Synthetic-Aperture Radar on Trees

Wavelength is an important feature to consider when working with SAR, as it determines how the radar signal interacts with the surface and how far a signal can penetrate objects like trees. In our project, we prefer Band-L and Band-P because of it's longer wavelength, they can penetrate through leafs by diffraction to contruct a full tree.

Geometrical Factors

Soil Moisture: SAR measurement of forests is sensitive to moisture and any changes of soil moisture due to precipitation events or irrigation can infuence the result.

Surface Inundation: Vegetated surfaces, particularly near rivers or in low elevation areas in wetlands, may be inundated seasonally or permanently due to the rise of the water level creating a smooth water body submerging the vegetation at diferent levels into the water

Wind:Wind may change the orientation of the leaves, twigs and small branches with respect to radar observational geometry.

Intercepted Water: After any rain events or early in the morning due to development of dews, there are water droplets on the leaves, causing both scattering and attenuation of the SAR signal.

Water Content: Changes of water content in trees and leaves from either stress, or daily and seasonally due to water loss and recharge of soil moisture impact to the result.

Reference: https://www.earthdata.nasa.gov/learn/backgrounders/what-is-sar

https://www.servirglobal.net/Global/Articles/Article/2674/sar-handbook-comprehensive-methodologies-for-forest-monitoring-and-biomass-estimation