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Emergence of seasonal delay of tropical rainfall during 1979–2019


Tropical rainfall exhibits a prominent annual cycle, with characteristic amplitude and phase representing the range between wet and dry seasons and their onset timing, respectively. Previous studies note enhanced amplitude over ocean and delayed phase over land in model projections of global warming, underpinned by first-order physical principles. However, it is unclear whether these changes have emerged in observations. Here we use gridded precipitation datasets to report a seasonal delay of 4.1 ± 1.1 and 4.2 ± 0.9 days (P < 0.05) during 1979–2019 over the northern tropical land and Sahel, respectively. Most of the delay is driven by external forcings, dominated by greenhouse gases (GHG) and anthropogenic aerosols (AER). Increasing GHG and decreasing AER in the recent decades delay rainfall by producing a moister atmosphere, thus increasing its lag in response to seasonal solar forcing. As GHG increase and AER decrease, these seasonal delays are projected to further amplify in the future.

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Fig. 1: Observed and simulated phase changes of precipitation annual cycle.
Fig. 2: Linear trends of precipitation inter-seasonal difference (SON – MAM) during 1979–2019.
Fig. 3: Energetic constraint on precipitation annual cycle phase changes under GHG and AER.
Fig. 4: Changes in annual-mean temperature and relative humidity under GHG and AER during 1850–2020.
Fig. 5: Future projection of precipitation annual cycle phase evolutions and energetic constraints in twenty-first century.

Data availability

The Climate Prediction Center (CPC) merged analysis of precipitation dataset is available at The Global Precipitation Climatology Project dataset is available at The PRECipitation REConstruction over Land dataset is available at The Global Precipitation Climatology Centre dataset is available at U-Delaware is available at The Climatic Research Unit dataset is available at The CPC dataset is available at

CMIP5 model outputs are available at CMIP6 model outputs are available at CESM1 LENS are available at MPI-GE are available at CanESM2 LENS are available at

Code availability

The code used to generate the figures and table are based on NCAR Command Language (NCL v.6.4.0; The codes used to calculate the observed and simulated seasonal phase of precipitation, conduct the atmospheric energetic analysis and produce the main figures are available at


  1. 1.

    Held, I. M. & Soden, B. J. Robust responses of the hydrological cycle to global warming. J. Clim. 19, 5686–5699 (2006).

    Article  Google Scholar 

  2. 2.

    Chou, C., Neelin, J., Chen, C. & Tu, J. Evaluating the ‘rich-get-richer’ mechanism in tropical precipitation change under global warming. J. Clim. 22, 1982–2005 (2009).

    Article  Google Scholar 

  3. 3.

    Chou, C., Tu, J.-Y. & Tan, P.-H. Asymmetry of tropical precipitation change under global warming. Geophys. Res. Lett. 34, L17708 (2007).

    Article  Google Scholar 

  4. 4.

    Chou, C. & Lan, C.-W. Changes in the annual range of precipitation under global warming. J. Clim. 25, 222–235 (2012).

    Article  Google Scholar 

  5. 5.

    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).

    CAS  Article  Google Scholar 

  6. 6.

    Dwyer, J. G., Biasutti, M. & Sobel, A. H. The effects of greenhouse gas-induced changes in SST on the annual cycle of zonal mean tropical precipitation. J. Clim. 27, 4545–4565 (2014).

    Article  Google Scholar 

  7. 7.

    Chadwick, R., Boutle, I. & Martin, G. Spatial patterns of precipitation change in CMIP5: why the rich do not get richer in the tropics. J. Clim. 26, 3803–3822 (2013).

    Article  Google Scholar 

  8. 8.

    Roderick, M. L., Sun, F., Lim, W. H. & Farquhar, G. D. A general framework for understanding the response of the water cycle to global warming over land and ocean. Hydrol. Earth Syst. Sci. 18, 1575–1589 (2014).

    Article  Google Scholar 

  9. 9.

    Byrne, M. P. & O’Gorman, P. A. The response of precipitation minus evapotranspiration to climate warming: why the ‘wet-get-wetter, dry-get-drier’ scaling does not hold over land. J. Clim. 28, 8078–8092 (2015).

    Article  Google Scholar 

  10. 10.

    Zhang, W., Zhou, T., Zhang, L. & Zou, L. Future intensification of the water cycle with an enhanced annual cycle over global land monsoon regions. J. Clim. 32, 5437–5452 (2019).

    Article  Google Scholar 

  11. 11.

    Biasutti, M. & Sobel, A. H. Delayed Sahel rainfall and global seasonal cycle in a warmer climate. Geophys. Res. Lett. 36, L23707 (2009).

    Article  Google Scholar 

  12. 12.

    Biasutti, M. Forced Sahel rainfall trends in the CMIP5 archive. J. Geophys. Res. 118, 1613–1623 (2013).

    Article  Google Scholar 

  13. 13.

    Seth, A., Rauscher, S. A., Rojas, M., Giannini, A. & Camargo, S. J. Enhanced spring convective barrier for monsoons in a warmer world? Climatic Change 104, 403–414 (2011).

    Article  Google Scholar 

  14. 14.

    Seth, A. et al. CMIP5 projected changes in the annual cycle of precipitation in monsoon regions. J. Clim. 26, 7328–7351 (2013).

    Article  Google Scholar 

  15. 15.

    Song, F., Leung, L. R., Lu, J. & Dong, L. Seasonally dependent responses of subtropical highs and tropical rainfall to anthropogenic warming. Nat. Clim. Change 8, 787–792 (2018).

    Article  Google Scholar 

  16. 16.

    Song, F., Lu, J., Leung, L. R. & Liu, F. Contrasting phase changes of precipitation annual cycle between land and ocean under global warming. Geophys. Res. Lett. 47, e2020GL090327 (2020).

    Google Scholar 

  17. 17.

    Thomson, D. J. The seasons, global temperature and precession. Science 268, 59–68 (1995).

    CAS  Article  Google Scholar 

  18. 18.

    Mann, M. E. & Park, J. Greenhouse warming and changes in the seasonal cycle of temperature: model versus observations. Geophys. Res. Lett. 23, 1111–1114 (1996).

    CAS  Article  Google Scholar 

  19. 19.

    Stine, A. R., Huybers, P. & Fung, I. Y. Changes in the phase of the annual cycle of surface temperature. Nature 457, 435–440 (2009).

    CAS  Article  Google Scholar 

  20. 20.

    Qian, C. & Zhang, X. Human influences on changes in the temperature seasonality in mid to high-latitude land areas. J. Clim. 28, 5908–5921 (2015).

    Article  Google Scholar 

  21. 21.

    Santer, B. D. et al. Human influence on the seasonal cycle of tropospheric temperature. Science 361, eaas8806 (2018).

    Article  CAS  Google Scholar 

  22. 22.

    Chou, C. et al. Increase in the range between wet and dry season precipitation. Nat. Geosci. 6, 263–267 (2013).

    CAS  Article  Google Scholar 

  23. 23.

    Marvel, K. et al. Observed and projected changes to the precipitation annual cycle. J. Clim. 30, 4983–4995 (2017).

    Article  Google Scholar 

  24. 24.

    Salzmann, M. Global warming without global mean precipitation increase? Sci. Adv. 2, e1501572 (2016).

    Article  Google Scholar 

  25. 25.

    Wu, P., Christidis, N. & Stott, P. Anthropogenic impact on Earth’s hydrological cycle. Nat. Clim. Change 3, 807–810 (2013).

    Article  Google Scholar 

  26. 26.

    Marvel, K. & Bonfils, C. Identifying external influences on global precipitation. Proc. Natl Acad. Sci. USA 110, 19301–19306 (2013).

    CAS  Article  Google Scholar 

  27. 27.

    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).

    Article  Google Scholar 

  28. 28.

    Eyring, V. et al. Overview of the Coupled Model Intercomparison Project phase 6 (CMIP6) experimental design and organization. Geosci. Model Dev. 9, 1937–1958 (2016).

    Article  Google Scholar 

  29. 29.

    Deser, C. et al. Insights from Earth system model initial-condition large ensembles and future prospects. Nat. Clim. Change 10, 277–286 (2020).

    Article  Google Scholar 

  30. 30.

    Kajikawa, Y., Yasunari, T., Yoshida, S. & Fujinami, H. Advanced Asian summer monsoon onset in recent decades. Geophys. Res. Lett. 39, L03803 (2012).

    Article  Google Scholar 

  31. 31.

    Zhan, Y., Ren, G. & Ren, Y. Start and end dates of rainy season and their temporal change in recent decades over East Asia. J. Meteorological Soc. Jpn. 94, 41–53 (2016).

    Article  Google Scholar 

  32. 32.

    Folland, C. K., Palmer, T. N. & Parker, D. E. Sahel rainfall and worldwide sea temperatures, 1901–85. Nature 320, 602–607 (1986).

    Article  Google Scholar 

  33. 33.

    Giannini, A., Saravanan, R. & Chang, P. Oceanic forcing of Sahel rainfall on interannual to interdecadal time scales. Science 302, 1027–1030 (2003).

    CAS  Article  Google Scholar 

  34. 34.

    Schwarz, M. et al. Changes in atmospheric shortwave absorption as important driver of dimming and brightening. Nat. Geosci. 13, 110–115 (2020).

    CAS  Article  Google Scholar 

  35. 35.

    Wild, M. Enlightening global dimming and brightening. Bull. Am. Meteorol. Soc. 93, 27–37 (2012).

    Article  Google Scholar 

  36. 36.

    Hoesly, R. M. et al. Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS). Geosci. Model Dev. 11, 369–408 (2018).

    CAS  Article  Google Scholar 

  37. 37.

    Song, F., Leung, L. R., Lu, J. & Dong, L. Future changes in seasonality of the North Pacific and North Atlantic subtropical highs. Geophys. Res. Lett. 45, 11,959–11,968 (2018).

    Google Scholar 

  38. 38.

    Giannini, A. & Kaplan, A. The role of aerosols and greenhouse gases in Sahel drought and recovery. Climatic Change 152, 449–466 (2018).

    Article  Google Scholar 

  39. 39.

    Evan, A. T., Flamant, C., Gaetani, M. & Guichard, F. The past, present and future of African dust. Nature 531, 493–495 (2016).

    CAS  Article  Google Scholar 

  40. 40.

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

    Article  Google Scholar 

  41. 41.

    Chiang, J. C. H. & Friedman, A. R. Extratropical cooling, interhemispheric thermal gradients, and tropical climate change. Annu. Rev. Earth Planet. Sci. 40, 383–412 (2012).

    CAS  Article  Google Scholar 

  42. 42.

    Frierson, D. M. W. et al. Contribution of ocean overturning circulation to tropical rainfall peak in the northern hemisphere. Nat. Geosci. 6, 940–944 (2013).

    CAS  Article  Google Scholar 

  43. 43.

    Schneider, T., Bischoff, T. & Haug, G. H. Migrations and dynamics of the intertropical convergence zone. Nature 513, 45–53 (2014).

    CAS  Article  Google Scholar 

  44. 44.

    Boos, W. R. & Korty, R. L. Regional energy budget control of the intertropical convergence zone and application to mid-Holocene rainfall. Nat. Geosci. 9, 892–897 (2016).

    CAS  Article  Google Scholar 

  45. 45.

    Biasutti, M. et al. Global energetics and local physics as drivers of past, present and future monsoons. Nat. Geosci. 11, 392–400 (2018).

    CAS  Article  Google Scholar 

  46. 46.

    Hwang, Y.-T., Frierson, D. M. W. & Kang, S. M. Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century. Geophys. Res. Lett. 40, 2845–2850 (2013).

    Article  Google Scholar 

  47. 47.

    Merlis, T. M. Does humidity’s seasonal cycle affect the annual-mean tropical precipitation response to extratropical forcing. J. Clim. 29, 1451–1460 (2016).

    Article  Google Scholar 

  48. 48.

    Merlis, T. M., Schneider, T., Bordoni, S. & Eisenman, I. The tropical precipitation response to orbital precession. J. Clim. 26, 2010–2021 (2013).

    Article  Google Scholar 

  49. 49.

    Trenberth, K. E., Caron, J. M. & Stepaniak, D. P. The atmospheric energy budget and implications for surface fluxes and ocean heat transports. Clim. Dyn. 17, 259–276 (2001).

    Article  Google Scholar 

  50. 50.

    Chiodo, G. & Haimberger, L. Interannual changes in mass consistent energy budgets from ERA-Interim and satellite data. J. Geophys. Res. 115, D02112 (2010).

    Google Scholar 

  51. 51.

    Neelin, J. & Held, I. M. Modeling tropical convergence based on the moist static energy budget. Mon. Weather Rev. 115, 3–12 (1987).

    Article  Google Scholar 

  52. 52.

    Xie, P. & Arkin, P. A. Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Am. Meteor. Soc. 78, 2539–2558 (1997).

    Article  Google Scholar 

  53. 53.

    Adler, R. F. et al. The version 2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present). J. Hydrometeor. 4, 1147–1167 (2003).

    Article  Google Scholar 

  54. 54.

    Chen, M., Xie, P., Janowiak, J. E. & Arkin, P. A. Global land precipitation: a 50-yr monthly analysis based on gauge observations. J. Hydrometeorol. 3, 249–266 (2002).

    Article  Google Scholar 

  55. 55.

    Harris, I. et al. Version 4 of the CRU TS monthly high-resolution gridded multivariate climate dataset. Sci. Data 7, 109 (2020).

    Article  Google Scholar 

  56. 56.

    Chen, M. et al. CPC Unified Gauge-Based Analysis of Global Daily Precipiation, Western Pacific Geophysics Meeting, Cairns, Australia, 29 July–1 August, 2008 (NOAA PSL, 2008);

  57. 57.

    Schneider, U. et al. Evaluating the hydrological cycle over land using the newly-corrected Precipitation climatology from the Global Precipitation Climatology Centre (GPCC). Atmosphere 8, 52 (2017).

    Article  Google Scholar 

  58. 58.

    Willmott, C. J. & Matsuura K. Terrestrial air temperature and precipitation: monthly and annual time series (1950–1999). University of Delaware (2015).

  59. 59.

    Jones, P. D. & Moberg, A. Hemispheric and largescale surface air temperature variations: an extensive revision and an update to 2001. J. Clim. 16, 206–223 (2003).

    Article  Google Scholar 

  60. 60.

    Peterson, T. C. & Vose, R. S. An overview of the Global Historical Climatology Network temperature database. Bull. Am. Meteorol. Soc. 78, 2837–2849 (1997).

    Article  Google Scholar 

  61. 61.

    Kay, J. E. et al. The community earth system model (CESM) large ensemble project: a community resource for studying climate change in the presence of internal climate variability. Bull. Am. Meteorol. Soc. 96, 1333–1349 (2015).

    Article  Google Scholar 

  62. 62.

    Maher, N. et al. The max planck institute grand ensemble: enabling the exploration of climate system variability. J. Adv. Model. Earth Syst. 11, 1–21 (2019).

    Article  Google Scholar 

  63. 63.

    Kushner, P. J. et al. Canadian snow and sea ice: assessment of snow, sea ice, and related climate processes in Canada’s Earth system model and climate-prediction system. Cryosphere 12, 1137–1156 (2018).

    Article  Google Scholar 

  64. 64.

    Kirchmeier-Young, M. C., Zwiers, F. W. & Gillett, N. P. Attribution of extreme events in Arctic Sea ice extent. J. Clim. 30, 553–571 (2017).

    Article  Google Scholar 

  65. 65.

    Song, F. Code for the emergence of seasonal delay of tropical rainfall during 1979-2019. Zenodo (2021).

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This research is supported by the US Department of Energy Office of Science Biological and Environmental Research as part of the Regional and Global Model Analysis program area. PNNL is operated for the Department of Energy by Battelle Memorial Institute under contract DE-AC05-76RL01830. The authors acknowledge the World Climate Research Program’s Working Group on Coupled Modeling, which is responsible for CMIP5 and CMIP6, and thank the climate modelling groups for producing and making available their model output. The authors also thank the NCAR CESM group for making the large-ensemble (LENS) experiments available, the MPI-ESM group for making the MPI-GE experiments available and the CanESM2 group for making the CanESM2 LENS experiments available. For CMIP5 and CMIP6, the US DOE’s Program for Climate Model Diagnostics and Intercomparison provides coordinating support and led the development of software infrastructure in partnership with the Global Organization for Earth System Science Portals.

Author information




F.S. and L.R.L. designed the research. F.S. performed the analysis, drew all the figures and wrote the first draft of the paper. All authors provided comments on different versions of the paper.

Corresponding authors

Correspondence to Fengfei Song or L. Ruby Leung.

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The authors declare no competing interests.

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Peer review information Nature Climate Change thanks Marc Salzmann 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.

Extended data

Extended Data Fig. 1 The observed and simulated phase changes of precipitation annual cycle over the NTL and Sahel in each dataset.

The time evolution of precipitation annual cycle phase in (a, c) eight observational datasets (OBS) and (b, d) five historical simulations ensembles (EXT) during 1979-2019 over (a-b) the NTL (0°-25°N) and (c-d) the Sahel. The numbers in the brackets show the total phase changes (days) during their respective periods (1979-2019 for GPCP, CMAP, PRECL, CPC, CRU and all EXT simulations; 1979-2017 for U-Delaware; 1979-2016 for GPCC; 1979-2014 for GHCN) and the confidence levels; the reference period is 1980-1999.

Extended Data Fig. 2 The observed and simulated phase changes of precipitation annual cycle over the southern tropical land in each dataset.

Same as Extended Data Fig. 1a,b but for the southern tropical land (0°-25°S).

Extended Data Fig. 3 The observed and simulated amplitude changes of precipitation annual cycle over the northern and southern tropical ocean in each dataset.

Same as Extended Data Fig. 1a,b but for the precipitation annual cycle amplitude over (a, c) the northern tropical ocean (0°-25°N) and (b, d) the southern tropical ocean (0°-25°S).

Extended Data Fig. 4 The linear trends of precipitation for the inter-seasonal difference (SON - MAM) during 1979-2019 in each simulation dataset.

The linear trends of precipitation (units: mm (day)-1 (41-year)-1) for the inter-seasonal difference of September-November (SON) minus March-May (MAM) in (a) CMIP5 MME, (b) CMIP6 MME, (c) CESM1 LENS, (d) MPI-GE and (e) CanESM2 LENS during 1979-2019. The black dots indicate the trend is significant at the 90% confidence level.

Extended Data Fig. 5 The observed and simulated phase changes of precipitation annual cycle over the Sahel during 1950-2014.

The time evolution of precipitation annual cycle phase (units: days) over the Sahel during 1950-2014 in (a) five observational datasets (CPC, CRU, GHCN, GPCC and U-Delaware) and (b) five external forcing simulations (CanESM2 LENS, CESM1 LENS, CMIP5, CMIP6, and MPI-GE). The reference period is 1980-1999. The black lines show the ensemble average and the fitting lines during 1950-1982 and 1979-2014 (the trend and confidence level are shown).

Extended Data Fig. 6 The linear trends of precipitation and each energy term for the inter-seasonal difference (SON - MAM) during 1979-2019.

The linear trends of the inter-seasonal difference of September-November (SON) minus March-May (MAM) in (a-b) precipitation (units: mm (day)-1 (171-year)-1), (c-d) atmospheric heat transport divergence (·AHT; units: W m-2 (171-year)-1), (e-f) vertically-integrated moist static energy tendency (\(- \frac{{\partial < h > }}{{\partial t}}\); units: W m-2 (171-year)-1), (g-h) net energy input to the atmosphere (Fnet; units: W m-2 (171-year)-1) and (i-j) latent heat flux (units: W m-2 (171-year)-1) during 1850-2020 in the (left panel) GHG and (right panel) AER simulations. The black dots indicate the trend is significant at the 90% confidence level.

Extended Data Fig. 7 The time evolution of the inter-seasonal difference (SON - MAM) of Fnet and its each term over the NTR (0°-25°N) under GHG and AER.

(left panels) GHG and (right panels) AER simulations. Units: W m-2. The red and blue lines show the linear trend during 1850-2020 and 1979-2019, respectively; the numbers in the brackets show the total changes during the corresponding period and the confidence levels. The reference period is 1980-1999.

Extended Data Fig. 8 The time evolution of the inter-seasonal difference (SON - MAM) of Fnet and its each term over the Sahel under GHG and AER.

The same as Extended Data Fig. 7 but over the Sahel.

Extended Data Fig. 9 The future projection of precipitation annual cycle phase evolutions and the energetic constraints in the 21st century in the southern tropical land.

The time evolution of (a) precipitation annual cycle phase (units: days). The overlaid purple line is the inter-seasonal difference (MAM - SON) of precipitation (units: mm day-1). (b) the inter-seasonal difference (MAM - SON) in the atmospheric heat transport divergence (·AHT; black line; units: W m-2), net energy input to the atmosphere (Fnet; red line; units: W m-2) and vertically-integrated moist static energy tendency (\(- \frac{{\partial < h > }}{{\partial t}}\); blue line; units: W m-2) over the southern tropical land (0°-25°S) in the CMIP5 MME during 1962-2099. The numbers in the brackets show the total changes during 1962-2099 and the confidence levels; the reference period is 1980-1999.

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Supplementary Tables 1 and 2, and Figs. 1–3.

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Song, F., Leung, L.R., Lu, J. et al. Emergence of seasonal delay of tropical rainfall during 1979–2019. Nat. Clim. Chang. 11, 605–612 (2021).

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