Two weeks ago, we, Lennéa and Daria, joined the cruise MSM114/2 (ARC) on the RV Maria S. Merian together with an interdisciplinary group of scientists from the MPI-M in Hamburg, the Hafencity University, the University of Cologne, the Royal Dutch Meteorological Institute, and the Polish Academy of Sciences.
The goal is to use the vessels transit from Mindelo on Cabo Verde to Punta Arenas in Chile (23.1. – 23.2.23) to investigate tropical convection within the Intertropical Convergence Zone (ITCZ), which we zig-zagged three times on our way south. On the way, we collect meteorological reference measurements. In contrast, others measure the ocean depth with sonars and conduct CTDs to learn more about the protistan community’s diversity and composition.
We joined the cruise with a microwave radiometer HATPRO (Humidity And Temperature PROfiler). The HATPRO faces the sky and measures microwave radiation emitted by the atmosphere. Through this, we get continuous profiles of temperature, humidity, liquid water content and water vapor content for the entire cruise.
In addition to the radiometer, we help Laura and Julia from Hamburg launch radiosondes every 3 hours during our journey through the ITCZ for ten days. Getting up at 4:30 in the morning to launch the first radiosonde of our shift isn’t particularly easy, but at least it brings the joy of beautiful tropical sunrises!
Sunrise in the ITZC in the middle of the Atlantic Ocean after an early radiosonde launch. (Picture by Lennéa Hayo, University of Cologne) Launch of a radiosonde by Daria Paul (University of Cologne) (Picture by Olaf Tuinder, KNMI)Radiosonde launch on Maria S. Merian seen from a drone with sensors for atmospheric profiling (Picture by Daniel Kępski, Institute of Geophysics Polish Academy of SciencesHeavy rain clouds shortly before leaving the ITCZ during the third crossing. (Picture by Julian Wagenhofer, University of Cologne)
Polarstern cruise PS131 (ATWAICE) was a multidisciplinary expedition to investigate sea ice melting processes in the warming Arctic, ocean currents affecting nutrient supply for flora and fauna, ocean impacts on the melt of glaciers at Greenland’s east coast, and to deploy seismometers at the Aurora Vent Field. The expedition started on 28th June 2022 in Bremerhaven and led us to the Fram Strait, the marginal sea ice zone north-west of Svalbard, to fast ice at the east coast of Greenland and to Scoresby Sund, before returning to Bremerhaven on 17th August 2022.
Our working group also joined the expedition with atmospheric measurements using microwave radiometers (HATPRO and MiRAC-P) and radiosondes (weather balloons). The microwave radiometers faced the sky and primarily measured radiation emitted by the atmosphere (oxygen, water vapor, and liquid droplets). An additional sky camera consisting of a GoPro Hero 10 Black and an infrared sensor was mounted next to the radiometers on the guard rail of Polarstern to give us information about the sky conditions. From the HATPRO data, we could already retrieve preliminary temperature and humidity profiles, as well as the total amount of water vapor (known as Integrated Water Vapour or IWV) and cloud liquid water path (LWP) with a high temporal resolution (1 second). Complementary to the radiometers, radiosondes give us high vertical but low temporal resolution of temperature and humidity profiles. An example of this is shown for an extraordinary warm and moist air intrusion event from 15th to 19th July 2022. IWV peaked at 35 kg m-2 (comparable to mid-latitude summer conditions), and the temperatures reached more than 18 °C at a few hundred meters altitude. With a mirror construction designed by Pavel Krobot and Rainer H.-Lind and attached to the radiometers, we could also directly observe the radiation emitted by the sea ice and ocean. These measurements will later be compared to skin temperature measurements of the sea ice taken by an infrared camera to estimate the sea ice emissivity. Another GoPro is also mounted on the infrared camera to provide a visual context of the sea ice conditions.
Atmospheric overview of a warm air intrusion event showing the time series of IWV (LWP) from HATPRO as blue (black) line, IWV computed from radiosonde humidity measurements as orange circles (a), absolute humidity profiles from radiosondes (b) and HATPRO (c), as well as temperature profiles from radiosondes (d) and HATPRO (zenith and boundary layer scans) (e).Sea ice conditions close to Aurora Vent Field. Janna Rückert (University of Bremen) and Andreas Walbröl (University of Cologne) adjust the mirror angles for sea ice emissivity scans.Starting sea ice work on the fast ice close to the east coast of Greenland.Radiosonde launched by Andreas Walbröl.Entrance of Scoresby Sund (Greenland) with some ice bergs.Janna Rückert launches the radiosonde on Research Vessel (RV) Polarstern at the entrance of Scoresby Sund while RV Maria S. Merian was in the background.Mountains and ice bergs of the fjord Scoresby Sund.Polarstern as seen from the ice during ice station work.Sampling of sea ice cores to obtain temperature, density and salinity profiles during an ice station.Same as P7136352_by_Janna_Rueckert.JPG, but with sunglasses.
What a successful day! P5, P6 and HALO had their first joint research flight on Sunday!
If you ask yourself “What is HALO? And what is special about a joint flight?” then read on…
First, let’s start with something you already know from the previous posts: P5 and P6 are polar aircraft, which participate in the HALO-(AC)³ campaign and which are stationed in Longyearbyen, Spitsbergen. The instruments belonging to the University of Cologne, namely the radar MiRAC and the microwave radiometer HATPRO, are installed on P5, which is a remote sensing aircraft. Contrary, P6 is equipped with in-situ instruments recording atmospheric parameters and cloud particles near the aircraft. Thus, P5 is mainly flying above the clouds at an altitude of around 3 km, whereas P6 is flying at lower altitudes directly through the clouds. Joint flight activities of the two polar aircraft provide in-situ and remote sensing observations of a lot of different parameters from the same cloud at the same time!
HALO at the airport in Kiruna, Sweden. (Photo: Henning Dorff)
Next, HALO comes into play. HALO stands for “High Altitude and Long Range Research Aircraft” and is operated by the German Aerospace Center (DLR). HALO carries remote sensing instruments similar to P5, but is able to fly at higher altitudes of about 10 km and travel much longer distances. During HALO-(AC)³ it is stationed in Kiruna, the northernmost city of Sweden, together with other scientists from our group. The aim is to observe how air masses change in the Arctic by measuring the temperature, humidity, cloudiness or aerosol concentration along the wind direction.
As often as possible, joint flights with all three aircraft will be realized, which is really difficult to coordinate! Another difficulty are the bad weather conditions in Longyearbyen making flights with the polar aircraft impossible. And sometimes the different platforms are interested in different clouds or air masses.
During the first joint flight, the flight conditions were very calm! Our instruments worked well and observed precipitating cloud structures over sea ice and open water. In one of the following posts we will have a first look at the observations!
View over broken sea ice from P5.
If you are interested in a video diary with short daily updates on the work routine in Longyearbyen, just follow AWIexpedition on Instagram!
Now the time has come: both aircraft, Polar 5 and 6, have arrived in Longyearbyen, Spitsbergen, yesterday afternoon!
Arrival of Polar 5 in Longyearbyen.
The aircraft belatedly started their ferry in Bremen on Thursday morning and had a stop for refueling in Tromsø over night. After the arrival in Longyearbyen, all hands were needed to unload the aircraft and prepare them for the first scientific flight.
Polar 5 after the landing at the airport Longyearbyen.
For Sunday, the first research flight is planned – provided that the weather condition is good enough for takeoff and landing! That means, that the cloud base has to be high enough to not directly fly into a low level cloud. This would bear the risk of a bad view and freezing of the propellers. And we do not want to risk a crash!
Hopefully, the plans can be realized. An update on the first flights will follow soon!
Last week we installed the radar MiRAC and radiometer HATPRO on the Polar 5. The whole installation took us three days, but the following time lapse video gives you an overall impression in only two minutes!
The video first shows the installation of the radar MiRAC which is covered by a belly pod below the aircraft. Then the screwing together of the HATPRO is shown.
MiRAC is a frequency-modulated continuous wave (FMCW) radar, an active remote sensing instrument, operating at 94 GHz with an additional microwave radiometer, which is a passive remote sensing instrument, recording at 89 GHz. The radar is hanging below the aircraft and is protected by a belly bod. The bottom of the pod has a hole so that the antennas of the instrument are able to transmit and receive microwave radiation. The transmitted signal is reflected by cloud droplets or the surface and received by the antennas again. These signals help us to detect clouds and to interpret their microphysical properties.
The radiometer HATPRO is installed inside the aircraft and is looking through a hole in the ground of the aircraft. HATPRO measures microwave radiation emitted by the surface and atmosphere below Polar 5. These observations contain information on the atmospheric humidity, precipitation, liquid water in clouds, as well as on the surface.
HATPRO inside the P5.
After the installation, it was time for a ground test, during which all instruments inside the P5 were connected to the aircraft electricity one after the other. Unfortunately, this did not work out as planned and after some minutes no electricity was available in the aircraft anymore. Nevertheless, the engineers repaired everything and the ground test could be completed successfully the very next day!
Before taking off to the Arctic, the instruments had to be tested during the flight as well. Thus, the first short flight took place over the North Sea and Helgoland. Luckily, all instruments on board worked properly!
Communication during the flight is only possible with a head set.
After the success in Bremen, we had to quickly pack our luggages. At the beginning of the week the great journey to the Arctic started. After a stop in Oslo and Tromsø, we arrived in Longyearbyen on Tuesday! Since then we are waiting for the Polar 5 and 6 and use the time to explore the area and plan the first research flights. We expect the aircraft to land in a few hours and will give an update on the arrival soon!
Part of preparing for a climate study in the Arctic involves preparing for polar bear emergencies. Blog followers will ask themselves: wait, but aren‘t we flying? Yes! But…safety training includes polar bear protection, as emergency landing on the ice is (an unlikely) possibility.
An image from the Arctic landscape… and a typical road sign in that region (photo credits: Pavel Krobot)
The ice is the home of the polar bears. Bears are very curious, and extraordinarily well adjusted to the Arctic environment. For a polar bear, a group of scientists means a great opportunity for some extra dinner. So even though many of us are faced by comments around „You‘re going to the Arctic: I hope you will see a polar bear“ we actually really want to avoid seeing one (other than from the plane).
But you never know, so better to prepare for the emergency case. This is why 6 of us spent a day at AWI Bremerhaven to learn about polar bears and their behaviors. We learned how to avoid meeting a bear, how to scare bears (hint: they don‘t like loud noises, including banging on cooking pots), and what to do when you see one from far away. For the troubling worst-case scenario of a bear attack, we were also trained on how to handle a rifle.
Insights from the group include: rifles are surprisingly heavy; we were lucky to have Arctic-like wind conditions as storm „Ylenia“ was passing the Bremerhaven area during our training; and fingers crossed for spotting a bear from the air!
During the past decades the Arctic climate is undergoing warming which impacts the local ecosystem and human infrastructure. To better understand the Arctic climate system and improve projections for the future, three aircraft will jointly observe various atmospheric processes over the North Atlantic near Spitsbergen during the HALO-(AC)³campaign in March and April 2022.
Group picture after the final rescue challenge with survival suits and life vests.
Researchers from our group visited Bremerhaven for an exciting two-day safety training in preparation for this campaign. We learned, how to avoid dangerous encounters with polar bears which actually spend most of their lifetime on the sea ice beneath the aircraft. Additionally, an exhausting sea survival training demonstrated the use of life rafts and other equipment in case of an emergency landing. During the training huge waves and a thunderstorm were imitated, including flashes, rain and thunder in a complete dark surrounding.
Impressions from the sea survival training at RelyOn Nutec in Bremerhaven, Germany.
The cloud radar MiRAC-A is mounted below the Polar 5 aircraft.
Moreover, the first instrument belonging to our institute is already mounted below the aircraft Polar 5! It is a radar called MiRAC-A which will detect clouds below the aircraft. The Polar 5 will be equipped with several remote sensing instruments from different institutions. Our working group will additionally install the microwave radiometer HATPRO. Updates on this installation, the calibration of the instruments and the test flights will follow!
Do you want to follow the upcoming activities in the Arctic and learn more about the HALO-(AC)³ campaign? Then follow our AWARES blog and the HALO-(AC)³ website, where updates and interesting background information on the project are provided.
