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Active microwave observations of diurnal and seasonal variations of canopy water content across the humid African tropical forests
Author(s) -
Konings Alexandra G.,
Yu Yifan,
Xu Liang,
Yang Yan,
Schimel David S.,
Saatchi Sassan S.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl072388
Subject(s) - environmental science , canopy , evapotranspiration , vapour pressure deficit , vegetation (pathology) , water content , atmospheric sciences , tree canopy , diurnal temperature variation , biomass (ecology) , dry season , hydrology (agriculture) , transpiration , ecology , geology , oceanography , medicine , botany , photosynthesis , geotechnical engineering , pathology , biology
A higher frequency of severe droughts under warmer temperatures is expected to lead to large impacts on global water and carbon fluxes and on vegetation cover—including possible widespread mortality. Monitoring the hydraulic state of vegetation as represented by the canopy water content will allow rapid assessment of vegetation water stress. Here we show the potential of active microwave backscatter observations at Ku band for monitoring the diurnal and seasonal variations of top‐of‐canopy water content. We focus on the humid tropical forests of Central Africa and examine spatiotemporal variations of radar backscatter from QuikSCAT (2001–2009) and RapidScat (2014–2016). Diurnal variations in RapidScat backscatter demonstrate the occurrence of widespread midday stomatal closure in this region. Increases in backscatter during the dry seasons in humid forests could be explained by both dry season leaf flushing (as supported by canopy structure) and vapor pressure deficit‐driven increases in evapotranspiration rates.