Water stress detection in the Amazon using radar

The Amazon rainforest plays an important role in the global water and carbon cycle, and though it is predicted to continue drying in the future, the effect of drought remains uncertain. Developments in remote sensing missions now facilitate large‐scale observations. The RapidScat scatterometer (Ku b...

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Bibliographic Details
Published inGeophysical research letters Vol. 44; no. 13; pp. 6841 - 6849
Main Authors Emmerik, Tim, Steele‐Dunne, Susan, Paget, Aaron, Oliveira, Rafael S., Bittencourt, Paulo R. L., Barros, Fernanda de V., Giesen, Nick
Format Journal Article
LanguageEnglish
Published Washington John Wiley & Sons, Inc 16.07.2017
Wiley
Subjects
Amazon
Backscatter
Backscattering
Canopies
Canopy
Carbon cycle
Detection
Diurnal cycle
Diurnal variations
Drought
Drying
Earth
hydrology
International Space Station
Missions
Plant growth
Radar
Radar backscatter
Radar detection
Rainforests
Remote sensing
Scatterometers
Stellar mass
Sun
Sun-synchronous orbits
vegetation
Water
Water deficit
Water stress
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Summary:The Amazon rainforest plays an important role in the global water and carbon cycle, and though it is predicted to continue drying in the future, the effect of drought remains uncertain. Developments in remote sensing missions now facilitate large‐scale observations. The RapidScat scatterometer (Ku band) mounted on the International Space Station observes the Earth in a non‐Sun‐synchronous orbit, which allows for studying changes in the diurnal cycle of radar backscatter over the Amazon. Diurnal cycles in backscatter are significantly affected by the state of the canopy, especially during periods of increased water stress. We use RapidScat backscatter time series and water deficit measurements from dendrometers in 20 trees during a 9 month period to relate variations in backscatter to increased tree water deficit. Morning radar bacskcatter dropped significantly with increased tree water deficit measured with dendrometers. This provides unique observational evidence that demonstrates the sensitivity of radar backscatter to vegetation water stress, highlighting the potential of drought detection and monitoring using radar. Key Points Simultaneous ground measurements of tree water status and RapidScat backscatter Diurnal variation in backscatter differs during wet and dry seasons Radar backscatter is sensitive to tree water stress in Amazon
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ISSN:0094-8276
1944-8007
DOI:10.1002/2017GL073747