Cebile storm over the Indian Ocean

During the last days in the remotest parts of the Indian Ocean a tropical cyclone was formed. Its name is Cebile and he reached the category strength 4. The storm was luckily formed far away from Madagascar, Sri Lanka and other inhabited islands, thus avoiding many damages and casualties. The cyclone has been captured by Sentinel-1 and Sentinel-3 missions a few hours apart: the purpose of this post is to show the ability of Copernicus data in the evaluation, study and identification of those kind of phenomenons from different points of view, thanks to its multi missions data.

The SLSTR image is the first image of the animation below and has been sensed by Sentinel-3A spacecraft on Jan 31st. That’s a thermal infrared image of an overnight acquisition: the temperature gradient is in grayscale; darker is a region, higher is its temperature. The entire storm is colder than its eye where indeed the wind speed is low: this other peculiarity of the storm can be appreciated thanks to the third image of the animation (OCN product), processed with Sentinel-1 SAR data in order to evaluate the speed of the winds. The eye of the cyclone is blue and this indicates air speed lower than the other parts of the storm: the strength of the wind is high near the eye and decreases as we get away from the centre.

Higher is the storm strength, higher is the wind speed and lower is the temperature. This trend is moreover reflected in the image in the middle where the sea waves under the storms are pictured: indeed the SAR penetrates the clouds so the image showed represents the sea waves moving in circles because of the storm itself. Please note that the two SAR images seem shifted compared to the SLSTR infrared: this is due to a later acquisition performed by Sentinel-1, so the storm moved. Besides its strength, the storm in the last days reached a massive extent too: the image below localizes the phenomenon and gives us an idea of how big was Cebile. From this sight we can even appreciate the curvature of the Earth.

[Palumbo G.,Tarchini S.]

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