## 3 Results
### Net Ecosystem Exchange  
Figure 7 illustrates an example of the MWI\({}_{\rm TMS}\) from 2009 over the course of the growing season. The increase in MWI\({}_{\rm TMS}\) from April to June (DOY 100-150) corresponds with the greening of the vascular plants. The subsequent senescence in the fall (September-October) can be seen in the decrease of the index values after the 243 DOY. Prior to green-up, and during senescence, reflectance in the red band is higher (decreased absorbance) than during the period with green foliage, leading to a smaller value in the numerator of the MWI\({}_{\rm TMS}\). During the peak of the vascular foliage biomass over the summer, the strong absorbance in the red band relative to the NIR leads to a larger value in the numerator, and an increase in MWI\({}_{\rm TMS}\). The decrease in MWI\({}_{\rm TMS}\) on DOY 235 corresponds to the end of August, the point of the growing season with high air temperature and low water table depth. The yearly average (snow- and cloud-free) MWI\({}_{\rm TMS}\) ranged from 3.08 (\(\sigma\) = 1.2) in 2000 to 3.77 (\(\sigma\) = 0.99) in 2003. The seasonal variability ranged from a \(\sigma\) = 0.57 (2001) to \(\sigma\) = 1.2 in 2000. MWI\({}_{\rm TMS}\) from all years follow a temporal trend similar to Figure 7.  
We found a significant (\(P\) = 0.003) relationship between the average yearly MWI\({}_{\rm TMS}\) and yearly cumulative NEE (Figure 8a). The data from 2001 only includes a single scene from the fall; therefore, the average MWI\({}_{\rm TMS}\) is biased towards a higher average value, illustrating the importance of including multiple scenes throughout the growing season. While a relationship was found between MWI\({}_{\rm OILS}\) and yearly cumulative NEE (Figure 8b), it was not significant (\(P\) = 0.12). Despite a range of NEE from strong CO\({}_{2}\) uptake to CO\({}_{2}\) source over the 2013-2016 period, additional years of data are necessary to establish a significant relationship. Compared to the MWI\({}_{\rm TMS}\), there is a greater range of values for MWI\({}_{\rm OILS}\). Based on Equations (2) and (3), the numerator of the MWI\({}_{\rm TMS}\) is only 3.2-3.6 times the magnitude of the reflectance in the denominator (green band). In contrast, the MWI\({}_{\rm OILS}\) values span nearly double  
Figure 6: (**A**) Digital surface model (DSM) of a 400 m\({}^{2}\) plot at the original 2 cm ground sampling distance from [12]; (**B**) spatially degraded DSM to 1 m pixels. Units represent orthographic height in meters; (**C**) water table depth (cm from the surface) from the SASI HSI; (**D**) water table depth (cm from the surface) draped over the 1 m DSM; (**E**) 0.6 cm ground sampling distance 3D point cloud of the surface of the bog from 3 June 2017. The yellow box outlines the 400 m\({}^{2}\) plot. The DSM was created following [12] with a Zenmuse X5S onboard a DJI Inspire 2 (Micro 4/3 sensor, DJI MFT 15 mm/1.7 aspherical lens, 20.8 MP effective pixels, 3 axis \(\pm\)0.01\({}^{\circ}\) gimbal). the range indicating, as expected, a greater sensitivity of Landsat 8 OLI to the phenospectral changes of the peatland (i.e., spectral changes as a function of phenology) [51]. The yearly average (snow- and cloud-free) MWIOLIS ranged from 4.26 (\(\sigma=0.66\)) in 2016 to 4.84 (\(\sigma=0.83\)) in 2014. The seasonal variability ranged from \(\sigma=0.66\) (2016) to \(\sigma=1.18\) in 2015. We found a marginally significant relationship (\(P=0.0049\)) between NEE measured at the time of image acquisition and MWIOLIS from individual Landsat 8 OLI scenes (Figure 8c). Similar to the MWI\({}_{\text{TM5}}\) trend in Figure 7, higher values of the index can be seen later in the growing season when the vascular plants are in full foliage. As seen with the yearly average data (Figure 8a,b), the larger values of MWI\({}_{\text{TM5/OLIS}}\) correspond to higher CO\({}_{2}\) uptake.