Ocean Wind Direction and Speed Estimation from SAR Radar Data / Imagery. Part 1. Measurement from SAR Data Using ESA SNAP

SAR (Synthetic Aperture Radar) data can have many information about earth surface that cant be obtained from Optical or thermal imagery. One of them is Ocean Winds data. Using SAR data, you can perform wind speed and direction estimation at the ocean area by analyzing the winds streaks that well recorded in SAR data. This wind speed and direction is an essential data in Oceanography or Marine Geomorphology because this data can be used for coastal dynamic analysis. On the other hand, direct wind measurement in the field sometimes costly and hard to do. 

I am going to deliver this topic into two parts. First is about how to measure wind speed and direction using SAR Data, and second is how to get post processed wind direction and speed data from publicly available SAR data. 

Now about how to directly measure wind speed and direction from SAR data, I already made a tutorial about how to do it in ESA-SNAP. ESA SNAP is a remote sensing software developed by European Space Agency (ESA) dedicated to process their wide line of remote sensing data products. ESA-SNAP have so many of dedicated, useful and easy to use SAR Processing Tools. One cool thing about this software is ESA provided this software for free, and you can download the software from this LINK. 

And for the tutorial, I am using ENVISAT-ASAR data, but this workflow can be applied to other Satellite SAR sensor like Sentinel-1, ERS, RADARSAT, ALOS PALSAR, and many others.