## 3 Results  
The average Scots pine TOC reflectance was approximately the same for the scatter angles \(\beta=55^{\circ}\) and \(90^{\circ}\), with significantly higher values produced across the spectrum at \(\beta=19^{\circ}\), the direction closest to hot spot (Figure 3a). This trend is mirrored in the fraction of sunlit needles for the three view angles (Figure 3b): the average sunlit fraction decreased as the scatter angle increased, but the difference in \(\alpha_{S}\) (0.04) between scatter angles \(55^{\circ}\) and \(76^{\circ}\) was smaller than between \(19^{\circ}\) and \(55^{\circ}\) (0.21), although all \(\alpha_{S}\) differences in scatter angles were significant (\(p<<0.01\)). Mean PRI, on the other hand, did not change monotonically with the scatter angle \(\beta\) (Figure 3c). The smallest PRI value of \(-0.052\) was measured for near-nadir direction (\(\beta=55^{\circ}\)) with near-similar values of \(-0.049\) and \(-0.046\) for the scatter angles \(\beta=19^{\circ}\) and \(\beta=76^{\circ}\), respectively. Despite the overlapping ranges in Figure 3c, \(t\)-tests indicated a significant difference (\(p<0.01\)) between the PRI values for three lines. The range of the within-view angle in PRI varied with the scatter angle from \(0.117\) at \(\beta=19^{\circ}\), to \(0.169\) at \(\beta=55^{\circ}\), and \(0.163\) at \(\beta=76^{\circ}\). The standard deviation in PRI was \(0.011\) at \(\beta=19^{\circ}\), \(0.162\) at \(\beta=55^{\circ}\), and \(0.158\) at \(\beta=76^{\circ}\). A true color image of the focus area highlights the spatial variation in Scots pine canopy brightness for all three scatter angles (Figure 4). The spatial variation in PRI (Figure 5) and sunlit fraction (Figure 6) were also visually compared for all three scatter angles. Figure 4: True color images of the focus area (red rectangle in Figure 2) inside the test polygon showing spatial variation in Scots pine canopy brightness for different scatter angles (\(\beta=19^{\circ}\) (**a**); \(\beta=55^{\circ}\) (**b**); \(\beta=76^{\circ}\) (**c**)). Purple pixels were masked out; normalized difference vegetation index (NDVI) \(<0.8\). Figure 3: Average Scots pine top of canopy (TOC) spectral reflectance (**a**), Scots pine canopy sunlit fraction (**b**) and Scots pine canopy photochemical reflectance index (PRI) (**c**) for three scatter angles (\(\beta=19^{\circ}\), \(55^{\circ}\) and \(76^{\circ}\)). The scatter angle closest to the hot spot (\(\beta=19^{\circ}\)) produced higher average TOC HDRF values than scatter angles \(55^{\circ}\) and \(76^{\circ}\) in the visible region (400-700 nm), but less reflectance in the near-infrared region (700-870 nm) (Figure 7) for any fixed interval of the sunlit fraction \(\alpha_{S}\). To investigate this, we divided the average TOC HDRF reflectance at the oblique angles (\(\beta=19^{\circ}\) and \(76^{\circ}\)) by the reflectance close to nadir (\(\beta=55^{\circ}\)). We observed a general decrease in the HDRF (\(19^{\circ}\))/HDRF (\(55^{\circ}\)) ratio with \(\alpha_{S}\), with especially strong dependence in the visible wavelengths. The ratio HDRF (\(76^{\circ}\))/HDRF (\(55^{\circ}\)) remained more constant and was close to unity across the whole measured spectrum (Figure 8). In both cases (HDRF (\(19^{\circ}\))/HDRF (\(55^{\circ}\)) and HDRF (\(76^{\circ}\))/HDRF (\(55^{\circ}\))), the highest HDRF ratio values were obtained for \(\alpha_{S}\) between 0.43 and 0.45. Figure 5: Spatial variation of the canopy PRI for \(\beta=19^{\circ}\) (**a)**; \(\beta=55^{\circ}\) (**b)**; and \(\beta=76^{\circ}\) (**c**). Purple pixels were masked out (NDVI \(<\) 0.8). The color scale is the same for all three rasters. Figure 6: Spatial variation of the canopy sunlit fraction for \(\beta=19^{\circ}\) (**a)**, \(\beta=55^{\circ}\) (**b)**, \(\beta=76^{\circ}\) (**c**). Purple pixels were masked out (NDVI \(<\) 0.8). The color scale is the same for all three rasters. Figure 7: Average Scots pine canopy TOC reflectance for sunlit fraction 0.26–0.29 (**a)**; 0.35–0.36 (**b)**; and 0.43–0.45 (**c**).