Is it possible to differentiate the roughness on the water surface by the action of the wind with regard to a turbulent flow in a channel with shape of funnel by backscattering analysis from time series of Sentinel-1?
The Orinoco River at Ciudad Bolivar station changes the width of 8 km to 1 km, producing vortexes and strong turbulence at this channel.
I would like to study this phenomenon in this sector of the river...
Partly yes. Provided you may have to go for VV pol since it is sensitive to wind. some wind data on intensity and direction also would be required from ground. The backscatter sensitivity can be modelled taking the details of the river dynamics at this station. Its an indirect way.
Hi Manju Sree,
Thank you very much for your response!. Certainly, I have information of wind speed and direction on this station at Ciudad Bolivar. The time series that I am working is with polarization VV, because as you said is more sensitive to detect changes of ruggedness related to the wind. My doubts comes from the part related to pre-processing of S-1 images, When the values are obtained in units of radar backscatter coefficient (dB).
Is it necessary to apply an angle correction to the scenes to do the comparisons?
I must use scenes taken at the same acquisition time?
I don't know if you have some information about this topic?
Best Regards,
Santiago
Hi Waqas Qazi,
Thank you for your comment. Please you might be a bit more specific with your answer related to "good river-scattering model"? I try to evaluate Radar backscattering coefficient (dB) variations (in time series of S-1 images) between flood periods and normal water level conditions with VV polarization. In general, a low backscatter return is expected due to the specular reflection of the radar signal on the water surface. However, wind and turbulence generated by the rapids strong and vortexes induced waves that can cause roughness on the water surface, which results in a high return signal.
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