EKO Total Sky Imager
Objective :
EKO is a total sky imagery manufactured system which enables us to visualize the whole sky (2pi steradians) above the Pic du Midi site. It routinely stores the local cloud cover as seen from the summit.
Examples of observations :
Acquisition mode :
EKO has been operated at PDM from June 2017 to December 2019, with visible daytime and nightime images every 5 minutes. During the night, a longer 34 s pause is made, for astronomy application. The acquisition frequency can be increased anytime in the context of field experiments or specific demands, with the possibility of making movies.
Image processing :
An algorithm (named ELIFAN) has been developed by Paul Barneould and evaluated by Omar Gabella, in order to estimate the cloud cover from each image. It is based on Red/Blue ratio thresholding, both with an absolute or a differential (with a clear sky library) approach. See Lothon et al. 2019 (AMT journal) for more details on ELIFAN.