Abstract
Abstract. From 25 May to 21 July 2017, the research vessel Polarstern performed the cruise PS106 to the high Arctic in the region north and northeast of Svalbard. The mobile remote-sensing platform OCEANET was deployed aboard Polarstern. Within a single container, OCEANET houses state-of-the-art remote-sensing equipment, including a multiwavelength Raman polarization lidar PollyXT and a 14-channel microwave radiometer HATPRO (Humidity And Temperature PROfiler). For the cruise PS106, the measurements were supplemented by a motion-stabilized 35 GHz cloud radar Mira-35. This paper describes the treatment of technical challenges which were immanent during the deployment of OCEANET in the high Arctic. This includes the description of the motion stabilization of the cloud radar Mira-35 to ensure vertical-pointing observations aboard the moving Polarstern as well as the applied correction of the vessels heave rate to provide valid Doppler velocities. The correction ensured a leveling accuracy of ±0.5∘ during transits through the ice and an ice floe camp. The applied heave correction reduced the signal induced by the vertical movement of the cloud radar in the PSD of the Doppler velocity by a factor of 15. Low-level clouds, in addition, frequently prevented a continuous analysis of cloud conditions from synergies of lidar and radar within Cloudnet, because the technically determined lowest detection height of Mira-35 was 165 m above sea level. To overcome this obstacle, an approach for identification of the cloud presence solely based on data from the near-field receiver of PollyXT at heights from 50 m and 165 m above sea level is presented. We found low-level stratus clouds, which were below the lowest detection range of most automatic ground-based remote-sensing instruments during 25 % of the observation time. We present case studies of aerosol and cloud studies to introduce the capabilities of the data set. In addition, new approaches for ice crystal effective radius and eddy dissipation rates from cloud radar measurements and the retrieval of aerosol optical and microphysical properties from the observations of PollyXT are introduced.
Highlights
The Arctic is one of the hotspots of global climate change
Auxiliary instruments for in situ and remote sensing observations installed aboard Polarstern as well as used during a 2-week ice floe-camp, which was performed in the vicinity of the research vessel (RV), were utilized for the studies presented in here
During the 2-week ice floe camp performed in the frame of PASCAL, a tethered balloon site was set up for turbulence and radiation observations (Egerer et al, 2019), and a network covering 15 pyranometers to determine the spatial variability in the solar radiation was installed (Barrientos Velasco et al, 2020)
Summary
The Arctic is one of the hotspots of global climate change. This is observed as a change of several parameters, such as the drastic decline of the Arctic sea ice during all seasons, but especially in summer, in both extent and thickness (Meier et al, 2014). In order to study the feedback mechanisms causing Arctic amplification, the initiative ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes and Feedback Mechanisms (AC) conducted two complementary field campaigns in the Arctic summer of 2017: Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD), an airborne campaign performed with the research aircraft Polar 5 and Polar 6, and the Physical feedbacks of Arctic planetary boundary layer, Sea ice, Cloud and AerosoL (PASCAL) expedition, deployed on and around the research ice breaker Polarstern (Macke and Flores, 2018; Wendisch et al, 2019) These campaigns took place in May and June 2017 in the regions north and northeast of Svalbard with the aim to combine remote sensing and in situ observations.
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