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Already shortly after the successful launch of the European Space Agency satellite Aeolus in August 2018, it turned out that dark current signal anomalies of single pixels (so-called hot pixels) on the Accumulation-Charge-Coupled Devices (ACCDs) of the Aeolus detectors detrimentally impact the quality of the aerosol and wind products potentially leading to wind errors of up to 4 m/s. This paper provides a detailed characterization of the hot pixels which occurred during the first one and a half years in orbit. The hot pixels are classified according to their characteristics to discuss their impact on wind measurements. Furthermore, mitigation approaches for the wind retrieval are presented and potential root causes for the hot pixel occurrence are discussed. The analysis of the dark current signal anomalies reveals a large variety of anomalies ranging from pixels with Random Telegraph Signal (RTS)-like characteristics to pixels with sporadic shifts in the median dark current signal. Moreover, the results indicate that the number of hot pixels has almost linearly increased during the observing period between 2018-09-02 until 2020-05-20 with 6 % of the ACCD pixels affected in total at the end of the period leading to 9.5 % at the end of mission lifetime. This work introduces dedicated instrument calibration modes and ground processors which allowed for a correction shortly after a hot pixel occurrence. The achieved performance with this approach avoids risky adjustments to the inflight hardware operation. It is demonstrated that the success of the correction scheme varies depending on the characteristics of each hot pixel itself. With the herein presented categorization, it is shown that multi-level RTS pixels with high fluctuation are the biggest challenge for the hot pixel correction scheme. Despite a detailed analysis in this framework, no conclusion could be drawn about the root cause of the hot pixel issue.

The sinking of the cargo ship SS El Faro is investigated by providing a comprehensive analysis of the wind, wave and ocean currents associated with Hurricane Joaquin. Using state-of-the-art reanaly...

This study assesses the skill of multimodel forecasts of 10-m wind speed, significant wave height, and mean wave period in the North Atlantic for the winter months. The 10-m winds from four North American multimodel ensemble models and three European Multimodel Seasonal-to-Interannual Prediction project (EUROSIP) models are used to force WAVEWATCH III experiments. Ten ensembles are used for each model. All three variables can be predicted using December initial conditions. The spatial maps of rank probability skill score are explained by the impact of the North Atlantic Oscillation (NAO) on the large-scale wind–wave relationship. Two winter case studies are investigated to understand the relationship between large-scale environmental conditions such as sea surface temperature, geopotential height at 500 hPa, and zonal wind at 200 hPa to the NAO and the wind–wave climate. The very strong negative NAO in 2008/09 was not well forecast by any of the ensembles while most models correctly predicted the sign of the event. This led to a poor forecast of the surface wind and waves. A Monte Carlo model combination analysis is applied to understand how many models are needed for a skillful multimodel forecast. While the grand multimodel ensemble provides robust skill, in some cases skill improves once some models are not included.

International audience; The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the universe today? How do habitable planets form? How common are life-bearing worlds? We describe how Origins was designed to answer these alluring questions. We discuss the key decisions taken by the Origins mission concept study team, the rationale for those choices, and how they led through an exploratory design process to the Origins baseline mission concept. To understand the concept solution space, we studied two distinct mission concepts and descoped the second concept, aiming to maximize science per dollar and hit a self-imposed cost target. We report on the study approach and describe the concept evolution. The resulting baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. The chosen architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch. The cryo-thermal system design leverages James Webb Space Telescope technology and experience.

This study assesses the skill of seasonal forecasts for the environmental variables of surface wind speed, ocean surface current speed and significant wave height in the North Pacific. The ultimate...

The U.K. on Partnership for Advanced Computing in Europe (PRACE) Weather-Resolving Simulations of Climate for Global Environmental Risk (UPSCALE) project, using PRACE resources, constructed and ran an ensemble of atmosphere-only global climate model simulations, using the Met Office Unified Model Global Atmosphere 3 (GA3) configuration. Each simulation is 27 years in length for both the present climate and an end-of-century future climate, at resolutions of N96 (130 km), N216 (60 km), and N512 (25 km), in order to study the impact of model resolution on high-impact climate features such as tropical cyclones. Increased model resolution is found to improve the simulated frequency of explicitly tracked tropical cyclones, and correlations of interannual variability in the North Atlantic and northwestern Pacific lie between 0.6 and 0.75. Improvements in the deficit of genesis in the eastern North Atlantic as resolution increases appear to be related to the representation of African easterly waves and the African easterly jet. However, the intensity of the modeled tropical cyclones as measured by 10-m wind speed remains weak, and there is no indication of convergence over this range of resolutions. In the future climate ensemble, there is a reduction of 50% in the frequency of Southern Hemisphere tropical cyclones, whereas in the Northern Hemisphere there is a reduction in the North Atlantic and a shift in the Pacific with peak intensities becoming more common in the central Pacific. There is also a change in tropical cyclone intensities, with the future climate having fewer weak storms and proportionally more strong storms.

This study assesses the influence of the El Niño–Southern Oscillation (ENSO) on global tropical cyclone activity using a 150-yr-long integration with a high-resolution coupled atmosphere–ocean general circulation model [High-Resolution Global Environmental Model (HiGEM); with N144 resolution: ~90 km in the atmosphere and ~40 km in the ocean]. Tropical cyclone activity is compared to an atmosphere-only simulation using the atmospheric component of HiGEM (HiGAM). Observations of tropical cyclones in the International Best Track Archive for Climate Stewardship (IBTrACS) and tropical cyclones identified in the Interim ECMWF Re-Analysis (ERA-Interim) are used to validate the models. Composite anomalies of tropical cyclone activity in El Niño and La Niña years are used. HiGEM is able to capture the shift in tropical cyclone locations to ENSO in the Pacific and Indian Oceans. However, HiGEM does not capture the expected ENSO–tropical cyclone teleconnection in the North Atlantic. HiGAM shows more skill in simulating the global ENSO–tropical cyclone teleconnection; however, variability in the Pacific is overpronounced. HiGAM is able to capture the ENSO–tropical cyclone teleconnection in the North Atlantic more accurately than HiGEM. An investigation into the large-scale environmental conditions, known to influence tropical cyclone activity, is used to further understand the response of tropical cyclone activity to ENSO in the North Atlantic and western North Pacific. The vertical wind shear response over the Caribbean is not captured in HiGEM compared to HiGAM and ERA-Interim. Biases in the mean ascent at 500 hPa in HiGEM remain in HiGAM over the western North Pacific; however, a more realistic low-level vorticity in HiGAM results in a more accurate ENSO–tropical cyclone teleconnection.

The authors present an assessment of how tropical cyclone activity might change owing to the influence of increased atmospheric carbon dioxide concentrations, using the U.K. High-Resolution Global Environment Model (HiGEM) with N144 resolution (~90 km in the atmosphere and ~40 km in the ocean). Tropical cyclones are identified using a feature-tracking algorithm applied to model output. Tropical cyclones from idealized 30-yr 2×CO2 (2CO2) and 4×CO2 (4CO2) simulations are compared to those identified in a 150-yr present-day simulation that is separated into a five-member ensemble of 30-yr integrations. Tropical cyclones are shown to decrease in frequency globally by 9% in the 2CO2 and 26% in the 4CO2. Tropical cyclones only become more intense in the 4CO2; however, uncoupled time slice experiments reveal an increase in intensity in the 2CO2. An investigation into the large-scale environmental conditions, known to influence tropical cyclone activity in the main development regions, is used to determine the response of tropical cyclone activity to increased atmospheric CO2. A weaker Walker circulation and a reduction in zonally averaged regions of updrafts lead to a shift in the location of tropical cyclones in the Northern Hemisphere. A decrease in mean ascent at 500 hPa contributes to the reduction of tropical cyclones in the 2CO2 in most basins. The larger reduction of tropical cyclones in the 4CO2 arises from further reduction of the mean ascent at 500 hPa and a large enhancement of vertical wind shear, especially in the Southern Hemisphere, North Atlantic, and northeast Pacific.

The vertex detectors at the International Linear Collider (ILC) (there will be two of them, one for each of two general purpose detectors) will certainly be built with silicon pixel detectors, either monolithic or perhaps vertically integrated. However, beyond this general statement, there is a wide range of options supported by active RandD programmes all over the world. Pixel-based vertex detectors build on the experience at the SLAC large detector (SLD) operating at the SLAC linear collider (SLC), where a 307 Mpixel detector permitted the highest physics performance at LEP or SLC. For ILC, machine conditions demand much faster readout than at SLC, something like 20 time slices during the 1 ms bunch train. The approach of the image sensor with in-situ storage (ISIS) is unique in offering this capability while avoiding the undesirable requirement of 'pulsed power'. First results from a prototype device that approaches the pixel size of 20 μm square, needed for physics, are reported. The dimensional challenge is met by using a 0.18 μm imaging CMOS process, instead of a conventional CCD process. © 2010 Elsevier B.V. All rights reserved.

The European Space Agency (ESA) and e2v, together with the Euclid Imaging Consortium, have designed and manufactured pre-development models of a novel imaging detector for the visible channel of the Euclid space telescope. The new detector is an e2v back-illuminated, 4k x 4k, 12 micron square pixel CCD designated CCD273-84. The backilluminated detectors have been characterised for many critical performance parameters such as read noise, charge transfer efficiency, quantum efficiency, Modulation Transfer Function and Point Spread Function. Initial analysis of the MTF and PSF performance of the detectors has been performed by e2v and at MSSL and the results have enabled the Euclid VIS CCD project to move in to the C/D or flight phase delivery contract. This paper describes the CCD273-84 detector, the test method used for MTF measurements at e2v and the test method used for PSF measurements at MSSL. Results are presented for MTF measurements at e2v over all pre development devices. Also presented is a cross comparison of the data from the MTF and PSF measurement techniques on the same device. Good agreement between the measured PSF Full Width Half Maximum and the equivalent Full Width Half Maximum derived from the MTF images and test results is shown, with results that indicate diffusion FWHM values at or below 10 micron for the CCD273-84 detectors over the spectral range measured. At longer wavelengths the diffusion FWHM is shown to be in the 6-8 micron range.

Background.This study evaluated whether a community psychiatric nurse (CPN) team providing a comprehensive aftercare service, using a case management approach, improves psychopathology and social functioning of the long-term mentally ill, and reduces hospital use compared with a generic CPN team.Method.Patients suffering from severe and persistent mental health problems were randomised to intensive aftercare or generic care after referral to the CPN manager. Each group contained 41 patients who were assessed at baseline and at 6, 12 and 18 months by an independent research psychologist. Outcome measures included the GAS, PSE, SAS, patient and relatives' satisfaction, number of admissions, and length of stay.Results.No difference between the groups was found on any of the outcome measures, despite the much higher number of contacts of the intensive (n = 52) versus generic CPNs (n = 13) and the much greater range of interventions.Conclusions.Intensive aftercare for people with persistent mental health problems was not found to be of greater benefit than generic CPN care. Many factors need to be considered for aftercare to be effective, including community resources, process of care, and staff training.

An imaging test bed has been constructed for exploring the design considerations for selecting the appropriate image sampling or Q for electro-optical earth imaging systems where Q is defined as (λf/#) / pixel pitch. The test bed includes errors such as image smear and shot noise produced by atmospheric haze. The value of Q can be varied by either changing the focal length of the imaging system or by varying the imaging aperture diameter. All of these parameters are varied to understand the effects on image quality. In this paper we explore practical design considerations for selecting Q for an electro-optical earth imaging system. In particular we will focus on image degradation caused by increasing Q by reducing the imaging aperture diameter.

International audience; For the first time, subelectron readout noise has been achieved with a camera dedicated to astronomical wavefront-sensing applications. The OCam system demonstrated this performance at a 1300 Hz frame rate and with 240 x 240 pixel frame size. ESO and JRA2 OPTICON jointly funded e2v Technologies to develop a custom CCD for adaptive optics (AO) wavefront-sensing applications. The device, called CCD220, is a compact Peltier-cooled 240 x 240 pixel frame-transfer eight-output back-illuminated sensor using the EMCCD technology. This article demonstrates, for the first time, subelectron readout noise at frame rates from 25 Hz to 1300 Hz and dark current lower than 0.01 e(-) pixel(-1) frame(-1). It reports on the quantitative performance characterization of OCam and the CCD220, including readout noise, dark current, multiplication gain, quantum efficiency, and charge transfer efficiency. OCam includes a low-noise preamplifier stage, a digital board to generate the clocks, and a microcontroller. The data acquisition system includes a user-friendly timer file editor to generate any type of clocking scheme. A second version of OCam, called OCam(2), has been designed to offer enhanced performance, a completely sealed camera package, and an additional Peltier stage to facilitate operation on a telescope or environmentally challenging applications. New features of OCam(2) are presented in this article. This instrumental development will strongly impact the performance of the most advanced AO systems to come.

For the first time, sub-electron read noise has been achieved with a camera suitable for astronomical wavefront-sensing (WFS) applications. The OCam system has demonstrated this performance at 1300 Hz frame rate and with 240×240-pixel frame rate. ESO and JRA2 OPTICON 2 have jointly funded e2v technologies to develop a custom CCD for Adaptive Optics (AO) wavefront sensing applications. The device, called CCD220, is a compact Peltier-cooled 240×240 pixel frame-transfer 8-output back-illuminated sensor using the EMCCD technology. This paper demonstrates sub-electron read noise at frame rates from 25 Hz to 1300 Hz and dark current lower than 0.01 e-/pixel/frame. It reports on the comprehensive, quantitative performance characterization of OCam and the CCD220 such as readout noise, dark current, multiplication gain, quantum efficiency, charge transfer efficiency... OCam includes a low noise preamplifier stage, a digital board to generate the clocks and a microcontroller. The data acquisition system includes a user friendly timer file editor to generate any type of clocking scheme. A second version of OCam, called OCam 2 , was designed offering enhanced performances, a completely sealed camera package and an additional Peltier stage to facilitate operation on a telescope or environmentally rugged applications. OCam 2 offers two types of built-in data link to the Real Time Computer: the CameraLink industry standard interface and various fiber link options like the sFPDP interface. OCam 2 includes also a modified mechanical design to ease the integration of microlens arrays for use of this camera in all types of wavefront sensing AO system. The front cover of OCam 2 can be customized to include a microlens exchange mechanism.

Digital Holography is a technique which provides a measurement of the complex field reflecting from a coherently illuminated object. When the measurement is performed with two carefully chosen wavelengths a phase difference map can be created providing a three dimensional map of the object. We present results from a laboratory experiment where the surface contours of coral are measured in seawater. Contour maps with step sizes on the order of 0.1 mm can easily be obtained. We propose that this technique be used to remotely monitor the growth of coral in an effort to quantify the health of coral beds. The technique is effective from space, aircraft, ships, buoys or rigid platforms such as a pier. In the last few years we have been successfully using this technique to measure objects through very turbulent atmosphere at ranges of up to 700 meters and we are now applying the concept to shoreline applications.

ESO and JRA2 OPTICON have jointly funded e2v technologies to develop a custom CCD for Adaptive Optic Wave Front Sensor (AO WFS) applications. The device, called CCD220, is a compact Peltier-cooled 240×240 pixel frametransfer 8-output back-illuminated sensor. Using the electron-multiplying technology of L3Vision detectors, the device is designed to achieve sub-electron read noise at frame rates from 25 Hz to 1,500 Hz and dark current lower than 0.01 e-/pixel/frame. The development has many unique features. To obtain high frame rates, multiple EMCCD gain registers and metal buttressing of row clock lines are used. The baseline device is built in standard silicon. In addition, two speculative variants have been built; deep depletion silicon devices to improve red response and devices with an electronic shutter to extend use to Rayleigh and Pulsed Laser Guide Star applications. These are all firsts for L3Vision CCDs. These CCD220 detectors have now been fabricated by e2v technologies. This paper describes the design of the device, technology trade-offs, and progress to date. A Test Camera, called "OCam", has been specially designed and built for these sensors. Main features of the OCam camera are extensively described in this paper, together with first light images obtained with the CCD220.

A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described.

Following successful manufacture of small-format trial devices we have now designed and manufactured large-format scientific CCDs in high resistivity silicon ('high-rho'). These devices are intended for 'full depletion' operation as backside illuminated sensors for very high red wavelength sensitivity and X-ray imaging spectroscopy at extended energies. Devices of 2k*512 and 2k*4k format, with both single and dual stage output circuits have been manufactured and tested. Design considerations, test results, and commercial manufacturing considerations will be addressed.

ESO and JRA2 OPTICON have funded e2v technologies to develop a compact packaged Peltier cooled 24 μm square 240x240 pixels split frame transfer 8-output back-illuminated L3Vision CCD3, L3Vision CCD for Adaptive Optic Wave Front Sensor (AO WFS) applications. The device is designed to achieve sub-electron read noise at frame rates from 25 Hz to 1,500 Hz and dark current lower than 0.01 e-/pixel/frame. The development has many unique features. To obtain high frame rates, multi-output EMCCD gain registers and metal buttressing of row clock lines are used. The baseline device is built in standard silicon. In addition, a split wafer run has enabled two speculative variants to be built; deep depletion silicon devices to improve red response and devices with an electronic shutter to extend use to Rayleigh and Pulsed Laser Guide Star applications. These are all firsts for L3Vision CCDs. The designs of the CCD and Peltier package have passed their reviews and fabrication has begun. This paper will describe the progress to date, the requirements and the design of the CCD and compact Peltier package, technology trade-offs, schedule and proposed test plan. High readout speed, low noise and compactness (requirement to fit in confined spaces) provide special challenges to ESO's AO variant of its NGC, New General detector Controller to drive this CCD. This paper will describe progress made on the design of the controller to meet these special needs.

Electron multiplying CCD (EMCCD) technology has found important initial applications in low light surveillance and photon starved scientific instrumentation. This paper discusses the attributes of the EMCCD which make it useful for certain space instruments, particularly those which are photon starved, and explores likely risks from the radiation expected in such instruments.

A new CCD sensor technology has been developed by Marconi Applied Technologies which effectively reduces read-out noise to less than one electron rms. A single low light level CCD can operate over a wide range of read-out rates from TV to slow-scan and give superior performance to that available from either intensified or slow-scan CCD sensors.

A radically new CCD development by Marconi Applied Technologies has enabled substantial internal gain within the CCD before the signal reaches the output amplifier. With reasonably high gain, sub-electron readout noise levels are achieved even at MHz pixel rates. This paper reports a detailed assessment of these devices, including novel methods of measuring their properties when operated at peak mean signal levels well below one electron per pixel. The devices are shown to be photon shot noise limited at essentially all light levels below saturation. Even at the lowest signal levels the charge transfer efficiency is good. The conclusion is that these new devices have radically changed the balance in the perpetual trade-off between readout noise and the speed of readout. They will force a re-evaluation of camera technologies and imaging strategies to enable the maximum benefit to be gained from these high-speed, essentially noiseless readout devices. This new LLLCCD technology, in conjunction with thinning (backside illumination) should provide detectors which will be very close indeed to being theoretically perfect., Contribution to SPIE conference proceedings HTML version: http://www.strw.leidenuniv.nl/~tubbs/papers/lllccd/sern_main.html

As the need for timely and accurate information becomes more important, healthcare organizations (HCOs) must learn how to get the best results from existing or new information technology (IT). While every organization has its own approach or culture regarding IT, many ignore some very simple tactics for optimizing their own IT. Often, the steps needed to improve IT performance are easily attained but not easily recognized. Overlooking these crucial steps can send an organization down many frustrating paths, ultimately increasing the cost of IT.

Electron Bombarded Charge Coupled Devices (EBCCD) which utilize a high performance Gallium Arsenide (GaAs) photocathode have been fabricated and characterized for performance and tube operating life. The EBCCD utilized an 11 mm diagonal, backside illuminated, frame transfer CCD compatible with RS170 video output. The CCD incorporated lateral anti-blooming structures optimized for backside operation. The EBCCD tube was proximity focused and operated with high gain (greater than 150) at low electron landing voltages (less than 2 kV). The EBCCD was integrated in a gated camera system with fast rise and fall times (less than 50 ns). Predicted operating life in a gated camera system as determined by accelerated tests is in excess of 12,000 hours, limited by photocathode degradation.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper explores practical design considerations for selecting Q for an electro-optical earth imaging system, where Q is defined as (λ FN) / pixel pitch. Analytical methods are used to show that, under imaging conditions with high SNR, increasing Q with fixed aperture cannot lead to degradation of image quality regardless of the angular smear rate of the system. The potential for degradation of image quality under low SNR is bounded by an increase of the detector noise scaling as Q. An imaging test bed is used to collect representative imagery for various Q configurations. The test bed includes real world errors such as image smear and haze. The value of Q is varied by changing the focal length of the imaging system. Imagery is presented over a broad range of parameters.

Phasing the sub apertures of a multiple aperture telescope is a difficult problem that has been addressed in various ways. Hartmann sensors and knife edge tests are techniques that work well for point source objects such as stars. Null fringe tracking is also suitable for point sources. However, none of these techniques are adequate for extended object imaging. Radial shearing white-light interferometers have been proposed and tested but are complicated to implement and have a strong object dependence. Laser metrology systems are extremely accurate but do not give a direct measurement of the phase errors and can be difficult to implement. Phase diversity is a very simple phasing technique that is suitable for extended objects and has developed into a mature technology over the past five years.