Journal ArticleDOI
Importance of rain evaporation and continental convection in the tropical water cycle
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TLDR
Measurements of the isotopic composition of water vapour near tropical clouds and over the tropical continents suggest that rainfall evaporation contributes significantly to lower troposphere humidity, and convection of vapour from both oceanic sources and evapotranspiration are the dominant moisture sources.Abstract:
Atmospheric moisture cycling is an important aspect of the Earth's climate system, yet the processes determining atmospheric humidity are poorly understood. For example, direct evaporation of rain contributes significantly to the heat and moisture budgets of clouds, but few observations of these processes are available. Similarly, the relative contributions to atmospheric moisture over land from local evaporation and humidity from oceanic sources are uncertain. Lighter isotopes of water vapour preferentially evaporate whereas heavier isotopes preferentially condense and the isotopic composition of ocean water is known. Here we use this information combined with global measurements of the isotopic composition of tropospheric water vapour from the Tropospheric Emission Spectrometer (TES) aboard the Aura spacecraft, to investigate aspects of the atmospheric hydrological cycle that are not well constrained by observations of precipitation or atmospheric vapour content. Our measurements of the isotopic composition of water vapour near tropical clouds suggest that rainfall evaporation contributes significantly to lower troposphere humidity, with typically 20% and up to 50% of rainfall evaporating near convective clouds. Over the tropical continents the isotopic signature of tropospheric water vapour differs significantly from that of precipitation, suggesting that convection of vapour from both oceanic sources and evapotranspiration are the dominant moisture sources. Our measurements allow an assessment of the intensity of the present hydrological cycle and will help identify any future changes as they occur.read more
Citations
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Widening of the tropical belt in a changing climate
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References
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Journal ArticleDOI
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The Changing Character of Precipitation
TL;DR: In this article, precipitation intensity, duration, frequency, and phase are as much of concern as total amounts, as these factors determine the disposition of precipitation once it hits the ground and how much runs off.
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Interaction of a Cumulus Cloud Ensemble with the Large-Scale Environment, Part I
Akio Arakawa,Wayne H. Schubert +1 more
TL;DR: In this paper, large-scale modification of the environment by cumulus clouds is discussed in terms of entrainment, detraining, evaporation, and subsidence, and budget equations for mass, static energy, water vapor, and liquid water are considered.
Journal ArticleDOI
Oxygen and hydrogen isotopes in the hydrologic cycle
TL;DR: In this article, the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes.
Journal ArticleDOI
The cause of decreased pan evaporation over the past 50 years.
TL;DR: In this article, the authors show that the decrease in evaporation is consistent with what one would expect from the observed large and widespread decreases in sunlight resulting from increasing cloud coverage and aerosol concentration.