## 4 Discussion
### Validity of Satellite-Derived Soil Moisture
While the ERA5 data captured broader trends in soil moisture, improvements in spatial resolution and sensor deployment strategies could enhance the detection of fine-scale variability. Vegetation Index Performance Across Seasons  
The NDVI, SAVI, and NDWI analysis revealed significant insights into the seasonal dynamics of vegetation health, growth stages, and water availability in the avocado orchard. The NDVI and SAVI were particularly useful for tracking the vegetative growth phases and canopy greenness [54; 55]. At the same time, the NDWI proved to be an effective tool for monitoring the water content in the vegetation, thereby providing insights into plant water stress. Both the NDVI and SAVI showed clear seasonal patterns, where the NDVI exhibited a gradual increase during the early months of the 2021 and 2022 growing seasons, reflecting the active vegetative growth of the avocado trees. The peak in NDVI values, occurring in the middle of each growing season, signaled maximum canopy greenness, corresponding to periods of high photosynthetic activity and optimal vegetative health [56; 57]. This increase in the NDVI was followed by a decline towards the end of the season, likely due to senescence or the harvest period [58], a common phenological change in fruit-bearing crops like avocados. The SAVI, which accounts for the soil's influence in sparsely vegetated areas, showed a similar seasonal trend, reinforcing its utility in monitoring vegetation cover in orchards with partial canopy coverage. In contrast, the NDWI was more sensitive to changes in water contents within the vegetation canopy. The NDWI values were generally low during the early stages of the growing season, corresponding to periods of minimal water availability. As the season progressed, the NDWI values increased, peaking during the wettest months when the vegetation was at its maximum water content. These increases in the NDWI were particularly evident during the wet season, highlighting the sensitivity of this index to fluctuations in water availability. The reduction in the NDWI during dry periods served as a clear indicator of water stress, making this index a valuable tool for monitoring the water status of crops. This analysis provided valuable insights into how vegetation responds to changing weather conditions, such as periods of water stress or growth phases. It contributed to understanding the interactions between vegetation health and soil moisture dynamics. Integrating these satellite-derived vegetation indices allowed for a comprehensive assessment of the orchard's seasonal dynamics. Phenological Patterns, Environmental Drivers, and Integration with Field Data  
The seasonal trends in vegetation indices (NDVI, SAVI, and NDWI) reflected the phenological stages of the avocado crop and its response to environmental factors such as temperature and precipitation. During the growing season, peak NDVI values coincidedwith the period of maximum vegetative growth, which aligned with favorable temperature and soil moisture conditions [59], as expected in temperate climates. Meteorological variables, particularly high temperatures and low precipitation during the dry season, significantly influenced the vegetation index dynamics [60]. These conditions contributed to a decline in vegetation indices towards the end of the year, indicating stress experienced by the trees. The temperature and VPD increase during dry periods heightened the atmospheric water demand, leading to higher evapotranspiration rates and reduced soil moisture availability. This was evident in the decline in the NDWI, which signaled water stress, particularly during dry spells, where high VPD values further intensified the effect. The relationship between precipitation and the NDWI was particularly noteworthy, as increases in moisture content following rainfall events correlated with sharp rises in NDWI values [61; 62]. This demonstrates the NDWI's effectiveness as a reliable indicator of water availability and plant water stress.