The Global Water Body Layer from TanDEM-X Interferometric SAR Data

The interferometric synthetic aperture radar (InSAR) data set, acquired by the TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) mission (TDM), represents a unique data source to derive geo-information products at a global scale. The complete Earth’s landmasses have been surveyed at least twice during the mission bistatic operation, which started at the end of 2010. Examples of the delivered global products are the TanDEM-X digital elevation model (DEM) (at a final independent posting of 12 m × 12 m) or the TanDEM-X global Forest/Non-Forest (FNF) map. The need for a reliable water product from TanDEM-X data was dictated by the limited accuracy and difficulty of use of the TDX Water Indication Mask (WAM), delivered as by-product of the global DEM, which jeopardizes its use for scientific applications, as well. Similarly as it has been done for the generation of the FNF map; in this work, we utilize the global data set of TanDEM-X quicklook images at 50 m × 50 m resolution, acquired between 2011 and 2016, to derive a new global water body layer (WBL), covering a range from −60∘ to +90∘ latitudes. The bistatic interferometric coherence is used as the primary input feature for performing water detection. We classify water surfaces in single TanDEM-X images, by considering the system’s geometric configuration and exploiting a watershed-based segmentation algorithm. Subsequently, single overlapping acquisitions are mosaicked together in a two-step logically weighting process to derive the global TDM WBL product, which comprises a binary averaged water/non-water layer as well as a permanent/temporary water indication layer. The accuracy of the new TDM WBL has been assessed over Europe, through a comparison with the Copernicus water and wetness layer, provided by the European Space Agency (ESA), at a 20 m × 20 m resolution. The F-score ranges from 83%, when considering all geocells (of 1∘ latitudes × 1∘ longitudes) over Europe, up to 93%, when considering only the geocells with a water content higher than 1%. At global scale, the quality of the product has been evaluated, by intercomparison, with other existing global water maps, resulting in an overall agreement that often exceeds 85% (F-score) when the content in the geocell is higher than 1%. The global TDM WBL presented in this study will be made available to the scientific community for free download and usage.

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Six years of total ozone column measurements from SCIAMACHY nadir observations

Atmospheric Measurement Techniques ◽

10.5194/amt-2-87-2009 ◽

2009 ◽

Vol 2 (1) ◽

pp. 87-98 ◽

Cited By ~ 39

Author(s):

C. Lerot ◽

M. Van Roozendael ◽

J. van Geffen ◽

J. van Gent ◽

C. Fayt ◽

...

Keyword(s):

Cross Sections ◽

Total Ozone ◽

Large Scale ◽

European Space Agency ◽

Data Sets ◽

Data Set ◽

Ozone Data ◽

Space Agency ◽

German Aerospace ◽

The Impact

Abstract. Total O3 columns have been retrieved from six years of SCIAMACHY nadir UV radiance measurements using SDOAS, an adaptation of the GDOAS algorithm previously developed at BIRA-IASB for the GOME instrument. GDOAS and SDOAS have been implemented by the German Aerospace Center (DLR) in the version 4 of the GOME Data Processor (GDP) and in version 3 of the SCIAMACHY Ground Processor (SGP), respectively. The processors are being run at the DLR processing centre on behalf of the European Space Agency (ESA). We first focus on the description of the SDOAS algorithm with particular attention to the impact of uncertainties on the reference O3 absorption cross-sections. Second, the resulting SCIAMACHY total ozone data set is globally evaluated through large-scale comparisons with results from GOME and OMI as well as with ground-based correlative measurements. The various total ozone data sets are found to agree within 2% on average. However, a negative trend of 0.2–0.4%/year has been identified in the SCIAMACHY O3 columns; this probably originates from instrumental degradation effects that have not yet been fully characterized.

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Interferometric swath processing of Cryosat data for glacial ice topography

The Cryosphere ◽

10.5194/tc-7-1857-2013 ◽

2013 ◽

Vol 7 (6) ◽

pp. 1857-1867 ◽

Cited By ~ 25

Author(s):

L. Gray ◽

D. Burgess ◽

L. Copland ◽

R. Cullen ◽

N. Galin ◽

...

Keyword(s):

European Space Agency ◽

Main Beam ◽

Synthetic Aperture Radar Interferometry ◽

Ice Cap ◽

Space Agency ◽

Digital Elevation ◽

Interferometric Phase ◽

Elevation Data ◽

Devon Ice Cap ◽

Cross Track

Abstract. We have derived digital elevation models (DEMs) over the western part of the Devon Ice Cap in Nunavut, Canada, using "swath processing" of interferometric data collected by Cryosat between February 2011 and January 2012. With the standard ESA (European Space Agency) SARIn (synthetic aperture radar interferometry) level 2 (L2) data product, the interferometric mode is used to map the cross-track position and elevation of the "point-of-closest-approach" (POCA) in sloping glacial terrain. However, in this work we explore the extent to which the phase of the returns in the intermediate L1b product can also be used to map the heights of time-delayed footprints beyond the POCA. We show that there is a range of average cross-track slopes (~ 0.5 to ~ 2°) for which the returns will be dominated by those beneath the satellite in the main beam of the antenna so that the resulting interferometric phase allows mapping of heights in the delayed range window beyond the POCA. In this way a swath of elevation data is mapped, allowing the creation of DEMs from a sequence of L1b SARIn Cryosat data takes. Comparison of the Devon results with airborne scanning laser data showed a mean difference of order 1 m with a standard deviation of about 1 m. The limitations of swath processing, which generates almost 2 orders of magnitude more data than traditional radar altimetry, are explored through simulation, and the strengths and weaknesses of the technique are discussed.

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The ExoMars Trace Gas Orbiter – First Martian Year in Orbit

10.5194/egusphere-egu2020-22228 ◽

2020 ◽

Author(s):

Håkan Svedhem ◽

Oleg Korablev ◽

Igor Mitrofanov ◽

Daniel Rodionov ◽

Nicholas Thomas ◽

...

Keyword(s):

Surface Science ◽

Dust Storm ◽

European Space Agency ◽

High Sensitivity ◽

Global Scale ◽

Trace Gas ◽

Full Potential ◽

Water Ice ◽

Surface Hydrogen ◽

Space Agency

The Trace Gas Orbiter, TGO, has in March 2020 concluded its first Martian year in its 400km, 74 degrees inclination, science orbit. It has been a highly successful year, starting with the rise, plateau and decay of the major Global Dust Storm in the summer of 2018. This has enabled interesting results to be derived on the water vapour distribution, dynamic behaviour and upward transport as a consequence of the dust storm. The characterisation of the minor species and trace gasses is continuing and a large number of profiles is produced every day. A dedicated search of methane has shown that there is no methane above an altitude of a few km, with an upper limit established at about 20 ppt (2&#8729;10-11). The solar occultation technique used by the spectrometers has definitely proven its strength, both for its high sensitivity and for its capability of making high resolution altitude profiles of the atmosphere. Climatological studies have been initiated and will become more important now that a full year has passed, even if the full potential will be visible only after a few Martian years of operation. The FREND instrument has characterised the hydrogen in the shallow sub-surface on a global scale at a spatial resolution much better than previous missions have been able. It has found areas at surprisingly low latitudes with significant amounts of sub-surface hydrogen, most likely in the form of water ice. The CaSSIS camera has made a high number of images over a large variety of targets, including the landing sites of the 2020 ESA and NASA rovers, Oxia Planum and the Jezero Crater. Stereo imaging has enabled topographic information and precise 3-D landscape synthesis.This presentation will summarise the highlights of the first Martian year and discuss planned activities for the near and medium term future.The ExoMars programme is a joint activity by the European Space Agency (ESA) and ROSCOSMOS, Russia. It consists of the ExoMars 2016 mission, launched 14 March 2016, with the Trace Gas Orbiter, TGO, and the Entry Descent and Landing Demonstrator, EDM, named Schiaparelli, and the ExoMars 2020 mission, to be launched in July/August 2020, carrying a Rover and a surface science platform to the surface of Mars.

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Gaia Data Release 2

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832900 ◽

2018 ◽

Vol 616 ◽

pp. A13 ◽

Cited By ~ 35

Author(s):

◽

F. Spoto ◽

P. Tanga ◽

F. Mignard ◽

J. Berthier ◽

...

Keyword(s):

Solar System ◽

A Priori ◽

European Space Agency ◽

Dramatic Improvement ◽

Individual Values ◽

Data Set ◽

Position Information ◽

Additional Information ◽

Space Agency ◽

Data Release

Context. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs. These asteroids have been already identified and have been numbered by the Minor Planet Center repository. Positions are provided for each Gaia observation at CCD level. As additional information, complementary to astrometry, the apparent brightness of SSOs in the unfiltered G band is also provided for selected observations. Aims. We explain the processing of SSO data, and describe the criteria we used to select the sample published in Gaia DR2. We then explore the data set to assess its quality. Methods. To exploit the main data product for the solar system in Gaia DR2, which is the epoch astrometry of asteroids, it is necessary to take into account the unusual properties of the uncertainty, as the position information is nearly one-dimensional. When this aspect is handled appropriately, an orbit fit can be obtained with post-fit residuals that are overall consistent with the a-priori error model that was used to define individual values of the astrometric uncertainty. The role of both random and systematic errors is described. The distribution of residuals allowed us to identify possible contaminants in the data set (such as stars). Photometry in the G band was compared to computed values from reference asteroid shapes and to the flux registered at the corresponding epochs by the red and blue photometers (RP and BP). Results. The overall astrometric performance is close to the expectations, with an optimal range of brightness G ~ 12 − 17. In this range, the typical transit-level accuracy is well below 1 mas. For fainter asteroids, the growing photon noise deteriorates the performance. Asteroids brighter than G ~ 12 are affected by a lower performance of the processing of their signals. The dramatic improvement brought by Gaia DR2 astrometry of SSOs is demonstrated by comparisons to the archive data and by preliminary tests on the detection of subtle non-gravitational effects.

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The International Soil Moisture Network: serving Earth system science for over a decade

10.5194/hess-2021-2 ◽

2021 ◽

Author(s):

Wouter Dorigo ◽

Irene Himmelbauer ◽

Daniel Aberer ◽

Lukas Schremmer ◽

Ivana Petrakovic ◽

...

Keyword(s):

Quality Control ◽

Soil Moisture ◽

European Space Agency ◽

Data Repository ◽

Reference Database ◽

Data Sets ◽

Scientific Publications ◽

Data Set ◽

Space Agency

Abstract. In 2009, the International Soil Moisture Network (ISMN) was initiated as a community effort, funded by the European Space Agency, to serve as a centralised data hosting facility for globally available in situ soil moisture measurements (Dorigo et al., 2011a, b). The ISMN brings together in situ soil moisture measurements collected and freely shared by a multitude of organisations, harmonizes them in terms of units and sampling rates, applies advanced quality control, and stores them in a database. Users can freely retrieve the data from this database through an online web portal (https://ismn.earth). Meanwhile, the ISMN has evolved into the primary in situ soil moisture reference database worldwide, as evidenced by more than 3000 active users and over 1000 scientific publications referencing the data sets provided by the network. As of December 2020, the ISMN now contains data of 65 networks and 2678 stations located all over the globe, with a time period spanning from 1952 to present.The number of networks and stations covered by the ISMN is still growing and many of the data sets contained in the database continue to be updated. The main scope of this paper is to inform readers about the evolution of the ISMN over the past decade,including a description of network and data set updates and quality control procedures. A comprehensive review of existing literature making use of ISMN data is also provided in order to identify current limitations in functionality and data usage, and to shape priorities for the next decade of operations of this unique community-based data repository.

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Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio-occultation data

Geoscientific Instrumentation Methods and Data Systems Discussions ◽

10.5194/gid-2-87-2012 ◽

2012 ◽

Vol 2 (1) ◽

pp. 87-106

Author(s):

B. Sánchez-Cano ◽

O. Witasse ◽

M. Herraiz ◽

S. M. Radicella ◽

J. Bauer ◽

...

Keyword(s):

Radio Occultation ◽

European Space Agency ◽

Planetary Science ◽

Data Set ◽

Mars Express ◽

Radio Science ◽

Space Agency ◽

Martian Ionosphere ◽

Occultation Data ◽

Ionospheric Sounding

Abstract. Since 2005 the Mars Advanced Radar and Ionospheric Sounding experiment (MARSIS) aboard Mars Express has acquired a unique data set on the ionosphere of Mars made up of ionospheric soundings taken by the instrument working in its Active Ionospheric Sounding (AIS) mode. These soundings play a role similar to those of modern Terrestrial digisondes in the analysis of our planet ionosphere and have allowed us to dramatically improve our knowledge about the Martian ionosphere. This paper describes this kind of data, which are available from the public Planetary Science Archive, and introduces the MAISDAT tool developed by the European Space Agency to analyze and derive the vertical profile of electron density. Comparisons with radio-occultation profiles obtained from Mars Express Radio Science instrument are performed to validate the procedure used in this study.

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The ExoMars Trace Gas Orbiter – Progress and future studies

10.5194/egusphere-egu21-16216 ◽

2021 ◽

Author(s):

Håkan Svedhem ◽

AnnCarine Vandaele ◽

Oleg Korablev ◽

Igor Mitrofanov ◽

Nicolas Thomas

Keyword(s):

Surface Science ◽

Dust Storm ◽

European Space Agency ◽

Daily Basis ◽

Global Scale ◽

Seasonal Effects ◽

Trace Gas ◽

Full Potential ◽

Water Ice ◽

Space Agency

The Trace Gas Orbiter, TGO, is now well into its second Martian year of operations. The first year has been a highly successful Martian year, starting with the rise, plateau and decay of the major Global Dust Storm in the summer of 2018. This has enabled interesting results to be derived on the dynamic behaviour as a consequence of the dust storm. A significant observations is the strong upward transport of water vapour that has been found during the dust storm. HCl has been detected for the first time in the Martian atmosphere, and characterisations of the other minor species and trace gasses are continuing. A large numbers of profiles are being produced on a daily basis. The dedicated search of methane is continuing and still shows that there is no methane above an altitude of a few km, with an upper limit established at about 20 pptv (2&#8729;10-11).We now have a full Martian year of observations after the Global dust storm, and seasonal effects can now be studied under normal conditions. Climatological studies, benefitting from the 400km, 74 degrees inclination non-solar synchronous orbit, have been initiated, even if the full potential will be visible only after a few Martian years of operation. The FREND instrument has characterised the hydrogen in the shallow sub-surface on a global scale, at a spatial resolution much better than previous missions have been able to do. It has found areas at surprisingly low latitudes with significant amounts of sub-surface hydrogen, most likely in the form of water ice. The CaSSIS camera has made a well above 15,000 of images over a large variety of targets, including the landing sites of the 2020 NASA and 2022 ESA rovers, Jezero Crater and Oxia Planum. Stereo imaging has enabled topographic information and precise 3-D landscape synthesis.This presentation will summarise the highlights and recent results and discuss planned activities for the near and medium term future.The ExoMars programme is a joint activity by the European Space Agency (ESA) and ROSCOSMOS, Russia. It consists of the ExoMars 2016 mission, launched 14 March 2016, with the Trace Gas Orbiter, TGO, and the Entry Descent and Landing Demonstrator, EDM, named Schiaparelli, and the ExoMars 2022 mission, to be launched in September 2022, carrying a Rover and a surface science platform to the surface of Mars.

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The ExoMars Trace Gas Orbiter - First Martian Year in Orbit

10.5194/epsc2020-802 ◽

2020 ◽

Author(s):

Håkan Svedhem ◽

Oleg Korablev ◽

Igor Mitrofanov ◽

Daniel Rodionov ◽

Nicolas Thomas ◽

...

Keyword(s):

Surface Science ◽

Dust Storm ◽

European Space Agency ◽

High Sensitivity ◽

Daily Basis ◽

Global Scale ◽

Trace Gas ◽

Full Potential ◽

Water Ice ◽

Space Agency

The Trace Gas Orbiter, TGO, concluded its first Martian year in orbit in March 2020. It has been a highly successful Martian year, starting with the rise, plateau and decay of the major Global Dust Storm in the summer of 2018. This has enabled interesting results to be derived on the dynamic behaviour as a consequence of the dust storm. One of the significant observations is a strong upward transport of water vapour that has been found during this time. Characterisations of the minor species and trace gasses are continuing and large numbers of profiles are being produced on a daily basis. A dedicated search of methane has shown that there is no methane above an altitude of a few km, with an upper limit established at about 20 pptv (2&#8729;10-11).The solar occultation technique applied by the spectrometers has definitely proven its strength, both for its high sensitivity and for its capability of making high-resolution altitude profiles of several parameters in the atmosphere. Climatological studies, benefitting from the 400km, 74 degrees inclination non-solar synchronous orbit, have been initiated and will become more important now that a full year has passed, even if the full potential will be visible only after a few Martian years of operation. The FREND instrument has characterised the hydrogen in the shallow sub-surface on a global scale, at a spatial resolution much better than previous missions have been able to do. It has found areas at surprisingly low latitudes with significant amounts of sub-surface hydrogen, most likely in the form of water ice. The CaSSIS camera has made a high number of images over a large variety of targets, including the landing sites of the 2020 NASA and 2022 ESA rovers, Oxia Planum and the Jezero Crater. Stereo imaging has enabled topographic information and precise 3-D landscape synthesis.This presentation will summarise the highlights of the first Martian year and discuss planned activities for the near and medium term future.The ExoMars programme is a joint activity by the European Space Agency (ESA) and ROSCOSMOS, Russia. It consists of the ExoMars 2016 mission, launched 14 March 2016, with the Trace Gas Orbiter, TGO, and the Entry Descent and Landing Demonstrator, EDM, named Schiaparelli, and the ExoMars 2020 mission, to be launched in July/August 2020, carrying a Rover and a surface science platform to the surface of Mars.

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Geophysical validation of temperature retrieved by the ESA processor from MIPAS/ENVISAT atmospheric limb-emission measurements

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-5439-2007 ◽

2007 ◽

Vol 7 (2) ◽

pp. 5439-5513 ◽

Cited By ~ 4

Author(s):

M. Ridolfi ◽

U. Blum ◽

B. Carli ◽

V. Catoire ◽

S. Ceccherini ◽

...

Keyword(s):

Michelson Interferometer ◽

European Space Agency ◽

Temperature Fields ◽

Retrieval Algorithm ◽

Data Set ◽

Weather Forecasts ◽

Mixing Ratios ◽

Remote Sensors ◽

Space Agency ◽

Instruments And Techniques

Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) has been operating since March 2002 onboard of the ENVIronmental SATellite of the European Space Agency (ESA). The high resolution (0.035 cm−1) limb-emission measurements acquired by MIPAS in the first two years of operation have very good geographical and temporal coverage and have been re-processed by ESA with the most recent versions (4.61 and 4.62) of the inversion algorithms. The products of this processing chain are geolocated profiles of temperature and of the volume mixing ratios of six key atmospheric constituents: H2O, O3, HNO3, CH4, N2O and NO2. As for all the measurements made with innovative instruments and techniques, this data set requires a thorough validation. In this paper we present a geophysical validation of the temperature profiles derived from MIPAS measurements by the ESA retrieval algorithm. The validation is carried-out by comparing MIPAS temperature with correlative measurements made by radiosondes, lidars, in-situ and remote sensors operated either from the ground or stratospheric balloons. The results of the intercomparison indicate that the bias of the MIPAS profiles is generally smaller than 1 or 2 K depending on altitude. Furthermore we find that, especially at the edges of the altitude range covered by the MIPAS scan, the random error estimated from the intercomparison is larger (typically by a factor of two to three) than the corresponding estimate derived on the basis of error propagation. In this work we also characterize the discrepancies between MIPAS temperature and the temperature fields resulting from the analyses of the European Centre for Medium-range Weather Forecasts (ECMWF). The bias and the standard deviation of these discrepancies are consistent with those obtained when comparing MIPAS to correlative measurements; however, in this case the detected bias has a peculiar behavior as a function of altitude. This behavior is very similar to that observed in previous studies and is suspected to be due to a problem in the ECMWF temperature.

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The impact of the ozone effective temperature on satellite validation using the Dobson spectrophotometer network

10.5194/amt-2015-343 ◽

2016 ◽

Author(s):

M. E. Koukouli ◽

M. Zara ◽

C. Lerot ◽

K. Fragkos ◽

D. S. Balis ◽

...

Keyword(s):

Effective Temperature ◽

Scale Validation ◽

European Space Agency ◽

Correlation Coefficients ◽

Global Scale ◽

Post Process ◽

Space Agency ◽

The World ◽

Effective Temperatures ◽

The Impact

Abstract. The main aim of the paper is to demonstrate an approach for post-processing of the Dobson spectrophotometers total ozone columns [TOCs] in order to compensate for their known stratospheric effective temperature (Teff) dependency and its resulting effect on the usage of the Dobson TOCs for satellite TOCs validation. The Dobson observations employed are those routinely submitted to the World Ozone and UV Data Centre (WOUDC) of the World Meteorological Organization whereas the effective temperatures have been extracted from two sources: the European Space Agency, ESA, Ozone Climate Change Initiative, Ozone-CCI, GODFIT version 3 (GOME-type Direct FITting) algorithm applied to the GOME2/MetopA, GOME2A, observations as well as the one derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) outputs. Both temperature sources are evaluated utilizing co-located Ozonesonde measurements also retrieved from the WOUDC database. Both GODFIT_v3 and ECMWF Teffs are found to be unbiased against the ozonesonde observations and to agree with high correlation coefficients, especially for latitudes characterized by high seasonal variability in Teff. The validation analysis shows that, when applying the GODFIT_v3 effective temperatures in order to post-process the Dobson TOC, the mean difference between Dobson and GOME2A GODFIT_v3 TOCs moves from 0.63 &pm; 0.66 to 0.26 &pm; 0.46 % in the Northern Hemisphere and from 1.25 &pm; 1.20 to 0.80 &pm; 0.71 % in the Southern Hemisphere. The existing solar zenith angle dependency of the differences has been smoothed out, with near-zero dependency up to the 60 to 65° bin and the highest deviation decreasing from 2.38 &pm; 6.6 to 1.37 &pm; 6.4 % for the 80 to 85° bin. We conclude that the global scale validation of satellite TOCs against collocated Dobson measurements benefits from a post-correction using suitably estimated Teffs.

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