## 5 Conclusions  
Our results show strong correlations between both \(\mathrm{SIF}_{\mathrm{FR}}\) and \(\mathrm{SIF}_{\mathrm{red}}\) and PAR (\(p<0.001\)) and photosynthetic measurements (YPSII, YNPQ, YNO and ETR; \(p<0.001\)) performed with the LIFT instrument over a diurnal cycle. When analysing measurements at seasonal scales, our results suggest that SIF indicates changes in ETR, YNO and leaf PAR, with all other changes being potentially explained by fluctuations in leaf pigments and maximum daily air temperature. Statistical analyses also suggest that short-term correlations between photosynthesis and SIF changes may be principally driven by collinearity between SIF and photosynthesis changes triggered by leaf PAR fluctuations. This study demonstrates one of the first operational simultaneous SIF and active chlorophyll fluorescence proximal remote sensing, thus allowing statistically significant linkage of SIF with ETR and YNO. Overall, our results indicate that leaf level correlations observed over diurnal time scales may not be present in seasonal trends, where longer term changes in plant pigments, temperature and irradiance become influential. However, the extent to which the observed leaf level correlations can be scaled to the top of canopy (TOC) using, for instance, a combination of an airborne variant of LIFT [49; 50] and canopy radiative transfer modelling [51; 52], requires further investigation. At TOC we would expect lower \(\text{SIF}_{\text{red}}\) due to reabsorption by canopy elements containing PAR absorbing pigments [53]. As such, leaf level \(\text{SIF}_{\text{red}}\) correlations may be weakened or not present at larger spatial scales. Additionally, SIF is commonly thought to be isotropically emitted from the leaf, making SIF retrieved at the leaf level minimally influenced be changes in solar irradiance and sensor viewing angularity [54]. At the canopy level SIF observations are strongly influenced by the angles between sun, foliage and measuring instruments [8; 54]. This means that leaf level diurnal SIF changes will be very likely different at TOC. Nevertheless, TOC relationships between \(\phi\)PSII, ETR and SIF published recently [7; 17; 43] suggest that novel leaf level correlations between YNO and \(\text{SIF}_{\text{FR}}\), identified in this study, may possibly hold at larger spatial scales, warranting future dedicated scaling experiments to test this hypothesis. Supplementary material may be found online at www.mdpi.com/2072-4292/9/6/604/s1, Figure S1: Relationship between PAM and LIFT measured YPSII calculated from Q\({}_{\text{A}}\) and PQ flashes, Figure S2: Relationship between leaf absorbance (400 to 700 nm) and leaf SPAD optical density measurements for avocado and orange jasmine leaves, Figure S3: 3D MDS analysis of seasonal changes in LIFT and QE Pro measurements, Figure S4: Scatterplots of daily measurements of \(\text{SIF}_{\text{red}}\) and \(\text{SIF}_{\text{FR}}\) against global PAR, NDVI and PRI from leaves of avocado and orange jasmine, Figure S5: Scatterplots of daily measurements of YSIFred and YSIFFR against LIFT measured photosynthetic parameters and leaf PAR from leaves of both avocado and orange jasmine, Figure S6: Scatterplots of daily measurements of \(\text{YSIF}_{\text{red}}\) and \(\text{YSIF}_{\text{FR}}\) against global PAR, NDVI and PRI from leaves of avocado and orange jasmine, Table S1: Matrix table of the smallest absolute angles between vectors from 3D MDS analysis, Table S2: Matrix table of p values and R2 values for correlations between YSIF (red and FR) and LIFT and QE Pro measurements, Video S1: Time-lapse of LIFT and QE Pro diurnal measurements. **Acknowledgments:** This project was supported by an Australian Research Council Discovery grant \"AirLIFT\" (DP140101488) and conducted in research facilities and with scientific equipment from the UOW and the Australian National University, with technical support for the LIFT instrument kindly provided by [PERSON].