Under anthropogenic warming, deep-tropical ascent of the intertropical convergence zone (ITCZ) is projected to contract equatorward1,2,3 while subtropical descent associated with the Hadley cell edge is predicted to expand poleward4. These changes have important implications for regional climate2,5,6,7, but their mechanisms are not well understood. Here we reveal a key role of enhanced equatorial surface warming (EEW) in driving the deep-tropical contraction and modulating the Hadley expansion. By shifting the seasonally warmed sea surface temperature equatorward, EEW reduces the meridional migration of the seasonal ITCZ and causes an annual-mean deep-tropical contraction. This process further contracts the subtropical circulation, as seen during El Niño, and counteracts the Hadley expansion caused by the global-scale warming. The EEW-induced contraction even dominates in the Northern Hemisphere early summer (June–July), when atmospheric circulation responses to the global-scale warming are weak8. Regionally, this alters the East Asian summer monsoon, shifting both the subtropical jet and Meiyu–Baiu rainband equatorward. Among models in Phase 5 of the Coupled Model Intercomparison Project9, the degrees of the equatorward shift in the ITCZ, the early-summer subtropical circulation and the East Asian summer monsoon are correlated with EEW. Our results suggest that a better constraint on EEW is critical for accurate projection of tropical and subtropical climate change.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data supporting the findings of this study are available within the manuscript and its supplementary information. Data associated with the GFDL-AM2.1 simulations are available at https://github.com/wenyuz/EEW. The AMIP and CMIP outputs can be obtained from the CMIP5 archive, accessed through http://www.ipcc-data.org/sim/gcm_monthly/AR5/Reference-Archive.html.
The data analysis code is available from the corresponding author on request.
Huang, P., Xie, S.-P., Hu, K., Huang, G. & Huang, R. Patterns of the seasonal response of tropical rainfall to global warming. Nat. Geosci. 6, 357–361 (2013).
Lau, W. K. M. & Kim, K.-M. Robust Hadley circulation changes and increasing global dryness due to CO2 warming from CMIP5 model projections. Proc. Natl. Acad. Sci. USA 112, 3630–3635 (2015).
Byrne, M. P. & Schneider, T. Narrowing of the ITCZ in a warming climate: physical mechanisms. Geophys. Res. Lett. 43, 11350–11357 (2016).
Lu, J., Vecchi, G. A. & Reichler, T. Expansion of the Hadley cell under global warming. Geophys. Res. Lett. 34, L06805 (2007).
Scheff, J. & Frierson, D. M. W. Robust future precipitation declines in CMIP5 largely reflect the poleward expansion of model subtropical dry zones. Geophys. Res. Lett. 39, L18704 (2012).
Norris, J. R. et al. Evidence for climate change in the satellite cloud record. Nature 536, 72–75 (2016).
Kossin, J. P., Emanuel, K. A. & Vecchi, G. A. The poleward migration of the location of tropical cyclone maximum intensity. Nature 509, 349–352 (2014).
Shaw, T. A. & Voigt, A. Tug of war on summertime circulation between radiative forcing and sea surface warming. Nat. Geosci. 8, 560–566 (2015).
Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc. 93, 485–498 (2012).
Neelin, J. D., Chou, C. & Su, H. Tropical drought regions in global warming and El Niño teleconnections. Geophys. Res. Lett. 30, 2275 (2003).
Byrne, M. P. & Schneider, T. Energetic constraints on the width of the intertropical convergence zone. J. Clim. 29, 4709–4721 (2016).
Byrne, M. P., Pendergrass, A. G., Rapp, A. D. & Wodzicki, K. R. Response of the intertropical convergence zone to climate change: location, width, and strength. Curr. Clim. Change Rep. 4, 355–370 (2018).
Held, I. M. The general circulation of the atmosphere. In Proc. 2000 Program of Study in Geophysical Fluid Dynamics 1–54 (Woods Hole Oceanographic Institution, 2000).
Walker, C. C. & Schneider, T. Eddy influences on Hadley circulations: simulations with an idealized GCM. J. Atmos. Sci. 63, 3333–3350 (2006).
Frierson, D. M. W., Lu, J. & Chen, G. Width of the Hadley cell in simple and comprehensive general circulation models. Geophys. Res. Lett. 34, L18804 (2007).
Liu, Z., Vavrus, S., He, F., Wen, N. & Zhong, Y. Rethinking tropical ocean response to global warming: the enhanced equatorial warming. J. Clim. 18, 4684–4700 (2005).
Vecchi, G. A. & Soden, B. J. Global warming and the weakening of the tropical circulation. J. Clim. 20, 4316–4340 (2007).
Dai, A. & Wigley, T. M. L. Global patterns of ENSO-induced precipitation. Geophys. Res. Lett. 27, 1283–1286 (2000).
Seager, R., Harnik, N., Kushnir, Y., Robinson, W. & Miller, J. Mechanisms of hemispherically symmetric climate variability. J. Clim. 16, 2960–2978 (2003).
Lu, J., Chen, G. & Frierson, D. M. W. Response of the zonal mean atmospheric circulation to El Niño versus global warming. J. Clim. 21, 5835–5851 (2008).
Donohoe, A., Atwood, A. R. & Byrne, M. P. Controls on the width of tropical precipitation and its contraction under global warming. Geophys. Res. Lett. https://doi.org/10.1029/2019GL082969 (2019).
Emanuel, K. A. On thermally direct circulations in moist atmospheres. J. Atmos. Sci. 52, 1529–1534 (1995).
Privé, N. C. & Plumb, R. A. Monsoon dynamics with interactive forcing. Part I: axisymmetric. Stud. J. Atmos. Sci. 64, 1417–1430 (2007).
Neelin, J. D. & Held, I. M. Modeling tropical convergence based on the moist static energy budget. Mon. Weather Rev. 115, 3–12 (1987).
Kang, S. M. & Lu, J. Expansion of the Hadley cell under global warming: winter versus summer. J. Clim. 25, 8387–8393 (2012).
Watt-Meyer, O. & Frierson, D. M. W. ITCZ width controls on Hadley cell extent and eddy-driven jet position and their response to warming. J. Clim. 32, 1151–1166 (2018).
Hilgenbrink, C. C. & Hartmann, D. L. The response of Hadley circulation extent to an idealized representation of poleward ocean heat transport in an aquaplanet GCM. J. Clim. 31, 9753–9770 (2018).
Chen, G., Plumb, R. A. & Lu, J. Sensitivities of zonal mean atmospheric circulation to SST warming in an aqua-planet model. Geophys. Res. Lett. 37, L12701 (2010).
Tandon, N. F., Gerber, E. P., Sobel, A. H. & Polvani, L. M. Understanding Hadley cell expansion versus contraction: insights from simplified models and implications for recent observations. J. Clim. 26, 4304–4321 (2012).
Sun, L., Chen, G. & Lu, J. Sensitivities and mechanisms of the zonal mean atmospheric circulation response to tropical warming. J. Atmos. Sci. 70, 2487–2504 (2013).
Sampe, T. & Xie, S.-P. Large-scale dynamics of the Meiyu-Baiu rainband: environmental forcing by the westerly jet. J. Clim. 23, 113–134 (2010).
Chen, J. & Bordoni, S. Orographic effects of the Tibetan Plateau on the East Asian summer monsoon: an energetic perspective. J. Clim. 27, 3052–3072 (2014).
Xie, S.-P. et al. Global warming pattern formation: sea surface temperature and rainfall. J. Clim. 23, 966–986 (2010).
Broccoli, A. J., Dahl, K. A. & Stouffer, R. J. Response of the ITCZ to Northern Hemisphere cooling. Geophys. Res. Lett. 33, L01702 (2006).
Kang, S. M., Held, I. M., Frierson, D. M. W. & Zhao, M. The response of the ITCZ to extratropical thermal forcing: idealized slab-ocean experiments with a GCM. J. Clim. 21, 3521–3532 (2008).
Schneider, T., Bischoff, T. & Haug, G. H. Migrations and dynamics of the intertropical convergence zone. Nature 513, 45–53 (2014).
GAMDT. The new GFDL global atmosphere and land model AM2–LM2: evaluation with prescribed SST simulations. J. Clim. 17, 4641–4673 (2004).
Dee, D. P. et al. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).
Bolton, D. The computation of equivalent potential temperature. Mon. Weather Rev. 108, 1046–1053 (1980).
This work is supported by the National Science Foundation (grant no. NSF-1637450) and Laboratory Directed Research and Development funding from Berkeley Lab, provided by the Director, Office of Science, of the US Department of Energy under contract no. DE-AC02-05CH11231. Numerical simulations were conducted using the computing resources provided by the NCAR Cheyenne: HPE/SGI ICE XA System (University Community Computing, https://doi.org/10.5065/D6RX99HX).
The authors declare no competing interests.
Peer review information Nature Climate Change thanks Michael Byrne and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhou, W., Xie, SP. & Yang, D. Enhanced equatorial warming causes deep-tropical contraction and subtropical monsoon shift. Nat. Clim. Chang. 9, 834–839 (2019). https://doi.org/10.1038/s41558-019-0603-9
Geophysical Research Letters (2020)
Geophysical Research Letters (2020)
Annals of the New York Academy of Sciences (2020)
Large-scale control on the frequency of tropical cyclones and seeds: a consistent relationship across a hierarchy of global atmospheric models
Climate Dynamics (2020)
Journal of Climate (2020)