Cloud Nowcasting: Motion Analysis of All-Sky Images Using Velocity Fields

Yezer Gonzalez, Cesar Lopez, Emilio Cuevas

Abstract

Cloud monitoring and prediction is crucial to air traffic and weather forecast. Clouds play a key role in solar radiation balance. These issues have prompted Sieltec Canarias S.L. and AEMET to develop an automatic system of cloud observation (SONA). This system provides cloud cover percentage using all-sky images, which are processed by neural networks. Once the system has detected and recorded cloud images, a cloud motion technique makes possible to obtain “velocity fields”, corresponding to different layers of clouds. The evolution in time of these velocity fields is a powerful tool to provide very short term forecasting (less than 1 hour) of cloudiness (known as cloud nowcasting). In the future, this information, combined with Radiative Transfer Models, may be used for solar radiation nowcasting (Global Horizontal Irradiance –GHI- and Direct Normal Irradiance –DNI-)

Keywords

Cloud nowcasting, cloud layers, velocity fields, all-sky images

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IMEKO-TC4-2013-053.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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