globalchange  > 影响、适应和脆弱性
DOI: 10.1002/2016JD025555
论文题名:
Impact of deep convection on the isotopic amount effect in tropical precipitation
作者: Tharammal T.; Bala G.; Noone D.
刊名: Journal of Geophysical Research: Atmospheres
出版年: 2017
卷: 122, 期:3
起始页码: 1505
结束页码: 1523
语种: 英语
英文关键词: deep convection ; fractionation efficiency ; isotope modeling ; isotopic enrichment ; tropical amount effect ; water isotopes
Scopus关键词: atmospheric convection ; climate modeling ; efficiency measurement ; isotopic analysis ; isotopic fractionation ; isotopic ratio ; parameterization ; precipitation (climatology) ; regression analysis ; sensitivity analysis ; slope dynamics ; stable isotope ; tropical region ; updraft ; water vapor ; Pacific Ocean ; Pacific Ocean (West)
英文摘要: The empirical “amount effect” observed in the distribution of stable water isotope ratios in tropical precipitation is used in several studies to reconstruct past precipitation. Recent observations suggest the importance of large-scale organized convection systems on amount effect. With a series of experiments with Community Atmospheric Model version 3.0 with water isotope tracers, we quantify the sensitivity of amount effect to changes in modeled deep convection. The magnitude of the regression slope between long-term monthly precipitation amount and isotope ratios in precipitation over tropical ocean reduces by more than 20% with a reduction in mean deep convective precipitation by about 60%, indicating a decline in fractionation efficiency. Reduced condensation in deep convective updrafts results in enrichment of lower level vapor with heavier isotope that causes enrichment in total precipitation. However, consequent increases in stratiform and shallow convective precipitation partially offset the reduction in the slope of amount effect. The net result is a reduced slope of amount effect in tropical regions except the tropical western Pacific, where the effects of enhanced large-scale ascent and increased stratiform precipitation prevail over the influence of reduced deep convection. We also find that the isotope ratios in precipitation are improved over certain regions in the tropics with reduced deep convection, showing that analyses of isotope ratios in precipitation and water vapor are powerful tools to improve precipitation processes in convective parameterization schemes in climate models. Further, our study suggests that the precipitation types over a region can alter the fractionation efficiency of isotopes with implications for the reconstructions of past precipitation. ©2017. American Geophysical Union. All Rights Reserved.
资助项目: "This study was funded by a grant from the Department of Science and Technology, Government of India. We acknowledge the Supercomputer Education and Research Center, Indian Institute of Science, Bangalore, India, for providing the supercomputer facilities to carry out the model simulations. We thank J. Srinivasan (Indian Institute of Science, Bangalore, India) for the helpful suggestions on our work. The isotopic version of the NCAR Community Atmosphere model was developed with support from the National Science Foundation Paleoclimate Program (award 1049104). The data sets and modeling results are available upon request to the corresponding author (thejna@caos.iisc.ernet.in).
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/62687
Appears in Collections:影响、适应和脆弱性
气候减缓与适应

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作者单位: Divecha Center for Climate Change, Indian Institute of Science, Bangalore, India; Divecha Center for Climate Change, Center for Atmospheric and Oceanic Sciences and Interdisciplinary Center for Water Research, Indian Institute of Science, Bangalore, India; College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States

Recommended Citation:
Tharammal T.,Bala G.,Noone D.. Impact of deep convection on the isotopic amount effect in tropical precipitation[J]. Journal of Geophysical Research: Atmospheres,2017-01-01,122(3)
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