CEE Seminar - How occult precipitation influences land surface processes across scales

Light rainfall, fog, and dew deposition (i.e., occult precipitation) have been shown to play a key role in ecosystem processes and resilience to extremes such as drought and wildfire. Occult precipitation describes hydrologic processes that provide water input to ecosystems but are typically not measured by rain gauges. Thus, the amount of additional water that ecosystems receive from occult precipitation remains unaccounted for in Earth system models (ESMs). Missing water inputs from occult precipitation may exacerbate existing uncertainties in ESMs when assessing ecosystem response and resilience to long-term changes in mean state and variability of climate, disturbances, and weather extremes. This knowledge gap stems from a lack of ground observations of occult precipitation and challenges with using remote sensing to detect light rainfall, fog, and dew. Accounting for this missing water input in ecosystem water, energy, and carbon budgets is critical. However, it is not only the amount of missing water input that influences vegetation activity in ESMs, but also the thermodynamic processes that accompany their presence and/or formation. In this talk, we will investigate how occult precipitation influences vegetation from the leaf to ecosystem to global scales, and the impacts on local atmospheric processes. Specifically, we will consider this problem from the leaf-scale where patterns of wetting and plant adaptations to wet conditions influence gas exchange, to regional and global scales where remote sensing algorithms influence our ability to quantify ecosystem gas exchange rates during periods of canopy wetting. This work highlights the need to better represent vegetation processes under wet conditions towards improving our understanding of land-atmosphere interactions under changing climate conditions and precipitation regimes.