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High-frequency Isotope Compositions Reveal Different Cloud-top and Vertical Stratiform Rainfall Structures in the Inland Tropics of Brazil
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  • Vinicius dos Santos,
  • Ana María Durán-Quesada,
  • Ricardo Sánchez-Murillo,
  • Didier Gastmans
Vinicius dos Santos
São Paulo State University

Corresponding Author:[email protected]

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Ana María Durán-Quesada
University of Costa Rica
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Ricardo Sánchez-Murillo
Department of Earth and Environmental Sciences, University of Texas at Arlington
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Didier Gastmans
São Paulo State University
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Abstract

Understanding the key drivers controlling rainfall stable isotope variations in inland tropical regions remains a global challenge. We present novel high-frequency isotope data (5-30 minute intervals) to disentangle the evolution of six stratiform rainfall events (N=112) during the passage of convective systems in inland Brazil (September 2019-June 2020). These systems produced stratiform rainfall of variable cloud features. Depleted stratiform events (δ18Oinitial ≤ -4.2 ‰ and δ18Omean ≤ -6.1 ‰) were characterized by cooler cloud-top temperatures (≤-38 °C), larger areas (≥ 48 km2), higher liquid-ice ratios (≥ 3.1), and higher melting layer heights (≥3.8 km), compared to enriched stratiform events (δ18Oinitial ≥ -3.8 ‰ and δ18Omean ≥ -5.1 ‰). Cloud vertical structure variability was reflected in a wide range of δ18O temporal patterns and abrupt shifts in d-excess. Our findings provide a new perspective to the ongoing debate about isotopic variability and the partitioning of rainfall types across the tropics.
26 Apr 2024Submitted to ESS Open Archive
26 Apr 2024Published in ESS Open Archive