Hi!,

Well...I´m pretty sure there is not an easy answer to your question. SAR is usually very sensitive to roughness, but roughness is not an absolute concept. Usually, rms height (s), and the correlation length (l) are used to characterize it. When you say rough terrain, you have to take the account the relationship between the wavelength of the instrument and how it relates to s and l. A certain soil for example can be very rough at the X band and smooth at the L band. There is also another aspect to take into account if the vegetation you are trying to analyze covers completely to soil and is well developed may be the effect of the soil roughness is not that significant, if not you may get backscatter from the soil. We have observed a similar issue even at the X band, that because of its wavelength, penetrates less. Regarding a correlation between LAI and backscatter, depending on the type of crop/land cover, and soil characteristics maybe you can find a correlation but from our experience, it can be tricky.

Hope it helps,

regards

Thank you Soledad for your input!

All the best,

Ebrahim

This is somewhat related: Article Exploitation of SAR and Optical Sentinel Data to Detect Rice...

I hope it helps.