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FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) will flight as the 9th ESA’s Earth Explorer mission, and an End-to-End Simulator (E2ES) has been developed as a support tool for the mission selection process and the subsequent development phases. The current status of the FORUM E2ES project is presented, together with the characterization of the capabilities of a full physics retrieval code applied to FORUM data. We show how the instrument characteristics and5the observed scene conditions impact on the spectrum measured by the instrument, accounting for the main sources of error related to the entire acquisition process, and the consequences on the retrieval algorithm. Both homogeneous and heterogeneous case studies are simulated in clear and cloudy conditions, validating the E2ES against two independent codes: KLIMA (clear sky) and SACR (cloudy sky). The performed tests show that the performance of the retrieval algorithm is compliant with the project requirements both in clear and cloudy conditions. The far infrared (FIR) part of the FORUM spectrum is shown to be10sensitive to surface emissivity, in dry atmospheric conditions, and to cirrus clouds, resulting in improved performance of the retrieval algorithm in these conditions. The retrieval errors increase with increasing the scene heterogeneity, both in terms of surface characteristics and in terms of fractional cloud cover of the scene.

The longwave downwelling spectral radiance measurements performed by means of the Far-Infrared Radiation Mobile Observation System (FIRMOS) spectrometer at the summit of the Mt. Zugspitze (German Alps) in the Winter 2018–2019, allowed to retrieve the optical and micro-physical properties of ice, mixed and water clouds, showing a good agreement of the statistical relationship between the ice water path and the ice optical depth with the ones from previous works. In this paper the optical depths retrieved from FIRMOS are initially compared with selected cases calculated from backscattering Light Detection And Ranging (LiDAR) data by using a transmittance method. Then, in order to compare the whole FIRMOS dataset, the power-law relationship between backscattering and extinction is used to apply the Klett method and automatize the routine. Minimizing the root mean square differences, the exponent of the relationship, the so called backscatter-extinction coefficient ratio, is assessed to be 0.85 with a variabiliy in the range 0.60–1.10 for ice clouds and 0.50 with a variability within 0.30–0.70 for mixed and water clouds.

Measurements of the spectrum of the atmospheric emission in the far-infrared (FIR) range, between 100 and 667 cm(-1) (100-15 mu m) are scarce because of the detection complexity and of the strong absorption of air at ground level preventing the sounding of the FIR from low altitude. Consequently, FIR measurements need to be made from high-altitude sites or on board airborne platforms or satellites. This paper describes the dataset of FIR spectral radiances of the atmosphere and snow surface emission measured in the 100-1000 cm(-1) range by the Far-Infrared Radiation Mobile Observation System (FIRMOS) instrument during a 2-month campaign carried out from the ground at about 3000m of altitude on the top of Mt. Zugspitze in the German Alps in 2018-2019. This campaign is part of the preparatory activity of a new space FIR mission, named Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM), which is under development by the European Space Agency (ESA). The dataset acquired during the campaign also includes all the additional measurements needed to provide a full characterisation of the observed atmospheric state and the local atmospheric and surface conditions. It includes co-located spectral measurements in the infrared range from 400 to 1800 cm(-1); lidar backscatter profiles; radio soundings of temperature, humidity and aerosol backscatter profiles; local weather parameters; and snow/ice microphysical properties. These measurements provide a unique dataset that can be used to perform radiative closure experiments to improve modelling parameters in the FIR that are not well-characterised, such as water vapour spectroscopy, scattering properties of cirrus clouds, and the FIR emissivity of the surface covered by snow. The consolidated dataset is freely available via the ESA campaign dataset website at https://doi.org/10.5270/ESA-38034ee (Palchetti et al., 2020a)., Earth System Science Data, 13 (9), ISSN:1866-3516, ISSN:1866-3508

For the preparation of the FORUM Earth Explorer mission, which will be launched by ESA in 2026, a mobile FTS prototype was developed to perform far-IR measurements of the atmospheric emission from ground-based sites and stratospheric bal- loons.

Remote sensing of the atmospheric composition from current and future satellites, such as the Sentinel missions of the Copernicus programme, yields an unprecedented amount of data to monitor air quality, ozone, UV radiation and other climate variables. Hence, full exploitation of the growing wealth of information delivered by spaceborne observing systems requires addressing the technological challenges for developing new strategies and tools that are capable to deal with these huge data volumes. The H2020 AURORA (Advanced Ultraviolet Radiation and Ozone Retrieval for Applications) project investigated a novel approach for synergistic use of ozone profile measurements acquired at different frequencies (ultraviolet, visible, thermal infrared) by sensors onboard Geostationary Equatorial Orbit (GEO) and Low Earth Orbit (LEO) satellites in the framework of the Copernicus Sentinel-4 and Sentinel-5 missions. This paper outlines the main features of the technological infrastructure, designed and developed to support the AURORA data processing chain as a distributed data processing and describes in detail the key components of the infrastructure and the software prototype. The latter demonstrates the technical feasibility of the automatic execution of the full processing chain with simulated data. The Data Processing Chain (DPC) presented in this work thus replicates a processing system that, starting from the operational satellite retrievals, carries out their fusion and results in the assimilation of the fused products. These consist in ozone vertical profiles from which further modules of the chain deliver tropospheric ozone and UV radiation at the Earth&rsquo, s surface. The conclusions highlight the relevance of this novel approach to the synergistic use of operational satellite data and underline that the infrastructure uses general-purpose technologies and is open for applications in different contexts.

Attack rate in Manaus Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) incidence peaked in Manaus, Brazil, in May 2020 with a devastating toll on the city's inhabitants, leaving its health services shattered and cemeteries overwhelmed. Buss et al. collected data from blood donors from Manaus and São Paulo, noted when transmission began to fall, and estimated the final attack rates in October 2020 (see the Perspective by Sridhar and Gurdasani). Heterogeneities in immune protection, population structure, poverty, modes of public transport, and uneven adoption of nonpharmaceutical interventions mean that despite a high attack rate, herd immunity may not have been achieved. This unfortunate city has become a sentinel for how natural population immunity could influence future transmission. Events in Manaus reveal what tragedy and harm to society can unfold if this virus is left to run its course. Science , this issue p. 288 ; see also p. 230

The herd immunity threshold is the proportion of a population that must be immune to an infectious disease, either by natural infection or vaccination such that, in the absence of additional preventative measures, new cases decline and the effective reproduction number falls below unity1. This fundamental epidemiological parameter is still unknown for the recently-emerged COVID-19, and mathematical models have predicted very divergent results2,3. Population studies using antibody testing to infer total cumulative infections can provide empirical evidence of the level of population immunity in severely affected areas. Here we show that the transmission of SARS-CoV-2 in Manaus, located in the Brazilian Amazon, increased quickly during March and April and declined more slowly from May to September. In June, one month following the epidemic peak, 44% of the population was seropositive for SARS-CoV-2, equating to a cumulative incidence of 52%, after correcting for the false-negative rate of the antibody test. The seroprevalence fell in July and August due to antibody waning. After correcting for this, we estimate a final epidemic size of 66%. Although non-pharmaceutical interventions, plus a change in population behavior, may have helped to limit SARS-CoV-2 transmission in Manaus, the unusually high infection rate suggests that herd immunity played a significant role in determining the size of the epidemic.

The first case of COVID-19 was detected in Brazil on 25 February 2020. We report and contextualize epidemiological, demographic and clinical findings for COVID-19 cases during the first 3 months of the epidemic. By 31 May 2020, 514,200 COVID-19 cases, including 29,314 deaths, had been reported in 75.3% (4,196 of 5,570) of municipalities across all five administrative regions of Brazil. The R0 value for Brazil was estimated at 3.1 (95% Bayesian credible interval = 2.4–5.5), with a higher median but overlapping credible intervals compared with some other seriously affected countries. A positive association between higher per-capita income and COVID-19 diagnosis was identified. Furthermore, the severe acute respiratory infection cases with unknown aetiology were associated with lower per-capita income. Co-circulation of six respiratory viruses was detected but at very low levels. These findings provide a comprehensive description of the ongoing COVID-19 epidemic in Brazil and may help to guide subsequent measures to control virus transmission.

Recent observations and model studies of the earth’s radiative energy balance have focused attention on the earth’s top of atmosphere (TOA) energy balance. This is the balance between the shortwave energy absorbed by the earth, which is represented by a spatially and temporally averaged absorbed flux , and the emitted longwave energy, which is represented by the corresponding averaged emitted flux . The TOA average net flux FN is defined as the difference between the two over the averaged area and time, which may be a local, regional, or global average. A global nonzero net flux represents a measure of imbalance between the energy being absorbed and emitted by the earth for the time interval in question. It is of interest to ask what the natural variability of the net flux might be and whether, during times of climate change, signals of important climate change processes might be detected against this natural background variation; examples of these signals include evidence of ocean heat storage, the effects of El Niño, and the radiative effects of volcanic eruptions. In this paper, the authors review the significance of the net flux, survey the observational evidence from a range of satellite instruments over several decades, and analyze some of the most recent observations from the Clouds and the Earth’s Radiant Energy System (CERES) program to determine what signals and what natural variability might be expected in the TOA net flux. Based on this analysis, the use of broadband radiation measurements for global climate change studies can be assessed.

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument was launched aboard the environmental satellite ENVISAT into its sun-synchronous orbit on 1 March 2002. The short-lived species NO2 is one of the key target products of MIPAS that are operationally retrieved from limb emission spectra measured in the stratosphere and mesosphere. Within the MIPAS validation activities, a large number of independent observations from balloons, satellites and ground-based stations have been compared to European Space Agency (ESA) version 4.61 operational NO2 data comprising the time period from July 2002 until March 2004 where MIPAS measured with full spectral resolution. Comparisons between MIPAS and balloon-borne observations carried out in 2002 and 2003 in the Arctic, at mid-latitudes, and in the tropics show a very good agreement below 40 km altitude with a mean deviation of roughly 3%, virtually without any significant bias. The comparison to ACE satellite observations exhibits only a small negative bias of MIPAS which appears not to be significant. The independent satellite instruments HALOE, SAGE II, and POAM III confirm in common for the spring-summer time period a negative bias of MIPAS in the Arctic and a positive bias in the Antarctic middle and upper stratosphere exceeding frequently the combined systematic error limits. In contrast to the ESA operational processor, the IMK/IAA retrieval code allows accurate inference of NO2 volume mixing ratios under consideration of all important non-LTE processes. Large differences between both retrieval results appear especially at higher altitudes, above about 50 to 55 km. These differences might be explained at least partly by non-LTE under polar winter conditions but not at mid-latitudes. Below this altitude region mean differences between both processors remain within 5% (during night) and up to 10% (during day) under undisturbed (September 2002) conditions and up to 40% under perturbed polar night conditions (February and March 2004). The intercomparison of ground-based NDACC observations shows no significant bias between the FTIR measurements in Kiruna (68° N) and MIPAS in summer 2003 but larger deviations in autumn and winter. The mean deviation over the whole comparison period remains within 10%. A mean negative bias of 15% for MIPAS daytime and 8% for nighttime observations has been determined for UV-vis comparisons over Harestua (60° N). Results of a pole-to-pole comparison of ground-based DOAS/UV-visible sunrise and MIPAS mid-morning column data has shown that the mean agreement in 2003 falls within the accuracy limit of the comparison method. Altogether, it can be indicated that MIPAS NO2 profiles yield valuable information on the vertical distribution of NO2 in the lower and middle stratosphere (below about 45 km) during day and night with an overall accuracy of about 10–20% and a precision of typically 5–15% such that the data are useful for scientific studies. In cases where extremely high NO2 occurs in the mesosphere (polar winter) retrieval results in the lower and middle stratosphere are less accurate than under undisturbed atmospheric conditions.

Interannual variability in spectrally resolved longwave radiances is quantified at a variety of spatial scales using 5 yr of IASI observations. Maximum variability is seen at the smallest scales investigated (10° zonal means) at northern and southern high latitudes across the center of the 15-µm CO2 band. As the spatial scale increases, the overall magnitude of interannual variability is reduced across the spectrum and the spectral shape of the variability changes. In spectral regions sensitive to conditions in the upper troposphere, the effect of increasing spatial scale is relatively small and at the global scale these parts of the spectrum show the greatest year-to-year variability. Conversely, the atmospheric window (8–12 µm), which is sensitive to variations in surface temperature and cloud, shows a marked reduction in interannual variability with increasing spatial scale. Over the 5 yr studied, at global scales the standard deviation in annual mean brightness temperature is less than 0.17 K across the spectrum, dropping to less than 0.05 K across the window. Spectrally integrating the IASI measurements to create pseudobroadband and window channels indicates a variation about the mean that is higher for the broadband channel than for the window channel at the global and quasi-global scales and over the Southern Hemisphere. These findings are in agreement with observations from CERES Terra over the same period and imply that at the largest spatial scales, over the period considered here, fluctuations in mid- to upper-tropospheric temperatures and water vapor, and not cloud or surface temperature, play the dominant role in determining the level of interannual variability in all-sky outgoing longwave radiation.

The retrieval of concentration vertical profiles of atmospheric constituents from spectroscopic measurements is often an ill-conditioned problem and regularization methods are frequently used to improve its stability. Recently a new method, that provides a good compromise between precision and vertical resolution, was proposed to determine analytically the value of the regularization parameter. This method is applied for the first time to real measurements with its implementation in the operational retrieval code of the satellite limb-emission measurements of the MIPAS instrument and its performances are quantitatively analyzed. The adopted regularization improves the stability of the retrieval providing smooth profiles without major degradation of the vertical resolution. In the analyzed measurements the retrieval procedure provides a vertical resolution that, in the troposphere and low stratosphere, is smaller than the vertical field of view of the instrument.

The present study reports life-table parameters and compares the longevity, fecundity, egg-to-adult development times and the length of the reproductive periods for five phytoseiid species (Typhlodromus annectens, Amblyseius californicus, A. idaeus, Euseius concordis, andPhytoseiulus macropilis) when reared onMononychellus progresivus orTetranychus urticae. Recommendations regarding the use of these species for classical biological control ofM. tanajoa in Africa are made.

Apodization, which is a tool frequently used for cosmetic representation and efficient modeling of a spectrum, is now also adopted in techniques for the quantitative retrieval of parameters from observed spectra. Whether apodization can help in quantitative spectroscopy is the subject of debate in the literature. We find that, when the considered spectral range is wide enough to accurately model the instrument line shape, the same results can be obtained with and without apodization of the spectrum. However, when a truncation error is introduced by the limited extension of the modeled spectral interval, apodization can efficiently reduce this error. Therefore it is possible to save computing time by using apodization.

The REFIR-PAD (Radiation Explorer in the Far InfraRed - Prototype for Applications and Development) Fourier transform spectroradiometer has successfully performed, at the end of June, 2005, a stratospheric balloon flight from Teresina, Brazil. The instrument has provided 8 hours worth of nadir-looking spectra acquired with a resolution of 0.5 cm -1 in the 100 to 1400 cm -1 spectral range, thus covering both the far-infrared range. containing the radiative signature of the upper tropospheric water vapour, and the better-known mid-infrared range, which provides validation with existing instruments. From the analysis of the calibrated spectra we obtain valuable information on the contribution to the Earth's outgoing long-wave radiation of water, both in the vapour and cloud form, in a region of the atmosphere, the upper-troposphere/lower-stratosphere, in which this contribution has a critical role.

The first spectral measurement of Earth’s emitted radiation to space in the widebandrange from 100 to 1400cm −1 with 0.5cm −1 spectral resolution is presented. The mea-surement was performed from a stratospheric balloon in tropical region using a Fourier 5 transform spectrometer, during a field campaign held in Brazilin June2005. The instru-ment, which has uncooled components including the detector module, is a prototypedeveloped as part of the study for the REFIR (Radiation Explorer in the Far InfraRed)space mission. This paper shows the results of the field campaign with particular atten-tion to the measurement capabilities of the prototype. The results are compared with 10 measurements taken by IASI-balloon (Infrared Atmospheric Sounding Interferometer –Balloon version), aboard the same platform, and with forward model estimations. Theinfrared signature of clouds is observed in the measurements. 1 Introduction The observation of the upwelling emission in the full relevant spectral range, from the

The MIPAS instrument, operating on board of the Envisat satellite, with its broad band and high resolution measurements has posed a major challenge to operational retrieval techniques. The code developed for the operational analysis of MIPAS measurements has proved that near-realtime operation is possible and that a three-dimensional picture of the atmospheric composition can be retrieved from satellite observations. The features and performances of MIPAS retrieval code are briefly recalled.

International audience; The MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument has been operating on-board the ENVISAT satellite since March 2002. In the first two years, it acquired in a nearly continuous manner high resolution (0.025 cm-1 unapodized) emission spectra of the Earth's atmosphere at limb in the middle infrared region. This paper describes the level 2 near real-time (NRT) and off-line (OL) ESA processors that have been used to derive level 2 geophysical products from the calibrated and geolocated level 1b spectra. The design of the code and the analysis methodology have been driven by the requirements for NRT processing. This paper reviews the performance of the optimized retrieval strategy that has been implemented to achieve these requirements and provides estimated error budgets for the target products: pressure, temperature, O3, H2O, CH4, HNO3, N2O and NO2, in the altitude measurement range from 6 to 68 km. From application to real MIPAS data, it was found that no change was needed in the developed code although an external algorithm was introduced to identify clouds with high opacity and to exclude affected spectra from the analysis. In addition, a number of updates were made to the set-up parameters and to auxiliary data. In particular, a new version of the MIPAS dedicated spectroscopic database was used and, in the OL analysis, the retrieval range was extended to reduce errors due to uncertainties in extrapolation of the profile outside the retrieval range and more stringent convergence criteria were implemented. A statistical analysis on the ?2 values obtained in one year of measurements shows good agreement with the a priori estimate of the forward model errors. On the basis of the first two years of MIPAS measurements the estimates of the forward model and instrument errors are in general found to be conservative with excellent performance demonstrated for frequency calibration. It is noted that the total retrieval error is limited by forward model errors which make effectless a further reduction of random errors. However, such a reduction is within the capabilities of MIPAS measurements, which contain many more spectral signatures of the target species than what has currently been used. Further work is needed to reduce the amplitude of the forward model errors, so that the random error and the total error budget can be reduced accordingly. The importance of the Averaging kernels for a full characterization of the target products is underlined and the equations are provided for their practical applications.

A Genetic Algorithm for environmental tomographic applications has been developed. This algorithm has been designed to be applied on the reconstruction of 2D concentration fields of atmospheric gas whose integral measurements are obtained by an open path tomographic system based on IR laser devices. Here, we focus on the performance analysis of the genetic reconstruction algorithm applied to simulated two-dimensional scalar fields by processing a set of one dimensional measurements.

The southern area of Italy is characterized by the presence of many active volcanic areas. In Pozzuoli (Napoli, Italy), an urban area characterized by high volcanic risk, a gaseous emitting site is present. CO2 is one of the emitted gases and the measurement of its atmospheric concentration is an important task in many environmental and scientific applications. A mobile IR laser system, able to measure the CO2 concentration along rectilinear atmospheric paths up to 1 km length, has been used in that area. The system computes the average concentration by processing the received IR laser radiation propagated along an open-air rectilinear link connecting the transmitter/receiver laser unit and a passive retroreflector device. The laser system scans a spectral range centered on 1580 nm wavelength. An isolated CO2 absorption line characterizes such range. A one-day measurement campaign has been made and more than 15 different atmospheric propagation links were considered moving the transmitter/receiver unit and some retroreflectors. The links were located over a gaseous emitting area whose extension is less than 100x100 square meters. A meteorological station was present and also temperature and wind measurements have been collected. CO2 measurements and meteorological data are presented and discussed. Moreover, the spatial configuration of the measurement links is such that ad-hoc tomographic data processing procedures are profitably usable. The two-dimensional time-averaged spatial distribution of the CO2 at about 1.5 meters over the monitored area is reported as retrieved by the tomographic procedures. Potential and perspectives of tomographic processing are also evidenced.

International audience; The first spectral measurement of Earth's emitted radiation to space in the wideband range from 100 to 1400 cm-1 with 0.5 cm-1 spectral resolution is presented. The measurement was performed from a stratospheric balloon in tropical region using a Fourier transform spectrometer, during a field campaign held in Brazil in June 2005. The instrument, which has uncooled components including the detector module, is a prototype developed as part of the study for the REFIR (Radiation Explorer in the Far InfraRed) space mission. This paper shows the results of the field campaign with particular attention to the measurement capabilities of the prototype. The results are compared with measurements taken by IASI-balloon (Infrared Atmospheric Sounding Interferometer – Balloon version), aboard the same platform, and with forward model estimations. The infrared signature of clouds is observed in the measurements.