The OMI instrument is an ultraviolet-visible imaging spectrograph that uses two-dimensional CCD detectors to register both the spectrum and the swath perpendicular to the flight direction with a 115° wide swath, which enables global daily ground coverage with high spatial resolution. This paper presents a number of examples of scientific results from the first two years in orbit, as well as a selection of in-flight radiometric, spectral and CCD detector performance and calibration results. The scientific results will show the OMI capability of measuring atmospheric phenomena with high spatial and temporal resolution. It will be shown that the OMI radiometric and spectral calibration are accurately understood. Radiation damage effects on the CCD detectors will be discussed in detail and it will be shown that it is possible to correct for the consequences to a large extent in order to minimise the impact on the scientific level-1 and level-2 data products.
We present SPEX, the Spectropolarimeter for Planetary Exploration, which is a compact, robust and low-mass spectropolarimeter designed to operate from an orbiting or in situ platform. Its purpose is to simultaneously measure the radiance and the state (degree and angle) of linear polarization of sunlight that has been scattered in a planetary atmosphere and/or reflected by a planetary surface with high accuracy. The degree of linear polarization is extremely sensitive to the microphysical properties of atmospheric or surface particles (such as size, shape, and composition), and to the vertical distribution of atmospheric particles, such as cloud top altitudes. Measurements as those performed by SPEX are therefore crucial and often the only tool for disentangling the many parameters that describe planetary atmospheres and surfaces. SPEX uses a novel, passive method for its radiance and polarization observations that is based on a carefully selected combination of polarization optics. This method, called spectral modulation, is the modulation of the radiance spectrum in both amplitude and phase by the degree and angle of linear polarization, respectively. The polarization optics consists of an achromatic quarter-wave retarder, an athermal multiple-order retarder, and a polarizing beam splitter. We will show first results obtained with the recently developed prototype of the SPEX instrument, and present a performance analysis based on a dedicated vector radiative transport model together with a recently developed SPEX instrument simulator.
TROPOMI, the Tropospheric Monitoring Instrument, is a passive UV-VIS-NIR-SWIR trace gas spectrograph in the line of SCIAMACHY (2002) and OMI (2004), instruments with the Netherlands in a leading role. Both instruments are very successful and remained operational long after their nominal life time.
TROPOMI is the next step, scheduled for launch in 2015. It combines the broad wavelength range from SCIAMACHY from UV to SWIR and the broad viewing angle push-broom concept from OMI, which makes daily global coverage in combination with good spatial resolution possible. Using spectral bands from 270-500nm (UV-VIS) 675-775nm (NIR) and 2305-2385nm (SWIR) at moderate resolution (0.25 to 0.6nm) TROPOMI will measure O3, NO2, SO2, BrO, HCHO and H2O tropospheric columns from the UV-VIS-NIR wavelength range and CO and CH4 tropospheric columns from the SWIR wavelength range. Cloud information will be derived primarily from the O2A band in the NIR. This will help, together with the aerosol information, in constraining the light path of backscattered solar radiation. Methane (CH4), CO2 and Carbon monoxide (CO) are the key gases of the global carbon cycle. Of these, Methane is by far the least understood in terms of its sources and is most difficult to predict its future trend. Global space observations are needed to inform atmospheric models. The SWIR channel of TROPOMI is designed to achieve the spectral, spatial and SNR resolution required for this task.
TROPOMI will yield an improved accuracy of the tropospheric products compared to the instruments currently in orbit. TROPOMI will take a major step forward in spatial resolution and sensitivity. The nominal observations are at 7 x 7 km2 at nadir and the signal-to-noises are sufficient for trace gas retrieval even at very low albedos (down to 2%). This spatial resolution allows observation of air quality at sub-city level and the high signal-to-noises means that the instrument can perform useful measurements in the darkest conditions.
TROPOMI is currently in its detailed design phase. This paper gives an overview of the challenges and current performances. From unit level engineering models first results are becoming available. Early results are promising and this paper discusses some of these early H/W results.
TROPOMI is the single payload on the Sentinel-5 precursor mission which is a joint initiative of the European Community (EC) and of the European Space Agency (ESA). The 2015 launch intends to bridge the data stream from OMI / SCIAMACHY and the upcoming Sentinel 5 mission. The instrument is funded jointly by the Netherlands Space Office and by ESA. Dutch Space is the instrument prime contractor. SSTL in the UK is developing the SWIR module with a significant contribution from SRON. Dutch Space and TNO are working as an integrated team for the UVN module. KNMI and SRON are responsible for ensuring the scientific capabilities of the instrument.
KEYWORDS: Sensors, Short wave infrared radiation, Spectroscopy, Space telescopes, Telescopes, Astronomical imaging, Calibration, Electronics, Near infrared, Space operations
The Tropospheric Monitoring Instrument TROPOMI is ready for system level verification. All sub-units have been integrated and tested and final integration at Dutch Space in Leiden has been completed. The instrument will be subjected to a testing and calibration program and is expected to be ready for delivery to the spacecraft early 2015. Using TROPOMI measurements, scientists will be able to improve and continue the study of the Earth’s atmosphere and to monitor air quality, on both global and local scale.
The TROPospheric Monitoring Instrument (TROPOMI) is a sun-backscatter imaging spectrometer. It is the single instrument on board ESA’s Copernicus Sentinel-5P satellite, which is now planned for launched in early 2017.
TROPOMI is the single instrument on ESA’s Sentinel 5 precursor satellite to be launched in October 2016. TROPOMI will measure the atmospheric constituents absorbing in the UV-SWIR wavelength range, being O3, NO2, SO2, CH4, CO, CH2O, and aerosol properties. TROPOMI is a sun back-scatter instrument in the line of SCIAMACHY and OMI with 4 spectrometer bands and a spectral resolution of 0.25 – 0.5 nm. Following the earlier sensors, firstly the spatial resolution is improved by a factor 6 (OMI) to 7 x 7 km2 and at the same time the sensitivity by an order of magnitude.
The paper discusses the instrument performances as acquired from on-ground performance / calibration measurements. For the calibration an extremely condensed measurement campaign of 4 months 24/7 measurements was performed with virtually no slack and still gathering all of the data necessary from on-ground measurements. Given the fact that the trace gas signals and their variation in the measured spectra can be quite small, calibration is crucial to get accurate results and this illustrates that TROPOMI is a highly success driven and efficient programme.
TROPOMI / Sentinel-5p bridges the data streams from on one hand OMI and SCIAMACHY and on the other hand the future Sentinel-5. It is the first of a series of satellites from the Copernicus programme devoted to air quality and will soon be ready for use.
The TROPOMI Earth-observing instrument is the single payload on board ESA's Sentinel-5 Precursor mission. It is the
successor of the Sciamachy instrument (ESA ENVISAT) and the OMI instrument (NASA EOS/Aura), and combines and
improves the best of both instruments. TROPOMI copies the push broom observation geometry of OMI allowing for
daily global coverage due to its instantaneous field of view of 108 degrees, or 2600 km swath on ground. From
Sciamachy the 2305 - 2385 nm Short-Wave Infra-Red (SWIR) observational band is copied with which methane and
carbon monoxide are observed.
This paper reports on the development of the SWIR detector module and the detailed characterization of the 1000x256
SWIR Saturn detector array produced by Sofradir (F) as measured with the SRON-developed Front-End Electronics. The
detailed characterization comprises not only the regular properties such as dark current, noise and photo-response, but
also more complex characteristics including non-linearity and memory. Characterization of the detection module was
performed for all operational parameters: detector temperature (135 - 145 K), bias voltage and integration time. Thanks
to the detector-characterization program, the operational clocking of the detector could be optimized, resulting in
significantly improved performance.
The Tropospheric Monitoring Instrument, TROPOMI, is a passive UV-VIS-NIR-SWIR spectrograph, which uses sun
backscattered radiation to study the Earth's atmosphere and to monitor air quality, on both global and local scale. It
follows in the line of SCIAMACHY (2002) and OMI (2004), both of which have been very successful. OMI is still
operational. TROPOMI is scheduled for launch in 2015. Compared with its predecessors, TROPOMI will take a major
step forward in spatial resolution and sensitivity. The nominal observations are at 7 x 7 km2 at nadir and the signal-tonoises
are sufficient for trace gas retrieval even at very low albedos (2 to 5%). This allows observations of air quality at
sub-city level. TROPOMI has reached CDR status and production of flight model units has started. Flight detectors have
been produced and detector electronics is expected to be finished by mid-2013. The instrument control unit is undergoing
extensive tests, to ensure full instrument functionality. Early results are promising and this paper discusses these H/W
results, as well as some challenges encountered during the development of the instrument.
The Tropospheric Monitoring Instrument (TROPOMI) is being developed for launch in 2014 on ESAs Sentinel 5
Precursor satellite. TROPOMI is a passive sun backscatter spectrograph using the ultraviolet-to-SWIR wavelengths to
have good sensitivity down to the surface. Together with its spatial resolution of 7 x 7 km2 it allows good observations
of sources and sinks of air quality and climate related gases and aerosols. This spatial resolution results in a high
fraction of cloud-free observations and is combined with a wide cross-flight swath to allow daily coverage of the
complete Earth.
The instrument has as predecessors the OMI instrument (Ozone Monitoring Instrument) on NASAs AURA satellite and
the SCIAMACHY instrument on ESAs ENVISAT, where the push broom concept is derived from OMI and the SWIR
observations from SCIAMACHY.
The wavelength bands of TROPOMI are a UV band (270 - 320 nm) for the ozone profile and SO2 products, a UVIS
band (320 - 500 nm) for O3, NO2, BrO, HCHO and OClO total columns, a NIR band (675 - 775 nm) for clouds and H2O
columns and a SWIR band (2305 - 2385 nm) for CH4 and CO columns and the HDO/H2O ratio.
The paper will give an overview of the challenges and current performances.
The TROPOMI UVN module is funded by the Netherlands and the SWIR module and platform is provided via ESA.
The instrument development is now a truly European programme with contributions from several countries.
SPEX (Spectropolarimeter for Planetary Exploration) was developed in close cooperation between scientific institutes
and space technological industries in the Netherlands. It is used for measuring microphysical properties of aerosols and
cloud particles in planetary atmospheres. SPEX utilizes a number of novel ideas. The key feature is that full linear
spectropolarimetry can be performed without the use of moving parts, using an instrument of approximately 1 liter in
volume. This is done by encoding the degree and angle of linear polarization (DoLP and AoLP) of the incoming light in
a sinusoidal modulation of the intensity spectrum.
Based on this principle, and after gaining experience from breadboard measurements using the same principle, a fully
functional prototype was constructed. The functionality and the performance of the prototype were shown by extensive
testing. The simulated results and the laboratory measurements show striking agreement.
SPEX would be a valuable addition to any mission that aims to study the composition and structure of planetary
atmospheres, for example, missions to Mars, Venus, Jupiter, Saturn and Titan. In addition, on an Earth-orbiting satellite,
SPEX could give unique information on particles in our own atmosphere.
We present the Spectropolarimeter for Planetary EXploration (SPEX), a high-accuracy linear spectropolarimeter
measuring from 400 to 800 nm (with 2 nm intensity resolution), that is compact (~ 1 liter), robust and
lightweight. This is achieved by employing the unconventional spectral polarization modulation technique, optimized
for linear polarimetry. The polarization modulator consists of an achromatic quarter-wave retarder and
a multiple-order retarder, followed by a polarizing beamsplitter, such that the incoming polarization state is
encoded as a sinusoidal modulation in the intensity spectrum, where the amplitude scales with the degree of
linear polarization, and the phase is determined by the angle of linear polarization. An optimized combination
of birefringent crystals creates an athermal multiple-order retarder, with a uniform retardance across the field
of view. Based on these specifications, SPEX is an ideal, passive remote sensing instrument for characterizing
planetary atmospheres from an orbiting, air-borne or ground-based platform. By measuring the intensity and
polarization spectra of sunlight that is scattered in the planetary atmosphere as a function of the single scattering
angle, aerosol microphysical properties (size, shape, composition), vertical distribution and optical thickness can
be derived. Such information is essential to fully understand the climate of a planet. A functional SPEX prototype
has been developed and calibrated, showing excellent agreement with end-to-end performance simulations.
Calibration tests show that the precision of the polarization measurements is at least 2 • 10-4. We performed
multi-angle spectropolarimetric measurements of the Earth's atmosphere from the ground in conjunction with
one of AERONET's sun photometers. Several applications exist for SPEX throughout the solar system, a.o. in
orbit around Mars, Jupiter and the Earth, and SPEX can also be part of a ground-based aerosol monitoring
network.
SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact instrument for spectropolarimetry,
and in particular for detecting and characterizing aerosols in planetary atmospheres. With its ~1-liter volume
it is capable of full linear spectropolarimetry, without moving parts. The degree and angle of linear polarization
of the incoming light is encoded in a sinusoidal modulation of the intensity spectrum by an achromatic
quarter-wave retarder, an athermal multiple-order retarder and a polarizing beam-splitter in the entrance pupil.
A single intensity spectrum thus provides the spectral dependence of the degree and angle of linear polarization.
Polarimetry has proven to be an excellent tool to study microphysical properties (size, shape, composition) of
atmospheric particles. Such information is essential to better understand the weather and climate of a planet.
The current design of SPEX is tailored to study Martian dust and ice clouds from an orbiting platform: a compact
module with 9 entrance pupils to simultaneously measure intensity spectra from 400 to 800 nm, in different
directions along the flight direction (including two limb viewing directions). This way, both the intensity and
polarization scattering phase functions of dust and cloud particles within a ground pixel are sampled while flying
over it. We describe the optical and mechanical design of SPEX, and present performance simulations and initial
breadboard measurements. Several flight opportunities exist for SPEX throughout the solar system: in orbit
around Mars, Jupiter and its moons, Saturn and Titan, and the Earth.
The Tropospheric Monitoring Instrument (TROPOMI) is currently planned for launch on ESA's Sentinel 5 precursor
satellite in the time frame of 2014. TROPOMI is an ultraviolet-to-SWIR wavelengths imaging spectrograph that uses
two-dimensional detectors to register both the spectrum and the swath perpendicular to the flight direction. The swath is
about 110 degrees wide to allow daily global coverage from the polar orbit of the Sentinel 5 precursor satellite. The
instrument follows the heritage of SCIAMACHY (ENVISAT, launch 2002) and OMI (AURA, launch 2004), but it has
been improved in several ways: the ground resolution is down to 7 x 7 km2, the instrument is fit for low albedo scenes
and the wavelength bands are optimized using the SCIAMACHY and OMI heritages to have the best trace gas products.
The first two improvements basically mean that the instrument aperture is much larger for TROPOMI and, related to
this, the reading of the detectors much faster. The selected wavelength bands for TROPOMI are UV1 (270-310 nm),
UV2 (310 - 370 nm), VIS (370 - 500 nm), NIR (675 - 775 nm) and SWIR (2305 - 2385 nm). The first three bands are
very similar to the OMI bands, the NIR has been added to improve on clouds and air mass corrections and the SWIR
allows measuring CH4 and CO. The paper discusses the development status on several topics, such as detector selection
and polarization scrambler performance simulations using the TIDE grid based level 2 scene simulator.
The TROPOspheric Monitoring Instrument (TROPOMI) is a UV/VIS/NIR/SWIR non-scanning nadir viewing imaging
spectrometer that combines a wide swath (110°) with high spatial resolution (8 x 8 km). Its main heritages are from the
Ozone Monitoring Instrument (OMI) and from SCIAMACHY. Since its launch in 2004 OMI has been providing, on a
daily basis and on a global scale, a wealth of data on ozone, NO2 and minor trace gases, aerosols and local pollution, a
scanning spectrometer launched in 2004. The TROPOMI UV/VIS/NIR and SWIR heritage is a combination of OMI and
SCIAMACHY.
In the framework of development programs for a follow-up mission for the successful Ozone Monitoring Instrument, we
have developed the so-called TROPOMI Integrated Development Environment. This is a GRID based software
simulation tool for OMI follow-up missions. It includes scene generation, an instrument simulator, a level 0-1b
processing chain, as well as several level 1b-2 processing chains. In addition it contains an error-analyzer, i.e. a tool to
feedback the level 2 results to the input of the scene generator.
The paper gives a description of the TROPOMI instrument and focuses on design aspects as well as on the performance,
as tested in the end-to-end development environment TIDE.
Robert Voors, David Donovan, Juan Acarreta, Michael Eisinger, Raffaella Franco, Dulce Lajas, Ricardo Moyano, Fabrizio Pirondini, Jose Ramos, Tobias Wehr
In 2013 an important ESA Core Explorer Mission, EarthCARE is scheduled to be launched. EarthCARE,
(the Earth, Clouds, Aerosol and Radiation Explorer) will comprise two active (a cloud-profiling radar (CPR)
and an high spectral resolution atmospheric lidar (ATLID)) and two passive (a Multi-spectral imager (MSI)
and a Broad-Band Radiometer (BBR)) instruments. With these, EarthCARE will enable cloud and aerosol
properties retrievals consistent with a Top-of-Atmospheric (TOA) flux accuracy of 10 Wm-2. This will be
achieved by simultaneously probing the atmosphere vertically with the active instruments in synergy with the
passive instruments.
In order to facilitate and optimize algorithm development and to quantify the effect of different instrument
configurations on the mission performance a simulator for EarthCARE (ECSIM) has been developed. ECSIM
relies strongly upon a previous prototype developed by ESA/KNMI where a combination of forward and retrieval
models (full End-to-End capabilities) have been included. In order to make this tool more useful within the
scientific and engineering communities, the prototype simulator has been embedded into a completely reorganized
architecture intended to improve a number of aspects:
*Complex algorithms have been enclosed within logical entities: models.
*Models are connected in a logical sequence with well-defined interfaces.
*Users can customize almost every mode's parameter values using configuration XML files.
*Model outputs are well documented and stored in easy to access NetCDF files.
*Complex simulations can be built up with a few mouse clicks.
*Users can run lengthy simulations automatically iterating through different parameter values.
*ECSIM can intercept and classify information and error messages from the simulations.
*A database is maintained with all the information generated by the system.
*It is possible to add third-party algorithms or tools to convert, analyze and visualize data extracted from generated products.
In-flight performance and calibration results of the Ozone Monitoring Instrument OMI, successfully launched on 15 July
2004 on the EOS-AURA satellite, are presented and discussed. The radiometric calibration in comparison to the high-resolution
solar irradiance spectrum from the literature convolved with the measured spectral slit function is presented. A
correction algorithm for spectral shifts originating from inhomogeneous ground scenes (e.g. clouds) is discussed.
Radiometric features originating from the on-board reflection diffusers are discussed, as well as the accuracy of the
calibration of the instrument's viewing properties. It is shown that the in-flight performance of both CCD detectors shows
evidence of particle hits by trapped high-energetic protons, which results in increased dark currents and increase in the
Random Telegraph Signal (RTS) behaviour.
In July 2004 Nasa's AURA satellite was launched carrying the Dutch-Finnish Ozone Monitoring Instrument and since then it is producing high quality trace gas measurements of a.o. ozone and NO2. The OMI is a non-scanning nadir viewing spectrograph with a wavelength coverage of 270 to 500 nm and a spectral resolution of 0.4 to 0.7 nm. It has a large spatial field-of-view of 114 degrees perpendicular to the flight direction and uses the resulting swath of 2600 km to measure the complete globe in a single day with ground pixels of nominally 13 km × 24 km. After a brief instrument overview, this paper discusses a number of in-flight performance issues, such as the wavelength calibration and the stray light correction.
OMI's wavelength calibration is based on fitting the sun's Fraunhofer structures, both on sun irradiance spectra and Earth radiance spectra. For the latter the cloud structures impact the wavelength results via inhomogeneous illumination of the spectrometer slit. This is explained together with the basics of a correction algorithm.
OMI has a carousel with three on-board sun diffusers. Measurements with the quartz volume diffuser will be used to show remaining diffuser features in the data. The measured irradiances are compared to the results obtained by convolving the high-resolution solar reference spectrum with the accurately calibrated spectral slit functions.
In the in-flight measurement data in the wavelength range below 300 nm spatial stray light features are observed, resulting from clouds observed at wavelengths above 300 nm. These features are shown together with an explanation of the means to analyze the in-orbit stray light performance.
The Ozone Monitoring Instrument (OMI) was launched on 15 July 2004 on NASA's EOS AURA satellite. The OMI instrument is an ultraviolet-visible imaging spectrograph that uses two-dimensional CCD detectors to register both the spectrum and the swath perpendicular to the flight direction with a 115 degrees wide swath, which enables global daily ground coverage with high spatial resolution. This paper presents a number of in-flight radiometric and spectral instrument performance and calibration results.
With the Dutch-Finnish Ozone Monitoring Instrument (OMI) hardware mounted on NASA's EOS-AURA spacecraft and the AURA planned for launch in 2004, we are working to prepare for flight. An important step in this preparation is the science validation of the software converting the instrument bit stream into (ir-) radiances, the 0-1b processor. The paper contains a description of the main elements of the 0-1b processor and it discusses the methods we have chosen for the validation process. Next it we discuss the outcomes of the various tests and thereby reveal the criticality of each of the algorithms. The algorithms we are dealing with are CCD detector corrections, algorithms to implement radiometric sensitivity of the instrument, stray light correction and the Fraunhofer lines based wavelength calibration algorithm. Because of the CCD, the stray light correction algorithm is two dimensional and the wavelength calibration algorithm is complex due to the fact that we aim at an extreme accuracy of 1/100 pixel or 2.10-3 nm. The validation partly makes use of the OMI Instrument Response Simulator and partly of on-ground performance and calibration measurement data.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.