This is NOT the end, it is the beginning.

The last days at the Operations Center and the IGS Apartments were a little bit strange. More and more people left the NAWDEX campaign. At the last weekend only four to five members of the planning team were left and had to organize our flights. Also the instrument teams have to stay to ensure the continuous measurements. Nevertheless the end of the observation period of NAWDEX was clearly visible and the tough girls and boys who stayed on Iceland for the whole 4.5 weeks could not wait to go home and see their family and friends.
On Saturday the last flight from and to Iceland was performed followed by a day-off which was used to explore the beauty of the island for the last time. On Monday no flights for FALCON and HALO were planned. This free time was used to get the aircraft ready for the transfer flights to Oberpfaffenhofen and to put all the ground-equipment together, pack it and make it ready for shipping to Germany.
Tuesday morning started quiet early because take-off time for HALO was planned for 09:00 and for FALCON around 08:35. Therefore the HALO Crew had to arrive at the SilverGate of the airport at 06:20 for the last security check followed by loading the private equipment into the aircraft and turning on the instruments.
Surprise, surprise..... The FAAM aircraft - the British research aircraft which was very hard to coordinate during the NAWDEX campaign - parked inside the hangar face to face with HALO ,.... From this side no further comments.
At 8 o'clock the hangar door was opened and HALO rolled out. Using the transfer from Iceland to Germany measurements were performed including dropsonde release in the worlds most crowded airspace. The flight plan also included a holding pattern above Jülich for calibration and validation with the ground based instruments located at this side.
Ten minutes before the calculated arrival time HALO touched the runway in Oberpfaffenofen. Only a few minutes after the FALCON aircraft. Both crews were warmly welcomed including real Bavarian beer, Brezn and Leberkäs. After 4.5 weeks these small things were such a great pleasure and everyone was very happy to be at home.
Only a few hours later - it is Wednesday morning now - the disassembling of the instruments started which should be finished until Friday noon. This means the measureing period of the NAWDEX campaign is terminated but most of the work is still to be done: analyzing and interpreting the huge amount of data, creative thinking and writing a lot of papers.
Therefore this is not the end it is just the beginning of a much longer period which should be marked by intense cooperation of all NAWDEX participants to get the most out of the last weeks. Let’s hope for this and see us again at the first NAWDEX workshop.

(Kevin Wolf)


As a non native English speaker, when I'm thinking at this word, I'm thinking at a day with sun, after that I realize it's a day off, so a day off with sun. But not in Iceland. When I have to wake up at 5:45 so I'll be in time for the departure at 6:10, to be at the security check, called Silver Gate, at 6:20 and after that at 6:45 to assist at the start of WALES.
The first thing I realize, after waking up, is the wind. The wind, just the like the movie Gone with the wind, was taken ad literam, you may be taken away by the strong wind.
After a first Frühstück, I meet with colleagues from DLR, to go to heat up the HSRL lidar. But first we have to pass the security check, just like an airport X Ray check, where I leave my passport and receive a visitor badge. We are at the security check, but the officers are not there. After 5 minutes of waiting they arrive. They also not receive the email concerning our arrival. So we wait. Every minute stayed here will delay the heating up of the lidar. After some phone calls, the email was resend and now they are preparing the badges. Again, they mistaken my name into Dragan. But that's ok. It's not the first time.
Here we meet other people from instruments, that have to make the calibration of the airborne sensors. Enthusiasm is not a word to describe their faces, but after several seconds, you realize the passion and dedication of these people have for their jobs.
After we passed the security check, we meet with the FX people, they are not from the special effects, as I tout the acronym comes, but they are the responsible with the aircraft, and they will lead us to the Halo.
As I enter the hangar I see Halo and two Falcons (French Safire and DLR's). Talking about old movies, just the Maltese Falcon was (still) missing.
After the external power of the aircraft is coupled, since the aircraft cannot be turned on in the hangar, we can start to work at instruments. The guys at the radiometer start the calibration using liquid nitrogen, while the lidar is gradually turned on, a process that last at least two hours, time for the lasers to work at its capacity. Meanwhile, the guys at SpecMax appear, and start their procedure to power on the camera.
After two hours, all the equipment is turned off and the Halo is taken out of hangar. Than the instruments are powered on again, since some of components needs further calibration. It is a process that cannot be hurried, as I already seen on Friday, it takes time for all the modules to reach the operational mode.
It's almost 9:10, and the flying personnel appear. Before getting in the plane a short beefing is taken, in which are reminded the objectives of the flight. I will skip this meeting, since is taken in German and my sampling rate in German language is 1 understt at every 100 words spoken.
As I see them going in the plane and the others, including me, leaving the plane, I have an envy feeling, since they will fly where some people just dream, they will perform measurements, of whom people at the ground are dependable and will have the chance to sample the most extreme parts of atmosphere. But I have the promise that the next days I will be also on board of the plane.
We are now leaving the airport, I'm recovering my ID, and my name, and going back to the apartments. It's time for the second Frühstück. After that I'm heading to the meeting conference. While i'm heading to the meeting room, I'm passing next to the forecasters rooms, where, even though there are several minutes until the meeting, they are still calculating and trying the find the optimal path for the next flights.
As the meeting starts, and are presented the plans for the next days, people's mind fly away at the aircrafts, they are checking the current status, if they are flying, if they have taking off or the evolution of weather on their path.
After the meeting is over, the meteorologist start regrouping in their room and making the calculation based on the ended meeting discussion.
As I leave the building and I'm heading up to the apartments building I look up in the sky, searching for the Halo, at least how much the wind allows me to look up, further beyond the clouds.
I receive the news that further testing should be taken after the aircraft arrival, so at 15:45 we should leave for the Silver gate.
Maybe I can get some rest until the afternoon departure … only if the workers from the apartments will not work near my room, to make noise… but it's Sunday, so they shouldn't.

Over and Out. For now,
Dragos (or, just for a few hours, Dragan)

Radiometer’s calibration Taking Halo out of the hangar

Scientific crew briefing before the departure Last discussions before the morning meeting

Repairing nacelle at my room’s window

(Dragos Ene)

Gullni hringurinn

Gullni hringurinn, or the golden circle, is the most famous route in south-west Iceland. The tour is about 300 km long and can be done in one day. Several other groups of the NAWDEX team did it before, so on our day off we decided to be full time tourists and do the golden circle. We chose to do the circle anticyclonally and headed north after passing Reykjavik. The first "real" stop was Þingvellir, a national park that is one of the three main attractions of the golden circle. Þingvellir marks one of the boundaries between the Eurasian und North American tectonic plates. In 930 the national parliament of Iceland was established there. We got to know how important this first stop was, when we saw a tourist showing the whole place to his beloved one via skype. Also the rain couldn't stop us from walking between the continents and, after being totally soaked, we continued our journey alternating between demanding everything the heater had to offer and opening the windows to stop taking a sauna.
Our next stop was the Great Geysir (second main attraction), eponym of all the geysers, including Strokkur (Icelandic for "churn") Geysir and Litli ("Little") Geysir that can be found in that area. Strokkur erupts every few minutes up to 30 meters and is thus stealing Great Geysirs attention, as Geysir is only erupting about 3 times per day. It is quite impressive standing so close to erupting water, but gets rather frustrating if you want to film the whole event without having 10 minutes of useless blubber material.
Only a few kilometers to the east we were visiting the third main attraction: Gullfoss ("golden waterfall"). Gulfoss is a very picturesque waterfall with two cascades and the occasional rainbow. Walking through the water droplets that were sprinkled on the path, we could even see a full closed rainbow.
But since one waterfall is never enough for a round trip (and we were just dry again), we decided to visit Seljalandsfoss and Skógafoss in the south of Iceland. The most important argument to visit Seljalandsfoss is that you can walk behind the waterfall. Being so close to the waterfall was a very nice and wet experience. Next and last stop was 60 meters high Skógafoss. This foss achieved to excel all the other fosses in terms of soaking us completely. I have to admit, I asked for it.
Finally, after around 12 hours and 500 km we were back at the apartments and ready for a really big and nice dinner.

Þingvallavatn Þingvellir

Between the continents Strokkur

Litli Geysir Gulfoss

Gulfoss group picture Seljalandsfoss group picture

Skógafoss Route

(Pila Bossmann)

Mission scientist on HALO

One of the most interesting and fun roles in NAWDEX is mission
scientist for a particular flight. I had the job for IOP4. The plan
was to fly into the center of ex-tropical cyclone Karl, to observe it
re-intensifying as a mid-latitude storm. In fact the plan was be there
right at the time of the most active deepening. The days leading up to
the flight were hectic because the forecasts were so unreliable. Three
days before the flight we three different forecast scenarios with
three different flight plans!
For IOP4 HALO carried two pilots, a mechanic, five instrument
scientists, and me. The official role of the mission scientists is to
ensure communication between the cockpit and the rest of the team,
assist the dropsonde operator in timing the release of the sondes, and
be ready to respond to any changes that come along. This could be air
traffic control telling us we can’t stick with our plan, or the latest
satellite image telling us we don’t want to.
I think I drove everyone a little crazy, asking the pilots about their
weather displays, looking over people’s shoulders at the quick-looks
from the instruments, and calling for new satellite pictures from
Volkmar, who was mission scientist on the ground. But it was worth
every minute. We made three cross-sections through Karl, tracking a
tropopause fold that descended all the way to the boundary layer,
measured 150kt winds at 600 hPa (turbulence!), and got amazing lidar
water vapor measurement in a very deep dry intrusion.
Here’s a picture of the interior of HALO, with me on the right, and
Axel and Manuel from the WALES team, monitoring their
perfectly-functioning instrument (not that Martin Wirth ever stops

The next picture is the “eye” of the ex-hurricane, where dry
stratospheric air has come down and folded underneath the cirrus cloud
of the warm conveyor belt outflow.
And last but not least, coming home to another beautiful Icelandic sunset.

(George Craig)

Bouncing ballons

Throughout the NAWDEX campaign several radiosonde launches are planned. The aim is to measure stratospheric gravity waves. We have small and big ballons to launch the sondes. Prior to the launch the sondes have to be linked to the reception station and the ballon has to be filled with helium. After tying the sonde to the ballon, the flight tower has to confirm the start of the radiosonde. Normally, we get a five minute time slot to launch the ballon. The launching times are 5 am, 11 am, 5 pm and 11 pm. The sondes reach a height between 30 and 36 km with the small ballons and up to 42 km with the big ballons.
At some point, the launching of the radiosondes became a challenge when the wind speed increased throughout up to roughly 50 knts. Due to the high wind speeds, not only the flights had to be cancelled. At first the brave scientists tried to launch the sondes nevertheless, but had to give up after the big ballon bounced inevitably into the hangar. So they used the small ballons and bet with the coast guard how high the ballon would come. They were also told that the wind, that forced us to cancel flights and, in the end, radiosonde launches, was actually just a breeze.

(Pila Bossmann & Florian Baur)

Natural hot tubes

Geothermal heat is widely used in Iceland to produce electricity through geothermal power plants. Also, ground water that is heated deep down exits from the Earth's crust and forms hot springs all over Iceland. Some of them are boiling hot, while others are only luke warm. Finding good hot springs demands for information, as to where a hot spring might be located, a good GPS tracking device, good shoes and last but not least: endurance. Sometimes hot springs are easy to find and even equipped by local people, whereas others are just big warm puddles in the middle of nowhere.
The famous hot river is located about an one hour driveway east of Reykjavik near the little town Hveragerði. After a little hike up the hill you can enjoy the warm water that leaks out from several places and forms a small river. This river was a popular place to visit for the NAWDEX crew.
Another hot spring was found at the Snæfellsnes peninsula about 250 km North of Keflavik and served as a good last stop at the road trip around the vulcano Snæfellsjökull.

Snaefellsnes hot spring 1 Snaefellsnes hot spring group picture

hot river hike 1 hot river hike 2
(Hot river)

hot river hike 3
(Hot river)

(Pila Bossmann)

Cloudless nights in Iceland

During the nighttime many scientists of NAWDEX turn their glance away from their laptops and weather models to the sky to watch the Auroras, also known as polar lights.
Auroras can mainly be seen in the high latitudes of the Arctic and Antartic. They appear when solar winds disturbe the magnetosphere, that is surrounding every astronomical object. The ionization of atmospheric components are a result of charged particles that are precipitated into the upper atmosphere during those disturbances and are responsible for the emittion of light, varying in colour and form.
The possible visibility of Auroras is measured in the planetary index "kp", ranging from numbers from 0 to 9. This number is a scale of geomagnetic activity and empirically indicates where the Aurora might be visible. The higher the number, the further to the mid-latitudes Aurora might be seen during cloudless nights.
In Iceland Auroras are visible during a kp index of 2 or higher. When they are very weak it is hard to spot them in the sky as they look more like a thin, grey cloud. With higher numbers the colours changes to a light green and can also look white, purple or red. The forms of the Aurora can vary between lines, spirals and broader fields.
Saturday the 24th of September marked the first day of very high kp numbers (>4) and mostly cloudless skies. Over the next days the kp numbers mostly ranged between 3 and 6 and every night people could see this spectacular natural phenomenon. A couple of scientists drove out to the lighthouse at Gardur to have a better and less light polluted view on the Auroras. The following pictures were taken at late Monday(26.09.16) and Wednesday (28.09.16) showing the smaller lighthouse at the tip of the peninsula Reykjanesskagi.

(Pila Bossmann)

4 days at the Ops-Center

Arriving roughly one and half week after the campaign started you could see that everyone in the Ops-Center has found his or her scope. Finding you own is a bit difficult at the beginning, so you just sit down, take you laptop and start looking at PV maps and moisture fluxes, too. But, you quickly learn how you can contribute something and everyone is happy about some input from others.
On monday the 26th there was a high moisture flux and strong WCBs south of Iceland that reached the south of Norway on the 28th bringing high precipitation. So HALO was send out on Tuesday together with a very excited Hanin as mission scientist on board to investigate this event. Because of the developing cyclone formerly known as Xun that will hit Iceland on the weekend, it was decided that the Ops crew had a day-off on wednesday and so the planning for the flights on saturday and sunday started after everyone had some time to relax.
Beside beeing a nice spot for the midterm party and the general meeting, the Ops-center is also a great place to work with a lot of people on different tasks where everyone can contribute his/her knowledge while looking at the current state of the atmosphere (or at least the latest model output of it).

(Christian Euler)

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Living in the Alex Guesthouse huts

After one week in Keflavík, the FX and Falcon teams have well settled in their huts belonging to the Alex Guesthouse which offers rustic, yet cozy, accommodation. Being located close to Keflavík airport, it is just a five-minute drive away from the Ops Center and the Silver Gate. Nevertheless, the location offers a fair amount of seclusion and tranquility. Each hut comes with a comfortable bed, a couch, a cooking area with refrigerator and a two-burner stove as well as a bathroom with shower. A special feature is the personal rainbow (see picture) which guides every resident to his private pot of gold (well… wood), provided suitable weather conditions.
Although the huts (or should they better be called chalets?) all look almost the same, there’s room for individuality. For instance, embellishing of the interior by hanging up a flag of your favorite football club or your mother's home country is highly recommended – and also helps to distinguish your own hut from the others. The degree of coziness has even doubled since the last campaign in May 2015 after a second heater was installed in each hut, boosting the temperature to a comfortable level regardless of the weather outside. The five-minute waiting time for warming up the water in the shower is still unchanged, though…
One of the amenities of the Alex Guesthouse is its close proximity to downtown Keflavík where we can choose from a variety of restaurants and shopping opportunities. Maybe more importantly, the local swimming pool, Vatnaveröld, is within walking distance of our temporary homes. The Vatnaveröld features multiple indoor and outdoor pools including hot-tubs and a sauna – the perfect place to unwind and wash away the cares of a day full of forecasting, planning, flying, data processing, etc. For the tough ones, there is also an ice water pool. Try it and you will get a taste of what it would feel like if you went for a swim in the Northern Atlantic. The sea survival course was a cakewalk compared to that!
Even though everyone has his own hut, people often gather for an evening beer or two. Our favorite: Hardcore IPA (no kidding!). The only question that needs to be answered every day is: “What hut are we meeting in tonight?”. No matter when the next flight is scheduled, there’s always time to get together for a chat, a good laugh or even a jam session. Yesterday, a classy (if not necessarily classical) quartet was formed by Philipp and Martina playing two ukuleles, Christian on the guitar and Axel who came all the way from the IGS Apartments with his drums. The band made quite a show and we are sure this wasn’t their last performance during our stay at the Alex Guesthouse. In the unlikely case that people can no longer stand each other’s idiosyncrasies, everybody simply retreats to his or her own private hut. So, in general, we are more than satisfied with our cute little houses just at the entry to Keflavík.

(Oliver Lux)

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Living in the IGS Apartments

Showing where HALO and Falcon spend their days when not flying - we will have a closer look on the IGS apartments where some of the scientist are sleeping while they are not in the Operations Center or at the airport.
The first days were really basic. Frank promised us that there will be a fully equipped kitchen including everything we need to get something to eat. Unfortunately it was not. No(t) (enough) chairs, no kettle, no glasses, no cups,... Not even dishes or knifes. Therefore, the first day was a little bit like camping and the good old Swiss army knife served us well. At the second day we made a point and wrote a whish-list to the manager of the IGS apartments including all the mentioned basic stuff above. As it arrives we were very happy, the cupboard started to fill up and we were able to cook some easy meals. As more and more persons arrived the capacity of the pots and pans was not enough. So there was a second whish-list with more pots and pans on it and also some luxury stuff like a toaster, a coffee-machine and a kettle was added. When this whole load of things arrived it was like Christmas and you can see the joy in Mario’s eyes. With these utilities the expectations rise and wonderful variations of dishes were created. Looking back at the first evening (noodles with tomato-sauce) the menu was extended by cooked fish with rice, self-made pizza, fried fish with potatoes, goulash or pancakes. Between the meals the kitchen serves as a second Operations Center also where the flights of the aircrafts are followed, problems are solved and plans are made (for the day off).
The kitchen - which is obviously the central room of our living - is not the only part of the apartments. The private rooms also offered some surprises. Not all of them were available at the first day and are still under renovation. Some windows have to be fixed but no one has to sleep outside. All in all the rooms are nice and well equipped for the basic needs of a field scientist. Beautiful mattress ensure a good night sleep. For some roommates the functionality of the shower was not clear at the first glance because the button who activates the shower head was kind of hidden in the fitting. This provided some fun at the following morning.
In summary one can say that we arrange us well and like it to live together in such a nice community.

(Kevin Wolf)



Working at the hangar

After successfully arriving in Keflavik and spending our first day off discovering Iceland the real work started. This means: let’s got to the hangar. HALO and Falcon are already waiting for us.
Before starting the work at the aircraft the first hurdle has to be overcome, the security check. There, the airport visitor badges have to be distributed and everyone has to be checked for illegal things and weapons of all kind. Passing the inspection and being airside the friendly drivers of SouthAir guides us the hangar. There, the DLR FX stuff sorted all the shipped boxes and containers with the equipment. Luckily the second container arrived on Tuesday evening. Now all necessary tools are available at the hangar.
Already on Monday the WALES crew set-up their cooler to run WALES on the ground and keeping the lasers at the right operation temperature. During flight a cooling device at the top of the aircraft is used for this purpose. Shortly before flight they cleaned the window which covers the inlet of telescope.
For SMART the usual calibration has to be performed. For this, small Ulbricht spheres are used - which produce homogeneous distributed (the technical term is: lambertian) radiation. This ensures constant data quality between every flight and during the whole campaign. Taking them as a reference the calibration of the laboratory is transferred into the hangar. All this effort is needed because even small disturbances in along the optical path can influence the proper measurement of the instrument.
Not only are the instruments important but also the persons who are dealing with them. To ensure proper training of the instrument PI's they were teaching each other how to operate the instruments and how to launch the important dropsondes.
On Wednesday shortly before flight specMACS flushed their spectrometer-system with gaseous nitrogen to reduce the humidity inside the instrument chamber. This lowers the propability of condensation at the outer window where the cameras look through HALO fuselage. Water and ice on the window reduces the transmissivity in the visible wavelength range and falsifies the infrared measurements. Therefore, decreasing the humidity is crucial to allow measurements in cold regions.
Further on the radiometers need a calibration. This is a 2-point-calibration using targets with an ambient temperature and a very low temperature - achieved with liquid nitrogen reaching a temperature of -196°C (77K). Using these two temperatures the calibration function is determined and used for data processing. The white devices on the photo show these targets which are made of special foam - opaque in the wavelength range of the human eye but transparent in the microwave range. Therefore the radiometers are looking directly on the liquid nitrogen measuring the low temperature.
At the same time the Falcon aircraft is maintained which carries two lidar systems for measureing the wind speed and direction. They tried to optimize the system performance and adjusted the lasers for proper wavelength-stability.
With all this work done, clean windows and fueled-up completely HALO and Falcon are well prepared for their first flight starting from Iceland. As everyone is curios for the results - let's see what this flight will bring...

(Kevin Wolf)





IOP-1: Go with the flow


The planning of the transfer flights for HALO and FALCON from Munich to Keflavik –scheduled for Thursday and Saturday- started beginning of the week. On Tuesday it already became apparent that there might be a NAWDEX ‘Golden Case’ showing up on Saturday: An upper-level trough was located South of Greenland with a ridge (with warm conveyor belt [WCB] outflow) building up to Iceland and a second trough was over Western Europe - perfect conditions for our airplanes travelling from Southern Germany to Iceland to catch the diabatic butterflies that travel up the WCB and disturb the downstream flow. During the course of the week this synoptic situation became more and more certain and the flight planning team saw the opportunity of turning the transfer flight into the first intensive observation period (IOP). This gave a lucky subset of the 85(!) NAWDEX participants the early opportunity to practice their flexibility (that meant some crew members and onboard scientists spontaneously trying to find accommodation in Munich on the first day of Oktoberfest) and they already got a glimpse of how quickly things can change during the planning-process (and later how rewarding it can be to go with the flow!).
On Saturday the Operation Center was turned fully operative and the first planning meeting took place – which, after the surprising encounter of a Golden Case right at the beginning of the campaign, revealed a very promising and exciting flow development for the coming days. In the early afternoon everyone on site rushed to the airport and bravely resisted the freezing Icelandic winds to welcome the airplanes – which arrived on schedule in the afternoon with satisfied mission scientists that reported on a successful zeroth campaign day.

(Lotte Bierdel)