Satellite and model-based characterization of canopy dew formation in tropical forests

Abstract:

The long-term trends of dew formation and their global patterns have received little attention, despite the wide acknowledgement that non-meteoric water can be a key source of water for many species, especially in tropical ecosystems. As such, accumulated and future effects of climate change on non-meteoric water occurrence remain an under-appreciated and unquantified factor in determining the risks that tropical ecosystems face.

In this presentation, we simulate patterns of global dew formation over the period 1901-2012 using the bias-corrected and down-scaled Princeton Global Forcing dataset. We investigate the degree to which climate change has influenced the amount and frequency of dew formation and speculate on the potential impact of these changes on dew-dependent tropical ecosystems. We compare our model results to contemporary global canopy water storage estimates derived from the SeaWinds Scatterometer aboard the QuikSCAT satellite using 6AM and 6PM microwave retrievals and a novel model of the impact of canopy water on satellite-based microwave backscatter.

Our dew formation results suggest significant decreases in dew formation over the past 30 years in tropical forests across South America and South East Asia. In contrast, we find that African tropical forests have experienced an increase in dew formation. Strong correlations between satellite-based canopy water storage and the dew formation model indicate the possibility of novel applications of microwave backscatter datasets in closed canopies ecosystems, such as the estimation of canopy interception or leaf-water content.