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The Double-ITCZ Bias in CMIP3, CMIP5 and CMIP6 Models Based on Annual Mean Precipitation

Tian, Baijun and Dong, Xinyu (2020) The Double-ITCZ Bias in CMIP3, CMIP5 and CMIP6 Models Based on Annual Mean Precipitation. Geophysical Research Letters, 47 (8). Art. No. e2020GL087232. ISSN 0094-8276. doi:10.1029/2020gl087232.

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The double‐intertropical convergence zone (ITCZ) bias is one of the most outstanding errors in all previous generations of climate models. Here, the annual double‐ITCZ bias and the associated precipitation bias in the latest climate models for Coupled Model Intercomparison Project (CMIP) Phase 6 (CMIP6) are examined in comparison to their previous generations (CMIP Phase 3 [CMIP3] and CMIP Phase 5 [CMIP5]). All three generations of CMIP models share similar systematic annual multi‐model ensemble mean precipitation errors in the tropics. The notorious double‐ITCZ bias and its big inter‐model spread persist in CMIP3, CMIP5, and CMIP6 models. Based on several tropical precipitation bias indices, the double‐ITCZ bias is slightly reduced from CMIP3 or CMIP5 to CMIP6. In addition, the annual equatorial Pacific cold tongue persists in all three generations of CMIP models, but its inter‐model spread is reduced from CMIP3 to CMIP5 and from CMIP5 to CMIP6.

Item Type:Article
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Tian, Baijun0000-0001-9369-2373
Dong, Xinyu0000-0003-4090-3653
Additional Information:© 2020 American Geophysical Union. Received 29 JAN 2020; Accepted 22 MAR 2020; Accepted article online 28 March 2020. This research was performed at Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA (80NM0018D0004) and supported by the NASA Science of Terra, Aqua, and Suomi NPP (TASNPP) program under Grant 444491. administered by Dr. Tsengdar Lee and Dr. Gail Skofronick‐Jackson. Data sets for this research are available in these references: Adler and Huffman (2018), Eyring et al. (2016), Huffman (2018), Meehl et al. (2007), and Taylor et al. (2012). The GPCP/TRMM and CMIP3/5/6 data were provided by the Obs4MIPs and CMIP project, respectively. We acknowledge the WCRP Working Group on Coupled Modeling (WGCM), which is responsible for CMIP, and the U.S. DOE's Program for Climate Model Diagnosis and Intercomparison (PCMDI), which provides coordinating support and leads development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We thank the climate modeling groups around the world for producing and making available their model output and Dr. Gudrun Magnusdottir (the Editor), Dr. Tapio Schneider, and two anonymous reviewers for their constructive comments and discussions that helped improving the quality of this paper.
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Subject Keywords:CMIP3; CMIP5; CMIP6; Double‐ITCZ bias; Climate Models; Precipitation
Issue or Number:8
Record Number:CaltechAUTHORS:20200408-085910259
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Official Citation:Tian, B., & Dong, X. (2020). The double‐ITCZ Bias in CMIP3, CMIP5 and CMIP6 models based on annual mean precipitation. Geophysical Research Letters, 47, e2020GL087232.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102396
Deposited By: Tony Diaz
Deposited On:08 Apr 2020 16:23
Last Modified:16 Nov 2021 18:11

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