Amazonian terrestrial water balance inferred from satellite-observed water vapor isotopes

Mingjie Shi , John R. Worden , Adriana Bailey , David Noone , Camille Risi (1) , Rong Fu , Sarah Worden , Robert Herman , Vivienne Payne , Thomas Pagano , Kevin Bowman , A. Anthony Bloom , Sassan Saatchi , Junjie Liu , Joshua B. Fisher

1 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)

Atmospheric humidity and soil moisture in the Amazon forest are tightly coupled to the region's water balance, or the difference between two moisture fluxes, evapotranspiration minus precipitation (ET-P). However, large and poorly characterized uncertainties in both fluxes, and in their difference, make it challenging to evaluate spatiotemporal variations of water balance and its dependence on ET or P. Here, we show that satellite observations of the HDO/H₂O ratio of water vapor are sensitive to spatiotemporal variations of ET-P over the Amazon. When calibrated by basin-scale and mass-balance estimates of ET-P derived from terrestrial water storage and river discharge measurements, the isotopic data demonstrate that rainfall controls wet Amazon water balance variability, but ET becomes important in regulating water balance and its variability in the dry Amazon. Changes in the drivers of ET, such as above ground biomass, could therefore have a larger impact on soil moisture and humidity in the dry (southern and eastern) Amazon relative to the wet Amazon.

Domains: Sciences of the Universe [physics]

Mingjie Shi, John R. Worden, Adriana Bailey, David Noone, Camille Risi, et al.. Amazonian terrestrial water balance inferred from satellite-observed water vapor isotopes. Nature Communications, 2022, 13, ⟨10.1038/s41467-022-30317-4⟩. ⟨insu-03726897⟩