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EUMETSAT initiated the research study Sentinel-3 Synergy Cloud Mask Development to explore a novel approach to synergistic cloud masking for OLCI and SLSTR, which is termed obstruction. The study included an Expert Workshop to critically debate the concept of obstruction and to review demonstration results. The six graphics on this poster explain the concept at a very non-technical level. Each graphic highlights a classic question, which arises in cloud masking. Right next to it, we give the classic answer. In no case, we consider the answer satisfying. We think that the answers cannot be satisfying, because the questions were somewhat misleading. We therefore reconsider the original question and, above it, pose a revised question, which puts the original question in the broader context of physics. Right next to the revised question, we describe how obstruction answers it.

Establishing an end-to-end uncertainty budget is essentially required for all ECVs of ESA’s Climate Change Initiative (CCI). The reference for expressing and propagating uncertainty consists of the GUM and its supplements, which describe multivariate analytic and Monte Carlo methods. But despite these guidelines, uncertainty propagation for ECVs remains challenging. Firstly, many retrieval algorithms do not incorporate the use of quantified uncertainty per datum. Analytic methods for propagating uncertainty require new algorithmic developments while Monte Carlo methods are straightforward to apply but lead to proliferation of computational and data curation resources. Secondly, operational radiometry data are usually not associated with a quantified uncertainty per datum, and error correlation structures between data are not quantified either. Deriving this information from original sensor telemetry and an according harmonisation with respect to an SI traceable satellite (SITSAT) reference is a future task. Nevertheless, it is feasible to explore and prepare ECV surface reflectance pre-processing for the use of uncertainty per Level 1 datum and error correlation structures among Level 1 data already now, based on instrument specifications and other simplifying assumptions.

This document provides the theoretical basis for the Sentinel-3OLCIIdePix. IdePix stands forIdentification ofPixel properties and is a multi-sensor pixel identification tool available as a SNAP (Sentinel Application Platform) plugin. IdePixprovides pixel identification algorithms for a wide variety of sensors like Sentinel-2 MSI, Sentinel-3 OLCI, MERIS, Landsat-8, MODIS, VIIRS, Proba-V or SPOT VGT. IdePix for Sentinel-3OLCIclassifies pixels of L1bproducts into a series of categories (flags) for further processing using a mono-temporal approach and background information. The Sentinel-3 OLCI IdePix derives cloud flags on two confidence levels, as well as cloud shadow, mountain shadow, snow/ice and water flags. This Algorithmic Theoretical Basis Document (ATBD) provides a scientific description of the methods used for the Sentinel-3OLCIIdePix

This document provides the theoretical basis for the Sentinel-2 MSI IdePix. IdePix stands forIdentification of Pixel properties and is a multi-sensor pixel identification tool available as a SNAP (Sentinel Application Platform) plugin. IdePixprovides pixel identification algorithms for a wide variety of sensors like Sentinel-2 MSI, Sentinel-3 OLCI, MERIS, Landsat-8, MODIS, VIIRS, Proba-V or SPOT VGT. IdePix for Sentinel-2 MSI classifies pixels of L1C products into a series of categories (flags) for further processing using a mono-temporal approach and background information. The IdePix processor derives water droplet based cloud flags and cirrus cloud flags on multiple confidence levels, as well as cloud shadow, mountain shadow, snow/ice and water flags. This Algorithmic Theoretical Basis Document (ATBD) provides a scientific description of the methods used for the Sentinel-2 MSI IdePix.

Presentation on the comparison of errors-in-variables and marginalised errors-in-variables harmonisation methods given by R. Quast during the FIDUCEO science meeting at NPL in January 2019. This presentation supplements the journal article: Giering, R.; Quast, R.; Mittaz, J.P.D.; Hunt, S.E.; Harris, P.M.; Woolliams, E.R.; Merchant, C.J. A Novel Framework to Harmonise Satellite Data Series for Climate Applications. Remote Sens. 2019, 11, 1002. doi:10.3390/rs11091002., {"references":["Giering, R.; Quast, R.; Mittaz, J.P.D.; Hunt, S.E.; Harris, P.M.; Woolliams, E.R.; Merchant, C.J. A Novel Framework to Harmonise Satellite Data Series for Climate Applications. Remote Sens. 2019, 11, 1002"]}

This report contains highlights of the scientific developments made during FIDUCEO that form the basis of the new Fundamental Climate Data Records (FCDRs) produced by the project, Previously curated at: http://cedadocs.ceda.ac.uk/1411/ Main files in this record: Attachment_0-13.pdf Item originally deposited with Centre for Environmental Data Analysis (CEDA) document repository by Miss Esther Conway. Transferred to CEDA document repository community on Zenodo on 2022-11-24

This document is one of the five documents that make up the D2-2 report on "traceability chains for FCDRs". Since the original project proposal our thoughts have refined and while this document describes the "sequence of measurement standards and calibrations that is used to relate a measurement result to a reference" (the VIM definition of a traceability chain), it is not presenting this in the form of a chain. This document provides an overview of the uncertainty analysis for the analysed sensors along with the methods to establish metrological traceability for the developed FCDRs. This document is specifically about the MVIRIFCDR. The document D2-2a provides an overview of the effects tables., Previously curated at: http://cedadocs.ceda.ac.uk/1403/ Main files in this record: D2-2 Report on MVIRI FCDR uncertainty.pdf Item originally deposited with Centre for Environmental Data Analysis (CEDA) document repository by Miss Esther Conway. Transferred to CEDA document repository community on Zenodo on 2022-11-24

Fundamental and thematic climate data records derived from satellite observations provide unique information for climate monitoring and research. Since any satellite operates over a limited period of time only, creating a climate data record requires the combination of space-born measurements from a series of several (often similar) satellites. Simple combination of measurements from several sensors, however, will produce an inconsistent climate data record because the behaviour of historical satellites in space was often different from their behaviour during pre-launch calibration in the laboratory. More scientific value can be derived from considering the series of historical and present satellites as a whole. Here we consider harmonisation as a process that obtains new calibration coefficients and a revised calibration model for each sensor by comparing the output of each satellite to radiometrically more accurate sensors using appropriate match-ups, such as simultaneous nadir overpasses. When we perform a comparison of two sensors using match- ups, we must take into account the fact that those sensors are not observing exactly the same Earth radiance. This is in part due to uncertainties in the collocation process itself, but also due to differences in the spectral response functions of the two instruments, even when nominally observing the same spectral band. We do not aim to correct for spectral response function differences, but to reconcile the calibration of different sensors given their estimated spectral response function differences. Here we present the concept of a framework that establishes calibration coefficients for several sensors simultaneously and rigorously with respect to their uncertainty and error covariance. We present the harmonisation and its mathematical formulation as a large-structured inverse problem. Solving this problem is a challenge because it involves some hundred million of match-ups and has significant error correlation in the measured data. We sketch different approaches to solve the harmonisation problem and present our first attempt to recalibrate AVHRR radiance from a series of nine NOAA and MetOp satellites. Presented at the EUMETSAT Meteorological Satellite Conference, Rome, October 2017.

The Meteosat Visible and Infrared (MVIRI) sensors on board Meteosat First Generation (MFG) geostationary satellites (1982 - today) acquire radiance every 30 minutes in a broad spectral band, ranging approximately from 0.4 to 1.1 µm and referred to as the visible (VIS) band.The original objective of the MFG programme was the acquisition of Earth images to provide the meteorological community with information on atmospheric circulation and weather. One of the objectives of the H2020 Fidelity and Uncertainty in Climate Data Records from Earth Observation (FIDUCEO) project is to re-evaluate the VIS acquisitions in a metrological rigorous way to generate new fundamental and thematic climate data records with traceable uncertainty and stability estimates. The clue to this re-evaluation is an accurate characterisation of the VIS spectral response functions, which were characterised poorly pre-launch and had apparently been degrading stronger in the blue than the near-infrared part of the VIS band.In consequence, a novel practice for a vicarious re-characterisation of the MVIRI VIS spectral response function has been developed. The so termed reverse engineering method applies advanced algorithmic differentiation techniques to calculate daily maximum posterior probability estimates of the sensor spectral response and accurate and traceable measures of its uncertainty and spectral error covariance.This presentation explains the key concepts of the method and imparts new findings and results of its application to the Meteosat Second Generation (MSG) Meteosat-10 and Meteosat-7 visible bands.Oral presentation given at the EUMETSAT Meteorological Satellite Conference, Rome, 2-6 October 2017.

Essay on the reconstruction of the Meteosat VIS band spectral response function in the course of the FIDUCEO project. Conference paper contributed to the ESA Living Planet Symposium, Prague, May 2016:Paper 1442 - Session title: Atmosphere & Climate PostersATMO-178 - Creating Fidelitous Climate Data Records from Meteosat First Generation VIS Band Observations

The Synergy processing of Sentinel-3 aims at making use of the combined information from the OLCI and SLSTR instruments to provide improved data for land surface vegetation analysis. The L2 processing makes use of the enhanced spectral and angular capabilities of a combined instrument (the SYN instrument) to produce a product with atmosphere-corrected surface reflectance and corresponding information on aerosol properties, whereas the VGT processing uses data from OLCI and SLSTR to provide products comparable to SPOT VGT-P and VGT-S. The L2 processing uses 18 OLCI spectral bands and 6 solar reflective bands in each SLSTR view (nadir and oblique). Thermal and atmospheric absorption bands are not considered. The images acquired for the synergy bands are co-located at OLCI spatial resolution. Aerosol retrieval is carried out at a coarser resolution (configurable). The retrieved Aerosol properties minimise an error metric based on pure spectral and dual-view spectral-angular models available as look-up tables for up to 40 different Aerosol models. The retrieval includes uncertainty estimates per pixel, based on the curvature of the error metric at the minimum. Retrieval failures are filled by means of distance-weighted averaging and a climatologic background model. Retrieved Aerosol properties and uncertainty estimates are interpolated to the full spatial resolution grid. Employing the look-up tables with the interpolated Aerosol properties as parameters yields surface reflectance and corresponding uncertainty estimates, considering uncertainty estimates at L1 and Aerosol retrieval uncertainties. The VGT processing uses the same 18 OLCI spectral bands as the L2 processing, but only three spectral bands in the SLSTR nadir view. The calculation of the SPOT VGT spectral bands (termed spectral band mapping) is carried out by means of atmospheric correction (aerosol from climatology), hyperspectral interpolation of surface reflectance, inverse hyperspectral atmospheric correction, and convolution with VGT response functions. The prototype Synergy processor consists of modules, which correspond to the individual processing steps. It is applicable to products of any size, because it processes data in chunks. The prototype is coded in C++ and uses the Open Multi-Processing technology to exploit multiple CPU cores. Poster presented at the ESA Sentinel-3 OLCI/SLSTR and MERIS/AATSR Workshop 2012 in Frascati, Italy.

A multi-sensor match-up dataset (MMD) is a set of temporal and spatial coincidences between multiple satellite datasets of both L1 and L2 retrievals and time series of corresponding measurements from various types of in situ instruments. The implementation of a multi-sensor matchup database (MMDB) is a fundamental requirement for the sea surface temperature (SST) system of ESA’s Climate Change Initiative (CCI), facilitating the continuous algorithm improvement cycle. For the production of the SST-CCI round-robin data package (RRDP) an SST multi-mission match-up system (MMS) has been developed and implemented for the first time. The MMDB covers a period of 20 years and includes satellite datasets from (A)ATSR, NOAA AVHRR, MetOp AVHRR and SEVIRI, passive microwave AMSR-E and TMI, GOME-2, OSI SAF, analysis and forecast datasets from ECMWF, and in-situ measurement time series recorded by buoys, drifters, moorings and ships. In total, the MMDB includes more than 6 million match-up records. The MMS runs on the Edinburgh Compute and Data Facility (ECDF) cluster and makes use of the Sun Grid Engine (SGE). It employs the ATSR Reprocessing for Climate (ARC) software to retrieve SST on arbitrary sets of match-up records. The database implementation is based on open-source PostgreSQL with PostGIS extension. Poster presented at the ESA Sentinel-3 OLCI/SLSTR and MERIS/AATSR Workshop 2012 in Frascati, Italy.

The SMOS Toolbox for BEAM (SMOS-Box) consists of a collection of BEAM compliant software modules for decoding, visualization and basic inspection and analysis of operational products from ESA's Soil Moisture and Ocean Salinity (SMOS) mission. Since March 2010 the SMOS Data Distribution Facility of the CEOS Cal/Val Portal is delivering mission data to principle investigators coordinating the calibration and validation of the SMOS instrumentation. In Proceedings of ESA Living Planet Symposium 2010, Bergen, Norway.

Extragalactic absorbers with column densities exceeding NH I > 2 × 1020 hydrogen atoms cm-2 are generally termed damped Ly alpha (DLA) systems. The absorbers are basically comprised of predominantly neutral gas, which is an essential prerequisite for the formation of stars. The spectroscopy of absorbers offers the best possibility to study the chemical composition of the supposed equivalents of the interstellar medium of local galaxies at an earlier stage of cosmic evolution. Absorbers in the sub-DLA range with NH I > 1019 cm-2 may consist of predominantly neutral gas, if the cosmic UV background is reduced. The observed kinematic structure of absorption lines as well as the column density and metallicty statistics of absorbers provide substantial tests for models of galaxy formation and cosmic structuring. Fine-structure lines offer the possibility to examine the temperature-redshift relation of the cosmic microwave background radiation predicted by Friedmann cosmology, or to infer the physical condition of the absorbing medium. Precise measurements of the relative positions of selected metal lines can impose stringent constraints on the cosmological variability of the fine structure constant alpha, which is an implication of many unifying theories currently discussed. The primary aim of this study is the examination of the ionization, abundance and dust depletion of metals in the sub-DLA absorber toward the QSO HE 0515-4414. The kinematic structure of metal absorption lines is discussed. Neutral carbon fine-structure lines are used to infer the temperature of the cosmic microwave background at redshift z = 1.15, and to diagnose the physical condition of the absorbing medium. Based on accurate positional measurements of individual components within an ensemble of selected Fe II resonance lines, the possible deviation of the fine structure constants from its current value is probed. High-resolution spectra obtained with the STIS and UVES spectrographs provide the empirical basis of this work. In the optical the quality of the data is exceptional. The program used for the analysis has been developed from scratch. The software is driven by an evolution strategy, which is based on a derandomized adaptation the covariance matrix. The strategy is proven to be a highly competitive algorithm capable of calculating an optimal line profile decomposition without requiring any particular initialization. The ionization conditions within the absorber have been analyzed using the simulation software Cloudy. The sub-DLA system with redshift z = 1.15 is unusual in several respects. The velocity interval of metal lines associated with the H I absorption extends for more than 700 km s-1, which is the second largest spread yet observed in this context. The extreme spread facillitates the unusual detection of two peripheral H I components located at distances of 530 and 240 km s-1 from the NH I = 8 × 1019 cm-2 main component. The associated metal lines consist of at least 31 components. The kinematic distribution of metal line components is bimodal, which is possibly indicating the presence of two interacting absorbers. This interpretation is supported by the finding of a nonuniform ionization structure. The main absorber essentially consists of predominantly neutral gas, whereas the periphery is highly ionized. For the former, the abundances ratios of refractory elements to zinc range from Galactic warm disk to halo-like and essentially undepleted patterns. The dust-corrected metallicity of the main absorber is almost solar [Fe/H] = -0.08 ± 0.19, whereas the uncorrected metallicity is [Zn/H] = -0.38 ± 0.04. The element abundances in the periphery do conform with solar composition. The cosmic microwave background is only a minor source of the observed population of excited fine-structure levels. The excitation is predominantly caused by local FUV radiation and collisions with hydrogen atoms. The kinetic temperature of the absorbing medium is some ten to hundred Kelvin. The measured deviation of the fine-structure constant from its present value da/a = (0.1 ± 1.7) × 10-6 does not confirm the detection of a cosmological variation found in the studies of John Webb and Michael Murphy. The present measurement has been affirmed by two further research teams. The present study shows that the chemical evolution of sub-DLA system toward HE 0515-4414 must have reached an advanced state. Since in this context regular DLA absorbers fall behind expectations at redshifts z < 1.5, the question arises whether the sub-DLA absorber examined in the present work is more than just an exceptional case. In particular at lower redshifts the population of sub-DLA absorbers is largely unknown. Modern Surveys setting the detection limit below the traditional threshold of NH I > 2 × 1020 cm-2 may provide interesting insights.

Context Extragalactic absorbers with column densities exceeding NH I > 2 × 1020 hydrogen atoms cm-2 are generally termed damped Ly alpha (DLA) systems. The absorbers are basically comprised of predominantly neutral gas, which is an essential prerequisite for the formation of stars. The spectroscopy of absorbers offers the best possibility to study the chemical composition of the supposed equivalents of the interstellar medium of local galaxies at an earlier stage of cosmic evolution. Absorbers in the sub-DLA range with NH I > 1019 cm-2 may consist of predominantly neutral gas, if the cosmic UV background is reduced..., thesis

Spectroscopy of QSO absorption lines provides essential observational input for the study of nucleosynthesis and chemical evo- lution of galaxies at high redshift. But new observations may indicate that present chemical abundance data are biased due to deficient spectral resolution and unknown selection effects: Recent high-resolution spectra reveal the hitherto unperceived chemi- cal nonuniformity of a molecule-bearing damped Lyman-alpha (DLA) system, and the still ongoing H/ESO DLA survey produces convincing evidence for the effect of dust attenuation. We present a revised analysis of the H2-bearing DLA complex toward the QSO HE 0515-4414 showing nonuniform differential depletion of chemical elements onto dust grains, and introduce the H/ESO DLA survey and its implications. Conclusively, we aim at starting an unbiased chemical abundance database established on high-resolution spectroscopic observations. New data to probe the temperature-redshift relation predicted by standard cosmology and to test the constancy of fundamental constants will be potential spin-offs.

The article presents joint constraints on the cosmological constant λ and the density parameter Ω from analyses of gravitational lensing statistics of the Jodrell Bank-VLA Astrometric Survey (JVAS), optical gravitational lens surveys from the literature, and CMB anisotropies., This research was supported in part by the European Commission, TMR Programme, Research Network Contract ERBFMRXCT96-0034 CERES.