Global Estimation of Canopy Water Content

In water limited environments, the density and water content of plant canopies is highly correlated with available soil moisture. Soil moisture limits the magnitude of evapotranspiration and changes the partitioning of sensible heat flux, thus altering downwind humidity. CalSpace will provide MODIS derived estimates of vegetation water content, addressing at different scales various measurements of water content: equivalent water thickness, fuel moisture content and relative canopy water content; each useful for different global modeling purposes that address key NASA Earth Science questions. The validation of the MODIS results will utilize a multiscale approach, from concurrent field measurements to cross-validations at global scales. We will assess as wide a range of environmental and climate conditions as possible within funding limits, taking advantage of shared databases and experiments. Evaluation of the temporal-series products for weekly and daily data at will be done at the regional scale based on theory, cross-validated where possible, and validated using field observations. We will provide the analytical code for the water content estimation to potential users in the research community to facilitate independent comparisons.

A MODIS canopy water content data product for both Terra and Aqua will contribute to answering climate change questions, specifically addressing variability and changes in the Earth's system, the driving forces producing these changes, and the responses, consequences and prediction of future biospheric changes. Specifically, knowledge of the spatial and temporal patterns of canopy water content will increase understanding of the cycling of water and its interaction with changing ecosystems. This product will provide a measure for monitoring the transformation of the Earth's surface, impacts of land cover and land use changes, which can be associated with sustainability of ecosystems. The MODIS product will also extend knowledge about the effect changes in canopy water content have on physiological functioning, and therefore on the carbon cycle. Another outcome will be enhanced understanding of the feedback relationships between variation in local-scale vegetation water stress and regional to global variations in climate. The MODIS data product will increase reliability of climate models since their predications will be based on more on accurate estimates of water and other biogeochemical cycles. Lastly, the MODIS water content product has important implications for detecting crop water stress and soil moisture in agriculture.