First ice station

Posted on 22. August 2024 by linnea

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

Posted on 14. August 2024 by linnea

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.

From left to right: ultrasonic, disdrometer, W-band radar, G-band radar ((c) J. Rückert)

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).

Polarstern Cruise PS131 – ATWAICE (WALSEMA)

Posted on 26. August 2022 by claudia

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.