Uncertainty characterization of AOD for the  AATSR dual and single view retrieval algorithms

Abstract. The uncertainty associated with satellite-retrieved aerosol properties is needed when these data are used to constrain chemical transport or climate models by using data assimilation. Global uncertainty as provided by comparison with independent ground-based observations is usually not adequate for that purpose. Rather the per-pixel uncertainty is needed. In this work we describe how these are determined in the AATSR dual and single view aerosol retrieval algorithms (ADV and ASV) which are used to retrieve aerosol optical properties from reflectance measured at the top of the atmosphere. AATSR is the Aerosol Along-Track Scanning Radiometer which flies on the European Space Agency Environmental Satellite ENVISAT. In addition, issues related to multi-year retrievals are described and discussed. The aerosol optical depth (AOD) retrieved for the year 2008 is validated versus ground-based AERONET sun photometer measurements with good agreement (r = 0.85). The comparison of the AOD uncertainties with those provided by AERONET shows that they behave well in a statistical sense. Other considerations regarding global multi-year aerosol retrievals are presented and discussed.

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Combining ExoMars’ Ma_MISS and Drill data

10.5194/epsc2020-882 ◽

2020 ◽

Author(s):

Alessandro Frigeri ◽

Maria Cristina De Sanctis ◽

Francesca Altieri ◽

Simone De Angelis ◽

Marco Ferrari ◽

...

Keyword(s):

Mechanical Properties ◽

Water Content ◽

Large Scale ◽

Mechanical Response ◽

European Space Agency ◽

Volcanic Rocks ◽

Space Agency ◽

Geophysical Imaging

The ExoMars Rover and Surface Platform planned for launch in 2022 is a large international cooperation between the European Space Agency and Roscosmos with a scientific contribution from NASA.&#160; Thales Alenia Space is the ExoMars mission industrial prime contractor.&#160; Besides sensors and instruments characterizing the surface at large scale, the ExoMars&#8217; rover Rosalind Franklin payload features some experiments devoted specifically to the characterization of the first few meters of the Martian subsurface. These experiments are particularly critical for the main ExoMars objective of detecting traces of present or past life forms on Mars, which may have been preserved within the shallow Martian underground [1]. Rosalind Franklin will be able to perform both non-invasive geophysical imaging of the underground [2] and subsurface in situ measurements thanks to the Drill unit installed on the rover. The Drill has been developed by Leonardo and its purposes are 1) to collect core samples to be analyzed in the Analytical Laboratory Drawer (ALD) onboard the Rover and 2) to drive the miniaturized spectrometer Ma_MISS within the borehole.&#160;&#160;&#160; Ma_MISS (Mars Multispectral Imager for Subsurface Studies, [3]) will collect mineralogic measurements from the rocks exposed into the borehole created by the Drill with a spatial resolution of 120 &#956;m down to 2 meters into the Martian subsurface. Rocks are composed of grains of minerals, and their reaction to an applied stress is related to the mechanical behavior of the minerals that compose the rock itself. The mechanical properties of a mineral depend mainly on the strength of the chemical bonds, the orientation of crystals, and the number of impurities in the crystal lattice. In this context, the integration of Ma_MISS measurements and drill telemetry are of great importance.&#160; The mechanical properties of rocks coupled with their mineralogic composition provide a rich source of information to characterize the nature of rocks being explored by ExoMars rover&#8217;s drilling activity. Within our study, we are starting to collect telemetry recorded during the Drill unit tests on several samples ranging from sedimentary to volcanic rocks with varying degrees of weathering and water content.&#160; In this first phase of the study, we focused our attention on the variation of torque and penetration speed between different samples, which have been found to be indicative of a particular type of rock or group of rocks and their water content.&#160;&#160; We are planning to analyze the same rocks with the Ma_MISS breadboard creating the link between the mineralogy and the mechanical response of the Drill.&#160;&#160;&#160;&#160;&#160;&#160; This will put the base for a more comprehensive and rich characterization of the in situ subsurface observation by Rosalind Franklin planned at Oxia Planum, Mars in 2023.&#160; &#160; Acknowledgments: We thank the European Space Agency (ESA) for developing the ExoMars Project, ROSCOSMOS and Thales Alenia Space for rover development, and Italian Space Agency (ASI) for funding the Ma_MISS experiment (ASI-INAF contract n.2017-48-H.0 for ExoMars MA_MISS phase E/science). &#160; References [1] Vago et al., 2017. Astrobiology, 17 6-7. [2] Ciarletti et al., 2017. Astrobiology, 17 6-7. [3] De Sanctis et al., 2017. Astrobiology, 17 6-7.

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Simulated Doppler Radar Observations of Inhomogeneous Clouds: Application to the EarthCARE Space Mission

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2007jtecha956.1 ◽

2008 ◽

Vol 25 (1) ◽

pp. 26-42 ◽

Cited By ~ 17

Author(s):

N. A. J. Schutgens

Keyword(s):

Doppler Radar ◽

European Space Agency ◽

Space Mission ◽

Information And Communications Technology ◽

Line Of Sight ◽

Radar Observations ◽

Space Agency ◽

Along Track ◽

Japan Aerospace Exploration Agency ◽

Spaceborne Radar

Abstract A new simulation technique for spaceborne Doppler radar observations that was developed specifically for inhomogeneous targets is presented. Cloud inhomogeneity affects Doppler observations in two ways. First, line-of-sight velocities within the instantaneous field of view are unequally weighted. As the large forward motion of a spaceborne radar contributes to these line-of-sight velocities this causes biases in observed Doppler speeds. Second, receiver voltages now have time-varying stochastical properties, increasing the inaccuracy of Doppler observations. The new technique predicts larger inaccuracies of observed Doppler speeds than the traditional random signal simulations based on the inverse Fourier transform. The accuracy of Doppler speed observations by a spaceborne 95-GHz radar [as part of the proposed European Space Agency (ESA)/Japan Aerospace Exploration Agency (JAXA)/National Institute for Information and Communications Technology (NICT) EarthCARE mission] is assessed through simulations for realistic cloud scenes based on observations made by ground-based cloud-profiling radars. Close to lateral cloud boundary biases as large as several meters per second occur. For half of the cloud scenes investigated, the distribution of the in-cloud bias has an rms of 0.5 m s−1, implying that a bias in excess of 0.5 m s−1 will not be uncommon. An algorithm to correct the bias in observed Doppler observations, based on the observed gradient of reflectivity along track, is suggested and shown to be effective; that is, the aforementioned rms bias reduces to 0.14 m s−1.

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The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

Atmospheric Measurement Techniques ◽

10.5194/amt-11-409-2018 ◽

2018 ◽

Vol 11 (1) ◽

pp. 409-427 ◽

Cited By ~ 26

Author(s):

Diego G. Loyola ◽

Sebastián Gimeno García ◽

Ronny Lutz ◽

Athina Argyrouli ◽

Fabian Romahn ◽

...

Keyword(s):

Near Infrared ◽

European Space Agency ◽

Recognition Algorithm ◽

Ozone Monitoring Instrument ◽

Monitoring Instrument ◽

Cloud Parameters ◽

Cloud Properties ◽

Space Agency ◽

Retrieval Algorithms ◽

Ozone Monitoring

Abstract. This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor (S5P) mission scheduled for launch in 2017. Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks). OCRA retrieves the cloud fraction using TROPOMI measurements in the ultraviolet (UV) and visible (VIS) spectral regions, and ROCINN retrieves the cloud top height (pressure) and optical thickness (albedo) using TROPOMI measurements in and around the oxygen A-band in the near infrared (NIR). Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with the Global Ozone Monitoring Experiment (GOME) on board the second European Remote-Sensing Satellite (ERS-2) over 20 years ago. The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers), and we present here UPAS cloud results using the Ozone Monitoring Instrument (OMI) and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms, and we discuss the future validation needs for OCRA and ROCINN.

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Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-1101-2012 ◽

2012 ◽

Vol 5 (1) ◽

pp. 1101-1151 ◽

Cited By ~ 2

Author(s):

S. A. Buehler ◽

E. Defer ◽

F. Evans ◽

S. Eliasson ◽

J. Mendrok ◽

...

Keyword(s):

Spectral Range ◽

European Space Agency ◽

Data Retrieval ◽

Submillimeter Wave ◽

Radiative Properties ◽

Ice Clouds ◽

Space Agency ◽

Retrieval Algorithms ◽

Wave Sensors ◽

Cloud Ice

Abstract. Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP) and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8), which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms) and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

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The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

10.5194/amt-2017-128 ◽

2017 ◽

Cited By ~ 1

Author(s):

Diego G. Loyola ◽

Sebastián Gimeno García ◽

Ronny Lutz ◽

Fabian Romahn ◽

Robert J. D. Spurr ◽

...

Keyword(s):

European Space Agency ◽

Recognition Algorithm ◽

Trace Gas ◽

Infrared Sensors ◽

Cloud Parameters ◽

Cloud Properties ◽

Low Clouds ◽

Space Agency ◽

Retrieval Algorithms ◽

Data Record

Abstract. This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor (S5P) mission scheduled for launch in 2017. Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks). OCRA retrieves the cloud fraction using TROPOMI measurements in the UV/VIS spectral regions and ROCINN retrieves the cloud top height (pressure) and optical thickness (albedo) using TROPOMI measurements in and around the oxygen A-band in the NIR. Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals, but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with GOME/ERS-2 over twenty years ago. Use of the oxygen A-band generates complementary cloud information (especially for low clouds), as compared to traditional thermal infrared sensors (as used in most meteorological satellites) that are less sensitive to low clouds due to reduced thermal contrast. The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers), and we present here UPAS cloud results using OMI and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms and we discuss the future validation needs for OCRA and ROCINN.

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Characterization of dark current signal measurements of the ACCDs used on-board the Aeolus satellite

10.5194/amt-2020-458 ◽

2020 ◽

Cited By ~ 1

Author(s):

Fabian Weiler ◽

Thomas Kanitz ◽

Denny Wernham ◽

Michael Rennie ◽

Dorit Huber ◽

...

Keyword(s):

Dark Current ◽

European Space Agency ◽

Current Signal ◽

Wind Retrieval ◽

Root Cause ◽

Space Agency ◽

Correction Scheme ◽

Successful Launch ◽

Wind Measurements

Abstract. Already shortly after the successful launch of the European Space Agency satellite Aeolus in August 2018, it turned out that dark current signal anomalies of single pixels (so-called hot pixels) on the Accumulation-Charge-Coupled Devices (ACCDs) of the Aeolus detectors detrimentally impact the quality of the aerosol and wind products potentially leading to wind errors of up to 4 m/s. This paper provides a detailed characterization of the hot pixels which occurred during the first one and a half years in orbit. The hot pixels are classified according to their characteristics to discuss their impact on wind measurements. Furthermore, mitigation approaches for the wind retrieval are presented and potential root causes for the hot pixel occurrence are discussed. The analysis of the dark current signal anomalies reveals a large variety of anomalies ranging from pixels with Random Telegraph Signal (RTS)-like characteristics to pixels with sporadic shifts in the median dark current signal. Moreover, the results indicate that the number of hot pixels has almost linearly increased during the observing period between 2018-09-02 until 2020-05-20 with 6 % of the ACCD pixels affected in total at the end of the period leading to 9.5 % at the end of mission lifetime. This work introduces dedicated instrument calibration modes and ground processors which allowed for a correction shortly after a hot pixel occurrence. The achieved performance with this approach avoids risky adjustments to the inflight hardware operation. It is demonstrated that the success of the correction scheme varies depending on the characteristics of each hot pixel itself. With the herein presented categorization, it is shown that multi-level RTS pixels with high fluctuation are the biggest challenge for the hot pixel correction scheme. Despite a detailed analysis in this framework, no conclusion could be drawn about the root cause of the hot pixel issue.

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A new phase in the production of quality-controlled sea level data

10.5194/essd-2017-23 ◽

2017 ◽

Author(s):

Graham D. Quartly ◽

Jean-François Legeais ◽

Michaël Ablain ◽

Lionel Zawadzki ◽

M. Joana Fernandes ◽

...

Keyword(s):

Sea Level ◽

Ocean Circulation ◽

Climate Models ◽

European Space Agency ◽

Satellite Orbits ◽

Second Phase ◽

Regional Patterns ◽

Internal Climate Variability ◽

Space Agency ◽

Global Mean Sea Level

Abstract. Sea level is an Essential Climate Variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project merges data from 9 different altimeter missions in a clear and well-documented manner, selecting the most appropriate satellite orbits and geophyiscal corrections in order to reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset (DOI:10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. However, the overall result of these changes is that the rate of rise of global mean sea level still equates to ~3.2 mm yr−1 during 1992-2015.

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ATmospheric LIDar (ATLID): European Space Agency Instrument Ready to Measure Aerosols and Thin Clouds in Atmosphere

10.20944/preprints202012.0333.v1 ◽

2020 ◽

Author(s):

João Pereira do Carmo ◽

Geraud de Villele ◽

Kotska Wallace ◽

Alain Lefebvre ◽

Kaustav Ghose ◽

...

Keyword(s):

Rayleigh Scattering ◽

Performance Test ◽

European Space Agency ◽

Laser Pulses ◽

Backscatter Signal ◽

Space Agency ◽

Explorer Mission ◽

Thin Cloud ◽

Atmospheric Backscatter ◽

Along Track

ATLID (ATmospheric LIDar) is the atmospheric backscatter LIDAR (Light Detection and Ranging) on board of the EarthCARE (Earth Cloud, Aerosol and Radiation Explorer) mission, the sixth Earth Explorer Mission of the ESA (European Space Agency) Living Planet Programme [1-5]. ATLID’s purpose is to provide vertical profiles of optically thin cloud and aerosol layers, as well as the altitude of cloud boundaries [6-10]. In order to achieve this objective ATLID emits short duration laser pulses in the UV, at a repetition rate of 51 Hz, while pointing in a near nadir direction along track of the satellite trajectory. The atmospheric backscatter signal is then collected by its 620 mm aperture telescope, filtered through the optics of the instrument focal plane assembly, in order to separate and measure the atmospheric Mie and Rayleigh scattering signals. With the completion of the full instrument assembly in 2019, ATLID has been subjected to an ambient performance test campaign, followed by a successful environmental qualification test campaign, including performance calibration and characterization in thermal vacuum conditions. In this paper the design and operational principle of ATLID is recalled and the major performance test results are presented, addressing the main key receiver and emitter characteristics. Finally, the estimated instrument, in-orbit, flight predictions are presented; these indicate compliance of the ALTID instrument performance against its specification and that it will meet its mission science objectives for the EarthCARE mission, to be launched in 2023.

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A new phase in the production of quality-controlled sea level data

Earth System Science Data ◽

10.5194/essd-9-557-2017 ◽

2017 ◽

Vol 9 (2) ◽

pp. 557-572 ◽

Cited By ~ 33

Author(s):

Graham D. Quartly ◽

Jean-François Legeais ◽

Michaël Ablain ◽

Lionel Zawadzki ◽

M. Joana Fernandes ◽

...

Keyword(s):

Sea Level ◽

Ocean Circulation ◽

Climate Models ◽

European Space Agency ◽

Rate Of Change ◽

Satellite Orbits ◽

Second Phase ◽

Regional Patterns ◽

Internal Climate Variability ◽

Space Agency

Abstract. Sea level is an essential climate variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high-accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project (SL_cci) merges data from nine different altimeter missions in a clear, consistent and well-documented manner, selecting the most appropriate satellite orbits and geophysical corrections in order to further reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. The overall result of these changes is that the rate of rise of global mean sea level (GMSL) still equates to ∼ 3.2 mm yr−1 during 1992–2015, but there is now greater confidence in this result as the errors associated with several of the corrections have been reduced. Compared with v1.1 of the SL_cci dataset, the new rate of change is 0.2 mm yr−1 less during 1993 to 2001 and 0.2 mm yr−1 higher during 2002 to 2014. Application of new correction models brought a reduction of altimeter crossover variances for most corrections.

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ATmospheric LIDar (ATLID): Pre-Launch Testing and Calibration of the European Space Agency Instrument That Will Measure Aerosols and Thin Clouds in the Atmosphere

Atmosphere ◽

10.3390/atmos12010076 ◽

2021 ◽

Vol 12 (1) ◽

pp. 76

Author(s):

João Pereira do Carmo ◽

Geraud de Villele ◽

Kotska Wallace ◽

Alain Lefebvre ◽

Kaustav Ghose ◽

...

Keyword(s):

Rayleigh Scattering ◽

Performance Test ◽

European Space Agency ◽

Laser Pulses ◽

Backscatter Signal ◽

Space Agency ◽

Explorer Mission ◽

Thin Cloud ◽

Atmospheric Backscatter ◽

Along Track

ATLID (ATmospheric LIDar) is the atmospheric backscatter Light Detection and Ranging (LIDAR) instrument on board of the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) mission, the sixth Earth Explorer Mission of the European Space Agency (ESA) Living Planet Programme. ATLID’s purpose is to provide vertical profiles of optically thin cloud and aerosol layers, as well as the altitude of cloud boundaries, with a resolution of 100 m for altitudes of 0 to 20 km, and a resolution of 500 m for 20 km to 40 km. In order to achieve this objective ATLID emits short duration laser pulses in the ultraviolet, at a repetition rate of 51 Hz, while pointing in a near nadir direction along track of the satellite trajectory. The atmospheric backscatter signal is then collected by its 620 mm aperture telescope, filtered through the optics of the instrument focal plane assembly, in order to separate and measure the atmospheric Mie and Rayleigh scattering signals. With the completion of the full instrument assembly in 2019, ATLID has been subjected to an ambient performance test campaign, followed by a successful environmental qualification test campaign, including performance calibration and characterization in thermal vacuum conditions. In this paper the design and operational principle of ATLID is recalled and the major performance test results are presented, addressing the main key receiver and emitter characteristics. Finally, the estimated instrument, in-orbit, flight predictions are presented; these indicate compliance of the ALTID instrument performance against its specification and that it will meet its mission science objectives for the EarthCARE mission, to be launched in 2023.

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