The flow field induced by multirotor drones is of high interest for atmospheric research, as it locally influences the atmosphere and therefore may have an impact on the sensors installed for ...atmospheric measurements. Further, on-board vibrations can cause significant interference with the measurement equipment. To investigate the near flow field, an approach combining measurements of pressure and temperature distribution in-flight and in a laboratory setup together with numerical simulations was applied. Existing high-frequency measurement equipment was piggybacked during the initial flight tests with a newly developed 25 kg quadcopter system in a low-cost early-stage-error approach to obtain initial data and experience. During the flights, high resolution sensors for measuring pressure, temperature, acceleration, and deformation were applied with different setups at different locations below one of the rotor planes, respectively, at one rotor arm, to determine the multicopter’s influence on pressure and temperature measurements, to investigate rotor arm deformations, and to obtain data to compare with numerical simulations of this rotor setup. An external Schlieren-type measurement technique was tested to visualise the rotor vortices. The applied measurement techniques proved to be suitable for acquiring the state of the rotor-induced flow, but with some limitations. The comparison of measurements and simulations showed basic agreement and allowed for the identification of necessary adaptations for subsequent studies. The interaction of the rotor wakes with the rotor arms could be identified as the main source of the measured structural vibrations. The need for necessary improvements in the measurement setup, flight operation, and simulation setup is presented in detail.
A profound knowledge of pollutant emissions and transport processes is essential to better assess the impact on local air quality, which ultimately affects human health. This is of special importance ...in the proximity of airports, as flight activities are a major source of ultrafine aerosol particles (UFP) that are associated with adverse health effects. A quantification of the aerosol population in the horizontal and in particular in the vertical distribution has not been sufficiently characterized so far, but is of crucial relevance, as the atmospheric boundary layer (ABL) is strongly interacting with aerosols. For this purpose, the fixed-wing research drone called ALADINA (Application of Light-weight Aircraft for Detecting in-situ Aerosol) was operated at a distance of approximately 4 km downwind of the German airport Berlin Brandenburg (BER) on October 11–19, 2021. During the investigation period, 140 vertical profiles of different meteorological parameters and aerosol particle sizes were obtained on six measurement days between the surface and up to a maximum altitude of 750 m above ground level (a.g.l.). The investigations indicate several features: The stability of the ABL is a key characteristic for the vertical distribution of aerosol population with highest concentrations close to ground. Inversion layers further enhance horizontal transport so that airport pollutants can be moved to a further distance away. The airborne observations of total particle number concentration (TNC) coincide with ground-based data from fix-point sites. They show a high variability depending on the distance to the plume as well as upwind position and highest concentrations of TNC related to rush hours of airport operations.
Air quality measurements usually consist of ground-based instrumentation at fixed locations. However, vertical profiles of pollutants are of interest for understanding processes, distribution, ...dilution and concentration. Therefore, a multicopter system has been developed to investigate the vertical distribution of the concentration of aerosol particles, black carbon, ozone, nitrogen oxides (NOx) and carbon monoxide and the meteorological parameters of temperature and humidity. This article presents the requirements by different users, the setup of the quadrocopter system, the instrumentation and the results of first applications. The vertical distribution of particulate matter next to a highway was strongly related to atmospheric stratification, with different concentrations below and above the temperature inversion present in the morning. After the qualification phase described in this article, two identically equipped multicopters will be used upwind and downwind of line or diffuse sources such as highways or urban areas to quantify the influence of their emissions on the local air quality.
The helicopter-borne measurement system HELiPOD is a platform for atmospheric and other environmental measurements to investigate local and regional phenomena. It can be operated in remote areas, as ...from a research vessel with a helicopter, without the need for a runway. This article presents the current design concept, technical details, and sensor package of HELiPOD, which was completely renewed for the deployment during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition across the North Polar Ocean in 2019/2020. It was updated for the deployment in the methane campaigns METHANE-To-Go-Poland to study methane emissions from coal mines in South Poland, and METHANE-To-Go-Nordstream, a follow-up campaign to study methane emissions from the Baltic Sea after the NordStream pipeline leaks in 2022. The HELiPOD has the dimensions of 5.2 m × 2.1 m × 1.2 m and a weight of around 325 kg. It provides the possibility for flight patterns on a horizontal scale of typically 100 m–100 km and at altitudes from 10 m up to 3 km. HELiPOD employs distributed data acquisition and central data synchronization, equipped with sensors relevant to five fields of research: atmospheric dynamics, trace gases, aerosols, radiation, and surface properties. The focus of this article is the technical realization, in particular the data acquisition system for about 60 sensors, as well as concepts for energy supply and thermal management. It describes the complementary use of different measurement principles and redundant sensors for improved data quality. Operational procedures are also discussed.
This paper describes the concept of the hyperspectral Earth-observing thermal infrared (TIR) satellite mission HiTeSEM (High-resolution Temperature and Spectral Emissivity Mapping). The scientific ...goal is to measure specific key variables from the biosphere, hydrosphere, pedosphere, and geosphere related to two global problems of significant societal relevance: food security and human health. The key variables comprise land and sea surface radiation temperature and emissivity, surface moisture, thermal inertia, evapotranspiration, soil minerals and grain size components, soil organic carbon, plant physiological variables, and heat fluxes. The retrieval of this information requires a TIR imaging system with adequate spatial and spectral resolutions and with day-night following observation capability. Another challenge is the monitoring of temporally high dynamic features like energy fluxes, which require adequate revisit time. The suggested solution is a sensor pointing concept to allow high revisit times for selected target regions (1-5 days at off-nadir). At the same time, global observations in the nadir direction are guaranteed with a lower temporal repeat cycle (>1 month). To account for the demand of a high spatial resolution for complex targets, it is suggested to combine in one optic (1) a hyperspectral TIR system with ~75 bands at 7.2-12.5 µm (instrument NEDT 0.05 K-0.1 K) and a ground sampling distance (GSD) of 60 m, and (2) a panchromatic high-resolution TIR-imager with two channels (8.0-10.25 µm and 10.25-12.5 µm) and a GSD of 20 m. The identified science case requires a good correlation of the instrument orbit with Sentinel-2 (maximum delay of 1-3 days) to combine data from the visible and near infrared (VNIR), the shortwave infrared (SWIR) and TIR spectral regions and to refine parameter retrieval.
In 2015, two major conferences focused on hyperspectral remote sensing and imaging spectroscopy were held in Luxembourg and Tokyo, respectively. They are namely the 9th EARSeL SIG Imaging ...Spectroscopy workshop and the 7th Workshop on Hyperspectral Image and Signal Processing. As a follow up to these conferences, the current special issue of JSTARS was launched and we are proud to present a selection of 48 excellent papers. The large number of papers, which were drawn from both extended versions of workshop presentations and traditional paper submissions, is indicative of the high level of research activity, interest, and applications in this field. The papers in this special issue cover a wide range of topics, including new imaging spectroscopy systems, research and applications of imaging spectroscopy, and advances in hyperspectral image and signal processing.
The "High resolution temperature and spectral emissivity mapping" (HiTeSEM) initiative aims at developing a conceptual instrument design for a hyperspectral thermal satellite to find answers for the ...most pressing research and data requirements within the scope of Food Security and Human Health. The satellite is proposed to consist of two long-wave infrared (LWIR) sensors, (1) a hyperspectral system with ~ 75 bands at 7.2 - 12.5 μm (NEΔT of <; 0.05 K) and a ground sampling distance (GSD) of 60 m and (2) a panchromatic (PAN) LWIR high resolution imager with two bands (8.0 - 10.25 μm and 10.25 - 12.5 μm, NEΔT of ~0.06 K) but a three times higher GSD of 20 m to extend the system to regional applications where higher spatial accuracy is required. For an accurate water vapor content (CWV) estimation, which is needed for accurate atmospheric correction and temperature-emissivity separation (TES), three wavelengths within the range 7.2-7.3 μm are used. Based on the science case, key regions of interest were identified in India, Asia, Andes mountains, Mediterranean ecosystems and densely-populated as well as growing regions.
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