Global atmospheric turbulence forecasting for free-space optical communications

Abstract

The optical turbulence in the Earth's atmosphere is a major limitation to free-space optical communications. It is therefore critical that we are able to model and forecast realistic atmospheric optical turbulence conditions for site selection, instrument development, instrument performance validation and network switching. Here, we present global maps of optical turbulence strength and associated parameters (Fried parameter, isoplanatic angle, coherence time and Rytov variance), from a turbulence forecasting tool. These maps can be used by the community to understand the expected performance of free-space optical systems anywhere in the world, day and night. These maps also demonstrate that optical turbulence can be modelled and visualised in the same manner as other aspects of the Earth's weather system such as wind, rain or temperature, opening the door for more advanced turbulence forecasting functionality. We show global averages, examples of temporal sequences and more detailed analysis from some example sites.

Assessment of adaptive optics‐corrected optical links statistics from integrated turbulence parameters through a Gaussian process metamodel

“…It was improved to include a separate boundary layer and enable stronger turbulence strength near the ground to be modeled. 50 The general circulation model used is ERA5 51 from the European Centre for Medium range Weather Forecasts (ECMWF). This model, from which the turbulence is calculated, has a spatial resolution of 0.3 along latitude and longitude and provides a forecast for every hour.…”

“…This model based on Tatarskii's is developed in Osborn and Sarazin 49 and was confronted successfully to on site measurements in Paranal. It was improved to include a separate boundary layer and enable stronger turbulence strength near the ground to be modeled 50 …”