rescued the moorings, recovered the glider, and executed all the CTD measurements, and MPI has already launched all the planned radiosondes. To celebrate this, tonight we are having a small party to have fun. From now, all the focus will be towards the process and analyze of the retrieved measurements.

The lidar is still measuring, and it will be working until we reach the exclusive EEZ of France, few days before our arrival to Emden.

[rv-sonne-lidar-experiment]

39 Days offshore, 4th of August

Yesterday, the glider was finally recovered by people from GEOMAR after several weeks working autonomously.

[rv-sonne-lidar-experiment]

38 Days offshore, 3rd of August

As I told you a few days ago, rain is almost constant in the ITCZ. We are traveling eastwards inside it, so although the temperatures are high (between 24°C and 28°C), yesterday we saw rain events almost every hour.

Figure: precipitation during the 2nd of August. The rain accumulation considers the total rain since the beginning of the campaign

Unexpectedly (since winds usually are calm in the ITCZ), the winds were strong. As you can see in the following figure, we saw 10-min average velocities above 18 m/s. Also, the sea was rough and wavy, as can be observed in the second figure below, with a comparison of the normal frequency distribution of the ship’s tilting (pitch and roll) for a calm day (the 31st of July) and yesterday. The peaks of the distributions on the 31st are around cero (0.4° and -0.1° for the pitch and roll, respectively), while the mean values on the 2nd of August are 1.3° and -1.1°. Additionally, the wider distribution of the tilting angles corresponding to yesterday indicates the more intense motion of the ship, with values above 4° for the pitch and below-3.5 for the roll.

Figure: 10-min averaged wind speed on the 2nd of August. The line color indicates the measurement height, going from 40 m (light green) to 250 m (dark blue)

Figure: normal frequency distributions of the pitch (above) and roll (below) angles on the 2nd of August (red) and the 31st of July (black)

[rv-sonne-lidar-experiment]

36 Days offshore, 1st of August

August just started, and it means that we are getting closer and closer to the end of the trip. Only around two more weeks to go. In the following figure, you can see the route of our cruise so far. We are currently in latitudes around 6 degrees north, moving eastwards to pick the glider up (see post on the 11th of July), which should be somewhere to the southeast of Cape Verde. Then, we will go towards the north, passing close to Cape Verde and the Canary Islands, and finally, we will reach Emden on the 17th.

Figure: route of the RV Sonne during our cruise until the noon of the 1st of August. The gaps around the Canary Islands and further north are due to the impossibility of measuring inside EEZs

[rv-sonne-lidar-experiment]

34 Days offshore, 30th of July

This afternoon we had the chance to make a short trip around the ship with one of the small powerboats from the vessel. We could see the difference between being on a big ship like the RV Sonne and a small boat. Definitely, I can confirm that being on board the Sonne is like being on land compared to the constant and fast tilting of the board. You can see some pictures of the tour below.

Photo: the small boat we used during our short route with me (and more people) on it

Photo: the small boat we used during our short route with me (and more people) on it

Photo: The RV Sonne from the powerboat during the trip

Photo: The RV Sonne from the powerboat during the trip

[rv-sonne-lidar-experiment]

33 Days offshore, 29th of July

Today I helped people from MPI with a radiosonde launch (after some training on how to do it). We are entering the Intertropical Convergence Zone (ITCZ), which is of particular interest to them. For this reason, they will be launching radiosondes every two hours for the next few days, and I will help them with some of the launches.

Photo: me launching a radiosonde

The ITCZ is a region near the equator that circles the Earth and where the trade winds from the Northern and Southern Hemisphere converge. The ITCZ can be recognized from satellite images as a solid band of clouds extending for several kilometers (you can see this in the figure below). The winds in this area are calm, and the intense solar heating and warm water increase the moisture and buoyancy of the air. With the help of the convergent trade winds, this air rises in the atmosphere and discharges the accumulated humidity with almost constant thunderstorms. You can see one of these thunderstorms in the following picture.

Photo: a thunderstorm close to the RV Sonne while crossing the ITCZ (photo credits: Henning Franke, MPI)

Figure: satellite image where the ITCZ can be observed as a band of clouds near the Equator. Image from NASA Earth Observatory

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32 Days offshore, 28th of July

After a few days sailing over the Southern Hemisphere, we crossed the Equator again this noon, and we are back in the Northern Hemisphere.

[rv-sonne-lidar-experiment]

30 Days offshore, 26th of July

This morning we are again near Brazil. Today even closer than last time, and particularly in front of the city of Natal. As you can see in the following picture, we could even distinguish the city skyline.

Photo: at the background, the skyline of Natal (Brazil) (photo credits: David Menzel)

Additionally, I forgot to tell you that we had a new fire drill yesterday in the morning. Below you can see a hilarious picture of the moment.

Photo: from left to right, Xaver (GEOMAR), Katharina (MPI), and me during the fire drill

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29 Days offshore, 25th of July

In order to do not get bored during our free time, we have organized a table football tournament. We often play it during the evening, but from now on, it is a serious competition. I will update you about my progress in the championship.

Apart from this, today we talked about these last weeks living like in the old times (before the covid pandemic). Thanks to the quarantine before the ship started, we don´t have to care about wearing masks, keeping the distance from the rest of the people, or not sharing anything with anybody. It is effortless to get used to “normal” life again, but I wonder if it would be so easy when we are back in Germany and need to get used to all the applicable restrictions.

[rv-sonne-lidar-experiment]

28 Days offshore, 24th of July

I am very happy with the lidar system so far. Since the problem with the antennas, it is running nominally. Hopefully, it will stay like this for the rest of the trip. In the figure below, you can observe the lidar wind speed and direction measurements (10-min averaged data at 60 m height) compared to the observations from the ship's weather station. As you can see, the (corrected) lidar measurements agree with the ship's retrieved information in terms of both wind speed and direction. However, there are also considerable differences in some periods, which could be due to several factors. Although I need to investigate this more deeply, it is very likely that the vessel's structure may significantly influence the measurements of the weather station when the wind blows from some directions relative to the boat. I will have a closer look to this during the next few days.

Figure: time series of lidar corrected measurements at 60 m height and observations from the ship´s meteorological station