Browsing by Autor "Ana Benarroch"

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Alphasat propagation experiment in Madrid: Processing of the first year of measurements
(2016) José Manuel Riera; Gustavo A. Siles; Pedro García-del-Pino; Ana Benarroch
Universidad Politecnica de Madrid (UPM) is participating in the Alphasat propagation experiment by measuring the copolar level of the Q-Band beacon at 39.4 GHz. In this paper the processing procedures are discussed and exemplified by their application to the first year of measurements (April 2014 to March 2015). In the first phase (data pre-processing), daily files of normalized duration are developed and a flag vector is generated. Excess attenuation and total attenuation are separately calculated in the following processing phases. The reference level is calculated on an event-by-event basis in the first case, and obtained from GNSS-based gas attenuation in the second one. The different procedures are described and some examples of events are presented together with statistics of the first year of measurements.
Alphasat propagation experiment in Madrid: Results on excess and total attenuation
(2017) José Manuel Riera; Domingo Pimienta‐del‐Valle; Pedro García-del-Pino; Gustavo A. Siles; Ana Benarroch
Universidad Politécnica de Madrid (UPM) is participating in the Alphasat propagation experiment by measuring the copolar level of the Q-Band beacon at 39.4 GHz since April 2014. In this paper the results of the first two complete years of measurements (until March 2016) are presented with regards to excess and total attenuation. The reference level is calculated on an event-by-event basis in the first case, and obtained from GNSS-based gas attenuation in the second one. The results reflect the variability of the meteorological conditions in the climate of Madrid, with strong differences among the months of the year and between the two years, reinforcing the need of having long-term propagation experiments to capture all the variability of the propagation effects.
Comparison Between ERA5 Cloud Parameters and Rainfall Rate in Madrid
(2024) Ana Benarroch; Gustavo A. Siles; Mishel Cuiza; José Manuel Riera
This ongoing study, conducted at UPM, investigates the relationship between rainfall rate and cloud parameters, using data sourced from ERA5 and experimental rainfall rate measurements collected with a disdrometer. The findings presented in this paper have been obtained using a comprehensive dataset spanning 6 years, including total cloud liquid water, cloud base height, total cloud cover, and rainfall rate. The statistical analysis presented comprises cumulative distributions, histograms, as well as scatter plots of the ERA5 cloud parameters against both the hourly average and maximum hourly rainfall rates. It has been found that low values of total cloud liquid water and cloud base height are more probable with simultaneous rain occurrence, whereas total cloud cover yields values equal or close to one, which is its highest value.
Comparison of the Height of the 0°C Isotherm With Several ERA5 Cloud Parameters
(2025) Ana Benarroch; Gustavo A. Siles; José Manuel Riera
The 0°C isotherm height is used in rain attenuation prediction models to calculate the rain height, as proposed in ITU-R Recommendations. In previous studies, the 0°C isotherm obtained for Madrid was compared with the 0° isotherm height provided by the European Centre for Medium-Range Weather Forecasts fifth-generation climate reanalysis (ERA5). In this paper, the comparison is extended to several ERA5 cloud parameters: cloud base height, total cloud liquid water content and total cloud ice water content. The results presented here include the monthly average, histograms of each parameter and binned scatter plots of pairs of parameters.
Height of the 0°C Isotherm and the Melting Layer in Madrid: Comparison of Estimations from Different Sensors
(2022) Ana Benarroch; Gustavo A. Siles; José Manuel Riera
The 0°C isotherm height is used in rain attenuation prediction models to calculate the rain height, as proposed in ITU-R Recommendations. In a previous study, statistical results on the variability of the 0°C isotherm were obtained for Madrid from ten years of radiosonde measurements. Such results are compared in this paper with statistics calculated using the 0°C isotherm height provided by ERA5 climatic reanalysis. The height of the melting layer was investigated previously through the comparison of the 0°C isotherm height, considered to be the top of the melting layer, with the height of the bottom of the melting layer derived from measurements performed with a vertical Doppler radar (MRR-2). The profiles of the velocity of falling particles provided by this radar have been used recently to calculate both the top and bottom of the melting layer. The first results are presented in this paper.
Heights of the 0°C Isotherm and the Bright Band in Madrid: Comparison and Variability
(2020) Ana Benarroch; Gustavo A. Siles; José Manuel Riera; Santiago Pérez-Peña
Rain attenuation prediction models may require rain height data that can be obtained from the 0°C isotherm height as proposed in ITU-R Recommendations and also from radiosonde measurements. Statistical results on the variability of the 0°C isotherm in all conditions and in rainy conditions are presented in this paper for ten years of radiosonde data. Concurrent with these data, nine years of rainfall measurements performed with a vertical Doppler radar (MRR-2) have allowed comparing the height of the 0°C isotherm with the height of the bottom of the bright band considering simultaneous events. The variability of both heights and of their difference has been investigated as well.
Long-term Experimental Results of Propagation in a Q-band Slant-Path Link
(2025) Domingo Pimienta‐del‐Valle; José Manuel Riera; Pedro García-del-Pino; Gustavo A. Siles; Ana Benarroch
A better characterization of the satellite propagation channel remains of paramount importance. Specifically, assessing the impact of the atmospheric effects in a Q/V band (40/50 GHz) satellite signal is critical when designing systems operating at such high frequency bands, which are receiving increasing attention and interest in last years. A long-term propagation experiment is being carried out in Madrid, receiving the 40-GHz beacon signal of the Alphasat satellite since 2014. This paper presents the rainfall rate and attenuation results for the first completed 9 years of the experiment, as well as to compare them with several ITU-R models. Moreover, excess attenuation is also compared with a distribution obtained from synthetizing 100 years of attenuation time series with the procedure of Rec. ITU-R P.1853-2. Both Rec ITU-R P.618-14 and the synthetized series approach yield similar results, each one behaves better for a specific probability interval.
Propagation Experiments in Madrid for the Ka and Q Bands: Recent Results and Rain Attenuation Modelling in the Earth-Satellite Channel
(2021) Domingo Pimienta‐del‐Valle; José Manuel Riera; Pedro García-del-Pino; Gustavo A. Siles; Ana Benarroch
Most of the available rain attenuation models have been derived on the basis of experimental measurements carried out only at frequency bands below 20 GHz or with little data above this value. Universidad Politécnica de Madrid (UPM) is carrying out two experimental campaigns at the Ka and Q bands, measuring two beacon signals at 19.7 GHz (from the KA-SAT satellite) and 39.4 GHz (from the Alphasat satellite). Five years of measurements for each experiment are now available and have been processed. Attenuation results are presented in this paper and are used to assess the performance of fifteen rain attenuation models available in the literature. The best results are provided by the NTUA model, although some other ones, including the one recommended by the ITU-R, also yield relatively good predictions.
Relationship between Cloud Cover and Rainfall Rate in Madrid: First Results
(2023) Ana Benarroch; Gustavo A. Siles; José Manuel Riera
A first analysis of the relationship between cloud cover and rainfall rate has been performed using two years of total cloud cover data provided by ERA5 and experimental rainfall rate measurements collected with a disdrometer at UPM. The results obtained include cumulative distributions and histograms of both parameters, and the scatter plots of total cloud cover against the hourly average of rainfall rate and hourly maximum rainfall rate. The duration of events has also been investigated for both parameters.
Variability of the 0° Isotherm: Monthly Variations and Correlation with Ground Temperature
(2019) Ana Benarroch; Gustavo A. Siles; José Manuel Riera
Rain attenuation prediction models usually require rain height data that can be derived from the 0°C isotherm height obtained as proposed in ITU-R Recommendations and also from radiosonde measurements. Communication systems that make use of fade mitigation techniques require accurate information on the parameters that describe the variability of the propagation channel caused by various impairments. Statistical results on the variations of the 0°C isotherm are presented in this paper focusing on the monthly variability and on the correlation with ground temperature.