Global root zone storage capacity from satellite-based evaporation

Global root zone storage capacity from satellite-based evaporation

Wang-Erlandsson, L. (TU Delft Water Resources; Stockholm University)
Bastiaanssen, W.G.M. (TU Delft Water Resources; IHE Delft Institute for Water Education)
Gao, H. (TU Delft Water Resources; Arizona State University)
Jägermeyr, Jonas (Potsdam Institute for Climate Impact Research)
Senay, Gabriel B. (North Central Climate Science Centre)
Van Dijk, Albert I J M
Guerschman, Juan P.
Keys, Patrick W. (Colorado State University)
Gordon, Line J. (Stockholm University)
Savenije, Hubert (TU Delft Water Resources)

2016-04-19

This study presents an "Earth observation-based" method for estimating root zone storage capacity-a critical, yet uncertain parameter in hydrological and land surface modelling. By assuming that vegetation optimises its root zone storage capacity to bridge critical dry periods, we were able to use state-of-the-art satellite-based evaporation data computed with independent energy balance equations to derive gridded root zone storage capacity at global scale. This approach does not require soil or vegetation information, is model independent, and is in principle scale independent. In contrast to a traditional look-up table approach, our method captures the variability in root zone storage capacity within land cover types, including in rainforests where direct measurements of root depths otherwise are scarce. Implementing the estimated root zone storage capacity in the global hydrological model STEAM (Simple Terrestrial Evaporation to Atmosphere Model) improved evaporation simulation overall, and in particular during the least evaporating months in sub-humid to humid regions with moderate to high seasonality. Our results suggest that several forest types are able to create a large storage to buffer for severe droughts (with a very long return period), in contrast to, for example, savannahs and woody savannahs (medium length return period), as well as grasslands, shrublands, and croplands (very short return period). The presented method to estimate root zone storage capacity eliminates the need for poor resolution soil and rooting depth data that form a limitation for achieving progress in the global land surface modelling community.

OA-Fund TU Delft

http://resolver.tudelft.nl/uuid:0692410c-9ab1-4497-8562-aee488aca8e4

https://doi.org/10.5194/hess-20-1459-2016

1027-5606

Hydrology and Earth System Sciences, 20 (4), 1459-1481

Institutional Repository

journal article

© 2016 L. Wang-Erlandsson, W.G.M. Bastiaanssen, H. Gao, Jonas Jägermeyr, Gabriel B. Senay, Albert I J M Van Dijk, Juan P. Guerschman, Patrick W. Keys, Line J. Gordon, Hubert Savenije