Design and Implementation of a Novel Multicopter Unmanned Aircraft System for Quantitative Studies of the Atmosphere

The call for creating new innovative meteorological instruments to help fulfill observational gaps in the atmospheric sciences has been gaining strength in the past few years. This comes along with the urgent need to increase the understanding of fast-evolving atmospheric processes to subsequently provide accurate and reliable weather forecasts in a timely manner. The increased interest in obtaining atmospheric observations with higher spatio-temporal resolution pushed scientists to begin exploring and harnessing new leading-edge engineering technology. For instance, affordable and accessible Unmanned Aircraft Systems (UASs) technology emerged within this timeframe and has since evolved rapidly. Many researchers and institutions have agreed that UASs are promising technology candidates for targeted in situ weather sampling, which has the potential to meet the stringent meteorological measurement requirements. However, the current market has shifted and shaped UASs for other applications that may be unsuitable or suboptimal for weather sampling. Special considerations were examined in this study to conceptualize a specialized weather UAS (WxUAS) capable of collecting reliable thermodynamic and kinematic measurements. While also performing similarly to conventional weather instruments, such as radiosondes, Doppler wind lidars, and meteorological towers, as well as providing a complementary role whenever measurement limitations arise. Therefore, given that the exploration of integrating weather instrumentation into UAS is rare, it is hypothesized that atmospheric measurements of a modified multicopter UAS that minimizes platform-induced errors can fill the thermodynamic and kinematic data gap in the planetary boundary layer (PBL). The proposed solution is a UAS-based in situ vertical profiler system, dubbed the CopterSonde, with necessary weather instrumentation, adequate sensor placement, and useful flight functions for optimal sampling of undisturbed air. This solution attempts to provide a holistic WxUAS design where the UAS itself was adapted to become not just a payload carrier but also part of the weather instrumentation system. Flow simulation studies backed with observations in the field were used to address sensor siting and mitigate sources of thermodynamic errors. Moreover, techniques for thermodynamic measurement correction, adaptable flight behavior, and 3D wind estimation were implemented using the experimental CopterSonde concept with results comparable to widely accepted conventional weather instruments. Additionally, the platform reliability was successfully demonstrated in different challenging environments, from freezing temperatures in Hailuoto, Finland, to high elevations in Colorado, USA. A robust concept of operation and decision-making algorithms were established to ensure safe flights during demanding field campaigns. As a result, the National Oceanic and Atmospheric Administration (NOAA) in the USA has recognized the CopterSonde as part of the approved UAS fleet for NOAA-related missions. Overall, the engineering advances shown in this work helped to produce an optimized UAS capable of collecting targeted and reliable weather observations. Even though the CopterSonde is an experimental design, this work can be used as a guideline to define future standards for WxUAS development and deployment