GI6.4

Since its creation in 2000, the European Facility for Airborne Research, EUFAR, evolved into the central network for the airborne research community in Europe. From the beginning until 2018, EUFAR has received funding within the different Framework Programmes of the European Commission. In January 2018, EUFAR became an AISBL (international non-profit association under Belgian law) establishing EUFAR as an independent legal structure and ensuring EUFAR’s future.

Via EUFAR Transnational Access, a range of aircraft and instrumentation has been made available to European researchers who do not have access to a suitable research infrastructure in their home country. This has provided both a comprehensive range of atmospheric in-situ measurements together with a variety of remote-sensing instruments and hyperspectral imagers for studies of land or water surfaces, vegetation etc. Examples of successful TA activities will be shown. In order that researchers should continue in future to have access to the most appropriate research aircraft and instrumentation to meet their science objectives independently of EC funding, EUFAR is now working to develop principles of Open Access (OA).

EUFAR supports Expert Working Group meetings to exchange knowledge and promote best practice across the range of activities involved in airborne research. These cover, for example, instrument developments, data processing software and the scientific uses of airborne data. Via its previous EC funding, EUFAR has been able to support training courses for early-career researchers to introduce them to the use of airborne measurements for environmental research. Where possible, new software tools resulting from these activities are provided openly via the EUFAR website. EUFAR also promotes access to its members' data from airborne platforms and instruments and will be working with the AERIS data centre in France to provide a data portal to assist with this.

This presentation will give an overview of EUFAR, its recent achievements and future plans.

How to cite: Brown, P. and Gerard, E.: EUFAR: the European Facility for Airborne Research, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15741, https://doi.org/10.5194/egusphere-egu21-15741, 2021.

Stratospheric balloons are useful platforms for various research and technology needs. They allow to collect valuable data in many science fields, e.g. atmospheric science and astrophysics; they can be used for demonstrations in preparation of new space and Earth observation missions; they can be used to provide calibration/validation data for Earth observation space missions, or for dropping test objects from the stratosphere.

Various types of balloons are available, corresponding to different missions: Zero Pressure Balloons (ZPB) for heavy payloads (100 kg to 3 tons) and short to medium duration (1 day to several days), Sounding Balloons (SB) for very light payloads (3 kg).

Payloads can be flown at various altitudes between the ground surface up to 40 km, according the type of balloon and the kind of mission. Compared to satellites, stratospheric balloons can be operated at relatively low cost and with shorter lead times from the experiment idea to the flight.

Mid-2017, a new Research Infrastructure called HEMERA has been selected by the European Commission within its programme Horizon 2020. The HEMERA objectives are to:

• Provide better and coordinated balloon access to the troposphere and stratosphere for scientific and technological research, in response to the scientific user needs.
• Attract new users to enlarge the community accessing the balloon infrastructure and foster scientific and technical collaboration.
• Enlarge the fields of science and technology research conducted with balloons.
• Improve the balloon service offered to scientific and technical users through innovative developments.
• Favour standardization, synergy, complementarities and industrialization through joint developments with greater cost-effectiveness.

The project is coordinated by CNES and involves 13 partners in total, from various European entities and Canada. The project was kicked-off in late January 2018 and will be executed during 2018-2022.

Six ZPB flights with a target payload mass of at least 150 kg are foreseen within HEMERA, offering free of charge access to users and scientists for various science measurements and/or for technology tests. In addition, several SB flights are foreseen. The launch sites will be Esrange in Sweden, Timmins in Canada, for the ZPB and Aire sur l'Adour in France for the SB. The selected experiments will fly on balloons during the years 2019-2022. 

Two Calls for Proposals were planned in the HEMERA project, the first was launched in 2018 and 39 answers from 12 countries have been received; 23 experiments have been selected. 31 answers have been received in the frame of the second call, from 10 countries. In total 39 experiments from 13 countries have been selected. The first HEMERA flights occurred in summer 2019 from Kiruna and Timmins.

In addition, Open Access to balloon data will be organized in the frame of the Data Center, giving access to science data collected during the flights. Networking activities are planned in order to promote the Infrastructure in the European countries, and Joint Research activities are conducted in order to improve as far as possible the balloon offer in the view of the user needs.

How to cite: Friedl-Vallon, F., Raizonville, P., Vargas, A., Dannenberg, K., Albano, M., Kirchhartz, R., Vachon, E., Abrahamsson, M., Boen, K., Dubois, X., Huret, N., Harris, N., Ubertini, P., and Pfeilsticker, K.: The HEMERA Balloon Research Infrastructure, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13035, https://doi.org/10.5194/egusphere-egu21-13035, 2021.

The Cooperation to Unravel the Role of the Atmospheric Aerosol over the Amazon Basin using drones (CURE-3AB) project has yielded new technical solutions to perform high quality in-situ atmospheric observations in the lower troposphere (0-2 km) with Unmanned Aerial Vehicles (UAVs). An Ozonesonde (EN-SCI ECC, Model 2Z), designed for regular O3 radio sounding, has been adapted to perform on-line measurements of Ozone onboard the drone. A 3D printed low-cost pollen/spore collector has been developed to replicate reference instruments (VPPS2000) and adapted to perform onboard our UAV. Finally, an optical particle counter (AlphaSense) and a custom-made drying system have been fitted on a third drone. The three vehicle/instrument tandems will be deployed in the proximity of the Amazonian Tall Tower Observatory during the CURE-3AB campaign (delayed due to pandemic). We present the instrumental developments, setups, and preliminary test results performed with our UAVs at the Cyprus Institute private airspace.

How to cite: Desservettaz, M., Keleshis, C., Antoniou, P., Vouterakos, P., Liu, Y., Constantinides, C., Agapiou, A., Sarda-Esteve, R., Baisne, D., Kok, G., and Sciare, J.: Development and adaptation of sensors and samplers for vertical profiling using fixed-wing drones in the context of the Cooperation to Unravel the RolE of Atmospheric Aerosols over the Amazonian Basin (CURE-3AB)., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12966, https://doi.org/10.5194/egusphere-egu21-12966, 2021.

A reduction of the anthropogenic emissions of CO₂ (carbon dioxide) is necessary to stop or slow down man-made climate change. To verify mitigation strategies, a global monitoring system such as the envisaged European Copernicus anthropogenic CO₂ monitoring mission (CO2M) is required. Those satellite data are going to be complemented and validated with airborne measurements. UAV (unmanned aerial vehicle) based measurements can provide a cost-effective way to contribute to these activities. Here we present the development of a sUAS (small unmanned aircraft system) to quantify the CO₂ emissions of a nearby point source from its downwind mass flux without the need for any ancillary data. Specifically, CO₂ is measured by an in situ NDIR (non-dispersive infrared) detector and the wind speed and direction is measured with a 2D ultrasonic acoustic resonance anemometer. In order to minimize the effect of rotor downwash, we calibrate the anemometer by analyzing wind measurements taken while following a suitable flight pattern and assuming stationary wind conditions. We quantify the quality of the CO₂ and wind measurements with an in-flight validation at the ICOS (Integrated Carbon Observation System) atmospheric station Steinkimmen (STE) near Bremen, Germany. By means of two flights downwind of the ExxonMobil natural gas processing facility in Großenkneten about 40km east of Bremen, Germany, we demonstrate how the measurements of elevated CO₂ concentrations can be used to infer mass fluxes of atmospheric CO₂ related to the emissions of the facility.

How to cite: Reuter, M., Bovensmann, H., Buchwitz, M., Borchard, J., Krautwurst, S., Gerilowski, K., and Burrows, J. P.: Development of a small unmanned aircraft system to derive CO2 emissions of anthropogenic point sources, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8465, https://doi.org/10.5194/egusphere-egu21-8465, 2021.

The GLORIA-B (Gimballed Limb Observer for Radiance Imaging of the Atmosphere - Balloon) instrument is an adaptation of the very successful GLORIA-AB imaging Fourier transform spectrometer (iFTS) flown on the research aircrafts HALO and M55 Geophysica. The high spectral resolution in the LWIR (Long Wave Infrared) allows for the retrieval of temperature and of a broad range of atmospheric trace gases, with the goal to retrieve O₃, H₂O, HNO₃, C₂H₆, C₂H₂, HCOOH, CCl₄, PAN, ClONO₂, CFC-11, CFC-12, SF₆, OCS, NH₃, HCN, BrONO₂, HO₂NO₂, N₂O₅ and NO₂. The radiometric sensitivity of the Balloon instrument is further increased in comparison with the GLORIA-AB instrument by having two detector channels on the same focal plane array, while keeping the same concept of a cooled optical system. This system improvement was achieved with minimal adaptation of the existing optical system.

The high spatial and temporal resolution of the instrument is ensured by the imaging capability of the Fourier transform spectrometer while stabilizing the line-of-sight in elevation with the instrument and in azimuth with the balloon gondola. In a single measurement lasting 13 seconds, the atmosphere can be sounded from mid-troposphere up to flight altitude, typically 30 km, with a vertical resolution always better than 1 km for most retrieved species; a spatial resolution up to 0.3 km can be achieved in favourable conditions. Temperature retrieval precision between 0.1 and 0.2 K is expected. A spectral sampling up to 0.0625 cm^-1 can be achieved.

The first flight of GLORIA-B shall take place during the late-summer polar jet turn-around at Kiruna/ESRANGE. This flight is organised in the frame of the HEMERA project and was scheduled for summer 2020, but was ultimately postponed to summer 2021. Beyond qualification of the first balloon-borne iFTS, the scientific goals of the flight are, among others, the quantification of the stratospheric bromine budget and its diurnal evolution by measuring vertical profiles of BrONO₂ in combination with BrO observations by the DOAS instrument of University Heidelberg on the same platform.

How to cite: Kretschmer, E., Friedl-Vallon, F., Gulde, T., Höpfner, M., Johansson, S., Kleinert, A., Maucher, G., Neubert, T., Nordmeyer, H., Piesch, C., Preusse, P., Riese, M., Schardt, G., Schönfeld, A., Ungermann, J., and Wetzel, G.: Balloon-borne GLORIA hyperspectral Limb and Nadir imager in the LWIR, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11674, https://doi.org/10.5194/egusphere-egu21-11674, 2021.

The Aerosol Limb Imager (ALI) is a multi-spectral imager capable designed to observe aerosol extinction and particle size profiles in the upper-troposphere lower-stratosphere. ALI uses a system of linear polarizers, a liquid crystal rotator, and an acoustic-optic tunable filter to select the linear polarization state and wavelength of limb scattered sunlight radiance between 600 nm and 1500 nm. From stratospheric balloon, spectral images have spatial resolution of <100 meters at the tangent point, and can produce useful aerosol observations between 5 km and 30 km in altitude. Of novelty is the polarimetric capability of ALI, which uses the orthogonal polarization states to detect cloud in the spectral data and facilitate its distinction from aerosol. Two previous iterations of the ALI instrument concept have already been successfully demonstrated, once in 2014 and again in 2018. Currently, a third iteration is being developed which improves upon the thermal, structural, and optical performance of the previous iterations. This improved iteration is scheduled for demonstration as part of the HEMERA program out of Kiruna, Sweden in the summer of 2021. This demonstration serves the larger objective of further proving the engineering and scientific readiness of the ALI instrument concept for eventual high-altitude aircraft and satellite platform deployments.  ALI is a proposed Canadian contribution to the NASA A-CCP satellite mission study.

How to cite: Letros, D., Bourassa, A., Loewen, P., Graham, L., Lloyd, N., Rieger, L., and Degenstein, D.: Improved multi-spectral polarimetric observations of UTLS aerosol and cloud from stratospheric balloon with the Aerosol Limb Imager, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6714, https://doi.org/10.5194/egusphere-egu21-6714, 2021.

infoBalloons 2.0 is a selected Sounding Balloon (SB) Experiments in the 2nd HEMERA Call for Proposals (HEMERA H2020. This project has received funding from the European Union's Horizon 2020 research and Innovation programme under grant agreement No 730970).

This is a solution (self-made app/software and budget friendly IoT sensors and TC/TM communication link) to collect and then analyze data regarding atmospheric sounding, flight info/data and LPWAN (Low Power Wide Area Network) performances during a stratospheric balloon flight. Optional also to take POV photos/video of the flight.

infoBalloons 2.0 is the natural evolution of infoBalloons. The old 1.0 system reports a bunch of environmental data to an Android self-made app (available on Google Play for free) being carried in the hot air balloons using budget friendly industrial IoT sensors called Blebricks. IoT sensors communicate with the Android app installed inside the pilote’s smartphone using Bluetooth protocol and then the app partially elaborates the data and transmits them into the cloud (iSENSE platform) using a data (3G/4G) connection. infoBalloons was used several times during test flights and also for example during the International Hot Air Balloons Meeting in Mondovì in January 2019; it was developed by a group of Scientific High School students (I.I.S. “Cigna-Baruffi-Garelli” – Mondovì [Italy]) with the technical support of John Aimo Balloons - [Italy] (hot air balloons flights), Bleb Technology - [Italy] (Blebricks, the budget friendly industrial IoT sensors), iSENSE team (iSENSE is a web system for sharing and visualizing scientific data, based at the Engaging Computing Group at the University of Massachusetts Lowell [USA]) and MIT App Inventor team (CSAIL - Massachusetts Institute of Technology [USA]). The work was also presented in the Poster Session at last MIT App Inventor Summit 2019 in Cambridge, MA – USA.

How to cite: Tealdi, P., Innocenti, F., and Aimo, G. (.: infoBalloons: an Italian High School educational self-made budget friendly STEM experience with hot air/stratospheric balloons, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13420, https://doi.org/10.5194/egusphere-egu21-13420, 2021.

Observations from aircraft and balloons with remote sensing instruments are an important method to investigate processes within the Earth environment. These applications require powerful computing systems that must be developed or adapted for the measurement task and requirements. In particular, imaging spectrometers generate high data rates by almost 10,000 pixels at about 4,000 frames per second. Accordingly, high performance is needed to provide operational control and data processing with high data bandwidth and the capability to store this data also during long duration flights.

A modular processing system architecture based on modified industrial grade board components has been developed to meet these high requirements for processing power and storage capacity. The major advantages of this approach are flexibility, (re)programmability, modularity and module re-use in order to attain lower development time and costs. However, it is a challenge to design this processing system to be suitable for the harsh environments of aircraft or balloon applications in terms of temperature range, humidity and vibration.

With an efficient approach ruggedized characteristics are achieved using a conduction cooled design in combination with components based on VPX standard and customized backplane transition modules in order to reduce operational risk with necessary measures of mitigation techniques. This approach results in a processing system that combines hardware and software redundancies to assure system availability and reliability for long duration flights.

In this presentation the compact flight proven system design is presented that has been used in recent years for high spectral resolution limb-observations by the GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) spectrometer aboard the HALO and Geophysica high-altitude aircrafts. Various system configurations and performance results will be shown, which have been achieved in the current design and will be applied in future balloon campaigns.

How to cite: Neubert, T., Schardt, G., Rongen, H., Zimmermann, E., Gulde, T., Kretschmer, E., Maucher, G., Preusse, P., Riese, M., Ungermann, J., and van Waasen, S.: High performance modular, compact and ruggedized processing system for airborne and balloon remote sensing instruments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7447, https://doi.org/10.5194/egusphere-egu21-7447, 2021.

High resolution remote sensing under harsh environmental condition on special carriers requires instruments which are more flexible und more ruggedized than devices off the shelf. Particularly addressing environmental research in polar and high alpine regions, a family of cameras developed by the DLR is presented. The MACS systems are specifically made for the use on airborne platforms. Due to scalability, small sensors like single sensors on rugged fixed-wing UAVs can be realized. The configuration can be extended to RGB/NIR/TIR oblique viewing rigs with up to 5 coordinated cameras on manned aircraft. By processing such images, photogrammetric products like change detection, classification, elevation models and mapping mosaics are derived for regional areas. Further applications are the evaluation of algorithms in the field of AI for spaceborne imagery or the investigation of acquiring a particular combination of spectral bands.

These systems are able to deal with extreme illumination conditions and flight envelopes. Based on recent projects, the presentation shows examples and experiences, such as acquisition of the world’s highest glacier in Nepal, thermal infrared permafrost mapping of Ny Ålesund / Svalbard and sea ice measurements with a ground resolution of 3cm in the Fram Strait. Ideas for future sensors are indicated such as an UAV-based system with instant image transmission and a lightweight, high resolution sensor for stratospheric platforms.

How to cite: Brauchle, J., Bucher, T., Hein, D., Berger, R., Gessner, M., and Stebner, K.: Capabilities and Applications of MACS Aerial Camera Systems for Environmental Research, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16302, https://doi.org/10.5194/egusphere-egu21-16302, 2021.

Spectroscopic direct sun remote sensing of the atmosphere offers an essential tool for determining atmospheric trace gas concentrations. The monitoring of ozone-depleting substances, such as halogen oxides in the middle atmosphere, contributes to observing the progress in restoring the ozone layer.

Here, we present a new compact solar occultation spectrometer for the UV/visible spectral range that can be mounted on stratospheric balloons such as deployed within the European HEMERA infrastructures. Due to its compactness, the instrument is suitable as a secondary payload.
The instrument, consisting of a solar tracker providing direct sunlight for two grating spectrometers, is designed for deployment on a high altitude balloon to measure total bromine and iodine inventories using solar occultation and the DOAS method. All components of the setup have been chosen to withstand low temperatures (>-80°C) and low pressures (>5 mbar) as expected during the flight, and to have minimal power consumption while being compact, lightweight and only cooling radiatively. To perform solar occultation measurements, the device can track the sun down to 10° below its horizon.

The solar tracker is based on a two-camera setup following the Camtracker [1]. One camera with a fish-eye lens (FoV 185°) that observes the sky gives the sun´s coarse position. The Alt-Azimuth mount projects direct sunlight onto a screen. When reaching this coarse position, the image of the second camera is used to center the solar image on the spectrometer entrance telescopes by adjusting both mirrors within a 100 Hz control loop.
The tracker can reach a tracking precision of ≤0.05° for expected perturbations of smaller than 2° s^-1. In lab experiments it was shown, that the tracker could handle even faster perturbations (larger than 3° s^-1).
The sunlight is coupled into the two spectrometers via a fiber-telescope setup.

Two stabilized spectrometers (Ocean Optics QE Pro Series, resolution 0.5 nm) with a wavelength range for UV (305 to 385 nm) and vis (415 to 515 nm) are assembled within an evacuated box inside a water-ice bath. The vacuum avoids vapors condensing on the CCD an it ensures a constant refractive index within the spectrometers throughout the flight. At the same time the water-ice bath acts as a thermal buffer to stabilize the temperature of both spectrometers. Stable water-ice bath temperatures were achieved for >12 hours with deviations smaller than 0.5°C.

Preliminary testing of the setup was conducted on a three-day stationary roof-based test campaign with nearly clear-sky conditions. We plan on further investigating the instrument´s performance under field conditions and finally deploy the instrument on a stratospheric balloon flight from Kiruna in summer 2021.

[1] Gisi, M. et al.: Camtracker: a new camera controlled high precision solar tracker system for FTIR-spectrometers, Atmospheric Measurement Techniques, URL www.atmos-meas-tech.net/4/47/2011/, 2011.

How to cite: Voss, K., Holzbeck, P., Kleinschek, R., Herlan, R., Grossmann, K., Pfeilsticker, K., and Butz, A.: A compact solar occultation instrument for the UV/Visible spectral range: instrument design and performance testing, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1516, https://doi.org/10.5194/egusphere-egu21-1516, 2021.

In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm developments, calibration/validation activities, simulation of future space-borne earth observation missions, as well as application developments related to remote sensing of the atmosphere, land, oceans, solid earth and cryosphere.

ESA has conducted over 150 airborne and ground based measurement campaigns in the last 37 years, of which more than 80 were carried out since 2005. During this period a large number of campaigns have supported the validation of ESA’s satellite missions including for example SMOS and CryoSat. Ongoing activities are focusing on e.g. Sentinel-5Precursor and the preparation of upcoming Earth Explorer missions such as BIOMASS, FLEX, and FORUM. These validation campaigns aim to provide fundamental information about the confidence of data products and their required uncertainties One challenge in this context is a comprehensive understanding and characterization of measurement uncertainty of the validation dataset and the spatial and temporal support or representativity of these.

We will provide an overview of applied strategies to tackle these aspects for existing satellite missions and outline concepts for future missions, and how these integrate into broader earth observation science strategies. In addition, we will highlight recent activities and outline planned activities for the coming years.

How to cite: Schüttemeyer, D., Casal, T., Davidson, M., Drusch, M., Kubanek, J., Oetjen, H., and Tudoroiu, M.: ESA’s Campaign Activities in Support of Earth Observation Projects: A focus on validation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16374, https://doi.org/10.5194/egusphere-egu21-16374, 2021.

The objective of the H2020 project “Copernicus Cal/Val Solution (CCVS)” is to define a holistic Cal/Val strategy for all ongoing and upcoming Copernicus Sentinel missions. This includes an improved calibration of currently operational or planned Copernicus Sentinel sensors and the validation of Copernicus core products generated by the payload ground segments. CCVS will identify gaps and propose long-term solutions to address currently existing constraints in the Cal/Val domain and exploit existing synergies between the missions. An overview of existing calibration and validation sources and means is needed before starting the gap analysis. In this context, this survey is concerned with measurement capabilities for aerial campaigns.

Since decades airborne observations are an essential contribution to support Earth-System model development and space-based observing programs, both in the domains of Earth Observation (radar and optical) as well as for atmospheric research. The collection of airborne reference data can be directly related to satellite observations, since they are collected in ideal validation conditions using well calibrated reference sensors. Many of these sensors are also used to validate and characterize postlaunch instrument performance. The variety of available aircraft equipped with different instrumentations ranges from motorized gliders to jets acquiring data from different heights to the upper troposphere. In addition, balloons are also used as platforms, either small weather balloons with light payload (around 3 kg), or open stratospheric balloons with big payload (more than a ton). For some time now, UAVs/drones are also used in order to acquire data for Cal/Val purposes. They offer a higher flexibility compared to airplanes, plus covering a bigger area compared to in-situ measurements on ground. On the other hand, they also have limitations when it comes to the weight of instrumentation and maximum altitude level above ground. This reflects the wide range of possible aerial measurements supporting the Cal/Val activities.

The survey will identify the different airborne campaigns. The report will include the description of campaigns, their spatial distribution and extent, ownership and funding, data policy and availability and measurement frequency. Also, a list of common instrumentation, metrological traceability, availability of uncertainty evaluation and quality management will be discussed. The report additionally deals with future possibilities e.g., planned developments and emerging technologies in instrumentation for airborne and balloon based campaigns.

This presentation gives an overview of the preliminary survey results and puts them in context with the Cal/Val requirements of the different Copernicus Sentinel missions.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the grant agreement No 101004242.

How to cite: Holzwarth, S., Bachmann, M., Pflug, B., Meygret, A., Bès, C., Tison, C., Pierangelo, C., Henry, P., Tack, F., van Roozendael, M., Motta, B., Ligi, M., Vendt, R., and Clerc, S.: Aerial Campaigns for Cal/Val purposes in the Context of Copernicus - Survey Results of the Project “Copernicus Cal/Val Solution (CCVS)”, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12091, https://doi.org/10.5194/egusphere-egu21-12091, 2021.

Sentinel-5 precursor (S-5p), launched on 13 October 2017, is the first mission of the Copernicus Programme dedicated to the monitoring of air quality, climate, ozone and UV radiation. The S-5p characteristics, such as the fine spatial resolution, introduce many new opportunities and challenges, requiring to carefully assess the quality and validity of the generated data products by comparison with independent measurements and analyses.

While routine validation is performed within the ESA Mission Performance Center (MPC) based on a limited number of Fiducial Reference Measurements (FRM), additional validation activities including aerial and ground-based campaigns are conducted in research mode as part of the S-5p Validation Team (S5PVT). The validation activities bring together various teams and instruments to address specific validation requirements and provide a more in-depth, complete insight into the S-5p instrument performance and the fitness for purpose of its data products. The acquired reference data sets allow to address product accuracy and precision, spatial and temporal validation requirements, algorithm parameters (a priori profiles, albedo, etc.) and specific requirements, such as validation of strongly polluted and heterogeneous scenes.

Here, we present a series of decentralized activities planned to take place in 2021-2022 (s5pcampaigns.aeronomie.be), which have been identified to address key priorities for S5-p validation.

A first set of activities concentrates on the main S-5p UV-Vis tropospheric products (NO₂, HCHO and SO₂). Airborne deployment, consisting of both in-situ spiral and remote sensing mapping flights, is planned over cities and industrial areas in Romania (Bucharest; Jiu valley), the German Ruhr area (Cologne; Duisburg; Dusseldorf), Berlin, and Belgium (Antwerp (port); Brussels). Airborne operations will be complemented with various deployments on the ground (MAX-DOAS, car-DOAS, sun-photometer, ceilometer, lidar, etc.). The validation activities over Berlin and Bucharest are focused on recurrent airborne observations with hyperspectral imagers in order to have a large number of flights (12 to 18) over a time interval of approximately one year, in order to have a large statistical data set covering variable meteorological and geo-physical conditions, as well as different overpass configurations.

A second set of activities will focus on the validation of SWIR data products (CO and CH₄). COCCON (COllaborative Carbon Column Observing Network) portable low-resolution EM27/SUN FTIR spectrometers will be deployed for an extended period at different sites in the world in order to obtain a good coverage of geophysical parameters (strong sources, background sites, sites with high humidity, etc.) and different ground scenes, e.g. very high/low albedo sites.

Additionally, synergies are created with large field campaigns, such as the Asian Summer Monsoon Chemical and Climate Impact Project (ACCLIP) and the 2021 NET-Sense HyTES Joint European Campaign which will provide airborne measurements of NO₂, CO, CH₄ columns and vertical profiles, among others.

The various airborne and ground-based instrument deployments will produce a key ensemble of independent reference observations. For each product, a core team will coordinate the validation tasks, making use of data collected in all relevant instrumental deployments.

How to cite: Tack, F., Sha, M., Merlaud, A., Nemuc, A., Schuettemeyer, D., Zehner, C., and Van Roozendael, M.: Sentinel-5p Validation Campaigns – Planned Activities in 2021-2022, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8889, https://doi.org/10.5194/egusphere-egu21-8889, 2021.

Validation campaign for satellite missions requires efforts in terms of planning, logistics and depends on the weather for its execution. Furthermore, passive instrumentation is more sensitive at the weather, since requires special atmospheric conditions (e.g., cloud-free sky) for optimum performance. In this paper are presented activities regarding the preparation of Sentinel 5P validation in Romania, activities funded by ESA that involve ground-based (fixed and mobile – by DOAS sensors), and airborne measurements.

Research aircraft is based on a Britten-Norman BN-2 Islander platform, custom modified to accommodate, within the cabin, instrumentation for in situ measurements of aerosols (e.g., an Aerosol Particle Sizer and a nephelometer), trace gases (e.g., Picarro, and NO₂ CAPS), and NO₂, SO₂ and H₂CO column measurements (e.g., custom made DOAS whiskbroom imager for high-resolution mapping). The aircraft modification, already certified by EASA, include also the installation of an air inlet for the in-situ measurements, a nadir window for the remote sensing, and a GPS antenna for the IMU.

Measurements are planned to start in the spring of 2021 and to last until the end of the year. Region of interest is Bucharest metropolitan area, a city affected by infringement from the EU regarding poor air quality. The strategy is to perform seasonal measurements for mapping the variability of all pollution sources, e.g.: higher production from the local power plants (providers for hot water and heating for the residential population) in winter, car traffic concentrated towards the north, east or west (depending by the season).

This variability is observed also from the TROPOMI measurements, more precisely in the NO₂ column concentration. During the spring and summer, the maximum is concentrated within the city centre, while for the autumn and winter, the area is more extended. Maximum values are recorded during the winter, as are shown from the 2019 and 2020 data. Moreover, the amount of S5P measurements during the winter is fewer compared with the summer, due to the presence of clouds, thus planning and execution of a campaign during wintertime being more challenging.

How to cite: Ene, D., Vasilescu, J., Boldeanu, M., Calcan, A., Ardelean, M., Constantin, D., Merlaud, A., and Schüttemeyer, D.: An integrated approach for the validation of Sentinel-5P with annual observation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11151, https://doi.org/10.5194/egusphere-egu21-11151, 2021.

Anthropogenic atmospheric emissions of the reactive nitrogen components nitrogen dioxide (NO₂) and ammonia (NH₃) have majorly altered the global nitrogen cycle in the past 100 years, with devastating consequences to biodiversity, soil, water and air quality. Thanks to effective legislation, NO2 emissions are declining worldwide. Unfortunately, this is not the case for NH3 for which a recent study reports yearly increases of around 2% in Europe and the U.S. and up to 6% in East Asia. 

Both species are currently actively monitored with several satellite sounders, which provide daily global measurements. Yet, the spatial resolution of current sounders is inadequate for resolving the highly heterogonous spatial distributions of both species. This is particularly the case for point source emitters, for which satellites are currently only able to quantify the largest and most isolated ones. To fill the important gap in the monitoring landscape, a satellite called Nitrosat has been proposed in answer to ESA’s Earth Explorer call.  The satellite would allow making simultaneous measurements of NO₂ and NH₃ at a spatial resolution of 500 meter. In support to the Nitrosat proposal, ESA has funded a project called NITRO-CAM (Nitrogen cycle airborne measurements), which aims at mapping simultaneously NO₂ and NH₃ in the Greater Berlin area using aircraft measurements. It is the results of this campaign that are presented here. These can be seen as proof-of-concept for Nitrosat, but are also interesting in their own right. A larger focus is given to NH₃, for which the presented measurements are the first of their kind.

Campaign flights were performed in the surroundings of Berlin in the autumn of 2020. A follow-up campaign is foreseen in early spring. Measurements are performed with BIRA’s UV-VIS spectrometer newly-developed SWING instrument for NO₂ and TELOPS thermal infrared HYPER-CAM for NH₃. Surveying gapless areas of at least 10 by 10 km, the measurements enable capturing the emissions of both point and area sources, and are suitable for degrading at various hypothetical satellite instrument footprints.  For NO₂ specifically, Berlin and nearby power plants are targeted, while for NH₃ the Piesteritz fertilizer factory is targeted, as well as rural areas in the surroundings of Berlin.   

How to cite: Clarisse, L., Tack, F., Ruhtz, T., Merlaud, A., Noppen, L., Van Damme, M., Schuettemeyer, D., Coheur, P., and Van Roozendael, M.: Aircraft observations of NO2 and NH3 over selected locations in Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12645, https://doi.org/10.5194/egusphere-egu21-12645, 2021.

Faithfull physical representation of summertime convection over the United Kingdom, and beyond, remains elusive in convection permitting (CP) numerical weather prediction (NWP) models.  Biases include the incorrect representation of the size and spatial distribution characteristics of convective elements, timing errors in the diurnal cycle of convection and under-representation of high-intensity precipitation events. A key requirement for model improvement is 3D observations of convective clouds, updrafts and turbulence along with the pre-convective environment.

Increased computational power and novel parameterisation schemes (e.g. CoMORPH: scale-aware convection scheme, CASIM: Cloud AeroSols Interactive Microphysics) are on the cusp of facilitating significant advances to the representation of convective cloud systems, both at high resolution cloud resolving scales from O(100m) to O(1km) and for CP ensemble prediction systems. Observational constraints are now required to validate and develop this suite of numerical modelling and the WesCon campaign has been designed for this purpose.

Met Office and University of Reading are planning an observational field campaign from June through to August 2023 to investigate summertime convection. Focussing on the Wessex region encompassing South West and South Central England we will benefit from the remote sensing capability of  the Chilbolton Observatory to observe clouds and precipitation (including a new X-band radar) and the research radar (C-band) at Met Office Wardon Hill (Dorset) to observe precipitation structures.

Up to 80 research flight hours with the FAAM BAe146 research aircraft (Facility for Airborne Atmospheric Measurement) will probe the thermal, dynamical, updraughts and microphysical structures of the planetary boundary layer and lower free-troposphere on horizontal length-scales from the turbulence scale O(1 m) to the mesoscale (10’s kms). Ground based measurements will be deployed across the region making observations of surface exchange, turbulence and boundary layer properties. Radiosondes and dropsondes along with aircraft profiles will probe the atmosphere in the vertical.

Airborne measurements will place particular emphasis on the pre-convective environment, convective inhibition (CIN) and the early stages of the development of convective systems.  The full lifecycle of convective systems will be observed from the vantage point of remote sensing observations.

Here we present the aims and measurement strategy of the WesCon campaign and solicit interest and involvement from other modelling or observations groups within the community who may wish to join us to collaborate.

How to cite: Barrett, P., Abel, S., Lean, H., Price, J., Stein, T., Stirling, A., and Darlington, T.: WesCon 2023: Wessex UK Summertime Convection Field Campaign, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2357, https://doi.org/10.5194/egusphere-egu21-2357, 2021.

In summer, melt ponds on arctic sea ice can cover up to 60% of the total sea ice area, significantly decreasing surface albedo. The latter also holds true for supraglacial lakes frequently forming in the ablation zone of the Greenland Ice Sheet. Therefore monitoring of both, melt ponds on sea ice and supraglacial lakes is of great importance. So far, detection algorithms for both phenomena have been developed seperately from each other. Here, we will use airborne optical data of supraglacial lakes acquired during a land ice campaign over north-east Greenland in 2013 and airborne images of melt ponds from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign to illustrate similarities and differences in the appearance of both phenomena. As an example study, we use an open source processing chain including the Open Drone Map software as well as the AMES stereo pipeline to generate orthorectified photo mosaics. On the basis of these datasets, we will discuss typical detection methods as well as the difficulties they face in the respective environment (f.e. confusion with shadows and bare ice). Besides a modified normalized difference water index we test an adapted random forest approach that was developed for the analysis of MOSAiC melt pond data and conclude with suggestions for future algorithm development.

How to cite: Neckel, N., Fuchs, N., Humbert, A., Helm, V., Birnbaum, G., Kaleschke, L., and Haas, C.: Observations of Arctic melt ponds and supragacial lakes from airborne camera data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10673, https://doi.org/10.5194/egusphere-egu21-10673, 2021.