From Polar Lights to Polar Flights – COMPEX-EC Takes Off!

After we arrived in Kiruna yesterday and were greeted with polar lights, today our research aircraft Polar 5 has landed – ready to begin the COMPEX-EC campaign! Over the next two weeks, we will conduct research flights, focusing on cloud analysis in connection with the recently launched EarthCARE satellite.
With all participants and equipment in place, flight planning is already in full swing. Using the mission support system (MSS), we are mapping out possible flight paths on a large screen. One of our key challenges? Aligning our flight tracks with the EarthCARE satellite’s orbit to ensure at least 30 minutes of overlapping observations. This requires precise coordination — timing is everything.
Another critical factor is the weather. We are analyzing weather maps to identify optimal conditions for our flights. Especially cloud coverage and wind play a role in deciding when and where we can fly. Together with Jonas from ESA, we have already had an extensive weather briefing, and the forecasts look promising for our first flight, expected to take place this Friday.
Our (AC)³ mascot, Arctic fox Mika, could also hardly wait to see Polar 5 land here. With big eyes, he watched with us as the research aircraft was maneuvered into the hangar and, of course, made sure that everything went smoothly when the luggage was removed.
Of course, we also took a look inside the cockpit with him.
He is really looking forward to this time and hopes to discover and experience a lot more.
Exciting days lie ahead— stay tuned as we share our experiences, flight updates, and first results right here on the blog!

Ready…Set…Go!

Over the last two weeks, instruments were installed, cables laid, and the seats tightened into the aircraft to prepare for the COMPEX-EC (Clouds over cOMPlEX environment – EarthCARE) campaign in Kiruna. During the first half of April (2.-16.4.2025), scientists from the Universities of Cologne and Leipzig will conduct an EarthCARE validation campaign with the Polar 5 research aircraft from the Alfred Wegener Institute. Equipped with a suite of cloud remote sensing instruments, we will make research flights along the track of the overpassing EarthCARE satellite to validate its performance. Stay tuned for some impressions and regular updates from Kiruna.

First ice station


A couple of days ago, we had the first ice station, where we measured the ice properties in the area covered by the radiometers. This means we looked at vertical profiles of temperature, salinity, and density in an ice core, surface roughness, the microstructure of snow and ice, and ice thickness, while one of us took over the watch for polar bears.

By now, we have also gotten used to staying up late (or waking up in the night) to launch a radiosonde at midnight which collects temperature, pressure, humidity and wind profiles until a height of about 35 kilometers. (Nils is currently leading our internal scoreboard with a radiosonde height of 35.4 km.)

The last couple of days were very foggy, but we could see higher clouds below zero degrees which look very promising for mixed phase hydrometeors!

First updates from VAMPIRE on PS144

Hello from the RV Polarstern! We left Tromsø last Friday for the journey to the Central Arctic Ocean for the VAMPIRE campaign (Water VApor, Mixed-Phase Clouds, and Sea Ice Emissivity over the Central ARctic OcEan)! With the help of Mario and Pavel for the first days, have now set up our wide range of instruments: the radars GraWAC and MiRAC-A, radiometers HATPRO and LHUMPRO, a disdrometer, an ultrasonic, an infrared camera, a sky camera, and a GoPro on the upper decks of the ship where we have a really nice view, and have started measuring.

Yesterday, we reached the first sea ice! A first ice station is planned for tomorrow or the day after, so look out for updates (just as we’ll be looking out for more polar bears).

HAMAG field study

Humidity profiles and Arctic Mixed-phase clouds as seen by Airborne W- and G-band radars

07. – 22.02.2024, Kiruna, Sweden

General information

The overarching objective of HAMAG is to test the University of Cologne’s novel G-band radar GRaWAC: G-band Radar for Water vapor and Arctic Clouds aboard AWI’s Polar 6 (C-GHGF) aircraft. GRaWAC will be embedded in a suite of remote sensing instruments (microwave radiometer, lidar, W-band radar) accompanied by dropped atmospheric soundings.

We will take off from Kiruna in Sweden and target mixed-phase clouds over various surfaces (ocean, sea ice in different stages) over the Gulf of Bothnian or along the Atlantic Norwegian coast depending on weather and ice conditions.

And who is we? Enthusiastic cloud scientists from the AWARES group from the Institute for Geophysics and Meteorology at University of Cologne with great support of AWI’s polar aircraft crew.

Follow our flights on flightradar!

RF06 – another survey to the frozen Gulf of Bothnia

Today’s research flight was a repetition of RF01 cruising down the Gulf of Bothnia from its northern end down South till we reach the cloud decks that usually form over the open ocean. This year’s ice extension is quite large and it takes us more than one hour to get there. Since the models did not forecast any clouds over the ice in the bay, we planned to use this section for sea ice emissivity measurements. But in contrast to the forecast we could see low clouds covering the ice surface, giving us the chance to see how the new radar performs on these.

Very thin clouds lying on the ground could not be seen, neither by the G- nor by the W-band radar. But very interestingly, the surface return and the patterns of ghost images changed as soon as clouds were in the beam width.

Cruising along the bay we reached thicker clouds organized in several layers. Between the layers, seeder-feeder effects could be seen in the radars as well as DAR signals of up to 7 dB. All in all another very successful flight with a lot of knowledge on our new GRaWAC radar.

RF05 – Open and closed cells

We flew over to the Norwegian coast off Tromso to sample beautiful open and closed cell convection (see satellite image) resulting from a cold air outbreak near Svalbard. Crisp and clear flight conditions in Kiruna made take-off and landing smooth, and after passing some textbook lenticularis clouds over the mountain range, we arrived at the very cloudy survey square over the ocean.

Terra MODIS image retrieved from worldview.earthdata.nasa.gov; Kiruna is the waypoint on the right, survey square is marked off the Norwegian coastline.

With our flight altitude of 10,000ft (about 3.3km), it was harder to distinguish the cells’ structure, but circular, open areas were easy to see in our instruments and with our eyes. Open cells, seen in the upper left corner of the sat image, are circular areas of clear air with clouds forming along the edges: cold air sinks down in the clear air, diverges at surface, and rises at the edges, leading to ring-shaped cloud formation. Closed cells (bottom left) work the other way around: warm, moist air rises in the cell’s center, while cold air sinks around the cell’s edge. The decks here additionally get influenced by air hitting the coast line, leading to accumulation of clouds. Both cell types produce different amount of rain which we could very well observe with both our radars!

Meet the HAMAG team

Before some of us left the team, we took the chance to take a picture of the HAMAG crew in front of our reliable research platform Polar 6 in Arena Arctica. In the middle underneath the fuselage, you can see the belly pod carrying our two radars, GRaWAC and MiRAC.

Outlook for tomorrow. For the first time, we will try a survey on the Norwegian coast.

RF04 – the day we were waiting for

It’s not a surprise, that when you are looking for clouds to measure, it is very likely that you find them as well at the airport you plan to operate from. That’s what we had to deal with today. But pilots were convinced that it was doable, we did it, and it turned out to be the day that you do not want to miss.

It has always been the plan to stay local and find a good cloud deck to test different radar settings and get the first real differential absorption signal from the two GRaWAC channels. We found suitable clouds East of Kiruan on a 100 nm North-South leg that we followed four times before being back at Kiruna after about 4.5 hours. The data we collected look beautiful and should be the ones we needed to make this campaign a full success.