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!

Polar-6 took off this morning after a very successful HAMAG campaign.

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.

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!

High pressure conditions gave us wonderfully sunny and crisp winter weather this weekend, but also made all the clouds disappear! We decided to target forecasted haze conditions towards Finland around Sodankylä to test our new radar GRaWAC’s sensitivity limits.
Good news: higher sensitivity to detect thin layers of cloud and haze, even close to the surface, compared to our existing cloud radar MiRAC! With today’s tests, we are optimistic that we will be able to detect Arctic haze over sea ice conditions around Svalbard, our survey area for upcoming campaigns where low-level haze is crucial for radiation characteristics. The fog today was mysterious – it looked like thicker clouds from far away, but once we reached the decks, conditions were such as seen below in the photo: we could see through it easily down to the ground. Our radar detected a 30m thickness.

We are making use of the weekend to plan upcoming flights for next week, and to start off with some coding to analyze first data measured on Friday. A high pressure system has been hanging around for a few days around, making the sky wonderfully blue without a single cloud in the vicinity of Kiruna.

Today, we took off at 10 am for the first survey flight over Bothnian bay – GRaWAC’s, our new G-band radar system’s, first time in the air! Fair weather conditions over the bay and great conditions for emissivity measurements over the frozen, clear-sky Northern bay part. Clouds were scarce, but once we reached open ocean, we started seeing them from the window, and in our radar measurements, well organized.

Next flight will be on Monday – stay tuned!

Research flight preparations have started!