C-band scattering simulation of a Scots pine shoot

Scots pine (Pinus sylvestris L.) has the widest distribution of any pine and is one of the most important timber trees in Europe and one of the main species of boreal forest, which have an important role in climate change studies. The leaf area index (LAI) is one of the key input parameters for the climate change models. Recently a relationship between C-band backscattering and the LAI has been detected for Scots pine. To understand the C-band microwave characteristics of Scots pine shoots the backscattering is simulated using the so-called discrete dipole approximation (DDA), which is the only possible, nearly exact method for this problem. The backscattering of the shoot is dominated by the needles. The VV/HH backscattering ratio of closely spaced parallel and perpendicular shoots averages to that of a single shoot. For a simulated whole Scots pine crown the VV/HH backscattering ratio is related to the total orientation distribution of the needles. The variation range of the VV/HH backscattering ratio was 0.95-1.25, which is close to empirical values.