In this work, the main tropospheric impairments on an Earth-space link are investigated using the ERA5 dataset. Indeed, when an electromagnetic wave crosses the troposphere, it has to face clouds, rain and gases that cause signal attenuation. These three types of attenuation are studied using the latest climate reanalysis produced by the European Centre for Medium-Range Weather Forecast in 2020, ERA5, providing hourly data on many atmospheric, land-surface and sea-state parameters. ERA5 has a number of innovative features. These include a significantly enhanced horizontal resolution, hourly output throughout and an uncertainty estimate .Therefore, the objective of this work is to assess if and to what extent the ERA5 data can be used to estimate directly the tropospheric attenuation, not withstanding their limited spatial and temporal resolutions. To this aim, the Earth-space link between the Alphasat satellite, a large geostationary communications satellite, and a ground station in Milan (Italy) is studied at two downlink beacons frequencies: 19.7 GHz and 39.4 GHz. The data of interest from the ERA5 dataset were dowloaded for the entire year of 2018. Clouds, rain and gaseous attenuations are calculated over the year using the ITU-R Recommendations. The total attenuation is also computed, as well as the complementary cumulative distribution functions for each dissipative constituent.
Questo lavoro tratta dei principali effetti troposferici su un collegamento Terra-Spazio utilizzando il set di dati ERA5. Infatti, quando un'onda elettromagnetica attraversa la troposfera attraversa nuvole, pioggia e gas che provocano l'attenuazione del segnale. Questi tre tipi di attenuazione sono studiati utilizzando l'ultima rianalisi climatologica prodotta dall'European Centre for Medium-Range Weather Forecast nel 2020, ERA5, che fornisce su base oraria molti parametri atmosferici, relativi alla superficie terrestre e all'oceano. ERA5 ha una serie di caratteristiche innovative. Queste includono una risoluzione orizzontale notevolmente migliorata, dati orari e una stima dell'incertezza. Pertanto, l'obiettivo di questo lavoro è valutare se e in quale misura i dati ERA5 possono essere utilizzati per stimare direttamente l'attenuazione troposferica, nonostante la loro limitata risoluzione spaziale e temporale. A tal fine, vengono analizzati i dati del collegamento Terra-Spazio tra il satellite Alphasat, un grande satellite per comunicazioni geostazionarie, e una stazione di terra installata a Milano (Italia) a due frequenze di downlink: 19,7 GHz e 39,4 GHz. I dati di interesse dal dataset ERA5 sono stati scaricati per l'intero anno 2018. L'attenuazione dovuta a nuvole, pioggia e gas sono calcolate nel corso dell'anno utilizzando le Raccomandazioni ITU-R. Viene calcolata anche l'attenuazione totale, così come le funzioni di distribuzione cumulativa complementare per ogni componente dissipativa.
Characterization of the tropospheric attenuation affecting Earth-space links using ERA5 data
Pelat, Estelle Audrey
2019/2020
Abstract
In this work, the main tropospheric impairments on an Earth-space link are investigated using the ERA5 dataset. Indeed, when an electromagnetic wave crosses the troposphere, it has to face clouds, rain and gases that cause signal attenuation. These three types of attenuation are studied using the latest climate reanalysis produced by the European Centre for Medium-Range Weather Forecast in 2020, ERA5, providing hourly data on many atmospheric, land-surface and sea-state parameters. ERA5 has a number of innovative features. These include a significantly enhanced horizontal resolution, hourly output throughout and an uncertainty estimate .Therefore, the objective of this work is to assess if and to what extent the ERA5 data can be used to estimate directly the tropospheric attenuation, not withstanding their limited spatial and temporal resolutions. To this aim, the Earth-space link between the Alphasat satellite, a large geostationary communications satellite, and a ground station in Milan (Italy) is studied at two downlink beacons frequencies: 19.7 GHz and 39.4 GHz. The data of interest from the ERA5 dataset were dowloaded for the entire year of 2018. Clouds, rain and gaseous attenuations are calculated over the year using the ITU-R Recommendations. The total attenuation is also computed, as well as the complementary cumulative distribution functions for each dissipative constituent.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/166625