Spaceborne Infrared Atmospheric Sounder

A report describes the development of the spaceborne infrared atmospheric sounder (SIRAS) - a spectral imaging instrument, suitable for observing the atmosphere of the Earth from a spacecraft, that utilizes four spectrometers to cover the wavelength range of 12 to 15.4 m with a spectral resolution that ranges between 1 part per 900 and 1 part per 1,200 in wavelength. The spectrometers are operated in low orders to minimize filtering requirements. Focal planes receive the dispersed energy and provide a spectrum of the scene. The design of the SIRAS combines advanced, wide-field refractive optics with high-dispersion gratings in a solid-state (no moving parts), diffraction-limited optical system that is the smallest such system that can be constructed for the specified wavelength range and resolution. The primary structure of the SIRAS has dimensions of 10 by 10 by 14 cm and has a mass of only 2.03 k

Mixed Valence Europium Nitridosilicate Eu2SiN3

The mixed valence europium nitridosilicate Eu2SiN3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH)2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a=542.3(11) pm, b=1061.0(2) pm, c=1162.9(2) pm, Z=8, 767 independent reflections, 37 parameters, R1=0.017, wR2=0.032). Eu2SiN3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN4 tetrahedra running parallel [100] with a maximum stretching factor fs=1.0. The compound is isostructural with Ca2PN3 and Rb2TiO3, and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu2+ and Eu3+, respectively. 151Eu Mössbauer spectroscopy of Eu2SiN3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu2+ and Eu3+ signals over the whole temperature range. The Eu2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 μB/f.u. and a small contribution of Eu3+, in accordance with Eu2+ and Eu3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at TC=24 K. DFT calculations of Eu2SiN3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu2+ and Eu3+

Plan de mantenimiento en equipos críticos

Proyecto Integrador (II)--FCEFN-UNC, 2021Fil: Gatica Pagano, Thomas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Escuela de Ingeniería Industrial; Argentina.En el presente proyecto tiene como objetivo el diseño de un plan de mantenimiento para los activos fijos críticos de la empresa F2J LIGHTING CORDOBA, la cual se dedica a la fabricación de proyectores principales y faros traseros de autos. La empresa presenta problemas en el mantenimiento de sus equipos, ya que las tareas necesarias para conservar y mejorar sus máquinas no está correctamente implementada. Para llegar al diseño de un plan óptimo, se realizó un estudio integral de la empresa. Se observaron los objetivos, metas, proceso de producción, como también el sistema de mantenimiento actual y un relevamiento de las máquinas de producción. Se seleccionó un grupo de máquinas dentro de la empresa, que son las inyectoras, ya que es una etapa clave dentro del proceso de producción, luego se procede a un cálculo de criticidad de máquinas, identificando las máquinas más importantes en el proceso y mediante una serie de indicadores se analiza la fiabilidad y el estado de funcionamiento de las mismas en relación a los objetivos establecidos por la empresa. Se procede a realizar una recolección de datos en donde se podrá observar las causas de las fallas y el impacto en tiempo que ocasionan sobre la producción. En base a la información recolectada y procesada, se propone realizar una mejora y actualización en la implementación del mantenimiento autónomo y el mantenimiento preventivo para de esta manera disminuir dichas causas de fallas. Por último, se estima que esta implementación tendrá una reducción en las perdidas de la compañía, puesto que se reducirá las fallas en las máquinas, optimizando el tiempo de producción y generando mayores beneficios.Fil: Gatica Pagano, Thomas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Escuela de Ingeniería Industrial; Argentina

The influence of tropospheric biennial oscillation on mid-tropospheric CO_2

Mid-tropospheric CO_2 retrieved from the Atmospheric Infrared Sounder (AIRS) was used to investigate CO_2 interannual variability over the Indo-Pacific region. A signal with periodicity around two years was found for the AIRS mid-tropospheric CO_2 for the first time, which is related to the Tropospheric Biennial Oscillation (TBO) associated with the strength of the monsoon. During a strong (weak) monsoon year, the Western Walker Circulation is strong (weak), resulting in enhanced (diminished) CO_2 transport from the surface to the mid-troposphere. As a result, there are positive (negative) CO2 anomalies at mid-troposphere over the Indo-Pacific region. We simulated the influence of the TBO on the mid-tropospheric CO_2 over the Indo-Pacific region using the MOZART-2 model, and results were consistent with observations, although we found the TBO signal in the model CO_2 is to be smaller than that in the AIRS observations

Propagating Alfvén waves in open structures with random structuring

The research leading to these results has received funding from the UK Science and Technology Facilities Council (consolidated grant ST/N000609/1), the European Union Horizon 2020 research and innovation programme (grant agreement No. 647214). IDM received funding from the Research Council of Norway through its Centres of Excellence scheme, project number 262622.We consider the behaviour of Alfvén waves propagating in a medium with random density perturbations. The imposed density perturbations have a broadband spectrum and their characteristic spatial scale may be defined according to the peak in the spectrum. The interaction of the boundary driven Alfvén waves with the medium generates reflections most efficiently when their wavelength is comparable to the spatial scale of the density perturbations. For our monotonic driver, this leads to the generation of quasi-periodic oscillations. The periods of oscillation of the propagating Alfvén waves is no longer only associated with the driver. Additional periodicities may be associated with one or more characteristic spatial scales in the density profile, or with beating between other spectral components. Multiple wave reflections cause oscillatory power to be retained at low altitudes, increasing opportunities to contribute to heating at those locations.Publisher PDFPeer reviewe

Modulation of Midtropospheric CO_2 by the South Atlantic Walker Circulation

Midtropospheric CO_2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO_2 over the South Atlantic Ocean. It was found that the area-averaged CO_2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December–March. This CO_2 contrast is due to the large-scale vertical circulation over this region. During December–March, there is sinking motion over the South Atlantic Ocean. The sinking motion brings high-altitude air with a slightly lower concentration of CO_2 to the midtroposphere. Meanwhile, air rising over South America brings near-surface air with a higher concentration of CO_2 to the midtroposphere. As a result, the AIRS midtropospheric CO_2 concentration is lower over the South Atlantic Ocean than over South America during December–March. The detrended AIRS midtropospheric CO_2 difference correlates well with the inverted and detrended 400-hPa vertical pressure velocity difference between the South Atlantic and South America. Results obtained from this study demonstrate the strong impact of large-scale circulation on the vertical distribution of CO_2 in the free troposphere and suggest that midtropospheric CO_2 measurements can be used as an innovative observational constraint on the simulation of large-scale circulations in climate models

Influence of Stratospheric Sudden Warming on AIRS Midtropospheric CO_2

Midtropospheric CO_2 retrievals from the Atmospheric Infrared Sounder (AIRS) were used to explore the influence of stratospheric sudden warming (SSW) on CO_2 in the middle to upper troposphere. To choose the SSW events that had strong coupling between the stratosphere and troposphere, the authors applied a principal component analysis to the NCEP/Department of Energy Global Reanalysis 2 (NCEP-2) geopotential height data at 17 pressure levels. Two events (April 2003 and March 2005) that have strong couplings between the stratosphere and troposphere were chosen to investigate the influence of SSW on AIRS midtropospheric CO_2. The authors investigated the temporal and spatial variations of AIRS midtropospheric CO_2 before and after the SSW events and found that the midtropospheric CO_2 concentrations increased by 2–3 ppm within a few days after the SSW events. These results can be used to better understand how the chemical tracers respond to the large-scale dynamics in the high latitudes

NOAA EON-IR CubeSat Study for Operational Infrared Soundings

NOAA is conducting a study with the NASA Jet Propulsion Laboratory (JPL) to investigate the technological readiness of a CubeSat-based temperature and water vapor sensor design. The sensor, if deployed in space, will help mitigate a potential gap in afternoon polar-orbiting sounder data. This technology may also support future NOAA operational missions to measure temperature and water vapor profiles in the lower troposphere. The sensor concept, called the Earth Observing Nanosatellite - IR (EON-IR), is a low cost-to-orbit way to mitigate a potential gap in data from the Cross-track Infrared Sounder (CrIS) instrument on the Joint Polar Satellite System (JPSS) spacecraft. EON-IR is a planned follow-on mission to the NASA JPL CubeSat Infrared Atmospheric Sounder (CIRAS) mission that will measure upwelling infrared radiation of the Earth in the Midwave Infrared (MWIR) region of the spectrum from space on a CubeSat. This presentation will cover the findings of study in the following areas: (A) increase reliability commensurate with a mission of two years in length or longer (B) examine the ability to provide full swath scanning (C) improve the EON-IR thermal/mechanical design (D) identify drivers and limitations to expand the EON-IR pathfinder channel capability to CrIS sensor capabilities. The presentation will detail the findings and the path forward for an NOAA EON-IR mission for gap mitigation. Numerical Weather Prediction (NWP) centers worldwide have demonstrated the value of hyperspectral infrared sounders to improving weather forecasts. The Atmospheric Infrared Sounder (AIRS) on the NASA Earth Observing System Aqua Spacecraft was the first hyperspectral infrared sounder to be used for operational forecast improvement. IR sounder radiances are assimilated into Global Circulation Models and NWP centers worldwide including the National Center for Environmental Prediction (NCEP), the European Center for Medium-Range Weather Forecast (ECMWF) and the UK Met Office

Retrieved Products from Simulated Hyperspectral Observations of a Hurricane

This research uses GCM derived products, with 1 km spatial resolution and sampled every 10 minutes, over a moving area following the track of a simulated severe Atlantic storm. Model products were aggregated over sounder footprints corresponding to 13 km in LEO, 2 km in LEO, and 5 km in GEO sampled every 72 minutes. We simulated radiances for instruments with AIRS-like spectral coverage, spectral resolution, and channel noise, using these aggregated products as the truth, and analyzed them using a slightly modified version of the operational AIRS Version-6 retrieval algorithm. Accuracy of retrievals obtained using simulated AIRS radiances with a 13 km footprint was similar to that obtained using real AIRS data. Spatial coverage and accuracy of retrievals are shown for all three sounding scenarios. The research demonstrates the potential significance of flying Advanced AIRS-like instruments on future LEO and GEO missions