Copernicus Sentinel-2 Collection-1: A Consistent Dataset of Multispectral Imagery with enhanced Quality

The Copernicus Sentinel-2 satellite mission, with its Sentinel-2A and Sentinel-2B units, offers since several years now a massive quantitative and qualitative resource for the Earth Observation community. Since the launch of Sentinel-2A in 2015, and Sentinel-2B in 2017, many lessons have been learnt leading to continuous improvements of the radiometric and the geometric performances. However, the current archive is composed of heterogenous processing baselines with inconsistent product formats and uneven data quality, which limits its use for multi-temporal monitoring applications. To overcome this limitation, the Copernicus program has undertaken a complete reprocessing with the latest processing baseline (05.00). It concerns the L1C (Top-OfAtmosphere reflectance) and L2A (Surface Reflectance) products. This paper recalls the features of Collection-1 products and gives an overview of the first validation results

Effects of β2 agonists on post-thoracotomy pain incidence

BACKGROUND: Pre-clinical research has shown beta2 -adrenoceptors to be essential for the antiallodynic action of antidepressant drugs in murine models of neuropathic pain and that sustained treatment with beta2 -agonists has an antiallodynic action. Here, we clinically investigated whether chronic beta2 -agonist treatments may influence the incidence of post-thoracotomy chronic pain, defined as pain that recurs or persists along a thoracotomy scar more than 2 months after surgery, either neuropathic or non-neuropathic. METHODS: We conducted an epidemiological study on patients operated by thoracotomy. Demographic data, medical history and treatments concomitant to the surgery were recorded at a follow-up visit. Information on perioperative treatments was collected from the anaesthesia records and confirmed by the patients. In patients with pain at the surgery level, post-thoracotomy chronic pain was assessed by clinical examination and numeric scale. Physical examination and DN4 questionnaire were used to discriminate neuropathic and non-neuropathic chronic pain at scar level. RESULTS: One hundred and eighty-nine patients were included. Eighty-one patients reported persisting thoracic pain, with neuropathic characteristics in 58 of them (30% of the 189 patients). The most common chronic drugs during the perioperative period were inhaled beta2 -agonists (28.6%). The chronic use of beta2 -agonists was an independent predictor of thoracic neuropathic pain (but not of non-neuropathic pain) and was associated with a five-fold decrease in the relative incidence of neuropathic pain [OR = 0.19 (0.06-0.45)]. CONCLUSIONS: These data suggest a possible influence of chronic beta2 -agonist treatments on neuropathic pain secondary to thoracotomy. This apparent preventive effect of beta2 -agonist treatments should warrant controlled clinical trials

Improved GOMOS/Envisat retrievals: focus on the upper troposphere and the lower stratosphere

International audienceGlobal Ozone Monitoring by Occultation of Stars (GOMOS) on board Envisat has performed about 440 000 night-time occultations during 2002–2012. Self-calibrating measurement principle, good vertical resolution and the wide vertical range from the troposphere up to the lower thermosphere make GOMOS profiles interesting for different analyses. Vertical profiles of ozone, NO2, NO3 and aerosols are retrieved from night-time UV-VIS spectrometer measurements.The GOMOS ozone data are of high quality in the stratosphere and the mesosphere, but the current operational retrieval algorithm (IPF v.6) is not optimized for retrievals in the upper troposphere–lower stratosphere (UTLS). In particular, validation of GOMOS profiles against ozonesonde data has revealed a substantial positive bias (up to 100%) in the UTLS region. The retrievals in the UTLS are challenging because of low signal-to-noise ratio and the presence of clouds.In this work, we present two advanced GOMOS algorithms, which are optimized for retrievals in the UTLS. One of the algorithms relies on the operational two-step inversion (the spectral inversion followed by the vertical inversion), while another uses one-step approach, i.e., direct fitting the profiles of all constituents. In the new retrievals, a special attention is paid to outlier filtering, the choice of aerosol extinction model, and the vertical resolution.The validation of new retrieved ozone profiles with ozonesondes has shown dramatic reduction of GOMOS ozone biases in the UTLS, for both algorithms. The new GOMOS ozone profiles are also in a very good agreement with measurements by MIPAS, ACE-FTS and OSIRIS satellite instruments in the UTLS. The known geophysical phenomena in the UTLS ozone are well reproduced with the advanced retrievals. In addition, we present GOMOS ozone profiles during the unprecedented stratospheric ozone loss in the Arctic in 2011.These studies have been performed in the framework of ESA-funded ALGOM (GOMOS Level 2 algorithm evolution studies) project. New GOMOS data will be made available via the ESA website

ESA's Atmospheric Chemistry Mission - A Status Report

The challenges in understanding the atmospheric chemistry processes for climate research and to model and forecast the air quality on regional scale are still manifold. Presently, ESA is providing atmospheric chemistry data both from their core missions ERS-2 and Envisat as well as from Third Party Missions (TPM). ESAs core atmospheric chemistry instruments onboard ERS-2 and ENVISAT are GOME, GOMOS, MIPAS and SCIAMACHY. With ERS-2 launched in 1995 and ENVISAT in 2002, these instruments are providing a rich dataset to the scientific community and supporting operational services since more than 14 years. Currently, data from the following missions can be provided through ESA: ACE-FTS and MAESTRO data from the CSA SCISAT mission, OSIRIS and SMR data from the SSC ODIN mission, TANSO-FTS AND -CAI data from the JAXA/NIES/MOE GOSAT mission. It is currently planned that also OMI data from the NASA AURA mission will be accessible through ESA. In addition to the operational data, ESA acknowledges that the science community is developing and providing a number of important, quality products based on ESA missions. The presentation will summarise the status of all the issues addressed above with a focus on ESA instruments, algorithm development and data distribution

Calibration approaches and quality aspects for the ENVISAT Atmospheric Chemistry instruments

ENVISAT carries on-board the three Atmospheric Chemistry instruments GOMOS, MIPAS and SCIAMACHY. These instruments use different measurement techniques and observation geometries for atmospheric remote sounding. All of them require regular calibrations permitting to account for long term degradation of instrument performances or for short term variation of measurement conditions. This paper gives an overview on the most relevant calibration aspects of the three instruments and illustrates how to improve calibration for an even higher data quality

Improved H2O GOMOS profiles using a new algorithm based on a Levenberg-Marquardt method

International audienceH2O plays a very important role in the upper troposphere and stratosphere. It has a strong radiative effect and it plays a key role in the ozone chemistry, being a source of HOx species involved in the catalytic destruction of ozone. The evolution of H2O in the lower stratosphere during the last decades is still not well determined. Contradictory results are obtained depending of the source of data (balloons, satellites).H2O measurements by GOMOS (Global Ozone Monitoring by Occultation of Stars) on board Envisat can play a significant role in this area. The two advantages of the stellar occultations method are the self-calibration nature and the well-defined geometry. The IPF 6 algorithm provides greatly improved H2O profiles compared to IPF5 due to a correction of the intra-pixel PRNU. However there is still some room for improvement. A new algorithm has been developed in which the wavelength assignment is improved, the new HITRAN 2012 database is used for H2O absorption and a Levenberg-Marquartdt method is applied for spectrum fitting instead of using look-up tables for the estimation of H2O slant columns. This new algorithm provides improved H2O profiles to be used for studies on H2O variability and trends in the UTLS.These studies have been performed in the framework of ESA-funded ALGOM (GOMOS Level 2 algorithm evolution studies) project

Seven years of data quality of the ENVISAT Atmospheric Chemistry missions: highlights, lessons learned and perspectives

The ENVISAT atmospheric chemistry instruments GOMOS, MIPAS and SCIAMACHY provide to the user community three separated, but complementary datasets of the most interesting trace gases, spanning a time interval of about seven years. With the project of extending the ENVISAT lifetime up to the end of 2013, the users will have the unique opportunity to investigate seasonal trend and long term evolution of several atmospheric phenomena over a time range of eleven years. This paper summarizes the activities performed in the frame of the data processing and quality assessment applied to the ENVISAT Atmospheric Chemistry instruments

The ENVISAT Atmospheric Chemistry missions: monitoring status and evolution

Three atmospheric chemistry sensors are on-board ENVISAT, launched on March 2002. Since then, the instruments and the processors have been accurately monitored in order to detect as early as possible any issue that could impact the quality of the data products. In this paper we show how the quality monitoring has evolved since the beginning of the mission and how the monitoring baseline and environment was adjusted to mission events like instrument anomalies and/or degradations and data processor issues and how the users benefit from this