SIRENA is a video-based coastal zone monitoring system designed and created at IMEDEA by the Group of Operational Oceanography. It is intended to be a low cost, automated, remote monitoring tool. Standard Commercial Off-The-Shelf (COTS) components coupled with open technologies were implemented to the acquire digital images, generate statistical products, transfer of information between the remote station and the data storage and processing center, perform post-processing of the digital images, and present results to the general public. A prototype system is currently installed and working in Cala Millor in the northeast coast of Mallorca Island, Spain.

Snapshot

During the image capture process, SIRENA stores an single image for each camera. Hence, an periodic snapshot is recorded. The user can chose which image to save or saving

any number of images during the acquisition process. This product can be the basis for beach and coastal zone management activities.

Mean Image

Mean images are generated to reduce the amount of data to be managed without loosing any significant information. The software is set-up to generate a mean image, per camera, per

hour,at a frequency of 7.5 Hz during 10 minutes. White pixels in the images indicate areas where waves are breaking, hence an indirect estimation of the position of submerged sandbars..

Variance Image

The image variance is employed to filter some postprocessing products indicating those areas where variability is higher.

These images can be useful for coastlinedetection, sand bar migration, and beach management activities.

Timestack and Pixel Arrays

Timestacks are cross-shore transects perpendicular to the coastline in which pixel intensity is stored. Thus, obtaining a spatial and temporal representation of way rays. Wave ray parameters and breaking zones can be determined from these. To obtain the wave number and angle the software can be configured to store an array of adjacent pixels.