This study underlines the important role of the transported black carbon (BC) mass concentration in the West African monsoon (WAM) area.
BC was measured with a micro-aethalometer
integrated in the ...payload bay of the unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting IN situ Aerosol). As part of the DACCIWA (Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa) project, 53 measurement flights were carried out at Savè, Benin, on 2–16 July 2016. A high variability of BC (1.79 to 2.42±0.31 µg m−3) was calculated along 155 vertical profiles that were performed below cloud base in the atmospheric boundary layer (ABL). In contrast to initial expectations of primary emissions, the vertical distribution of BC was mainly influenced by the stratification of the ABL during the WAM season. The article focuses on an event (14 and 15 July 2016) which showed distinct layers of BC in the lowermost 900 m above ground level (a.g.l.). Low concentrations of NOx and CO were sampled at the Savè supersite near the aircraft measurements and suggested a marginal impact of local sources during the case study. The lack of primary BC emissions was verified by a comparison of the measured BC with
the model COSMO-ART (Consortium for Small-scale Modelling–Aerosols and Reactive Trace gases) that was applied for the field campaign period.
The modelled vertical profiles of BC led to the assumption that the measured BC was already altered, as the size was mainly dominated by the accumulation mode. Further, calculated vertical transects of wind speed and BC presume that the observed BC layer was transported from the south with maritime inflow but was mixed vertically after the onset of a nocturnal low-level jet at the measurement site. This report contributes to the scope of DACCIWA by linking airborne BC data with ground observations and a model, and it illustrates the importance of a more profound understanding of the interaction between BC and the ABL in the WAM region.
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.
The unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting in situ Aerosols) has been established as an important tool for boundary layer research. For simplified ...integration of additional sensor payload, a flexible and reliable data acquisition system was developed at the Institute of Flight Guidance, Technische Universität (TU) Braunschweig. The instrumentation consists of sensors for temperature, humidity, three-dimensional wind vector, position, black carbon, irradiance and atmospheric particles in the diameter range of ultra-fine particles up to the accumulation mode. The modular concept allows for straightforward integration and exchange of sensors. So far, more than 200 measurement flights have been performed with the robustly-engineered system ALADINA at different locations. The obtained datasets are unique in the field of atmospheric boundary layer research. In this study, a new data processing method for deriving parameters with fast resolution and to provide reliable accuracies is presented. Based on tests in the field and in the laboratory, the limitations and verifiability of integrated sensors are discussed.
Abstract
Global climate change poses significant societal and political challenges. The rapid increase in the near-surface air temperatures and the drastic retreat of the Arctic sea ice during summer ...are not well represented by climate models. The data sets introduced here intend to help improving the current understanding of the ongoing Arctic climate changes. In particular, this study considers observations from 24 helicopter flights (June–September 2020) and 5 flights with the helicopter-towed probe HELiPOD (May–July 2020) during MOSAiC. Distributions of various surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, and bare ice) were determined using fisheye camera images. They were related to collocated broadband irradiance measurements to analyse the temporal and spatial changes of the surface albedo. Multiple linear regression was applied to assign the measured areal albedo to the corresponding surface-types. The resulting surface-type fractions, the albedo data and respective upward and downward broadband solar irradiances of several flights throughout the melting and refreezing season are provided.
The combination of two well-established methods, of quadrocopter-borne air sampling and methane isotopic analyses, is applied to determine the
source process of methane at different altitudes and to ...study mixing processes. A proof-of-concept study was performed to demonstrate the
capabilities of quadrocopter air sampling for subsequently analysing the methane isotopic composition δ13C in the laboratory. The
advantage of the system compared to classical sampling on the ground and at tall towers is the flexibility concerning sampling location, and in
particular the flexible choice of sampling altitude, allowing the study of the layering and mixing of air masses with potentially different spatial origin
of air masses and methane. Boundary layer mixing processes and the methane isotopic composition were studied at Polder Zarnekow in
Mecklenburg–West Pomerania in the north-east of Germany, which has become a strong source of biogenically produced methane after rewetting the
drained and degraded peatland. Methane fluxes are measured continuously at the site. They show high emissions from May to September, and a strong
diurnal variability. For two case studies on 23 May and 5 September 2018, vertical profiles of temperature and humidity were recorded up to an
altitude of 650 and 1000 m, respectively, during the morning transition. Air samples were taken at different altitudes and analysed in the
laboratory for methane isotopic composition. The values showed a different isotopic composition in the vertical distribution during stable
conditions in the morning (delta values of −51.5 ‰ below the temperature inversion at an altitude of 150 m on 23 May 2018 and at an
altitude of 50 m on 5 September 2018, delta values of −50.1 ‰ above). After the onset of turbulent mixing, the isotopic composition was
the same throughout the vertical column with a mean delta value of −49.9 ± 0.45 ‰. The systematically more negative delta values
occurred only as long as the nocturnal temperature inversion was present. During the September study, water samples were analysed as well for
methane concentration and isotopic composition in order to provide a link between surface and atmosphere. The water samples reveal high variability
on horizontal scales of a few tens of metres for this particular case. The airborne sampling system and consecutive analysis chain were shown to provide
reliable and reproducible results for two samples obtained simultaneously. The method presents a powerful tool for distinguishing the source process
of methane at different altitudes. The isotopic composition showed clearly depleted delta values directly above a biological methane source when
vertical mixing was hampered by a temperature inversion, and different delta values above, where the air masses originate from a different footprint
area. The vertical distribution of methane isotopic composition can serve as tracer for mixing processes of methane within the atmospheric boundary
layer.
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.
Unmanned aerial systems (UAS) fill a gap in high-resolution observations of meteorological parameters on small scales in the atmospheric boundary layer (ABL). Especially in the remote polar areas, ...there is a strong need for such detailed observations with different research foci. In this study, three systems are presented which have been adapted to the particular needs for operating in harsh polar environments: The fixed-wing aircraft M 2 AV with a mass of 6 kg, the quadrocopter ALICE with a mass of 19 kg, and the fixed-wing aircraft ALADINA with a mass of almost 25 kg. For all three systems, their particular modifications for polar operations are documented, in particular the insulation and heating requirements for low temperatures. Each system has completed meteorological observations under challenging conditions, including take-off and landing on the ice surface, low temperatures (down to −28 ∘ C), icing, and, for the quadrocopter, under the impact of the rotor downwash. The influence on the measured parameters is addressed here in the form of numerical simulations and spectral data analysis. Furthermore, results from several case studies are discussed: With the M 2 AV, low-level flights above leads in Antarctic sea ice were performed to study the impact of areas of open water within ice surfaces on the ABL, and a comparison with simulations was performed. ALICE was used to study the small-scale structure and short-term variability of the ABL during a cruise of RV Polarstern to the 79 ∘ N glacier in Greenland. With ALADINA, aerosol measurements of different size classes were performed in Ny-Ålesund, Svalbard, in highly complex terrain. In particular, very small, freshly formed particles are difficult to monitor and require the active control of temperature inside the instruments. The main aim of the article is to demonstrate the potential of UAS for ABL studies in polar environments, and to provide practical advice for future research activities with similar systems.
Currently, the main in situ upper air database for numerical weather prediction relies on radiosonde and aircraft-based information. Typically, radiosondes are launched at specific sites daily, up to ...four times per day, and data are distributed worldwide via the GTS net. Aircraft observations are limited to frequent flight routes, and vertical profiles are provided in the vicinity of large cities. However, there are large areas with few radiosonde launches, in particular above the oceans and in the polar areas. In this article, the development and technical details of the unmanned aerial system LUCA (Lightweight Unmanned high Ceiling Aerial system) are described. LUCA has the potential to complement radiosonde and aircraft-based observations up to 10 km in altitude. The system ascends and descends (by electrical power) in spiral trajectories and returns to the launching site. This article discusses the requirements for obtaining high data availability under mid-European and Antarctic conditions, with highly automated take-offs and landings under high surface winds, the capacity to deal with icing, and the ability to operate under high wind speeds. The article presents technical solutions for the design and construction of the system and demonstrates its potential.
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.
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