The study of climate change based on spectral radiances of outgoing infrared radiation measured by different space-borne spectroradiometers, requires careful intercalibration of these instruments.The results of SI-1/Meteor-28 (-29) (1977, 1979) and IKFS-2/Meteor-M N2 (in orbit operation since 2015) FTIR spectrometers intercalibration are presented in this paper to clarify the results of IR atmospheric spectra changes over the past 40 years, previously obtained by authors.The double-difference method is applied due to the impossibility of direct (synchronous) comparisons.Calculations of the infrared atmospheric spectra based on the radiosonde data and carbon dioxide data carried out using the LBLTRM radiation code are used as reference measurements.It was found that both the mean and standard deviation for double differences after selecting the most reliable measurements do not exceed 1-2 mW/(m 2 •sr•cm -1 ) in almost the entire spectral range under consideration 660-1350 cm -1 , which indicates a good calibration agreement between two instruments.

The first Russian advanced infrared (IR) atmospheric sounder IKFS-2 was launched in July 2014 on the "Meteor-M" No. 2 meteorological satellite. It is planned that this instrument and similar devices will continue to operate until 2025 aboard the current and subsequent satellites of "Meteor-M" series. IKFS-2 is a Fourier transform spectrometer covering the spectral domain of 5-15 mu m. It belongs to a class of hyper-spectral IR sounders, designed to measure the outgoing IR radiance spectra and to provide information on the thermodynamic parameters and the composition of the atmosphere such as vertical temperature and humidity profiles, estimates of the ozone and other trace gases total column amounts. In the paper, the IKFS-2 operation on board "Meteor-M" No. 2 is analyzed, including the assessment of the measurements' quality (the errors of radiometric and spectral calibration) and their information content. Since launch, the instrument performance has been remained stable, and the actual IKFS-2 characteristics (threshold value of NESR, uncertainty of onboard radiometric and spectral calibrations, spectral resolution) meet the planned requirements. There is a good agreement between IKFS-2 measurements and measurements of independent satellite instruments (SEVIRI, IASI). The paper also provides an overview of the developed scientific basis for simulation and interpretation ("inversion") of satellite measurements. The examples of output IKFS-2 level 2 products (vertical profiles of temperature and humidity, total ozone content) are given together with the error analysis. The performance of atmospheric (temperature and humidity) profile retrievals and the feasibility of total ozone content estimates are evaluated by comparison with independent ground-based or satellite measurements. (C) 2019 The Authors. Published by Elsevier Ltd.

Abstract—Comparisons of outgoing IR radiation spectra measured bу Fourier SI-1 spectrometer in 1977 and 1979 from the Meteor-28 and -29 satellites to numerical calculations on the basis of the modern LBLRTM code and data of atmospheric radio sounding are carried out. In most cases, mean differences between measurements and calculations do not exceed 2 mW/(m2 sr cm–1) in the 660–1600 cm–1 spectral range. Standard deviations and mean square differences are, on average, 2–4 mW/(m2 sr cm–1). These values are greater bу about 1 mW/(m2 sr cm–1) than relevant differences between calculations and measurements for modern IKFS-2 spectrometer. Comparisons of experimental spectra of 1977, 1979 and 2015–2016 have shown that, on average, the intensity of outgoing IR radiation measured bу the IKFS-2 device, is bу 0.5–3.0 mW/(m2 sr cm–1) less than SI-1 radiation measurements onboard Meteor-28 and -29 satellites obtained 40 years ago. This effect may be associated with the СО2 increase in the atmosphere and the resulting raising of radiating atmosphere layers to tropospheric layers with а smaller temperature.

The results of the commissioning of the IKFS-2 instrument and its subsequent operation onboard the Meteor-M no. 2 polar orbiting meteorological satellite are presented. Comparison of the IKFS-2 data with independent satellite measurements shows that its performance characteristics are in accordance with the design specification. It is therefore possible to realize the IKFS-2 mission objectives for obtaining data on the meteorological parameters and composition of the atmosphere.

The outgoing radiation spectra measured by the IRFS-2 spectrometer onboard Meteor-M no. 2 satellite have been analyzed. Some statistical parameters of more than 10 6 spectra measured in spring in 2015 have been calculated. The radiation brightness temperature varied from ∼300 K (surface temperature) up to ∼210 K (tropopause temperature). The quite high variability of the longwave measured radiation has been demonstrated. The signal-to-noise ratio distinctively decreases in the shortwave region (higher than 1300 cm –1 ). Intercomparisons of IR sounders IRFS-2 with IASI and CrIS spectra showed that the discrepancies in the average spectra and their variability do not exceed measurement errors in the spectral region 660–1300 cm –1 . A comparison of specially chosen pairs of the simultaneously measured spectra showed that the differences between IRFS-2 and European instruments in the region of the 15-μm CO 2 band and the transparency windows 8–12 μm are less than 1 mW/(m 2 sr cm –1 ) and no more than the differences between the two IASI instruments (-A and -B). The differences between measured and simulated spectra are less than 1 mW/(m 2 sr cm –1 ) in the mean part of CO 2 band. However, starting from 720 cm –1 , values appear that reach 2–4 mW/(m 2 sr cm –1 ). This is caused by the absence of precise information about the surface temperature. Further investigations into the possible reasons for the observed disagreements are required in order to improve both the method of initial processing and the radiative model of the atmosphere.

Preliminary results of a space experiment using the IKFS-2 infrared sounder (Meteor-M2 satellite) showed high-quality of measurements of spectra of the outgoing thermal radiation of the atmosphere–surface system and the adequacy of developed IR radiation atmospheric models in the 15-μm carbon gas absorption band used to recover the vertical profiles of the atmospheric temperature. Outgoing radiation spectra measured by IKFS-2 instruments make it possible to restore vertical temperature profiles with errors close to 1K in most of the 0–30 km high-altitude region, except for the lower troposphere and altitudes above 30 km, where these errors are close to 2–3K.

Among payload of Meteor-M No.2 satellite (launched July 8th, 2014) the hyperspectral infrared sounder IRFS-2 is considered to be one of the key instruments for operational meteorology and climatology.The hyperspectral infrared sounder IRFS-2 provides measurements of the IR spectra in the range 5-15 μm.This paper describes the algorithm of comparison between radiances observed from IRFS-2 with SEVIRI (Meteosat-10) data.SEVIRI can be used as a reference instrument because its radiometric calibration has proven to be stable and high-accuracy.According to the comparison results, an average IRFS-2 calibration error for channels 7.3, 8.7, 9.7, 10.8, and 12.0 μm does not exceed 0.1-0.2K.In the mean for channel 13.4 μm the brightness temperature measured by SEVIRI is less on 1K then effective temperature calculated from IASI data because of the shift in own calibration of SEVIRI.Similar findings were reported in the survey of WMO's Global Space-based Inter-Calibration System (GSICS) where the comparison of radiances measured by SEVIRI and IASI (Metop-A, -B) was performed.

A spaceborne Fourier-transform infrared (FTIR) spectrometer was designed for measuring the spectra of the outgoing Earth’s atmosphere radiation and serves for providing for the needs of online meteorology and climatology with regard to obtaining the following kinds of data: vertical profiles of temperature and humidity profiles in the troposphere and the lower stratosphere, the general and altitudinal ozone distribution, concentrations of small gaseous constituents, temperature of the underlying surface, etc. At present, works are underway at the Keldysh Research Centre for creating IKFS-series FTIR spectrometers for satellites in Sun-synchronous orbits: the IKFS-2 instrument for the Meteor-M spacecraft no. 2 of the Meteor-3M space complex (developed and supplied for testing together with the spacecraft) and an advanced IKFS-3 instrument for the Meteor-MP fourth-generation hydrometeorological and oceanographic space complex for Earth monitoring (at the developmental stage). The composition, functional diagram, and technical specifications of the FTIR spectrometers are presented.

Бортовой инфракрасный (ИК) Фурье-спектрометр предназначен для измерения спектров исходящего излучения атмосферы Земли и служит для обеспечения нужд оперативной метеорологии и климатологии в части получения следующих видов информации: вертикальные профили температуры и влажности в тропосфере и нижней стратосфере, общее и высотное распределение озона, концентрации малых газовых составляющих, температура подстилающей поверхности и др. В настоящее время в ГНЦ ФГУП “Центр Келдыша” широко развернуты работы по созданию аппаратуры серии ИКФС для спутников на солнечно-синхронных орбитах: прибор ИКФС-2 для космического аппарата “Метеор-М” № 2 космического комплекса “Метеор-3М” (разработан и поставлен для проведения испытаний в составе КА); перспективный прибор ИКФС-3 для гидрометеорологического и океанографического космического комплекса мониторинга Земли четвертого поколения “Метеор-МП” (в стадии разработки). В статье представлены состав, функциональная схема и технические характеристики ИК-Фурье-спектрометров.

A method and equipment for optical diagnostics of liquid‐fuel; rocket engines (LR) is described. Experimental data on minimum detactable concentrations of such metals as Fe, Al, Mn, and Ni in the plume have been obtained. The radiation spectra of the plume of the engines of stages II and III of the Proton carrier rocket (CR) and of the full‐scale oxygen‐kerosene LR have been measured.

An experimental setup created on the basis of an infrared Fourier spectrometer and intended for an analysis of ultrasmall impurities in liquids and gases is described. Results of experimental studies of the vapor of ultrapure ammonium and nonsymmetric dimethylhydrazine are reported. It is shown that the limiting mole concentration of the detected impurities amounts to about (3–9)·10−4% for different types of gases.