Hurricane Irma from SAR
Hurricane Irma, the second most powerful Atlantic basin hurricane in recorded history, has been captured also from SAR sensor of Copernicus Sentinel 1 radar.
The radar waves can penetrate all weather conditions including clouds and rain.
Hurricane Irma over Dominican Republic 2017-09-10 (https://earth.nullschool.net)
A SAR image is a measure of the amount of energy reflected back to the radar antenna following interaction of the transmitted pulse with the ocean’s surface.
The degree of backscatter depends on the roughness of the surface at the scale of the radar wavelength.
Irma’s passage over the Dominican Republic 2017-09-07 H-10:30. Image from Sentinel-1 DT01EB76. Mosaic built with GDAL.
In the SAR image of Irma’s passage over the Dominican Republic 2017-09-10 at 10:30, the sea surface shows the effects of hurricanes having waves with a similar behaviour to the one of these storms depicted in optical cloud images but with much higher resolution.
Furthermore, in the Sentinel-1 imagery, the eye of the hurricane appears darker than its surrounding area because the wind speed at the centre of the hurricane is lower.
Another impressive image from the Sentinel-1 is the Irma’s passage to Florida.
Irma’s passage over the Florida 2017-09-07 H-23:29. Image from Sentinel-1 DT018320. Mosaic built with GDAL.
It is worthwhile to note that the surface waves of the ocean have the circular shape due to the effects of the hurricane.
Surface waves of lakes and rivers have the same direction of the ocean surface waves, demonstrating the great strength of Irma.
On the left side of the image, the brightest part is the central part of the cyclone, where there is more scattering signal.
Below details of Irma’s eye and the surface waves of the inland rivers and lakes. are shown.
https://www.fws.gov/southeast/news/2017/09/hurricane-irma-how-we-are-responding/ http://www.sciencedirect.com/science/article/pii/S1878029611005226
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