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Observed Tightening of Tropical Ascent in Recent Decades and Linkage to Regional Precipitation Changes

Su, Hui and Wu, Longtao and Zhai, Chengxing and Jiang, Jonathan H. and Neelin, J. David and Yung, Yuk L. (2020) Observed Tightening of Tropical Ascent in Recent Decades and Linkage to Regional Precipitation Changes. Geophysical Research Letters, 47 (3). Art. No. e2019GL085809. ISSN 0094-8276. doi:10.1029/2019gl085809.

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Climate models predict that the tropical ascending region should tighten under global warming, but observational quantification of the tightening rate is limited. Here we show that the observed spatial extent of the relatively moist, rainy and cloudy regions in the tropics associated with large‐scale ascent has been decreasing at a rate of −1%/decade (−5%/K) from 1979 to 2016, resulting from combined effects of interdecadal variability and anthropogenic forcings, with the former contributing more than the latter. The tightening of tropical ascent is associated with an increase in the occurrence frequency of extremely strong ascent, leading to an increase in the average precipitation rate in the top 1% of monthly rainfall in the tropics. At the margins of the convective zones such as the Southeast Amazonia region, the contraction of large‐scale ascent is related to a long‐term drying trend about −3.2%/decade in the past 38 years.

Item Type:Article
Related URLs:
URLURL TypeDescription
Su, Hui0000-0003-1265-9702
Wu, Longtao0000-0001-8447-8180
Zhai, Chengxing0000-0002-0291-4522
Jiang, Jonathan H.0000-0002-5929-8951
Neelin, J. David0000-0001-9414-9962
Yung, Yuk L.0000-0002-4263-2562
Additional Information:© 2020 American Geophysical Union. Received 14 OCT 2019; Accepted 16 JAN 2020; Accepted article online 21 JAN 2020. This work was performed at Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. This study is supported by NASA ACMAP‐AST and MAP projects. J. D. N. is supported by the NSF AGS‐1540518 Grant. Data Statement: The original reanalysis data sets, observations, and CMIP5 model simulations used in this study are all publicly available. The websites to download these data are as follows: ERA‐I (‐full‐moda/levtype=sfc/); MERRA‐2 (‐2/data_access/); JRA‐55 (; GPCP precipitation ( OAFlux ( NOAA OLR (; HadCRU4 Ts (; CMIP5 (http://cmip‐ The methods to process the data and generate the results are described in detail in the paper. Please contact the corresponding author at for any questions.
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:Circulation; ITCZ; Precipitation; Ascent; Tightening; Drying
Issue or Number:3
Record Number:CaltechAUTHORS:20200122-145021587
Persistent URL:
Official Citation:Su, H., Wu, L., Zhai, C., Jiang, J. H., Neelin, J. D., & Yung, Y. L. (2020). Observed tightening of tropical ascent in recent decades and linkage to regional precipitation changes. Geophysical Research Letters, 47, e2019GL085809.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100854
Deposited By: Tony Diaz
Deposited On:22 Jan 2020 23:00
Last Modified:16 Nov 2021 17:57

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