Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer

In this thesis, consisting of five scientific papers, I investigate the potential of unmanned aircraft systems (UAS) in stable boundary layer (SBL) research, by developing and applying a new innovative observation strategy. In this strategy we supplement ground-based micrometeorological observations from masts and remote-sensing systems with a number of different UAS. To achieve good agreement between the different systems employed in this approach, I further investigate the quality and intercomparability of UAS-based observations of atmospheric temperature, humidity, pressure and wind, and develop and apply common, best-practice data processing methods. In Paper I we give a brief introduction to the ISOBAR project and provide an overview over the first SBL campaign at Hailuoto and the prevailing synoptic, sea-ice and micrometeorological conditions. We demonstrate the quality of our measurement approach by combining UAS profile data with observations from the wind and temperature sensing systems. Repeated UAS temperature profiles give detailed insight into the temporal evolution of the SBL, which we find was often subject to rapid temperature changes affecting the entire depth of the SBL. We further highlight the potential of the sampled data by detailed investigations of a case study, featuring rapid shifts in turbulent regimes and strong elevated thermal instabilities, which were likely to result from the instability of an elevated internal gravity wave. In Paper II we assess the quality and intercomparability of UAS-based atmospheric observations from the most extensive intercomparison experiment to date. We evaluate the precision and bias of temperature, humidity, pressure, wind speed and direction observations from 38 individual UAS with 23 unique sensor configurations based on observations next to a 18-m mast equipped with reference instruments. In addition, we investigate the influence of sensor response on the quality of temperature and humidity profiles. By grouping the different sensor–platform combinations with respect to the type of aircraft, sensor type and sensor integration (i.e., measures for aspiration and radiation shielding), we attempt to draw general conclusions from the intercomparison results. Overall, we find most observation systems in good agreement with the reference observations, however, some systems showed fairly large biases. In general, hovering multicopters showed less variability than fixed-wing systems and we attribute this finding to the difference in sampling strategies. The most consistent observations of the mean wind were achieved by multicopter-mounted sonic anemometers. Sensor response errors were smaller for fine-bed thermistors compared to temperature sensors of integrated-circuit type, and sensor aspiration proofed to be substantially relevant. We conclude, that sensor integration considerations, like radiation shielding and aspiration, are likely to be as important as the choice of the sensor type, and give a couple of recommendations for future perspectives on UAS-based atmospheric measurements. Paper III presents the ISOBAR project to a broader scientific audience, including a description of the two measurement campaigns, ISOBAR17 and ISOBAR18 and the contrasting meteorological and sea ice conditions. We further provide an overview on the micrometeorological conditions during the 13 intensive observational periods (IOPs), which resulted in detailed data sets on the SBL in unprecedented spatiotemporal resolution. Numerous cases with very-stable stratification under clear-sky and weak-wind conditions were observed, featuring a variety of different SBL processes. These processes resulted in rapid changes in the SBL’s vertical structure. Based on selected in-depth case studies, we investigate the interactions of turbulence in the very stable boundary layer (VSBL) with different processes, i.e., a shear instability, associated with a low-level jet; a rapid and strong cooling event, observed a couple of meters above the ground; and a wave-breaking event, caused by the enhancement of wind shear. In a first qualitative model validation experiment we use data from one IOP to assess the performance of three different types of numerical models. Only the turbulence resolving large-eddy simulation model is found capable of reproducing a VSBL structure similar to the one observed during the IOP. The other models, i.e., an operational weather prediction and a single-column model, substantially overestimated the depth of the SBL. Paper IV introduces a new fixed-wing UAS for turbulence observations and first results from validation experiments carried out during ISOBAR18. Airborne observations of mechanical turbulence from straight horizontal flight paths are compared to corresponding eddy-covariance measurements mounted on a 10-m mast during weakly stable conditions with moderate wind speeds. Different average and spectral turbulence quantities, as well as mean wind speed and direction were computed for both systems and compared to each other. The UAS observations of mean wind and turbulence are in good agreement with the reference observations and the turbulence spectra agree qualitatively in the onset of the inertial subrange and the turbulence production range. Minor differences are likely to be caused by a slightly elevated UAS flight level and additional small altitude variations in the presence of relatively strong vertical gradients. In a second comparison, vertical profiles of mean wind and turbulence variables, determined from straight horizontal UAS flights at several different levels are compared qualitatively to profile observations from the 10-m mast and a phased-array sodar system providing 10-min averaged wind and vertical velocity variance profiles above 35 m. Qualitatively, the results agree well for the first two out of three profiles. During the third profile, the UAS data indicate the existence of a low-level jet but not an upside-down boundary layer structure, which would be expected due to the elevated source of turbulence. This observation is, however, not supported by the other measurement systems. Instead, the sodar data indicate a strong decrease in wind speed during the time of this profile. The fact that the lower part of the UAS profile was sampled before the start of the strongest transition, resulted in a seemingly wrong shape of the vertical profiles. This finding highlights the relevance of non-stationarity and the importance of additional reference systems for the correct interpretation of UAS sampled turbulence profiles. Paper V explores the potential of a new method to estimate profiles of turbulence variables in the SBL. In this method we apply a gradient-based scaling scheme for SBL turbulence to multicopter profiles of temperature and wind, sampled during ISOBAR18. We first validate this method by scaling turbulence observations from three levels on a 10-m mast with the corresponding scaling parameters, and comparing the resulting non- dimensional parameters to the semi-empirical stability functions proposed for this scheme. The scaled data from the three levels largely collapse to the predicted curves, however, minor differences between the three levels are evident. We attribute this discrepancy to the non-ideal observation heights for the determination of vertical gradients at the upper turbulence observation level. After the successful validation we apply this method to UAS profiles, by computing profiles of the gradient Richardson number to which we then apply the stability functions to derive turbulence variables. We demonstrate this approach based on three case studies covering a broad range of SBL conditions and boundary layer heights. Since the application of this scaling scheme is only valid within the SBL, we estimate the boundary layer height from the sodar and two different methods based on UAS data. Comparisons at the lowest levels against turbulence variables from the 10-m mast and at higher levels against a Doppler wind lidar, which also provides estimates of some turbulence variables, indicate broad agreement and physical meaningful results of this method. Supplementing the findings from the five scientific papers, this thesis also provides the detailed description on the methodology and data processing procedures, I applied for the synthesis of observations from UAS, micrometeorological masts and boundary layer remote-sensing systems. Furthermore, I present results on the validation of the different wind observation methods, using lidar wind observations as the common reference. Finally, I provide an outlook on future perspectives of SBL and UAS-based boundary-layer research, and how further developments in SBL observation strategies may benefit from recent and future developments.Doktorgradsavhandlin

Proof of concept for wind turbine wake investigations with the RPAS SUMO

The Small Unmanned Meteorological Observer (SUMO) has been operated in the vicinity of five research turbines of the Energy Research Centre of the Netherlands (ECN) at the test site Wieringermeer. The intention of the campaign was to proof the capability of the system for wind turbine wake investigations also for situations above rated wind speed. In rather high wind conditions of 15-20 ms−1 on May 10, 2014, the system showed a satisfying in-flight behavior and performed five racetrack flights. The racetrack patterns flown parallel to the row of the five turbines (four flights downstream the turbine row, one upstream) enable the characterization and investigation of the strength, i.e. the reduction in the mean wind, and structure, i.e. the horizontal extension and turbulent kinetic energy (TKE) distribution of single turbine wakes.publishedVersio

Operationalisation of Mild Cognitive Impairment: A Graphical Approach

A new online tool allows mapping of the different classifications of mild cognitive impairment

Atmospheric Drivers of Wind Turbine Blade Leading Edge Erosion: Review and Recommendations for Future Research

Leading edge erosion (LEE) of wind turbine blades causes decreased aerodynamic performance leading to lower power production and revenue and increased operations and maintenance costs. LEE is caused primarily by materials stresses when hydrometeors (rain and hail) impact on rotating blades. The kinetic energy transferred by these impacts is a function of the precipitation intensity, droplet size distributions (DSD), hydrometeor phase and the wind turbine rotational speed which in turn depends on the wind speed at hub-height. Hence, there is a need to better understand the hydrometeor properties and the joint probability distributions of precipitation and wind speeds at prospective and operating wind farms in order to quantify the potential for LEE and the financial efficacy of LEE mitigation measures. However, there are relatively few observational datasets of hydrometeor DSD available for such locations. Here, we analyze six observational datasets from spatially dispersed locations and compare them with existing literature and assumed DSD used in laboratory experiments of material fatigue. We show that the so-called Best DSD being recommended for use in whirling arm experiments does not represent the observational data. Neither does the Marshall Palmer approximation. We also use these data to derive and compare joint probability distributions of drivers of LEE; precipitation intensity (and phase) and wind speed. We further review and summarize observational metrologies for hydrometeor DSD, provide information regarding measurement uncertainty in the parameters of critical importance to kinetic energy transfer and closure of data sets from different instruments. A series of recommendations are made about research needed to evolve towards the required fidelity for a priori estimates of LEE potential.publishedVersio

Intercomparison of Small Unmanned Aircraft System (sUAS) Measurements for Atmospheric Science During the LAPSE-RATE Campaign

Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric measurement data from the Lower Atmospheric Process Studies at Elevation—a Remotely piloted Aircraft Team Experiment (LAPSE-RATE) field campaign. We evaluate a total of 38 individual sUAS with 23 unique sensor and platform configurations using a meteorological tower for reference measurements. We assess precision, bias, and time response of sUAS measurements of temperature, humidity, pressure, wind speed, and wind direction. Most sUAS measurements show broad agreement with the reference, particularly temperature and wind speed, with mean value differences of 1.6 ± 2.6 °C and 0.22 ± 0.59 m/s for all sUAS, respectively. sUAS platform and sensor configurations were found to contribute significantly to measurement accuracy. Sensor configurations, which included proper aspiration and radiation shielding of sensors, were found to provide the most accurate thermodynamic measurements (temperature and relative humidity), whereas sonic anemometers on multirotor platforms provided the most accurate wind measurements (horizontal speed and direction). We contribute both a characterization and assessment of sUAS for measuring atmospheric parameters, and identify important challenges and opportunities for improving scientific measurements with sUAS

ARTEFACTS: How do we want to deal with the future of our one and only planet?

The European Commission’s Science and Knowledge Service, the Joint Research Centre (JRC), decided to try working hand-in-hand with leading European science centres and museums. Behind this decision was the idea that the JRC could better support EU Institutions in engaging with the European public. The fact that European Union policies are firmly based on scientific evidence is a strong message which the JRC is uniquely able to illustrate. Such a collaboration would not only provide a platform to explain the benefits of EU policies to our daily lives but also provide an opportunity for European citizens to engage by taking a more active part in the EU policy making process for the future. A PILOT PROGRAMME To test the idea, the JRC launched an experimental programme to work with science museums: a perfect partner for three compelling reasons. Firstly, they attract a large and growing number of visitors. Leading science museums in Europe have typically 500 000 visitors per year. Furthermore, they are based in large European cities and attract local visitors as well as tourists from across Europe and beyond. The second reason for working with museums is that they have mastered the art of how to communicate key elements of sophisticated arguments across to the public and making complex topics of public interest readily accessible. That is a high-value added skill and a crucial part of the valorisation of public-funded research, never to be underestimated. Finally museums are, at present, undergoing something of a renaissance. Museums today are vibrant environments offering new techniques and technologies to both inform and entertain, and attract visitors of all demographics.JRC.H.2-Knowledge Management Methodologies, Communities and Disseminatio

The potential science and engineering value of samples delivered to Earth by Mars sample return

© The Meteoritical Society, 2019. Executive Summary: Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re-evaluate and update the sample-related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub-objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub-Objectives for MSR Identified by iMOST: Objective 1 Interpret the primary geologic processes and history that formed the Martian geologic record, with an emphasis on the role of water. Intent To investigate the geologic environment(s) represented at the Mars 2020 landing site, provide definitive geologic context for collected samples, and detail any characteristics that might relate to past biologic processesThis objective is divided into five sub-objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. Intent To understand the preserved Martian sedimentary record. Samples A suite of sedimentary rocks that span the range of variation. Importance Basic inputs into the history of water, climate change, and the possibility of life 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. Intent To evaluate at least one potentially life-bearing “habitable” environment Samples A suite of rocks formed and/or altered by hydrothermal fluids. Importance Identification of a potentially habitable geochemical environment with high preservation potential. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. Intent To evaluate definitively the role of water in the subsurface. Samples Suites of rocks/veins representing water/rock interaction in the subsurface. Importance May constitute the longest-lived habitable environments and a key to the hydrologic cycle. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. Intent To constrain time-variable factors necessary to preserve records of microbial life. Samples Regolith, paleosols, and evaporites. Importance Subaerial near-surface processes could support and preserve microbial life. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. Intent To provide definitive characterization of igneous rocks on Mars. Samples Diverse suites of ancient igneous rocks. Importance Thermochemical record of the planet and nature of the interior. Objective 2 Assess and interpret the potential biological history of Mars, including assaying returned samples for the evidence of life. Intent To investigate the nature and extent of Martian habitability, the conditions and processes that supported or challenged life, how different environments might have influenced the preservation of biosignatures and created nonbiological “mimics,” and to look for biosignatures of past or present life.This objective has three sub-objectives: 2.1 Assess and characterize carbon, including possible organic and pre-biotic chemistry. Samples All samples collected as part of Objective 1. Importance Any biologic molecular scaffolding on Mars would likely be carbon-based. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. Samples All samples collected as part of Objective 1. Importance Provides the means of discovering ancient life. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Samples All samples collected as part of Objective 1. Importance Planetary protection, and arguably the most important scientific discovery possible. Objective 3 Quantitatively determine the evolutionary timeline of Mars. Intent To provide a radioisotope-based time scale for major events, including magmatic, tectonic, fluvial, and impact events, and the formation of major sedimentary deposits and geomorphological features. Samples Ancient igneous rocks that bound critical stratigraphic intervals or correlate with crater-dated surfaces. Importance Quantification of Martian geologic history. Objective 4 Constrain the inventory of Martian volatiles as a function of geologic time and determine the ways in which these volatiles have interacted with Mars as a geologic system. Intent To recognize and quantify the major roles that volatiles (in the atmosphere and in the hydrosphere) play in Martian geologic and possibly biologic evolution. Samples Current atmospheric gas, ancient atmospheric gas trapped in older rocks, and minerals that equilibrated with the ancient atmosphere. Importance Key to understanding climate and environmental evolution. Objective 5 Reconstruct the processes that have affected the origin and modification of the interior, including the crust, mantle, core and the evolution of the Martian dynamo. Intent To quantify processes that have shaped the planet's crust and underlying structure, including planetary differentiation, core segregation and state of the magnetic dynamo, and cratering. Samples Igneous, potentially magnetized rocks (both igneous and sedimentary) and impact-generated samples. Importance Elucidate fundamental processes for comparative planetology. Objective 6 Understand and quantify the potential Martian environmental hazards to future human exploration and the terrestrial biosphere. Intent To define and mitigate an array of health risks related to the Martian environment associated with the potential future human exploration of Mars. Samples Fine-grained dust and regolith samples. Importance Key input to planetary protection planning and astronaut health. Objective 7 Evaluate the type and distribution of in-situ resources to support potential future Mars exploration. Intent To quantify the potential for obtaining Martian resources, including use of Martian materials as a source of water for human consumption, fuel production, building fabrication, and agriculture. Samples Regolith. Importance Production of simulants that will facilitate long-term human presence on Mars. Summary of iMOST Findings: Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M-2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity. Our ability to interpret the source geologic units and processes by studying sample sub sets is highly dependent on the quality of the sample context. In the case of the M-2020 samples, the context is expected to be excellent, and at multiple scales. (A) Regional and planetary context will be established by the on-going work of the multi-agency fleet of Mars orbiters. (B) Local context will be established at field area- to outcrop- to hand sample- to hand lens scale using the instruments carried by M-2020. A significant fraction of the value of the MSR sample collection would come from its organization into sample suites, which are small groupings of samples designed to represent key aspects of geologic or geochemical variation. If the Mars 2020 rover acquires a scientifically well-chosen set of samples, with sufficient geological diversity, and if those samples were returned to Earth, then major progress can be expected on all seven of the objectives proposed in this study, regardless of the final choice of landing site. The specifics of which parts of Objective 1 could be achieved would be different at each of the final three candidate landing sites, but some combination of critically important progress could be made at any of them. An aspect of the search for evidence of life is that we do not know in advance how evidence for Martian life would be preserved in the geologic record. In order for the returned samples to be most useful for both understanding geologic processes (Objective 1) and the search for life (Objective 2), the sample collection should contain BOTH typical and unusual samples from the rock units explored. This consideration should be incorporated into sample selection and the design of the suites. The retrieval missions of a MSR campaign should (1) minimize stray magnetic fields to which the samples would be exposed and carry a magnetic witness plate to record exposure, (2) collect and return atmospheric gas sample(s), and (3) collect additional dust and/or regolith sample mass if possible

Multiethnic Exome-Wide Association Study of Subclinical AtherosclerosisCLINICAL PERSPECTIVE

The burden of subclinical atherosclerosis in asymptomatic individuals is heritable and associated with elevated risk of developing clinical coronary heart disease (CHD). We sought to identify genetic variants in protein-coding regions associated with subclinical atherosclerosis and the risk of subsequent CHD

Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer

In this thesis, consisting of five scientific papers, I investigate the potential of unmanned aircraft systems (UAS) in stable boundary layer (SBL) research, by developing and applying a new innovative observation strategy. In this strategy we supplement ground-based micrometeorological observations from masts and remote-sensing systems with a number of different UAS. To achieve good agreement between the different systems employed in this approach, I further investigate the quality and intercomparability of UAS-based observations of atmospheric temperature, humidity, pressure and wind, and develop and apply common, best-practice data processing methods. In Paper I we give a brief introduction to the ISOBAR project and provide an overview over the first SBL campaign at Hailuoto and the prevailing synoptic, sea-ice and micrometeorological conditions. We demonstrate the quality of our measurement approach by combining UAS profile data with observations from the wind and temperature sensing systems. Repeated UAS temperature profiles give detailed insight into the temporal evolution of the SBL, which we find was often subject to rapid temperature changes affecting the entire depth of the SBL. We further highlight the potential of the sampled data by detailed investigations of a case study, featuring rapid shifts in turbulent regimes and strong elevated thermal instabilities, which were likely to result from the instability of an elevated internal gravity wave. In Paper II we assess the quality and intercomparability of UAS-based atmospheric observations from the most extensive intercomparison experiment to date. We evaluate the precision and bias of temperature, humidity, pressure, wind speed and direction observations from 38 individual UAS with 23 unique sensor configurations based on observations next to a 18-m mast equipped with reference instruments. In addition, we investigate the influence of sensor response on the quality of temperature and humidity profiles. By grouping the different sensor–platform combinations with respect to the type of aircraft, sensor type and sensor integration (i.e., measures for aspiration and radiation shielding), we attempt to draw general conclusions from the intercomparison results. Overall, we find most observation systems in good agreement with the reference observations, however, some systems showed fairly large biases. In general, hovering multicopters showed less variability than fixed-wing systems and we attribute this finding to the difference in sampling strategies. The most consistent observations of the mean wind were achieved by multicopter-mounted sonic anemometers. Sensor response errors were smaller for fine-bed thermistors compared to temperature sensors of integrated-circuit type, and sensor aspiration proofed to be substantially relevant. We conclude, that sensor integration considerations, like radiation shielding and aspiration, are likely to be as important as the choice of the sensor type, and give a couple of recommendations for future perspectives on UAS-based atmospheric measurements. Paper III presents the ISOBAR project to a broader scientific audience, including a description of the two measurement campaigns, ISOBAR17 and ISOBAR18 and the contrasting meteorological and sea ice conditions. We further provide an overview on the micrometeorological conditions during the 13 intensive observational periods (IOPs), which resulted in detailed data sets on the SBL in unprecedented spatiotemporal resolution. Numerous cases with very-stable stratification under clear-sky and weak-wind conditions were observed, featuring a variety of different SBL processes. These processes resulted in rapid changes in the SBL’s vertical structure. Based on selected in-depth case studies, we investigate the interactions of turbulence in the very stable boundary layer (VSBL) with different processes, i.e., a shear instability, associated with a low-level jet; a rapid and strong cooling event, observed a couple of meters above the ground; and a wave-breaking event, caused by the enhancement of wind shear. In a first qualitative model validation experiment we use data from one IOP to assess the performance of three different types of numerical models. Only the turbulence resolving large-eddy simulation model is found capable of reproducing a VSBL structure similar to the one observed during the IOP. The other models, i.e., an operational weather prediction and a single-column model, substantially overestimated the depth of the SBL. Paper IV introduces a new fixed-wing UAS for turbulence observations and first results from validation experiments carried out during ISOBAR18. Airborne observations of mechanical turbulence from straight horizontal flight paths are compared to corresponding eddy-covariance measurements mounted on a 10-m mast during weakly stable conditions with moderate wind speeds. Different average and spectral turbulence quantities, as well as mean wind speed and direction were computed for both systems and compared to each other. The UAS observations of mean wind and turbulence are in good agreement with the reference observations and the turbulence spectra agree qualitatively in the onset of the inertial subrange and the turbulence production range. Minor differences are likely to be caused by a slightly elevated UAS flight level and additional small altitude variations in the presence of relatively strong vertical gradients. In a second comparison, vertical profiles of mean wind and turbulence variables, determined from straight horizontal UAS flights at several different levels are compared qualitatively to profile observations from the 10-m mast and a phased-array sodar system providing 10-min averaged wind and vertical velocity variance profiles above 35 m. Qualitatively, the results agree well for the first two out of three profiles. During the third profile, the UAS data indicate the existence of a low-level jet but not an upside-down boundary layer structure, which would be expected due to the elevated source of turbulence. This observation is, however, not supported by the other measurement systems. Instead, the sodar data indicate a strong decrease in wind speed during the time of this profile. The fact that the lower part of the UAS profile was sampled before the start of the strongest transition, resulted in a seemingly wrong shape of the vertical profiles. This finding highlights the relevance of non-stationarity and the importance of additional reference systems for the correct interpretation of UAS sampled turbulence profiles. Paper V explores the potential of a new method to estimate profiles of turbulence variables in the SBL. In this method we apply a gradient-based scaling scheme for SBL turbulence to multicopter profiles of temperature and wind, sampled during ISOBAR18. We first validate this method by scaling turbulence observations from three levels on a 10-m mast with the corresponding scaling parameters, and comparing the resulting non- dimensional parameters to the semi-empirical stability functions proposed for this scheme. The scaled data from the three levels largely collapse to the predicted curves, however, minor differences between the three levels are evident. We attribute this discrepancy to the non-ideal observation heights for the determination of vertical gradients at the upper turbulence observation level. After the successful validation we apply this method to UAS profiles, by computing profiles of the gradient Richardson number to which we then apply the stability functions to derive turbulence variables. We demonstrate this approach based on three case studies covering a broad range of SBL conditions and boundary layer heights. Since the application of this scaling scheme is only valid within the SBL, we estimate the boundary layer height from the sodar and two different methods based on UAS data. Comparisons at the lowest levels against turbulence variables from the 10-m mast and at higher levels against a Doppler wind lidar, which also provides estimates of some turbulence variables, indicate broad agreement and physical meaningful results of this method. Supplementing the findings from the five scientific papers, this thesis also provides the detailed description on the methodology and data processing procedures, I applied for the synthesis of observations from UAS, micrometeorological masts and boundary layer remote-sensing systems. Furthermore, I present results on the validation of the different wind observation methods, using lidar wind observations as the common reference. Finally, I provide an outlook on future perspectives of SBL and UAS-based boundary-layer research, and how further developments in SBL observation strategies may benefit from recent and future developments