http://hdl.handle.net/20.500.11765/1070 2026-04-11T13:08:08Z http://hdl.handle.net/20.500.11765/15386 Título : Characterization of the instrument temperature dependence of Brewer total ozone column measurements [Discussion paper] Autor : Berjón, Alberto; Redondas, Alberto; Sildoja, Meelis-Mait; Nevas, Saulius; Wilson, Keith M.; León-Luis, Sergio Fabián; el-Gawhary‏, Omar‏; Fountoulakis, Ilias Resumen : The instrumental temperature correction to be applied to the ozone measurements by the Brewer spectrophotometers is derived from measurements of the irradiance from an internal halogen lamp in the instrument. These characterisations of the Brewer instruments can be carried out within a thermal chamber, varying the temperature from -5◦C to +45◦C, or during field measurements, making use of the natural change in ambient temperature. However, the internal light source used to determine 5 the thermal sensitivity of the instrument could be affected in both methods by the temperature variations as well, which may affect the determination of the temperature coefficients. In order to validate the standard procedures for determining Brewer’s temperature coefficients, two independent experiments using both external light sources and the internal lamps have been performed within the ATMOZ Project. The results clearly show that the traditional methodology based on the internal lamps is not affected by possible temperature effects on the internal lamps. The three methodologies yielded equivalents results, with differences in total ozone column below 0.08% for a mean diurnal temperature variation of 10◦ 10 C. 2017-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/14864 Título : Wind Forecasting Based on the HARMONIE Model and Adaptive Finite Elements Autor : Oliver, Albert; Rodríguez, Eduardo; Escobar, José María; Montero García, Gustavo; Hortal Reymundo, Mariano; Calvo Sánchez, Francisco Javier; Cascón, José Manuel; Montenegro Armas, Rafael Resumen : In this paper, we introduce a new method for wind field forecasting over complex terrain. The main idea is to use the predictions of the HARMONIE meso-scale model as the input data for an adaptive finite element mass-consistent wind model. The HARMONIE results (obtained with a maximum resolution of about 1 km) are refined in a local scale (about a few metres). An interface between both models is implemented in such a way that the initial wind field is obtained by a suitable interpolation of the HARMONIE results. Genetic algorithms are used to calibrate some parameters of the local wind field model in accordance to the HARMONIE data. In addition, measured data are considered to improve the reliability of the simulations. An automatic tetrahedral mesh generator, based on the meccano method, is applied to adapt the discretization to complex terrains. The main characteristic of the framework is a minimal user intervention. The final goal is to validate our model in several realistic applications on Gran Canaria island, Spain, with some experimental data obtained by the AEMET in their meteorological stations. 2015-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/14863 Título : Remote sensing of lunar aureole with a sky camera: Adding information in the nocturnal retrieval of aerosol properties with GRASP code Autor : Román, Roberto; Torres, Benjamín; Fuertes, David; Cachorro, Victoria E.; Dubovik, Oleg; Toledano, Carlos; Cazorla, Alberto; Barreto Velasco, África; Bosch, Juan Luis; Lapyonok, Tatsiana; González, Ramiro; Goloub, Philippe; Perrone, Maria Rita; Olmo Reyes, Francisco José; Frutos Baraja, Ángel Máximo de; Alados Arboledas, Lucas Resumen : The use of sky cameras for nocturnal aerosol characterization is discussed in this study. Two sky cameras are configured to take High Dynamic Range (HDR) images at Granada and Valladolid (Spain). Some properties of the cameras, like effective wavelengths, sky coordinates of each pixel and pixel sensitivity, are characterized. After that, normalized camera radiances at lunar almucantar points (up to 20° in azimuth from the Moon) are obtained at three effective wavelengths from the HDR images. These normalized radiances are compared in different case studies to simulations fed with AERONET aerosol information, giving satisfactory results. The obtained uncertainty of normalized camera radiances is around 10% at 533 nm and 608 nm and 14% for 469 nm. Normalized camera radiances and six spectral aerosol optical depth values (obtained from lunar photometry) are used as input in GRASP code (Generalized Retrieval of Aerosol and Surface Properties) to retrieve aerosol properties for a dust episode over Valladolid. The retrieved aerosol properties (refractive indices, fraction of spherical particles and size distribution parameters) are in agreement with the nearest diurnal AERONET products. The calculated GRASP retrieval at night time shows an increase in coarse mode concentration along the night, while fine mode properties remained constant. 2017-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/14862 Título : Statistical Atmospheric Parameter Retrieval Largely Benefits from Spatial-Spectral Image Compression Autor : García Sobrino, Joaquín; Serra-Sagristà, Joan; Laparra, Valero; Calbet, Xavier; Camps-Valls, Gustau Resumen : The Infrared Atmospheric Sounding Interferometer (IASI) is flying on board of the Metop satellite series, which is part of the EUMETSAT Polar System (EPS). Products obtained from IASI data represent a significant improvement in the accuracy and quality of the measurements used for meteorological models. Notably, IASI collects rich spectral information to derive temperature and moisture profiles –among other relevant trace gases–, essential for atmospheric forecasts and for the understanding of weather. Here, we investigate the impact of near-lossless and lossy compression on IASI L1C data when statistical retrieval algorithms are later applied. We search for those compression ratios that yield a positive impact on the accuracy of the statistical retrievals. The compression techniques help reduce certain amount of noise on the original data and, at the same time, incorporate spatial-spectral feature relations in an indirect way without increasing the computational complexity. We observed that compressing images, at relatively low bitrates, improves results in predicting temperature and dew point temperature, and we advocate that some amount of compression prior to model inversion is beneficial. This research can benefit the development of current and upcoming retrieval chains in infrared sounding and hyperspectral sensors. 2017-01-01T00:00:00Z