Dr. Armin Loescher Profile

Dr. Armin Loescher

at European Space Agency

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Publications (7)

Proceedings Article | 2 October 2020 Presentation + Paper

The ESA Sentinel next-generation land & ocean optical imaging architectural study, an overview

Armin Löscher, Philippe Martimort, Simon Jutz, Ferran Gascon, Craig Donlon, Ilias Manolis, Umberto del Bello

Proceedings Volume 11530, 115300B (2020) https://doi.org/10.1117/12.2572871

KEYWORDS: Optical imaging, Satellites, Imaging systems, Multispectral imaging, Astronomical imaging, Space operations, Ocean optics, Optical components, Radiometry, Earth observing sensors

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Proceedings Article | 15 September 2020 Paper

The European Copernicus mission for anthropogenic CO2 emission monitoring

Jean-Loup Bézy, Valérie Fernandez, Bernd Sierk, Armin Löscher, Herbert Nett, Yasjka Meijer

Proceedings Volume 11501, 1150103 (2020) https://doi.org/10.1117/12.2566038

KEYWORDS: Carbon dioxide, Nitrogen dioxide, Clouds, Aerosols, Space operations, Satellite communications, Meteorological satellites, Satellites, Atmospheric monitoring, Spatial resolution

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As part of the European Copernicus Programme, the European Commission (EC) and the European Space Agency (ESA) together with the support of Eumetsat and the European Centre for Medium-Range Weather Forecasts (ECMWF) are initiating the development of operational satellites for measurements of anthropogenic carbon dioxide (CO₂) emissions. The CO₂ Monitoring (CO2M) mission shall provide atmospheric CO₂ measurements at 4 km² spatial resolution and a precision and systematic error better than 0.7 ppm and 0.5 ppm respectively in column-average dry-air mole fractions of CO₂ (XCO₂). The demanding requirements necessitate a payload composed of several instruments, which simultaneously perform co-located measurements. The main CO₂ instrument is a 250 km swath pushbroom imaging spectrometer allowing to retrieve XCO₂ from reflectance measurements in the Near-Infrared (747-773 nm) and Short-Wave Infrared spectral regions (1590-1675 nm and 1990-2095 nm). The observations for CO₂ concentration will be complemented by measurements of nitrogen dioxide (NO₂) columns over the same area. The NO₂ measurements from the visible region (405-490 nm) will serve as a tracer for plumes of CO₂ emission resulting from high temperature combustion, which will facilitate plume identification and mapping from (fossil fuel) power plants and large cities. The third component of the payload is a multiple-angle polarimeter, performing high-precision measurements of aerosol (and cloud) properties. Its measurements of polarized radiance under various observation angles will allow a precise light path correction. The resulting improved knowledge of the effective optical path due to scattering will reduce XCO₂ bias error. Retrievals will be successful not only under clear sky conditions, but also under moderate aerosols loading and hence significantly increase the yield of useful XCO₂ retrievals. The strong sensitivity of the XCO₂ retrieval to cloud contamination calls also for a cloud-imager capable of detecting small tropospheric clouds and cirrus cover with an accuracy of 1% to 5% and with a sampling better than 400 m.

Proceedings Article | 5 September 2019 Open Access

A new approach to climatology from space: laser occultation

S. Mottini, A. Loescher, M. Aguirre

Proceedings Volume 10565, 1056565 (2019) https://doi.org/10.1117/12.2552630

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Human activities have been identified as critical contributors to climate changes. Modern industrial development and increasing urbanisation have been affecting the environment at an unprecedented scale since the 19th century. In the two last decades the process has become even faster, also due to the impressive development of largely populated countries like India and China. Historical data records testify a direct correlation between increase in atmospheric CO₂ levels and Earth's temperatures but processes underlying climate regulation and changes are only partially known. The improvement of knowledge of atmosphere and climate processes needs the availability of complete and reliable data about atmospheric composition and properties and space-based observations play a primary role. Implementation of a demonstration mission based on an occultation technique at optical wavelengths is proposed. Observations in the infrared spectral range vest a particular importance because this band exhibits many absorptive spectral lines due to greenhouse gases, identified as the main responsible of global warming, thus H₂O, CO₂, CH₄, N₂O, O₃, and others can be observed with high accuracy. It is expected that the mission will demonstrate technical feasibility of an optical payload for limb sounding observations and provide useful inputs to climatic benchmarking (greenhouse gases and wind profile, as well as atmospheric thermodynamic properties). The identification and the preliminary definition of the instrument architecture and the identification of the critical technologies have been among the main tasks. Possible design options for the laser transmitter and the receiver are discussed, considering available technological solutions and technical constraints. Potential technological criticalities are illustrated too. The creation of performance models, analytical and numerical, facilitates and addresses the payload design activity, both at instrument level and at general system level.

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Proceedings Article | 12 July 2019 Open Access

The European CO2 Monitoring Mission: observing anthropogenic greenhouse gas emissions from space

Bernd Sierk, Jean-Loup Bézy, Armin Löscher, Yasjka Meijer

Proceedings Volume 11180, 111800M (2019) https://doi.org/10.1117/12.2535941

KEYWORDS: Signal to noise ratio, Carbon monoxide, Spectral resolution, Interference (communication), Spatial resolution, Spectrometers, Near infrared, Short wave infrared radiation, Aerosols, Clouds

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Responding to plans of the European Commission for extending the observation capabilities of the Copernicus programme, the European Space Agency (ESA) has initiated Phase A industrial (technical feasibility) studies for several new space-borne Earth Observation missions. High priority is given to a constellation of LEO satellites in Sunsynchronous orbit with the purpose of observing anthropogenic carbon dioxide (CO₂) emissions [European Commission, 2017]. The observing system shall acquire images of CO₂ concentration in terms of dry air column-averaged mole fractions (XCO₂), providing complete global land coverage at high spatial resolution (4 km²) within five days. The demanding requirements call for a payload comprising a combination of multiple instruments, which perform simultaneous measurements. The XCO2 is inferred from reflectance measurements in the Near-Infrared (NIR) and Short-Wave Infrared spectral regions (SWIR). This requires at least three spatially co-registered push-broom imaging spectrometers, measuring spectral radiance and solar irradiance in the NIR (747-773 nm), SWIR-1 (1595-1675 nm) and SWIR-2 (1990-2095 nm) at moderate spectral resolving power (R~5000-7000). In addition, the observations for CO₂ concentration will be complemented by Differential Optical Absorption Spectroscopy (DOAS) measurements of nitrogen dioxide (NO₂) over the same area. The NO₂ measurements in the visible region (400-500 nm) are expected to serve as a tracer for plumes of high CO₂ concentration resulting from high temperature combustion, which will facilitate plume identification and mapping. The third component of the payload is a multiple-angle polarimeter (MAP), performing high-precision measurements of aerosol (and cloud) properties. Its measurements of polarized radiance under various observation angles are expected to reduce XCO₂ bias error and significantly increase the yield of useful retrievals from the NIR and SWIR spectra. The complex observation architecture, involving multiple instruments and platforms, call for optimized observational requirements, driven by the primary goal of detecting and quantifying point-sources of greenhouse gas emissions. In particular, high single-sounding precision is essential for identifying plumes of elevated CO₂ concentration from instantaneous image acquisitions without regional and temporal averaging. This translates into stringent requirements for Signal-to-noise ratio (SNR), as well as spatial co-registration and spectral stability, which drive the instrument design. The presentation will introduce the different elements of the candidate Copernicus mission, in view of the ambitious mission goals. The payload components and observation requirements are addressed with special emphasis on the derivation of the SNR and spectral resolution requirements, which determine the instrument sizing.

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Proceedings Article | 17 November 2017 Open Access

The CarbonSat candidate mission for imaging greenhouse gases from space: concepts and system requirements

B. Sierk, J. Caron, J.-L. Bézy, A. Löscher, Y. Meijer, P. Jurado

Proceedings Volume 10563, 105633I (2017) https://doi.org/10.1117/12.2304154

KEYWORDS: Reflectivity, Polarization, Carbon monoxide, Absorption, Gases, Near infrared, Spectrometers, Spatial resolution, Signal to noise ratio, Short wave infrared radiation

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CarbonSat is a candidate mission for ESA's Earth Explorer program, currently undergoing industrial feasibility studies. The primary mission objective is the identification and quantification of regional and local sources and sinks of carbon dioxide (CO₂) and methane (CH₄). The mission also aims at discriminating natural and anthropogenic fluxes. The space-borne instrument will quantify the spatial distribution of CO₂ and CH₄ by measuring dry air column-averaged mixing ratios with high precision and accuracy (0.5 ppm for CO₂ and 5 ppb for CH₄). These products are inferred from spectrally resolved measurements of Earth reflectance in three spectral bands in the Near Infrared (747-773 nm) and Short Wave Infrared (1590-1675 nm and 1925-2095 nm), at high and medium spectral resolution (0.1nm, 0.3 nm, and 0.55 nm). Three spatially co-aligned push-broom imaging spectrometers with a swath width <180 km will acquire observations at a spatial resolution of 2 x 3 km² , reaching global coverage every 12 days above 40 degrees latitude (30 days at the equator). The targeted product accuracy translates into stringent radiometric, spectral and geometric requirements for the instrument. Because of the high sensitivity of the product retrieval to spurious spectral features of the instrument, special emphasis is placed on constraining relative spectral radiometric errors from polarisation sensitivity, diffuser speckles and stray light. A new requirement formulation targets to simultaneously constrain both the amplitude and the correlation of spectral features with the absorption structures of the targeted gases. The requirement performance analysis of the so-called effective spectral radiometric accuracy (ESRA) establishes a traceable link between instrumental artifacts and the impact on the level-2 products (column-averaged mixing ratios). This paper presents the derivation of system requirements from the demanding mission objectives and report preliminary results of the feasibility studies.

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Proceedings Article | 17 November 2017 Open Access

The CarbonSat candidate mission: radiometric and spectral performances over spatially heterogeneous scenes

J. Caron, B. Sierk, J.-L. Bezy, A. Loescher, Y. Meijer

Proceedings Volume 10563, 105633J (2017) https://doi.org/10.1117/12.2304186

KEYWORDS: Distortion, Spectrometers, Point spread functions, Telescopes, Diffraction, Astronomical imaging, Sensors, Space telescopes, Reflectivity, Near infrared

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Proceedings Article | 26 September 2014 Paper

The CarbonSat candidate mission: imaging greenhouse gas concentrations from space

Bernd Sierk, Jerôme Caron, Armin Löscher, Yasjka Meijer, Jean-Loup Bézy, Michael Buchwitz, H. Bovensmann

Proceedings Volume 9218, 92181F (2014) https://doi.org/10.1117/12.2061930

KEYWORDS: Carbon dioxide, Stray light, Reflectivity, Polarization, Near infrared, Spatial resolution, Absorption, Signal detection, Short wave infrared radiation, Sensors

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