A Multivariate Probabilistic Framework for Tracking the Intertropical Convergence Zone: Analysis of Recent Climatology and Past Trends

Mamalakis, Antonios; Foufoula‐Georgiou, Efi

doi:10.1029/2018gl079865

Cited by 13 publications

(12 citation statements)

References 52 publications

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“…Yet, this assumption may not be true over specific regions or in specific seasons 42 , and so, this ambiguity in the regional ITCZ definition is problematic. For the purpose of this study, we have used a multivariate probabilistic framework 43 , which tracks the ITCZ over different longitudes and seasons by simultaneously assessing the statistics of multiple variables, and thus increasing the robustness of the tracking approach (see studies 59 , 93 , 94 for other similar approaches). In particular, we consider overlapping longitudinal windows, and use the window-mean precipitation and OLR (the two most common variables in the ITCZ literature) to track the ITCZ.…”

Section: Methodsmentioning

confidence: 99%

“…However, the framework is general and applicable in considering any single variable, and/or jointly distributed multiple variables to define the ITCZ. See [ 43 ] for more information.…”

Section: Methodsmentioning

confidence: 99%

“…For each model simulation, we estimate seasonal and annual-mean changes of the ITCZ position as a function of longitude (in 1° increments), while also considering the effect of the models’ present-day ITCZ biases on the revealed changes. Given the existing ambiguity in the literature as to a regional ITCZ definition 42 , we clarify that for the purposes of this study, the position of the ITCZ is defined as the latitude of maximum (above a specific quantile) precipitation and minimum outgoing longwave radiation (OLR) in each longitude, using a probabilistic approach 43 (see Methods ). For the sake of completeness, we also present results based on simpler, univariate precipitation or OLR indices/maps to assess ITCZ changes.…”

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confidence: 99%

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Zonally contrasting shifts of the tropical rain belt in response to climate change

et al. 2021

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Future changes in the position of the intertropical convergence zone (ITCZ; a narrow band of heavy precipitation in the tropics) with climate change could affect the livelihood and food security of billions of people. Although models predict a future narrowing of the ITCZ, uncertainties remain large regarding its future position, with most past work focusing on zonal-mean shifts. Here we use projections from 27 state-of-the-art (CMIP6) climate models and document a robust zonally-varying ITCZ response to the SSP3-7.0 scenario by 2100, with a northward shift over eastern Africa and the Indian Ocean, and a southward shift in the eastern Pacific and Atlantic Oceans. The zonally-varying response is consistent with changes in the divergent atmospheric energy transport, and sector-mean shifts of the energy flux equator. Our analysis provides insight about mechanisms influencing the future position of the tropical rainbelt, and may allow for more robust projections of climate change impacts.

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Section: Methodsmentioning

confidence: 99%

“…However, the framework is general and applicable in considering any single variable, and/or jointly distributed multiple variables to define the ITCZ. See [ 43 ] for more information.…”

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Zonally contrasting shifts of the tropical rain belt in response to climate change

et al. 2021

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“…In particular, the ITCZ is found only in the NH 4–12° latitude belt over the central and eastern Pacific and the Atlantic. The South Pacific convergence zone (SPCZ) (Haffke & Magnusdottir, 2013; Vincent, 1994) is a surface convergence zone in the Southern Hemisphere (SH) oriented in a northwest‐southeast manner extending from the Indo‐Pacific warm pool to the south central Pacific (Haffke & Magnusdottir, 2013; Mamalakis & Foufoula‐Georgiou, 2018). Similar northwest‐southeast oriented surface convergence zones also exist in the SH Atlantic and Indian Oceans.…”

Section: Introductionmentioning

confidence: 99%

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

Tian

Dong

2020

Geophysical Research Letters

191

152

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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.Plain Language Summary The double-intertropical convergence zone (ITCZ) bias is one of the most outstanding errors in all previous generations of climate models that may reduce the reliability of future climate prediction based on these models. The models have two ITCZs (i.e., zonally elongated narrow belt of high precipitation) in both hemispheres, over the equatorial central and eastern Pacific and Atlantic, instead of one ITCZ over the northern hemisphere in observations except for a short period in March and April. Here, we examine such bias in the latest models for Coupled Model Intercomparison Project (CMIP) Phase 6 (CMIP6) based on long-term annual mean precipitations in observations and models and compare the biases among the recent three generations of CMIP models (CMIP3, CMIP5, and CMIP6). We find that the double-ITCZ bias with a big inter-model spread persists in all CMIP models and still remains a serious problem in the latest CMIP6 models. However, the bias is slightly reduced in CMIP6 models from CMIP3 or CMIP5 models based on several precipitation bias indices. In addition, the annual equatorial Pacific cold tongue bias also persists in all CMIP models, but its inter-model spread is reduced from CMIP3 to CMIP5 and from CMIP5 to CMIP6.

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“…In late boreal summer, the intertropical convergence zone migrates close to the Philippines (see ref. 5 ) and the southern Hadley cell expands the most 6 , dominating the atmospheric meridional circulation over the western tropical Pacific (see e.g., ref. 7 and Supplementary Figure 7 in M18) and connecting the areas of NZI and EPI.…”

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confidence: 99%

Reply to: A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation

Mamalakis

Randerson

et al. 2019

Nat Commun

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A Multivariate Probabilistic Framework for Tracking the Intertropical Convergence Zone: Analysis of Recent Climatology and Past Trends

Cited by 13 publications

References 52 publications

Zonally contrasting shifts of the tropical rain belt in response to climate change

Zonally contrasting shifts of the tropical rain belt in response to climate change

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

Reply to: A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation

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