The purpose of the basic research project ISOBAR (Innovative Strategies for Observation in the Arctic Atmospheric Boundary Layer) is to increase our understanding of the Atmospheric Boundary Layer (ABL) in the Arctic. In particular, we aim to study the physical processes governing the turbulent exchange under stable conditions, which are not well represented in current Numerical Weather Prediction (NWP) and climate models, due to insufficient parameterization schemes for the Stable Boundary Layer (SBL). Applying new innovative observation strategies, which include meteorological Remotely Piloted Aircraft Systems (RPAS) in addition to well-established ground based and profiling systems, we will provide data sets on the turbulent structure of the SBL, with unique spatial and temporal resolution. The project includes the test and characterization of the RPAS based turbulence sensors through laboratory experiments and a validation campaign at DWD observatory in Lindenberg. Three different RPAS systems, the Multipurpose Atmospheric Sensor Carrier (MASC, for long-range horizontal turbulence measurements), the Small Unmanned Meteorological Observer (SUMO, for turbulence measurements and vertical profiles) and the Advanced Mission and Operation Research (AMOR) multicopter system (for vertical profiles of the Surface Layer and fixed-location turbulence measurements) will be applied during two four-week long campaigns.