## 3 Results
### Backscatter Characteristics  
Figure 5 provides boxplots--showing the minimum, lower quartile (25%), median (50%), upper quartile (75%), maximum--of the land cover classes (see Table 2) for select polarimetric features of X-Band (TSX), C-Band (R-2) and L-Band (ALOS and ALOS-2). Figure 5a-i display the backscatter characteristics of the land cover classes concerning the HH, HV and VV sigma nought intensities in decibels (dB). Figure 5j-o shows the information of the model-based (power) decomposition features of the Yamaguchi Decomposition of C-Band (R-2) and L-Band (ALOS-2) as DBLB3, VOL3 and ODD3; in dB. Figure 5p-x shows the boxplots of the land cover classes for the Kennaugh Matrix elements K0, K3 and K4 of HH/VV-polarized X-Band (TSX), quad-polarized C-Band (R-2) and quad-polarized L-Band (ALOS-2) data in dB. The class OL showed a unique range of intensity values in the K0 and VV of X- and C- Band, the VOL3 and ODD3 of C-Band, and the K4 and HV of X-, C- and L-Band data. The scattering differences between water and land were clearly pronounced, as water was generally characterized by a low intensity value. This is because water surface was relatively calm, thus it was not observed as rough; the shallow angle incidence angles of the X- and C-Band data, and the longer wavelength of the L-Band. If the water surface were to become rough due to higher wind speeds, higher intensity values of K0 would be observed, thus complicating the separation of the classes. In such cases it is assumed that K3 and K4 will still be suitable to separate land from water, since both are indicators for double bounce scattering, typically minimal for water. Further, BS and BM showed increased HH, VV, HV, DBL3 and ODD3 scattering at C- and L-Band compared to other classes. The range of values observed for the BW class was more unique for L-Band features, than X- and C-Band features. The most distinct values were for L-Band VOL3; as the BW's median value exceeded +5 dB, compared to the median value of all other land cover classes. Scattering from BW at L-Band is therefore characterized by high intensity values for HH, VOL3 and ODD3, with medians of about \(-\)10 dB and \(-\)7 dB; whereas at C-Band the scattering from BW is characterized by high HH and ODD3 intensities. The median intensity of BW is comparably low in X-Band HH and differences of BW's statistics to BS and HT are less pronounced. Thus, independent of wavelength and decomposition technique, the data were sensitive to scattering differences between land and water (OL), and between sandy bare ground (BS) and mixed non-vegetated sediment (BM). BM had higher backscatter than BS, which can be attributed to the higher surface roughness of BM (grain sizes of 2.0 mm-256.0 mm) compared to BS (grain sizes of 0.0625 mm-2.0 mm), which leads to higher backscatter intensities.The difference between HT and ST scattering is characterized by increased HV, VOL3, and K0 intensities at X- and C-Band; however, there is substantial overlap in their distributions and the differences between median values were small; ranging from +2 dB (X-Band HV) to +3 dB (C-Band VOL3) between HT and ST. The largest differences in HT and ST statistics were nevertheless found for VOL3 of the C-Band data, but the data ranges of HT and ST (lower quantile to upper quantile) also overlap the ranges of BM, BW, WI and WT. Therefore, the X- and C-Band showed higher volume scattering intensities from shrub dominated tundra (ST) compared to herb dominated tundra (HT). This is likely due to a higher proportion of volume scattering in the shrub plants, which is caused by the relatively short wavelength. Contrarily, the L-Band HV and volume scattering intensities (VOL3) were not sensitive to this difference.