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Amazonian Moisture Recycling Revisited Using WRF with Water Vapor Tracers
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  • Francina Dominguez,
  • Jorge Eiras-Barca,
  • Zhao Yang,
  • David Bock,
  • Raquel Nieto,
  • Luis Gimeno
Francina Dominguez
University of Illinois at Urbana-Champaign-Department of Atmospheric Sciences

Corresponding Author:[email protected]

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Jorge Eiras-Barca
Defense University Center at the Spanish Naval Academy
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Zhao Yang
Pacific Northwest National Laboratory
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David Bock
National Center for Supercomputing Applications
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Raquel Nieto
EPhysLab (Environmental Physics Laboratory), Universidad de Vigo
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Luis Gimeno
Universidad de Vigo
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Previous studies have estimated that 25% to 35% of Amazonian precipitation comes from evapotranspiration (ET) within the basin. However, due to simplifying assumptions of traditional models, these studies primarily focus on large spatial and temporal scales. In this work we use the Weather Research and Forecast (WRF) regional climate model with the added capability of water vapor tracers to track the moisture from Amazonian ET at the native WRF resolution. The tracers reveal that the well-mixed assumption of simpler models does not hold, as local ET is more efficiently rained out of the atmospheric column than remote sources of moisture, particularly in the eastern part of the basin. Recycled precipitation shows a strong annual and semi-annual signal, associated with the passage of the Inter-Tropical Convergence Zone. The tracers also reveal a strong diurnal cycle of Amazonian water vapor related to the diurnal cycle of ET, convective precipitation and advected moisture. ET increases from early morning into the afternoon, some of this moisture is rained out through convective storms in the early evening, while later in the night strong winds associated with the South American Low Level Jet advect moisture downwind. Visualizing the Amazonian water vapor highlights its diurnal beating pattern and suggests that the Amazon has “younger” water than other regions in the globe, with very efficient recycling of local moisture.
27 Feb 2022Published in Journal of Geophysical Research: Atmospheres volume 127 issue 4. 10.1029/2021JD035259