Cloud Cover Nowcasting and Active Cloud Clearing for Optical Satellite Communications

Abstract

Fast internet access is needed for daily communication, data transfer, industry, entertainment and much more. However, in many rural areas all over the world fast internet access is still not available. Especially in places where broadband access with fiber cables is not feasible alternatives must be found. A solution proposed by Giggenbach et al. [1] is a very high throughput satellite (VHTS) system that delivers fast internet via the Ka-band. In Europe, one geostationary (GEO) satellite is sufficient to close this gap. Yet, a high amount of radio frequency (RF) ground stations (about 60) is needed for the feeder link of the satellite. This is where optical data transmission starts to play a role surpassing the bandwidth of RF transmission by several orders of magnitude [1]. For optical feeder links the problem of cloud blockages arises because the telecommunication laser does not penetrate through clouds and fogs [2]. In order to obtain an outage probability of less than 10−5 an intercontinental system over Europe and Africa is needed with at least twelve optical ground stations (OGS)[1]. In the first part of this master thesis nowcast models are analysed to forecast the cloud cover to plan OGS handovers within the next few hours. Additionally, cloud cover data from the Meteosat Second Generation (MSG) weather satellite distributed by Deutscher Wetterdienst (DWD) is validated with an infrared (IR) all sky imager in Oberpfaffenhofen. The nowcasted cloud coverage is evaluated for different optical ground station sites. The validation and evaluation is specifically designed for the blockage of optical links to different satellite positions. In the second part of this master thesis a different approach is followed to establish an optical connection to the satellite without getting blocked by clouds...