Steven Dewitte

Steven Dewitte
Royal Meteorological Institute of Belgium · Observations

About

154
Publications
22,198
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,451
Citations
Citations since 2016
22 Research Items
939 Citations
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150

Publications

Publications (154)
Article
Full-text available
Wide field-of-view imaging optics offer a huge potential for space-based Earth observation enabling the capture of global data. Reflective imaging telescopes are often favored, as they do not show chromatic aberrations and are less susceptible to radiation darkening than their refractive counterparts. However, the main drawback of reflective telesc...
Article
Full-text available
We report on a near-infrared imaging spectrometer for sensing the three most prominent greenhouse gases in the atmosphere (water vapor, carbon dioxide and methane). The optical design of the spectrometer involves freeform optics, which enables achieving exceptional performance and allows progressing well beyond the state-of-the-art in terms of comp...
Article
Full-text available
Recent solar physics missions have shown the definite role of waves and magnetic fields deep in the inner corona, at the chromosphere-corona interface, where dramatic and physically dominant changes occur. HiRISE (High Resolution Imaging and Spectroscopy Explorer), the ambitious new generation ultra-high resolution, interferometric, and coronagraph...
Article
Full-text available
Total Solar Irradiance (TSI) quantifies the solar energy received by the Earth and therefore is of direct relevance for a possible solar influence on climate change on Earth. We analyse the TSI space measurements from 1991 to 2021, and we derive a regression model that reproduces the measured daily TSI variations with a Root Mean Square Error (RMSE...
Article
Full-text available
To improve precipitation estimation accuracy, new methods, which are able to merge different precipitation measurement modalities, are necessary. In this study, we propose a deep learning method to merge rain gauge measurements with a ground-based radar composite and thermal infrared satellite imagery. The proposed convolutional neural network, com...
Article
Full-text available
Artificial Intelligence (AI) is an explosively growing field of computer technology, which is expected to transform many aspects of our society in a profound way. AI techniques are used to analyse large amounts of unstructured and heterogeneous data and discover and exploit complex and intricate relations among these data, without recourse to an ex...
Article
Full-text available
The measurement of the Earth’s Outgoing Longwave Radiation plays a key role in climate change monitoring. This measurement requires a compact wide-field-of-view camera, covering the 8–14 µm wavelength range, which is not commercially available. Therefore, we present a novel thermal wide-field-of-view camera optimized for space applications, featuri...
Article
Full-text available
Geostationary observations offer the unique opportunity to resolve the diurnal cycle of the Earth's Radiation Budget at the top of the atmosphere (TOA), crucial for climate-change studies. However, a drawback of the continuous temporal coverage of the geostationary orbit is the fixed viewing geometry. As a consequence, imperfections in the angular...
Preprint
Full-text available
Geostationary observations offer the unique opportunity to resolve the diurnal cycle of the Earth's Radiation Budget at the top of the atmosphere (TOA), crucial for climate-change studies. However, a drawback of the continuous temporal coverage of the geostationary orbit is the fixed viewing geometry. As a consequence, imperfections in the angular...
Article
Full-text available
We report on the conceptual design of a new wide field-of-view shortwave camera, for measuring Earth’s reflected solar radiation. The camera comprises a commercial-off-the-shelf CMOS sensor, and a custom-designed wide field-of-view lens system with an opening angle of 140°. The estimated effective nadir resolution is 2.2 km. The simulated stand-alo...
Article
Full-text available
Climate on Earth is determined by the Earth Radiation Budget (ERB), which quantifies the incoming and outgoing radiative energy fluxes. The ERB can be monitored by non-scanning wide field-of-view radiometers, or by scanning narrow field-of-view radiometers. We propose an enhanced design for the wide field-of-view radiometer, with as key features th...
Article
Full-text available
This paper proposes a multimodal and multi-task deep-learning model for instantaneous precipitation rate estimation. Using both thermal infrared satellite radiometer and automatic rain gauge measurements as input, our encoder–decoder convolutional neural network performs a multiscale analysis of these two modalities to estimate simultaneously the r...
Article
Full-text available
Decadal changes of the Reflected Solar Radiation (RSR) as measured by CERES from 2000 to 2018 are analysed. For both polar regions, changes of the clear-sky RSR correlate well with changes of the Sea Ice Extent. In the Arctic, sea ice is clearly melting, and as a result the earth is becoming darker under clear-sky conditions. However, the correlati...
Article
Full-text available
The Earth Radiation Budget (ERB) at the top of the atmosphere quantifies how the earth gains energy from the sun and loses energy to space. Its monitoring is of fundamental importance for understanding ongoing climate change. In this paper, decadal changes of the Outgoing Longwave Radiation (OLR) as measured by the Clouds and Earth’s Radiant Energy...
Article
Full-text available
The Earth Radiation Budget at the top of the atmosphere quantifies how the Earth gains energy from the Sun and loses energy to space. It is of fundamental importance for climate and climate change. In this paper, the current state-of-the-art of the satellite measurements of the Earth Radiation Budget is reviewed. Combining all available measurement...
Article
We present the composite measurements of total solar irradiance (TSI) as measured by an ensemble of space instruments. The measurements of the individual instruments are put on a common absolute scale, and their quality is assessed by intercomparison. The composite time series is the average of all available measurements. From 1984 April to the pre...
Conference Paper
PICARD is a mission devoted to solar variability observation, through imagery and radiometric measurements, with the goal to provide data for scientific investigation first in the area of solar physics, and second in the assessment of the influence of the solar variability on the Earth climate variability. PICARD contains a double program with in-s...
Conference Paper
Full-text available
Within CM SAF, datasets of Top-Of-Atmosphere (TOA) radiation products from the Geostationary Earth Radiation Budget (GERB) instruments on the Meteosat Second Generation (MSG) satellites have been released in 2013. Since no GERB instrument was available on the Meteosat First Generation (MFG) satellites, only the period 2004-2011 is covered. As an al...
Article
Full-text available
The Bolometric Oscillation Sensor (BOS) is a broadband radiation measurement instrument onboard the PICARD satellite that was active between 2010 and 2014. The main detector is a thermistor attached black coated surface, which was permanently exposed to space without any optical and aperture accessories. The temperature measurements are used within...
Article
Full-text available
The Bolometric Oscillation Sensor (BOS) is a broadband radiation measurement instrument onboard the PICARD satellite that was active between 2010 and 2014. The main detector is a thermistor attached black coated surface, which was permanently exposed to space without any optical and aperture accessories. The temperature measurements are used within...
Article
Full-text available
The equator-to-pole radius difference (Δr=R eq−R pol) is a fundamental property of our star, and understanding it will enrich future solar and stellar dynamical models. The solar oblateness (Δ⊙) corresponds to the excess ratio of the equatorial solar radius (R eq) to the polar radius (R pol), which is of great interest for those working in relativi...
Article
Full-text available
The bolometric oscillation sensor (BOS) is a broadband radiation measurement instrument onboard the PICARD satellite that has been active between 2010 and 2014. The main detector is a thermistor attached black coated surface, which was permanently exposed to space without any optical and aperture accessories. The temperature measurements are used w...
Conference Paper
Full-text available
Since the launch of the first artificial satellite in 1957, more than 6,000 satellites have been sent into space. Despite technological advances, the space domain remains little accessible. However, with the miniaturization of electronic components, it has recently become possible to develop small satellites with which scientific goals can be addre...
Conference Paper
Full-text available
PICARD is an investigation dedicated to the simultaneous measurement of the absolute total and spectral solar irradiance, the diameter and solar shape, and to the Sun's interior probing by the helioseismology method. The spacecraft was successfully launched into a Sun-synchronous dawn-dusk orbit on 15 June 2010 by a DNEPR-1 launcher for a life expe...
Article
Full-text available
The Picard spacecraft was successfully launched on June 15, 2010, into a Sun synchronous orbit. The mission represents one of the European contributions to solar observations and Essential Climate Variables (ECVs) mea- surements. The payload is composed of a Solar Diameter Imager and Surface Mapper (SODISM) and two radiometers: SOlar VAriability Pi...
Article
Full-text available
The Meteosat satellites have been operational since the early eighties, creating so far a continuous time period of observations of more than 30 years. In order to use this data for climate data records, a consistent calibration is necessary between the consecutive instruments. Studies have shown that the Meteosat First Generation (MFG) satellites...
Article
Full-text available
We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was t...
Article
Since the early 1980s, the geostationary Meteosat instruments have been observing the earth at a high temporal and spatial resolution. The data record contains more than 30 years of observations and has become very useful for climate monitoring. With a compilation of 10 satellites, it is crucial to reach the highest possible consistency between the...
Conference Paper
Since 2004, accurate top-of-the-atmosphere (TOA) broadband reflected solar and emitted thermal fluxes are available from the Geostationary Earth Radiation Budget (GERB) instruments on board the Meteosat Second Generation satellites. In the EUMETSAT Climate Monitoring SAF, those data are used to estimate monthly and daily mean TOA radiation products...
Conference Paper
Full-text available
The Picard satellite was successfully launched in a 6-18 orbit on 15 June 2010. The Sovap Total Solar Irradiance (TSI) instrument started its measurements on 21 July 2010. From July to October 2010 Sovap made low exposure measurements in its nominal operation mode, roughly once per month. On 18 October the operation mode was changed. The right chan...
Conference Paper
Full-text available
The Earth Radiation Budget (ERB) and its geographical distribution is intimately linked with the earth’s climate and with the general circulation. We analyze 10 years of global Clouds and the Earth’s Radiant Energy System (CERES) measurements from 2000 to 2010 and 8 years of diurnally resolved Geostationary Earth Radiation Budget (GERB) from 2004 t...
Article
Full-text available
For more than 30 years, the Meteosat satellites have been in a geostationary orbit around the earth. Because of the high temporal frequency of the data and the long time period, this database is an excellent candidate for fundamental climate data records (FCDRs). One of the prerequisites to create FCDRs is an accurate and stable calibration over th...
Chapter
In order to understand and model the mechanisms that drive the changes observed in the Sun on several time scales, the PICARD mission will carry out several simultaneous measurements that include the total and spectral solar irradiance, solar diameter, limb shape and solar oscillations. The instruments consist of two radiometers, three four-channel...
Article
The Picard satellite was successfully launched in a 6-18 orbit on 15 June 2010. Our Sovap TSI instrument started its measurements on 21 July 2010. From July to October 2010 Sovap made low exposure measurements in its nominal operation mode, roughly once per month. On 18 October the operation mode was changed. The right channel has been opened perma...
Chapter
A near real-time assimilation and forecast system of aerosols has been developed by integration in the ECMWF IFS code within the GEMS project. The GEMS aerosol modeling system is novel as it is the first aerosol model fully coupled to a NWP model with data assimilation. Aerosol optical depth (AOD) data of the MODIS instrument on Terra and Aqua sate...
Article
Full-text available
A near real-time system for assimilation and forecasts of aerosols, greenhouse and trace gases, extending the ECMWF Integrated Forecasting System (IFS), has been developed in the framework of the Global and regional Earth-system Monitoring using Satellite and in-situ data (GEMS) project. The GEMS aerosol modeling system is novel as it is the first...
Article
PICARD is a scientific micro satellite (140 kg) developed and operated by CNES, with international partnerships; it was launched on June 15, 2010 and has been successfully operating since then. Its mission is devoted to sun variability observation, through imagery and radiometric measurements, with the goal to provide data for scientific investigat...
Article
Full-text available
The PICARD is a French CNES micro-satellite mission which was successfully launched on June 15, 2010 by the Russian DNEPR launcher. Its objectives are the study of the origin of the solar variability and the relations between the Sun and the Earth's climate. The duration of the mission is about two years with possibility to extend to three or more...
Article
PICARD is a scientific mission of the French space agency CNES. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. The payload was launched on 15 june 2010 in a Sun Synchronous Orbit at 725 km altitude. The mission life time is two years, however to be extended...
Article
Full-text available
Flares are powerful energy releases occurring in stellar atmospheres. Solar flares, the most intense energy bursts in the solar system, are however hardly noticeable in the total solar luminosity. Consequently, the total amount of energy they radiate 1) remains largely unknown and 2) has been overlooked as a potential contributor to variations in t...
Article
Current measurements from DIARAD/VIRGO, PMO6V/VIRGO and ACRIM3 radiometers are of the same order of magnitude, but differ from TIM/SORCE by about 4.5 W m À2 . This difference is higher than the sum of the claimed individual absolute uncertainties of the instruments. In this context, the SOLAR payload on the International Space Station embarks the S...
Article
PICARD mission is dedicated to the study of the solar activity origin using several key solar measurements. The project also includes development of the solar convective zone and climate models to evaluate the consequences for the Earth'climate of the solar activity. The measure-ments are the total and spectral solar irradiance, solar diameter, lim...
Article
Full-text available
The DynaMICCS mission is designed to probe and understand the dynamics of crucial regions of the Sun that determine solar variability, including the previously unexplored inner core, the radiative/convective zone interface layers, the photosphere/chromosphere layers and the low corona. The mission delivers data and knowledge that no other known mis...
Article
Whenever possible, intercomparisons of Earth radiation budget data from different spaceborne instruments should be made as they are important steps in the overall validation process. Intercomparisons are also key elements to compile long-term climate datasets by merging data from several instruments. In this study the GERB Edition-1 and CERES Editi...
Article
The Geostationary Earth Radiation Budget (GERB) instrument is the first to measure the earth radiation budget from a geostationary orbit. This allows a full sampling of the diurnal cycle of radiation and clouds – which is important for climate studies, as well as detailed process studies, e.g. the lifecycle of clouds or particular aerosol events su...
Article
Because space-borne radiometers do not measure the Earth’s outgoing fluxes directly, angular distribution models (ADMs) are required to relate actual radiance measurement to flux at given solar angle, satellite-viewing geometries, surface, and atmospheric conditions. The conversion of one footprint broad-band radiance into the corresponding flux re...
Article
During solar cycle 23, which is now close to its end, variations of the total solar irradiance were measured by six different instruments, providing four independent time series of the irradiance variation over the complete solar cycle. A new composite time series constructed using five of these six instruments provides unprecedented instrument sta...
Article
It is generally believed that the climate on earth is changing due to a radiation imbalance at the top of the atmosphere, resulting in a net heating of the earth. Until now it has not been possible to directly measure this net heating due to apparently unsurmountable calibration challenges. The small radiation imbalance is the difference between th...