EOWAVE - Earth Observation of Water and Vegetation

Global warming is expected to amplify the global water cycle, which will lead to an increase the frequency and intensity of storms, floods, and droughts. The negative impact of droughts on vegetation will impact future food security and reduce the efficiency of vegetation as a sink of atmospheric carbon-dioxide, thus further exacerbating global warming. However, climate model predictions are uncertain as the long-term effects of drought on vegetation are only poorly understood due to lack of suited observational data. But the recent release of various long-term satellite-based datasets of soil moisture (produced by CLIMERS) and other climate and vegetation variables has created new avenues. In EOWAVE we will use these datasets to unravel the role of water availability in driving vegetation dynamics and to asses how climate change has affected this relationship. The results will be used to improve state-of-the-art climate models that support the IPCC climate assessments.

The overarching goal of EO-WAVE is to reduce uncertainties in our knowledge on how soil moisture drives vegetation growth over space and time.Using long-term Earth Observation datasets of the water and carbon cycles we will try to address two major scientific challenges: Scientific Challenge 1 (SC1) will seek an answer to the question “How does soil moisture drive vegetation growth?” while Scientific Challenge 2 (SC2) addresses the question “How does climate change affect the relationship between soil moisture and vegetation”?

In particular, the project targets the following objectives:

1.       Empirically quantify the effect of drought on vegetation growth.

2.       Identify key deficiencies in water-vegetation interaction in state-of-the-art Earth System Models and provide observational support for improving the parameterisation of processes in these models.

3.       Identify changes in vegetation dynamics (trends and extremes) over time and quantify the relative role of water availability herein.

A schematic overview of the project structure and tasks is given below.

Recent work: Microwave data for vegetation productivity

Vegetation presents a key feature in our climate system as it affects both water and carbon cycle. Characterising large-scale vegetation dynamics can contribute to understanding complex interactions between plants and their abiotic resources. Monitoring vegetation using microwave satellite observations provides complementary information to the commonly used optical data due to the higher penetration depth of microwave radiation and their sensitivity to the vegetation water content. Therefore, microwave Vegetation Optical Depth (VOD) can be used to analyse water related processes governing vegetation growth. VOD is available from active and passive sensors and from different frequencies in the microwave domain, for vegetation monitoring most notably L-, C-, X-, and Ku-band. The sensitivity of VOD to the vegetation cover varies with frequency and sensor type. Thus, a comparison of multiple VOD datasets with respect to the targeted vegetation properties is necessary to make full use of microwave satellite observations for describing large-scale ecosystem dynamics.

CLIMERS members involved

 Results and publications