International audienceOn 7 February 2008, the SOLAR payload was placed onboard the International Space Station. It is composed of three instruments, two spectrometers and a radiometer. The two spectrometers allow us to cover the 16 - 2900 nm spectral range. In this article, we first briefly present the instrumentation, its calibration and its performance in orbit. Second, the solar spectrum measured during the transition between Solar Cycles 23 to 24 at the time of the minimum is shown and compared with other data sets. Its accuracy is estimated as a function of wavelength and the solar atmosphere brightness-temperature is calculated and compared with those derived from two theoretical models
Abstract. The ionospheric response to solar extreme ultraviolet (EUV) variability during 2011–2014 is shown by simple proxies based on Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment solar EUV spectra. The daily proxies are compared with global mean total electron content (TEC) computed from global TEC maps derived from Global Navigation Satellite System dual frequency measurements. They describe about 74 % of the intra-seasonal TEC variability. At time scales of the solar rotation up to about 40 days there is a time lag between EUV and TEC variability of about one day, with a tendency to increase for longer time scales.
UV derivative spectroscopy is investigated for its potential in online control of various processes. One typical application is emission monitoring of several pollutants such as SO2, NO, NO2, NH3, and aromatic hydrocarbons. The proposed method gains selectivity and sensitivity by using the first and second derivative of the transmission spectrum with respect to wavelength. These derivatives are generated in an optical manner and are compared empirically for the first time with the known numerical derivative spectroscopy and conventional transmission spectroscopy. The generation of the optical derivatives is discussed. For demonstration of the feasibility, laboratory monitoring results are reported. With the use of a sample pathlength of 10 cm with this optical method, detection limits are determined to be 4 ppm, compared to 11 ppm with numerically calculated signals and 20 ppm obtained by using the transmission only. Typically a time resolution of below three minutes is achieved. Emphasis is also laid on the treatment of an observed nonlinearity by means of chemometric calibration and evaluation algorithms such as principal component regression (PCR) and partial least-squares (PLS).
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