24 Mar The nowcast
By exploiting the full-Earth viewing potential of geostationary satellites, the team have developed a system that delivers regional ‘nowcasts’ of the solar radiation spectrum calculated on a high resolution grid at 15-minute intervals. “We use satellite-derived cloud optical properties and other atmospheric parameters (eg. aerosols and trace gasses) in combination with radiative transfer modelling and neural networks in order to achieve this goal,” explains Kazadzis.
The system and frequency of measurement is dependent on the Meteosat Second Generation 3(MSG3) satellite orbiting the Earth at an altitude of 36,000 km. “This satellite continuously monitors the Earth disk every 15 minutes with a spatial resolution of approximately 0.05 degrees longitude by 0.05 degrees latitude,” outlines Kosmopoulos, or put more simply, around 2.5 x 2.5km. Each of these 2.5km2 units is a pixel for which the team calculates the solar radiation spectrum and an array of new solar energy products.
Armed with this system, the NOA team accurately measure surface radiation at high spatial and temporal resolution, analysing past levels, monitoring current levels and even accurately forecasting radiation up to one hour ahead, whatever the weather. The quality of their forecasts have been validated by comparisons with actual measurements solar solar radiometer instruments under the national project “Thespia”, says Taylor.