Arno Keppens

Arno Keppens
Belgian Institute for Space Aeronomy | BIRA-IASB · Division of Atmospheric Composition

MSc, PhD

About

77
Publications
22,964
Reads
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939
Citations
Citations since 2017
31 Research Items
650 Citations
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2017201820192020202120222023020406080100120140
2017201820192020202120222023020406080100120140
2017201820192020202120222023020406080100120140
Additional affiliations
January 2012 - present
Belgian Institute for Space Aeronomy
Position
  • Researcher
February 2011 - December 2011
KU Leuven
Position
  • Research Associate
November 2010 - January 2011
National Institute of Standards and Technology
Position
  • Guest Researcher
Education
October 2008 - June 2009
Ghent University
Field of study
  • Philosophy of Science
October 2006 - June 2009
Ghent University
Field of study
  • Academic Specific Teacher Training (AILO)
October 2002 - June 2006
Ghent University
Field of study
  • Physics

Publications

Publications (77)
Article
Full-text available
A method is developed that removes a priori information from remotely sensed atmospheric state profiles. This consists of a Wiener deconvolution, whereby the required cost function is obtained from the complete data fusion framework. Asserting that the deconvoluted averaging kernel matrix has to equal the unit matrix, results in an iterative proces...
Article
Full-text available
Ozone in the troposphere affects humans and ecosystems as a pollutant and as a greenhouse gas. Observing, understanding and modelling this dual role, as well as monitoring effects of international regulations on air quality and climate change, however, challenge measurement systems to operate at opposite ends of the spatio-temporal scale ladder. Ab...
Article
Full-text available
Accurate knowledge of cloud properties is essential to the measurement of atmospheric composition from space. In this work we assess the quality of the cloud data from three Copernicus Sentinel-5 Precursor (S5P) TROPOMI cloud products: (i) S5P OCRA/ROCINN_CAL (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks;...
Article
Full-text available
Remote sensing of the atmospheric composition from current and future satellites, such as the Sentinel missions of the Copernicus programme, yields an unprecedented amount of data to monitor air quality, ozone, UV radiation and other climate variables. Hence, full exploitation of the growing wealth of information delivered by spaceborne observing s...
Conference Paper
MIPAS is a Fourier Transform interferometer that measured the atmospheric emission at limb in the middle infrared on board the ENVISAT satellite. These measurements allowed the global monitoring of the three-dimensional (latitude, longitude and altitude) distribution of concentrations of many species, during both day and night, for 10 years, from J...
Article
Full-text available
Remote sensing of atmospheric state variables typically relies on the inverse solution of the radiative transfer equation. An adequately characterized retrieval provides information on the uncertainties of the estimated state variables as well as on how any constraint or a priori assumption affects the estimate. Reported characterization data shoul...
Article
Full-text available
The QA4ECV (Quality Assurance for Essential Climate Variables) version 1.1 stratospheric and tropospheric NO2 vertical column density (VCD) climate data records (CDRs) from the OMI (Ozone Monitoring Instrument) satellite sensor are validated using NDACC (Network for the Detection of Atmospheric Composition Change) zenith-scattered light differentia...
Preprint
Full-text available
Ozone in the troposphere affects humans and ecosystems as a pollutant and as a greenhouse gas. Observing, understanding and modelling this dual role, as well as monitoring effects of international regulations on air quality and climate change, however, challenge measurement systems to operate at opposite ends of the spatio-temporal scale ladder. On...
Preprint
Full-text available
Accurate knowledge of cloud properties is essential to the measurement of atmospheric composition from space. In this work we assess the quality of the cloud data derived from Copernicus Sentinel-5 Precursor (S5P) TROPOMI radiance measurements: cloud top height and cloud optical thickness (retrieved with the S5P OCRA/ROCINN_CAL algorithm), cloud he...
Article
Full-text available
AURORA (Advanced Ultraviolet Radiation and Ozone Retrieval for Applications) is a three-year project supported by the European Union in the frame of its H2020 Call (EO-2-2015) for “Stimulating wider research use of Copernicus Sentinel Data”. The project addresses key scientific issues relevant for synergistic exploitation of data acquired in differ...
Preprint
Full-text available
Abstract. The QA4ECV version 1.1 stratospheric and tropospheric NO<sub>2</sub> vertical column density (VCD) climate data records (CDR) from the satellite sensor OMI are validated, using NDACC zenith scattered light DOAS (ZSL-DOAS) and Multi Axis-DOAS (MAX-DOAS) data as a reference. The QA4ECV OMI stratospheric VCD have a small bias of ~ 0.2 Pmolec...
Preprint
Full-text available
Remote sensing of atmospheric state variables typically relies on the inverse solution of the radiative transfer equation. An adequately characterized retrieval provides information on the uncertainties of the estimated state variables as well as on how any constraint or a priori assumption affects the estimate. Reported characterization data shoul...
Article
Full-text available
In October 2017, the Sentinel-5 Precursor (S5P) mission was launched, carrying the TROPOspheric Monitoring Instrument (TROPOMI), which provides a daily global coverage at a spatial resolution as high as 7 km × 3.5 km and is expected to extend the European atmospheric composition record initiated with GOME/ERS-2 in 1995, enhancing our scientific kno...
Article
Full-text available
Many applications of atmospheric composition and climate data involve the comparison or combination of vertically resolved atmospheric state variables. Calculating differences and combining data require harmonization of data representations in terms of physical quantities and vertical sampling at least. If one or both datasets result from a retriev...
Article
Full-text available
In October 2017, the Sentinel-5 Precursor (S5p) mission was launched, carrying the TROPOspheric Monitoring Instrument, TROPOMI, which provides a daily global coverage at a spatial resolution as high as 7 km × 3.5 km and is expected to extend the European atmospheric composition record initiated with GOME/ERS-2 in 1995, bringing up significant new c...
Article
Full-text available
Many applications of atmospheric composition and climate data involve the comparison or combination of vertically resolved atmospheric state variables. Calculating differences and combining data require harmonization of data representations in terms of physical quantities and vertical sampling at least. If one or both datasets result from a retriev...
Conference Paper
Full-text available
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The analysis of MIPAS measurements allows to study the temporal evolution of numerous species of interest for the study of the ozone in the stratosphere, pollu...
Article
Full-text available
With the launch of the Sentinel-5 Precursor (S-5P, lifted-off on 13 October 2017), Sentinel-4 (S-4) and Sentinel-5 (S-5)(from 2021 and 2023 onwards, respectively) operational missions of the ESA/EU Copernicus program, a massive amount of atmospheric composition data with unprecedented quality will become available from geostationary (GEO) and low E...
Conference Paper
Full-text available
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The maintenance and the upgrade of both L1 and L2 ESA processors are accomplished in the frame of the Quality Working Group, where a fruitful collaboration amo...
Article
Full-text available
This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and...
Article
Full-text available
Atmospheric ozone plays a key role in air quality and the radiation budget of the Earth, both directly and through its chemical influence on other trace gases. Assessments of the atmospheric ozone distribution and associated climate change therefore demand accurate vertically resolved ozone observations with both stratospheric and tropospheric sens...
Technical Report
This document describes the methodology adopted in the C3S_312a_Lot4 – Ozone procurement service for the quality assurance of the C3S ozone CDRs, with details on the ground-based measurements used as a reference for satellite validation, the specific technical solutions implemented to enable level-3 and level-4 data comparisons, and the metrics dev...
Article
Full-text available
The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) is a level-3 data record, which combines individual sensor products into one single cohesive record covering the 22-year period from 1995 to 2016, generated in the frame of the European Space Agency's Climate Change Initiative Phase II. It is based on level-2 total ozone data produced b...
Article
Full-text available
This paper assesses the quality of IASI/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3) v20151001 software for nine years (2008–2017) through an extensive inter-comparison and validation exercise using independent observation...
Article
Full-text available
Atmospheric ozone plays a key role in air quality and the radiation budget of the Earth, both directly and through its chemical influence on other trace gases. Assessments of the atmospheric ozone distribution and associated climate change therefore demand accurate vertically-resolved ozone observations with both stratospheric and tropospheric sens...
Article
Full-text available
The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) is a Level-3 data record, which combines individual sensor products into one single cohesive record covering the 22 year period from 1995 to 2017, generated in the frame of the European Space Agency's Climate Change Initiative Phase-II. It is based on Level-2 total ozone data produced b...
Conference Paper
Full-text available
MIPAS on ENVISAT performed almost continuous measurements of atmospheric composition from June 2002 to April 2012. ESA Level 2 processor, based on the Optimized Retrieval Model (ORM), originally designed for the Near Real Time analysis and developed by an European Consortium led by IFAC, is currently refined and used for the reanalysis of the full...
Technical Report
Can be downloaded at https://cds.climate.copernicus.eu/cdsapp#!/dataset/ozone-monthly-gridded-data-from-1970-to-present?tab=doc
Technical Report
This document describes the methodology adopted in the C3S_312a_Lot4 – Ozone procurement service for the quality assurance of the C3S ozone CDRs, with details on the ground-based measurements used as a reference for satellite validation, the specific technical solutions implemented to enable level-3 and level-4 data comparisons, and the metrics dev...
Technical Report
Full-text available
Available at https://earth.esa.int/documents/700255/2683862/TN-BIRA-IASB-MultiTASTE-Phase-F-SCIA-SGP6-Iss1-RevB.pdf
Presentation
Full-text available
While it has become evident that the ozone trend has changed sign around the mid-1990s, the debate is still open as to how uncertain the profile trend estimates are. There is currently no community-wide consensus whether there is statistically significant observational evidence for the recovery of stratospheric ozone. As a step forward, we review t...
Technical Report
Full-text available
Available at https://earth.esa.int/documents/700255/2621625/TN-BIRA-IASB-MultiTASTE-Phase-F-MIPAS-ML2PP7-Iss1-RevB
Article
Full-text available
The ozone profile records of a large number of limb and occultation satellite instruments are widely used to address several key questions in ozone research. Further progress in some domains depends on a more detailed understanding of these data sets, especially of their long-term stability and their mutual consistency. To this end, we made a syste...
Conference Paper
Full-text available
Atmospheric ozone is an Essential Climate Variable which impacts the radiation budget of the Earth, interacts with atmospheric dynamics and climate, and influences chemically other radiatively active species. As part of the Ozone Climate Change Initiative (Ozone_cci) project, a large number of ozone data sets have been generated from a full suite o...
Conference Paper
Full-text available
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ESA's ENVISAT satellite performed almost continuous measurements of the global atmospheric composition for approximately 10 years, from July 2002 to April 2012. The operational ESA data retrieval processor, based on the algorithm ORM (Optimized Retrieval Model), originally des...
Technical Report
Full-text available
Available at https://earth.esa.int/documents/700255/708299/TN-BIRA-IASB-MultiTASTE-Phase-F-VR1-Iss2-RevA.pdf
Article
Full-text available
The ozone profile records of a large number of limb and occultation satellite instruments are widely used to address several key questions in ozone research. Further progress in some domains depends on a more detailed understanding of these data sets, especially of their long-term stability and their mutual consistency. To this end, we make a syste...
Article
The MIPAS spectrometer onboard the Envisat platform observed infrared emission from the Earth's limb between 2002 and 2012. It recorded high-resolution spectra during day and night, from pole to pole and between 6 and 70 km altitude in the nominal measurement mode or up to 170 km in special measurement modes, producing daily more than 1000 vertical...
Article
Full-text available
A methodology for the round-robin evaluation and the geophysical validation of ozone profile data retrieved from nadir UV backscatter satellite measurements is detailed and discussed, consisting of data set content studies, information content studies, co-location studies, and comparisons with reference measurements. Within the European Space Agenc...
Article
Full-text available
Daily global analyses and 5-day forecasts are generated in the context of the European Monitoring Atmospheric Composition and Climate (MACC) project using an extended version of the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The IFS now includes modules for chemistry, deposition and emissi...
Preprint
Full-text available
Daily global analyses and 5 day forecasts are generated in the context of the European Monitoring Atmospheric Composition and Climate (MACC) project using an extended version of the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). IFS now includes modules for chemistry, deposition and emission o...
Article
Full-text available
A methodology for the round-robin evaluation and geophysical validation of ozone profile data retrieved from nadir UV backscatter satellite measurements is detailed and discussed, consisting of dataset content studies, information content studies, co-location studies, and comparisons with reference measurements. Within ESA's Climate Change Initiati...
Article
Full-text available
The electrical-thermal-optical characteristics of AlGaInP yellow and InGaN/GaN blue LEDs under electrical stresses were studied. Since the increase of effective acceptor concentration on p-type side, the forward voltages of AlGaInP decrease after 3155 h aging. And the operating voltage of high forward bias expansion for InGaN/GaN is due to the incr...
Presentation
Over the past 30 years various space-based limb-looking instruments have recorded complementary data on the distribution of ozone in the Earth’s atmosphere. The synergistic use of those data records will improve, on the global scale and in the long term, our understanding of interactions between changes in ozone, ultraviolet radiation and climate....
Conference Paper
Full-text available
Various international initiatives intend to build a merged data record on the vertical profile of ozone, an Essential Climate Variable, which should allow the study of processes on the long term and at the global scale. With its three atmospheric limb profilers, Envisat adds significantly to the pseudo-global ozone profile monitoring initiated sinc...
Conference Paper
Full-text available
The relative spectral radiant flux error caused by phosphor fluorescence during integrating sphere measurements is investigated both theoretically and experimentally. Integrating sphere and goniophotometer measurements are compared and used for model validation, while a case study provides additional clarification. Criteria for reducing fluorescenc...