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Regional and seasonal variations of the double-ITCZ bias in CMIP5 models


Current climate models represent the zonal- and annual-mean intertropical convergence zone (ITCZ) position in a biased way, with an unrealistic double precipitation peak straddling the equator in the ensemble mean over the models. This bias is seasonally and regionally localized. It results primarily from two regions: the eastern Pacific and Atlantic (EPA), where the ITCZ in boreal winter and spring is displaced farther south than is observed; and the western Pacific (WP), where a more pronounced and wider than observed double ITCZ straddles the equator year-round. Additionally, the precipitation associated with the ascending branches of the zonal overturning circulations (e.g., Walker circulation) in the Pacific and Atlantic sectors is shifted westward. We interpret these biases in light of recent theories that relate the ITCZ position to the atmospheric energy budget. WP biases are associated with the well known Pacific cold tongue bias, which, in turn, is linked to atmospheric net energy input biases near the equator. In contrast, EPA biases are shown to be associated with a positive bias in the cross-equatorial divergent atmospheric energy transport during boreal winter and spring, with two potential sources: tropical biases associated with equatorial sea surface temperatures (SSTs) and tropical low clouds, and extratropical biases associated with Southern Ocean clouds and north Atlantic SST. The distinct seasonal and regional characteristics of WP and EPA biases and the differences in their associated energy budget biases suggest that the biases in the two sectors involve different mechanisms and potentially different sources.

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\(\langle \cdot \rangle\) :

Mass-weighted column integration

\((\cdot )^\dagger\) :

Divergent flux component

\((\cdot )_0\) :

Equatorial average (5\(^\circ\)S–5\(^\circ\)N)

\((\cdot )_{\phi _1-\phi _2}\) :

Area-weighted meridional average between latitudes \(\phi _1\) and \(\phi _2\)

e :

Moist enthalpy

h :

Moist static energy

\(A_P\) :

Tropical precipitation asymmetry index

\(E_P\) :

Equatorial precipitation index


Atmospheric energy transport

\(\langle vh \rangle _0^\dagger\), \({\text{AET}}_0^\dagger\) :

Meridional component of the cross-equatorial divergent atmospheric energy flux

\(\langle uh \rangle _0^\dagger\) :

Equatorial average of the zonal component of the divergent atmospheric energy flux


Energy flux equator


Energy flux prime meridian

NEI, I :

Atmospheric net energy input

\(I^*\) :

Local atmospheric net energy input (NEI plus zonal energy fluxes across atmospheric columns) minus energy storage


Double-ITCZ bias


ECMWF interim reanalysis


Eastern Pacific and Atlantic sector (240\(^\circ\)E–0\(^\circ\))


Western Pacific sector (150\(^\circ\)E–240\(^\circ\)E)


  • Adam O, Bischoff T, Schneider T (2016a) Seasonal and interannual variations of the energy flux equator and ITCZ. Part I: Zonally averaged ITCZ position. J Clim 29:3219–3230. doi:10.1175/JCLI-D-15-0512.1

    Article  Google Scholar 

  • Adam O, Bischoff T, Schneider T (2016b) Seasonal and interannual variations of the energy flux equator and ITCZ. Part II: Zonally varying shifts of the ITCZ. J Clim 29:7281–7293. doi:10.1175/JCLI-D-15-0710.1

    Article  Google Scholar 

  • Adam O, Schneider T, Brient F, Bischoff T (2016c) Relation of the double-ITCZ bias to the atmospheric energy budget in climate models. Geophys Res Lett 43:7670–7677

    Article  Google Scholar 

  • Adler RF, Huffman GJ, Chang A, Ferraro R, Xie PP, Janowiak J, Rudolf B, Schneider U, Curtis S, Bolvin D, Gruber A, Susskind J, Arkin P, Nelkin E (2003) The Version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979-present). J Hydrometeor 4:1147–1167

    Article  Google Scholar 

  • Bischoff T, Schneider T (2014) Energetic constraints on the position of the Intertropical Convergence Zone. J Clim 27:4937–4951. doi:10.1175/JCLI-D-13-00650.1

    Article  Google Scholar 

  • Bischoff T, Schneider T (2016) The equatorial energy balance, ITCZ position, and double ITCZ bifurcations. J Clim 29:2997–3013. doi:10.1175/JCLI-D-15-0328.1

    Article  Google Scholar 

  • Boos WR, Korty RL (2016) Regional energy budget control of the intertropical convergence zone and application to mid-Holocene rainfall. Nat Geosci 9:892–897. doi:10.1038/ngeo2833

    Article  Google Scholar 

  • Broccoli AJ, Dahl KA, Stouffer RJ (2006) Response of the ITCZ to northern hemisphere cooling. Geophys Res Lett 33(L01):702. doi:10.1029/2005GL024546

    Google Scholar 

  • Brown J, Moise A, Colman R (2013) the south pacific convergence zone in CMIP5 simulations of historical and future climate. Clim Dyn 41(2179). doi:10.1007/s00382-012-1591-x

  • Buckley MW, Marshall J (2016) Observations, inferences, and mechanisms of Atlantic meridional overturning circulation variability: a review. Rev Geophys 54:5–63. doi:10.1002/2015RG000493

  • Chiang JCH, Bitz CM (2005) Influence of high latitude ice cover on the marine Intertropical Convergence Zone. Clim Dyn 25:477–496

    Article  Google Scholar 

  • Chiang JCH, Friedman AR (2012) Extratropical cooling, interhemispheric thermal gradients, and tropical climate change. Ann Rev Earth Planet Sci 40:383–412

    Article  Google Scholar 

  • Dee D, Uppala SM, Simmons AJ, Berrisford P, Poli P, Kobayashi S, Andrae U, Balmaseda M, Balsamo G, Bauer P, ACM PB, Beljaars, van de Berg L, N JB, Bormann, Delsol C, Dragani R, Fuentes M, Geer A, Haimberger L, Healy S, Hersbach H, Holm E, Isaksen L, Kallberg P, Kohler M, Matricardi M, McNally A, Monge-Sanz B, Morcrette JJ, Park BK, Peubey C, de Rosnay P, Tavolato C, Thepaut JN, Vitart F, (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Quart J Roy Meteor Soc 137:553–597

  • Donohoe A, Battisti DS (2013) The seasonal cycle of atmospheric heating and temperature. J Clim 26:4962–4980

    Article  Google Scholar 

  • Donohoe A, Marshall J, Ferreira D, McGee D (2013) The relationship between ITCZ location and cross-equatorial atmospheric heat transport: from the seasonal cycle to the last glacial maximum. J Clim 26:3597–3618

    Article  Google Scholar 

  • Donohoe A, Marshall J, Ferreira D, Armour K, McGee D (2014) The interannual variability of tropical precipitation and interhemispheric energy transport. J Clim 27:3377–3392

    Article  Google Scholar 

  • Fasullo JT, Trenberth KE (2008) The annual cycle of the energy budget. Part II: Meridional structures and poleward transports. J Clim 21:2313–2325

    Article  Google Scholar 

  • Fermepin S, Bony S (2014) Influence of low-cloud radiative effects on tropical circulation and precipitation. J Adv Model Earth Syst 6:513–526. doi:10.1002/2013MS000288

    Article  Google Scholar 

  • Frierson DMW, Hwang YT, Fuckar NS, Seager R, Kang SM, Donohoe A, Maroon EA, Liu X, Battisti DS (2013) Contribution of ocean overturning circulation to tropical rainfall peak in the northern hemisphere. Nat Geosci 6:940–944. doi:10.1038/ngeo1987

    Article  Google Scholar 

  • Green B, Marshall J (2017) Coupling of trade winds with ocean circulation damps itcz shifts. J Clim 30:4395–4411. doi:10.1175/JCLI-D-16-0818.1

    Article  Google Scholar 

  • Hawcroft M, Haywood JM, Collins M, Jones A, Jones AC, Stephens G (2016) Southern Ocean albedo, inter-hemispheric energy transports and the double ITCZ: global impacts of biases in a coupled model. Clim Dyn 48:2279–2295. doi:10.1007/s00382-016-3205-5

    Article  Google Scholar 

  • Hirota N, Takayabu YN (2013) Reproducibility of precipitation distribution over the tropical oceans in cmip5 multi-climate models compared to cmip3. Clim Dyn 41(11):2909–2920. doi:10.1007/s00382-013-1839-0

    Article  Google Scholar 

  • Hwang YT, Frierson DMW (2013) Link between the double-Intertropical Convergence Zone problem and cloud biases over the Southern Ocean. Proc Natl Acad Sci 110:4935–4940. doi:10.1073/pnas.1213302110

    Article  Google Scholar 

  • Kang SM, Xie SP (2014) Dependence of climate response on meridional structure of external thermal forcing. J Clim 27:5593–5600

    Article  Google Scholar 

  • Kang SM, Held IM, Frierson DMW, Zhao M (2008) The response of the ITCZ to extratropical thermal forcing: Idealized slab-ocean experiments with a GCM. J Clim 21:3521–3532

    Article  Google Scholar 

  • Karnauskas KB, Ummenhofer CC (2014) On the dynamics of the Hadley circulation and subtropical drying. Clim Dyn 42:2259–2269. doi:10.1007/s00382-014-2129-1

    Article  Google Scholar 

  • Kato S, Rose FG, Sun-Mack S, Miller WF, Chen Y, Rutan DA, Stephens GL, Loeb NG, Minnis P, Wielicki BA, Winker DM, Charlock TP, Jr PWS, Xu K, Collins WD, (2011) Improvements of top-of-atmosphere and surface irradiance computations with CALIPSO-, CloudSat-, and MODIS-derived cloud and aerosol properties. J Geophys Res 116(D19):209. doi:10.1029/2011JD016050

  • Kay JE, Wall C, Yettella V, Medeiros B, Hannay C, Caldwell P, Bitz C (2016) Global climate impacts of fixing the Southern Ocean shortwave radiation bias in the community earth system model (CESM). J Clim 29:4617–4636. doi:10.1175/JCLI-D-15-0358.1

    Article  Google Scholar 

  • Li G, Xie SP (2012) Origins of tropical-wide SST biases in CMIP multi-model ensembles. Geophys Res Lett 39(L22):703

    Google Scholar 

  • Li G, Xie SP (2014) Tropical biases in CMIP5 multi-model ensemble: the excessive equatorial Pacific cold tongue and double ITCZ problems. J Clim 27:1765–1780

    Article  Google Scholar 

  • Lin JL (2007) The double-ITCZ problem in IPCC AR4 coupled GCMs: Ocean–atmosphere feedback analysis. J Clim 20:4497–4525

    Article  Google Scholar 

  • Loeb NG, Wielicki BA, Doelling DR, Smith GL, Keyes DF, Kato S, Manalo-Smith N, Wong T (2009) Toward optimal closure of the Earth’s top-of-atmosphere radiation budget. J Clim 22:748–766

    Article  Google Scholar 

  • Marshall J, Donohoe A, Ferreira D, McGee D (2014) The ocean’s role in setting the mean position of the inter-tropical convergence zone. Clim Dyn 42:1967–1979. doi:10.1007/s00382-013-1767-z

    Article  Google Scholar 

  • Mechoso CR, Robertson A, Barth? N, Davey M, Delecluse P, Gent P, Ineson S, Kirtman B, Latif M, Treut HL, Nagai T, Neelin J, Philander S, Polcher J, Schopf P, Stockdale T, Suarez M, Terray L, Thual O, Tribbia J, (1995) The seasonal cycle over the tropical pacific in coupled ocean-atmosphere general circulation models. Mon Wea Rev 123:2825–2838

  • Oueslati B, Bellon G (2015) The double ITCZ bias in CMIP5 models: interaction between SST, large-scale circulation and precipitation. Clim Dyn 44:585–607

    Article  Google Scholar 

  • Peixoto JP, Oort AH (1992) Physics of climate. American Institute of Physics

  • Schneider T, Bischoff T, Haug GH (2014) Migrations and dynamics of the intertropical convergence zone. Nature 513:45–53. doi:10.1038/nature13636

    Article  Google Scholar 

  • Shekhar R, Boos WR (2016) Improving energy-based estimates of monsoon location in the presence of proximal deserts. J Clim 29:4741–4761. doi:10.1175/JCLI-D-15-0747.1

    Article  Google Scholar 

  • Siongco AC, Hohenegger C, Stevens B (2015) The atlantic ITCZ bias in CMIP5 models. Clim Dyn 45(5):1169–1180. doi:10.1007/s00382-014-2366-3

    Article  Google Scholar 

  • Smith T, Reynolds R, Peterson T, Lawrimore J (2008) Improvements to NOAA’s historical merged land-ocean surface temperature analysis (1880–2006). J Clim 21:2283–2296

    Article  Google Scholar 

  • de Szoeke SP, Xie SP (2008) The tropical eastern pacific seasonal cycle: assessment of errors and mechanisms in IPCC AR4 coupled ocean–atmosphere general circulation models. J Clim 21(11):2573–2590. doi:10.1175/2007JCLI1975.1

    Article  Google Scholar 

  • Tian B (2015) Spread of model climate sensitivity linked to double-intertropical convergence zone bias. Geophys Res Lett 42:4133–4141. doi:10.1002/2015GL064119

    Article  Google Scholar 

  • Trenberth K, Caron J (2001) Estimates of meridional atmosphere and ocean heat transports. J Clim 14:3433–3443

    Article  Google Scholar 

  • Trenberth KE (1997) Using atmospheric budgets as a constraint on surface fluxes. J Clim 10:2796–2809. doi:10.1175/ 1520-0442(1997) 010,2796:UABAAC.2.0.CO;2

    Article  Google Scholar 

  • Trenberth KE, Fasullo JT (2012) Tracking Earth’s energy: from El Niño to global warming. Surv Geophys 33:413–426

    Article  Google Scholar 

  • Trenberth KE, Caron JM, Stepaniak DP (2001) The atmospheric energy budget and implications for surface fluxes and ocean heat transports. Clim Dyn 17:259–276

    Article  Google Scholar 

  • Vellinga M, Wood RA (2002) Global climatic impacts of a collapse of the Atlantic thermohaline circulation. Clim Change 54:251–267

    Article  Google Scholar 

  • Weller E, Cai W (2013) Realism of the indian ocean dipole in cmip5 models: the implications for climate projections. J Clim 26:6649–6659. doi:10.1175/JCLI-D-12-00807.1

    Article  Google Scholar 

  • Wielicki BA, Barkstrom B, Harrison E, Lee R, Smith G, Cooper J (1996) Clouds and the Earth’s Radiant Energy System (CERES): an Earth observing system experiment. Bull Am Meteor Soc 77:853–868

    Article  Google Scholar 

  • Woelfle MD, Bretherton CS, Frierson DMW (2015) Time scales of response to antisymmetric surface fluxes in an aquaplanet gcm. Geophys Res Lett 42(7):2555–2562. doi:10.1002/2015GL063372,2015GL063372

    Article  Google Scholar 

  • Xiang B, Zhao M, Held IM, Golaz JC (2017) Predicting the severity of spurious ’double ITCZ’ problem in CMIP5 coupled models from AMIP simulations. Geophys Res Lett 44:1520–1527. doi:10.1002/2016GL071992

    Article  Google Scholar 

  • Xie P, Arkin P (1996) Analyses of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions. J Clim 9:840–858

    Article  Google Scholar 

  • Zhang GJ, Wang H (2006) Toward mitigating the double ITCZ problem in NCAR CCSM3. Geophys Res Lett 33(L06):709. doi:10.1029/2005GL025229

    Google Scholar 

  • Zhang X, Liu H, Zhang M (2015) Double ITCZ in coupled ocean-atmosphere models: from CMIP3 to CMIP5. Geophys Res Lett 42:8651–8659

    Article  Google Scholar 

  • Zheng Y, Lin JL, Shinoda T (2012) The equatorial Pacific cold tongue simulated by IPCC AR4 coupled GCMs: Upper ocean heat budget and feedback analysis. J Geophys Res 117(C05):024. doi:10.1029/2011JC007746

    Google Scholar 

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We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups (Fig. 1) for producing and making available their model output. For CMIP the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We would also like to thank our anonymous reviewers for their contributions to the presentation of this work.

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Correspondence to Ori Adam.

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Adam, O., Schneider, T. & Brient, F. Regional and seasonal variations of the double-ITCZ bias in CMIP5 models. Clim Dyn 51, 101–117 (2018).

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  • ITCZ
  • Double-ITCZ bias
  • Atmospheric energy budget
  • CMIP5 models