Application of the shipborne remote sensing supersite OCEANET for profiling of Arctic aerosols and clouds during Polarstern cruise PS106

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. PS106 contributed observations for the initiative "Arctic Amplification: Climate Relevant Atmospheric and Surface Processes and Feedback Mechanisms (AC)3" which involves numerous projects aiming on understanding the role of atmospheric and surface processes in the ongoing rapid changes in the Arctic climate. As one of the central facilities of (AC)3, 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 multi-wavelength Raman polarization lidar PollyXT and a 14-channel microwave radiometer HATPRO. 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-stare observations aboard the moving Polarstern. Also, low-level clouds and the presence of fog 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 165m 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 50m and 165m above sea level is presented. In addition, we provide an overview of the data processing chain of the OCEANET observations and demonstrate case studies of aerosol and cloud studies to introduce the capabilities of the dataset. The retrieval of aerosol optical and microphysical properties from the observations of PollyXT is presented by means of observations performed during the ice floe camp. Synergies between the remote sensing instruments and auxiliary observations from aboard Polarstern were analyzed by means of Cloudnet which provides as primary output a target classification mask. This target classification is the basis for value-added products such as liquid- and ice-cloud microphysical properties, cloud dynamics which can in subsequent steps be used as input for the investigation of cloud microphysical processes, radiative transfer calculations, or model evaluation. To this end, new approaches for ice crystal effective radius and eddy dissipation rates have been implemented into Cloudnet.