Tag Archives: Hamburg

When you meet a hard boundary, the reflection starts

When I look at the picture above, I see basically three different zones on the surface of the lake.

The yellow zone, which is under the direct influence of the wind, where the water is full of small waves, and then two other zones.

In the red zone, the water isn’t under direct influence of the wind any more, we see clear, parallel wave crests propagating towards the shore. I’ve marked some of them below.

While they are still to the left of the wooden edge, not much happens. But once they hit the edge, we enter the “green zone”: The incoming wave crests get reflected at the wooden edge. They start propagating out onto the lake, getting longe and longer over time, while the red wave crests continue running further and further into the green zone, so we get interference between the incoming and reflected wave crests. Pretty cool! :)

Muddy water watching on my lunch break. Turbulence and all the good stuff!

This might not be the kind of water that people usually like to look at during their lunch break — I admit, it does not look particularly inviting. But look at how much the mud can tell us about what’s going on in the water!

I love how the overexposed seagull is stirring up a muddy wake as it paddles through the shallow water. Would you have thought that it was THAT shallow and that a small bird paddling along would create such a mess?

I love all the different kinds of structures in these pictures. The mud that has fallen dry and that shows all these canyon-like shapes where the water has run off. The mixing of waters with different mud concentrations, thus different colors. And then the muddy trajectory of the seagull.

Focussing on the mixing of water masses: See the lighter, sediment-loaded plume flowing from somewhere to the right over to the lower left of the picture below? And do you notice how different the shear-induced mixing looks from the paddling-induced one?

Here is the same spot again, only seconds later. See how dynamic the plume is, entraining clearer water as it flows along, eddying at its sides?

And what did you do during your lunch break? :-)

When commuting is actually enjoyable. #wavewatching

What I love about my job (in addition to the awesome job itself, obviously)? That my office is located in pretty much the coolest spot in Hamburg when it comes to touristy views of the city. So much great wave watching (and ship watching) to be done here!

For example below, see the small ferry on the right, and how well you see the bow waves in this kind of light?

And below, it has turned and is heading out into the main Elbe arm and you can spot the turbulent wake that reflects the sun very differently from the rest of the water on either side.

And then just casually strolling past dry docks, container terminals, huuuge ships…

I really enjoy this every day! Hamburg, the gateway to the world.

I see a new hashtag in my future #oceanographyofpuddleswithreflectionsofElbphilharmonie

There is a theme these days: one of Hamburg’s most famous sights, the concert hall called Elbphilharmonie.

And not only is it a pretty impressive buildings, it’s located right at the port of Hamburg, and, more importantly, right across from my new work place!

Yesterday morning there was a lot of ice on the puddle in front of it (above), this morning, by the time I got there, it was crushed (below).

And when I left tonight, there was some drizzle in the air and I did not feel like checking on the puddle.

Are you going to see this every day now? No, fear not — there are some cool blog posts in the pipeline! :-)

Here is to new beginnings!

From dawn til dusk (which wasn’t actually as long a time as it sounds ;-)), first day in my new job as programme manager of the citizen science project on biodiversity “GEO-Tag der Natur“. I am looking forward to great views on the way to and from work! And I am suuuper excited to be starting this job! I will tell you more about it once I had the chance to settle in a little.

Even though wave watching is not part of the job, I could not help but notice those puddles. Not only because of the reflections of Elbphilharmonie on them, but because when I arrived there was a little ice on them (see above)! Which was gone when I left, but there were some tiny wind ripples (see below). Which one do you think is more beautiful? I can’t decide!

Let’s guess tides!

Actually, there is no need to guess. If you tilt your head 45 degrees to the left, you are looking at Hamburg the way it would be shown on a map, North up. The Elbe river, which you see in the foreground, flows east-to-west into the North Sea. And now there are at least two spots in the image below where you can see fronts in the water, more turbid water in the main river bed, clearer water in side arms and bays. Those fronts always start at upstream headlands and go downstream from there, therefore it must be ebb tide, with the water going out into the North Sea. Easy peasy :-)

Funny how “upstream” and “downstream” make so little sense in a tidal river, yet everybody knows what I mean…

Would be interesting to see if you can see fronts when the tide is coming in, too, when the muddy river water is pushed into the more stagnant side arms and bays. I expect so but don’t actually know. Maybe I will be able to observe it on some future flight?

Why waves propagate so slowly into smooth patches of water

The morning I went to Heligoland I spent some time in the port of Hamburg, trying to film a phenomenon I had recently chatted about with the author of this inspiring guest post: How waves seem to propagate super slowly into smooth patches of water. It turned out to be really difficult to film (because ships didn’t go where I expected them to go [you see me walk a couple of steps half way through the video below, because I needed to get away where a boat was docking], other ships cross the water you are filming, and because filming water is pretty difficult in general).

Here is my best attempt:

So why does it seem to take waves so surprisingly long to propagate into smooth patches of water? Well, because what we see and notice is the phase speed of waves, with which the crests propagate. But the wave field itself only propagates with group speed, which is half the phase speed. So from the movement we notice, waves should be invading the smooth patches twice as fast as they actually do!

Now I need to go and find a good way to film this phenomenon…

Yet another view of the Port of Hamburg

Not all adventures are oceanographic!

Last week I had the chance to join students and alumni of the interdisciplinary bachelor project at Hamburg University of Technology for a flight above the port of Hamburg.

The students were flying for the very first time, so it got quite exciting at times, especially during turns.


But luckily they were quick learners and brought us home safely. Always nice to arrive at Hamburg Airport!


For all of you getting nervous now, let me take a step back and show you another picture:

We had the amazing opportunity to visit the German Aerospace Centre (DLR) in Braunschweig. And a couple of the students actually got the opportunity to fly the flight simulator! Even though I didn’t get to (sniff!) – it was absolutely fascinating. Even though the simulator opens up into a well-lit room, as you see in the picture above, it was so easy to forget we were staring at simulated landscapes in a simulated plane. It was really exciting! Some people even started feeling sick from all the turning. And we all kept staring out of the “windows” to see which part of the town we were flying over and whether we could spot our campus. Also the technology is pretty cool: the three projectors you see in the image above project onto concave mirrors, which makes the image be far away enough so the eye doesn’t focus on the screen, which makes the whole experience feel completely realistic.

We also got to see other parts of DLR which were pretty exciting, too, like the 3D view of Mars’s surface. Did you know that the highest mountain in our solar system is on Mars, and that it’s 22 km high? I bet you did not.

Thanks, Uta and Siska, for organizing this great field trip!



Floating dry dock in the Port of Hamburg

Just because it’s fascinating.

On my recent trips through the Port of Hamburg one thing has fascinated me a lot – the floating dry dock. It’s right there when you get off the tube and walk towards the port:


Dry docks in the Port of Hamburg. A classical dry dock “Elbe 17” on the left, and a floating dry dock on the right.

The floating dry dock basically has a u-shaped profile of water tanks that can be flooded or emptied to adjust the buoyancy of the whole structure. As the tanks are flooded, the dry dock sinks and a ship can drive in. Then the tanks are emptied, the dock floats up, carrying the ship out of the water so people can work on it above water. Voila.

In the picture above you see some kind of dark fabric blocking the view into he floating dry dock on the right. How disappointing. But when Jenny and I were there we got lucky:

IMG_7290As we went past, we got a glimpse of the stern of the ship inside. And a little while later, the front had been opened up, too.

Here we can even see the bow of the ship.


I think it is really cool to be able to see a ship propped up and out of the water like that.

 And still cooler – a while later they started to flood the dock, so it was starting to sink and the ship was starting to float. (And don’t you just looooove this view of the port? No? Is it just me?)

When you compare the (obviously not heavily loaded) Cap San Diego in front of the dock with the ship inside, the ship in the dock seems to be almost floating already, too. Sadly we couldn’t continue watching until the ship sailed out of the dock. But we saw plenty of other cool ships and stuff, so I guess I shouldn’t complain :-)





Currents in the Port of Hamburg

But not what you think!

I’ve been visiting the Port of Hamburg on all of my weekends recently. First when J&J&T came to visit and Torge described the huge thunderstorm, then more recently when Jenny came to visit. The Port of Hamburg is a tidal port with water levels changing approximately 3 meters between high- and low tide. Hence currents are pretty strong during ebb and flood and a lot is going on oceanographically speaking.

So Jenny and I were strolling along the water’s edge when suddenly we noticed a tug behaving strangely.


A tug in the Port of Hamburg.

It just sat in one place, but was producing a lot of turbulence for no obvious reason.


Tug pushing against the Cap San Diego in the Port of Hamburg.

Then, maybe 100 meters away, a second tug was behaving even more strangely: It sat flush against the museum ship Cap San Diego and pushed against it, producing again a lot of turbulence.

What was going on?

Anyway, clearly the tugs weren’t only producing turbulence, but also pretty strong currents. Watch the movie to see what kept us entertained there for quite some time:

Seeing the first boat being swung around so badly was pretty scary (and after that first one, the tug visibly tuned down the engine), but after having watched six or so little boats pass the tug, we lost interest and went on a boat ourselves to explore the harbor from a different point of view. So maybe 45 minutes later and a bit further downstream, we suddenly spotted the Cap San Diego!


The Cap San Diego on the Elbe river, downstream of the Port of Hamburg.

I wasn’t aware this ship was still sailing – I had only ever seen it as a museum ship, moored at Landungsbrücken. But I have since learned that it does indeed still sail. If you pay enough, that is. Apparently a while back it was rented by my university for a practical, where students of ship building measured the propulsion and engineering students something else. I will have to make sure I’ll be on board if that happens again!

Anyway, isn’t Hamburg beautiful?

After having finished our harbor tour, more sightseeing, lunch, and some more sightseeing, Jenny and I went up on St. Michael’s Church for its nice view over the whole city. And guess what we saw?

No thunderstorms this time, but Cap San Diego coming back into port!