• Arias, P. A., R. Fu, C. D. Hoyos, W. Li, and L. Zhou, 2011: Changes in cloudiness over the Amazon rainforests during the last two decades: Diagnostic and potential causes. Climate Dyn., 37, 11511164, https://doi.org/10.1007/s00382-010-0903-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Arias, P. A., R. Fu, C. Vera, and M. Rojas, 2015: A correlated shortening of the North and South American monsoon seasons in the past few decades. Climate Dyn., 45, 31833203, https://doi.org/10.1007/s00382-015-2533-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Arraut, J. R., and P. Satyamurty, 2009: Precipitation and water vapor transport in the Southern Hemisphere with emphasis on the South American region. J. Appl. Meteor. Climatol., 48, 19021912, https://doi.org/10.1175/2009JAMC2030.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Betts, A. K., and C. Jakob, 2002: Study of diurnal cycle of convective precipitation over Amazonia using a single column model. J. Geophys. Res., 107, 4732, https://doi.org/10.1029/2002JD002264.

    • Search Google Scholar
    • Export Citation
  • Boers, N., N. Marwan, H. M. Barbosa, and J. Kurths, 2017: A deforestation-induced tipping point for the South American monsoon system. Sci. Rep., 7, 41489, https://doi.org/10.1038/srep41489.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bombardi, R. J., and L. M. V. Carvalho, 2009: IPCC global coupled climate model simulations of the South America Monsoon System. Climate Dyn., 33, 893916, https://doi.org/10.1007/s00382-008-0488-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bony, S., and Coauthors, 2015: Clouds, circulation and climate sensitivity. Nat. Geosci., 8, 261268, https://doi.org/10.1038/ngeo2398.

  • Butt, N., M. New, G. Lizcano, and Y. Malhi, 2009: Spatial patterns and recent trends in cloud fraction and cloud-related diffuse radiation in Amazonia. J. Geophys. Res., 114, D21104, https://doi.org/10.1029/2009JD012217.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Butt, N., P. A. de Oliveira, and M. H. Costa, 2011: Evidence that deforestation affects the onset of the rainy season in Rondonia, Brazil. J. Geophys. Res., 116, D11120, https://doi.org/10.1029/2010JD015174.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cai, W., and Coauthors, 2014: Increasing frequency of extreme El Niño events due to greenhouse warming. Nat. Climate Change, 4, 111116, https://doi.org/10.1038/nclimate2100.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cox, P. M., R. A. Betts, M. Collins, P. P. Harris, C. Huntingford, and C. D. Jones, 2004: Amazonian forest dieback under climate-carbon cycle projections for the 21st century. Theor. Appl. Climatol., 78, 137156.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cox, P. M., and Coauthors, 2008: Increasing risk of Amazonian drought due to decreasing aerosol pollution. Nature, 453, 212215, https://doi.org/10.1038/nature06960.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Davidi, A., I. Koren, and L. Remer, 2009: Direct measurements of the effect of biomass burning over the Amazon on the atmospheric temperature profile. Atmos. Chem. Phys., 9, 82118221, https://doi.org/10.5194/acp-9-8211-2009.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Davidson, E. A., and Coauthors, 2012: The Amazon basin in transition. Nature, 481, 321328, https://doi.org/10.1038/nature10717.

  • Debortoli, N. S., V. Dubreuil, B. Funatsu, F. Delahaye, C. Henke de Oliveira, S. Rodrigues-Filho, C. Hiroo Saito, and R. Fetter, 2015: Rainfall patterns in the Southern Amazon: A chronological perspective (1971–2010). Climatic Change, 132, 251264, https://doi.org/10.1007/s10584-015-1415-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553597, https://doi.org/10.1002/qj.828.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Deser, C., and M. S. Timlin, 1997: Atmosphere–ocean interaction on weekly timescales in the North Atlantic and Pacific. J. Climate, 10, 393408, https://doi.org/10.1175/1520-0442(1997)010<0393:AOIOWT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doughty, C. E., S. R. Loarie, and C. B. Field, 2012: Theoretical impact of changing albedo on precipitation at the southernmost boundary of the ITCZ in South America. Earth Interact., 16, https://doi.org/10.1175/2012EI422.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Durieux, L., L. A. T. Machado, and H. Laurent, 2003: The impact of deforestation on cloud cover over the Amazon arc of deforestation. Remote Sens. Environ., 86, 132140, https://doi.org/10.1016/S0034-4257(03)00095-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Enfield, D. B., A. M. Mestas-Nuñez, D. A. Mayer, and L. Cid-Serrano, 1999: How ubiquitous is the dipole relationship in tropical Atlantic sea surface temperatures? J. Geophys. Res., 104, 78417848, https://doi.org/10.1029/1998JC900109.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Enfield, D. B., A. M. Mestas-Nuñez, and P. J. Trimble, 2001: The Atlantic multidecadal oscillation and its relation to rainfall and river flows in the continental U.S. Geophys. Res. Lett., 28, 20772080, https://doi.org/10.1029/2000GL012745.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., and Coauthors, 2009a: Spatiotemporal rainfall variability in the Amazon Basin Countries (Brazil, Peru, Bolivia, Colombia and Ecuador). Int. J. Climatol., 29, 15741594, https://doi.org/10.1002/joc.1791.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., and Coauthors, 2009b: Contrasting regional discharge evolutions in the Amazon basin (1974–2004). J. Hydrol., 375, 297311, https://doi.org/10.1016/j.jhydrol.2009.03.004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., J. Ronchail, J. L. Guyot, C. Junquas, P. Vauchel, W. Lavado, G. Drapeau, and R. Pombosa, 2011: Climate variability and extreme drought in the upper Solimões River (western Amazon Basin): Understanding the exceptional 2010 drought. Geophys. Res. Lett., 38, L13406, https://doi.org/10.1029/2011GL047862.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., J. Ronchail, F. Frappart, W. Lavado, W. Santini, and J. L. Guyot, 2013: The major floods in the Amazonas River and tributaries (western Amazon basin) during the 1970–2012 period: A focus on the 2012 flood. J. Hydrometeor., 14, 10001008, https://doi.org/10.1175/JHM-D-12-0100.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., J. A. Marengo, J. Ronchail, J. Molina Carpio, L. Noriega Flores, and J. L. Guyot, 2014: The extreme 2014 flood in south-western Amazon basin: The role of tropical-subtropical South Atlantic SST gradient. Environ. Res. Lett., 9, 124007, https://doi.org/10.1088/1748-9326/9/12/124007.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Espinoza, J. C., H. Segura, J. Ronchail, G. Drapeau, and O. Gutierrez-Cori, 2016: Evolution of wet-day and dry-day frequency in the western Amazon basin: Relationship with atmospheric circulation and impacts on vegetation. Water Resour. Res., 52, 85468560, https://doi.org/10.1002/2016WR019305.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Evan, A. T., A. K. Heidinger, and D. J. Vimont, 2007: Arguments against a physical long-term trend in global ISCCP cloud amounts. Geophys. Res. Lett., 34, L04701, https://doi.org/10.1029/2006GL028083.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fearnside, P. M., 2008: The roles and movements of actors in the deforestation of Brazilian Amazonia. Ecol. Soc., 13, 23, https://doi.org/10.5751/ES-02451-130123.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fernandes, K., and Coauthors, 2011: North Tropical Atlantic influence on western Amazon fire season variability. Geophys. Res. Lett., 38, L12701, https://doi.org/10.1029/2011GL047392.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fu, R., and W. Li, 2004: The influence of the land surface on the transition from dry to wet season in Amazonia. Theor. Appl. Climatol., 78, 97110, https://doi.org/10.1007/s00704-004-0046-7.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fu, R., and Coauthors, 2013: Increased dry-season length over southern Amazonia in recent decades and its implication for future climate projection. Proc. Natl. Acad. Sci. USA, 110, 18 11018 115, https://doi.org/10.1073/pnas.1302584110.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gloor, M., and Coauthors, 2013: Intensification of the Amazon hydrological cycle over the last two decades. Geophys. Res. Lett., 40, 17291733, https://doi.org/10.1002/grl.50377.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grimm, A. M., and J. P. Saboia, 2015: Interdecadal variability of the South American precipitation in the monsoon season. J. Climate, 28, 755775, https://doi.org/10.1175/JCLI-D-14-00046.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Heiblum, R. H., I. Koren, and G. Feingold, 2014: On the link between Amazonian forest properties and shallow cumulus cloud fields. Atmos. Chem. Phys., 14, 60636074, https://doi.org/10.5194/acp-14-6063-2014.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Horel, J. D., A. N. Hahmann, and J. E. Geisler, 1989: An investigation of the annual cycle of convective activity over the tropical Americas. J. Climate, 2, 13881403, https://doi.org/10.1175/1520-0442(1989)002<1388:AIOTAC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kousky, V. E., 1988: Pentad outgoing longwave radiation climatology for the South American sector. Rev. Bras. Meteor., 3, 217231.

  • Laurance, W. F., A. K. M. Albernaz, P. M. Fearnside, H. L. Vasconcelos, and L. V. Ferreira, 2004: Deforestation in Amazonia. Science, 304, 11091111, https://doi.org/10.1126/science.304.5674.1109b.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lewis, S. L., P. M. Brando, O. L. Phillips, G. M. van der Heijden, and D. Nepstad, 2011: The 2010 Amazon drought. Science, 331, 554, https://doi.org/10.1126/science.1200807.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, W., and R. Fu, 2004: Transition of the large-scale atmospheric and land surface conditions from the dry to the wet season over Amazonia as diagnosed by the ECMWF Re-Analysis. J. Climate, 17, 26372651, https://doi.org/10.1175/1520-0442(2004)017<2637:TOTLAA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Liebmann, B., and J. Marengo, 2001: Interannual variability of the rainy season and rainfall in the Brazilian Amazon basin. J. Climate, 14, 43084318, https://doi.org/10.1175/1520-0442(2001)014<4308:IVOTRS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Liebmann, B., and C. R. Mechoso, 2011: The South American monsoon system. The Global Monsoon System: Research and Forecast, 2nd ed. C. Chang, Y. Ding, and R. H. Johnson, Eds., World Scientific, 137–157.

    • Crossref
    • Export Citation
  • Liebmann, B., S. J. Camargo, A. Seth, J. A. Marengo, L. M. Carvalho, D. Allured, R. Fu, and C. S. Vera, 2007: Onset and end of the rainy season in South America in observations and the ECHAM 4.5 atmospheric general circulation model. J. Climate, 20, 20372050, https://doi.org/10.1175/JCLI4122.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Machado, L. A., H. Laurent, and A. A. Lima, 2002: Diurnal march of the convection observed during TRMM-WETAMC/LBA. J. Geophys. Res., 107, 8064, https://doi.org/10.1029/2001JD000338.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Machado, L. A., H. Laurent, N. Dessay, and I. Miranda, 2004: Seasonal and diurnal variability of convection over the Amazonia: A comparison of different vegetation types and large scale forcing. Theor. Appl. Climatol., 78, 6177, https://doi.org/10.1007/s00704-004-0044-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Malhi, Y., and Coauthors, 2009: Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest. Proc. Natl. Acad. Sci. USA, 106, 20 61020 615, https://doi.org/10.1073/pnas.0804619106.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. C. Francis, 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Amer. Meteor. Soc., 78, 10691080, https://doi.org/10.1175/1520-0477(1997)078<1069:APICOW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., 2004: Interdecadal variability and trends of rainfall across the Amazon basin. Theor. Appl. Climatol., 78, 7996, https://doi.org/10.1007/s00704-004-0045-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., and J. C. Espinoza, 2016: Extreme seasonal droughts and floods in Amazonia: Causes, trends and impacts. Int. J. Climatol., 36, 10331050, doi:10.1002/joc.4420.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., B. Liebmann, V. E. Kousky, N. P. Filizola, and I. C. Wainer, 2001: Onset and end of the rainy season in the Brazilian Amazon basin. J. Climate, 14, 833852, https://doi.org/10.1175/1520-0442(2001)014<0833:OAEOTR>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., and Coauthors, 2008: The drought of Amazonia in 2005. J. Climate, 21, 495516, https://doi.org/10.1175/2007JCLI1600.1.

  • Marengo, J. A., J. Tomasella, W. Soares, L. M. Alves, and C. A. Nobre, 2010: Extreme climatic events in the Amazon basin: Climatological and hydrological context of previous floods. Theor. Appl. Climatol., 107, 7385, https://doi.org/10.1007/s00704-011-0465-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., J. Tomasella, L. M. Alves, W. R. Soares, and D. A. Rodriguez, 2011: The drought of 2010 in the context of historical droughts in the Amazon region. Geophys. Res. Lett., 38, L12703, https://doi.org/10.1029/2011GL047436.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., and Coauthors, 2012: Recent developments on the South American monsoon system. Int. J. Climatol., 32, 121, https://doi.org/10.1002/joc.2254.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Molina-Carpio, J., J. C. Espinoza, P. Vauchel, J. Ronchail, B. Gutierrez, J. L. Guyot, and L. Noriega, 2017: The hydroclimatology of the upper Madeira River basin: Spatio-temporal variability and trends (1967–2013). Hydrol. Sci. J., 62, 911927, https://doi.org/10.1080/02626667.2016.1267861.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Norris, J. R., 2001: What can cloud observations tell us about climate variability? Space Sci. Rev., 94, 375380, https://doi.org/10.1023/A:1026704314326.

    • Search Google Scholar
    • Export Citation
  • Norris, J. R., 2005: Multidecadal changes in near-global cloud cover and estimated cloud cover radiative forcing. J. Geophys. Res., 110, D08206, https://doi.org/10.1029/2004JD005600.

    • Search Google Scholar
    • Export Citation
  • Norris, J. R. and A. Slingo, 2009: Trends in observed cloudiness and Earth’s radiation budget: What do we not know and what do we need to know? Clouds in the Perturbed Climate System: Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation, J. Heintzenberg and R. J. Charlson, Eds., MIT Press, 17–36.

    • Crossref
    • Export Citation
  • Parker, D., C. Folland, A. Scaife, J. Knight, A. Colman, P. Baines, and B. Dong, 2007: Decadal to multidecadal variability and the climate change background. J. Geophys. Res., 112, D18115, https://doi.org/10.1029/2007JD008411.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Petersen, W. A., and S. A. Rutledge, 2001: Regional variability in tropical convection: Observations from TRMM. J. Climate, 14, 35663586, https://doi.org/10.1175/1520-0442(2001)014<3566:RVITCO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ronchail, J., J. Guyot, J. Villar, P . Fraizy, G. Cochonneau, E. De Oliveira, N. Filizola, and J. J. Ordenez, 2006. Impact of the Amazon tributaries on major floods at Óbidos. IAHS Publ., 308, 220–225.

  • Rossow, W. B., and R. A. Schiffer, 1999: Advances in understanding clouds from ISCCP. Bull. Amer. Meteor. Soc., 80, 22612288, https://doi.org/10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Running, S. W., 2006: Is global warming causing more, larger wildfires? Science, 313, 927928, https://doi.org/10.1126/science.1130370.

  • Saraiva, I., M. A. F. Silva Dias, C. A. R. Morales, and J. M. B. Saraiva, 2016: Regional variability of rain clouds in the Amazon basin as seen by a network of weather radars. J. Appl. Meteor. Climatol., 55, 26572675, https://doi.org/10.1175/JAMC-D-15-0183.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Satyamurty, P., C. P. Wanzeler da Costa, and A. O. Manzi, 2013: Moisture sources for the Amazon basin: A study of contrasting years. Theor. Appl. Climatol., 111, 195209, https://doi.org/10.1007/s00704-012-0637-7.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schiffer, R. A., and W. B. Rossow, 1983: The International Satellite Cloud Climatology Project (ISCCP): The first project of the World Climate Research Programme. Bull. Amer. Meteor. Soc., 64, 779784, https://doi.org/10.1175/1520-0477-64.7.779.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schiro, K. A., J. D. Neelin, D. K. Adams, and B. R. Lintner, 2016: Deep convection and column water vapor over tropical land versus tropical ocean: A comparison between the Amazon and the tropical western Pacific. J. Atmos. Sci., 73, 40434063, https://doi.org/10.1175/JAS-D-16-0119.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sena, E. T., and P. Artaxo, 2015: A novel methodology for large-scale daily assessment of the direct radiative forcing of smoke aerosols. Atmos. Chem. Phys., 15, 54715483, https://doi.org/10.5194/acp-15-5471-2015.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sena, E. T., P. Artaxo, and A. L. Correia, 2013: Spatial variability of the direct radiative forcing of biomass burning aerosols and the effects of land use change in Amazonia. Atmos. Chem. Phys., 13, 12611275, https://doi.org/10.5194/acp-13-1261-2013.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Silva, V., and V. E. Kousky, 2012: The South American monsoon system: Climatology and variability. Modern Climatology, S.-Y. Wang, Ed., InTech, 123–152.

  • Silva Dias, M. A., and L. M. Carvalho, 2017. The South American monsoon system. The Global Monsoon System: Research and Forecast, 3rd ed. World Scientific, 25–33.

    • Crossref
    • Export Citation
  • Vera, C., and Coauthors, 2006: Towards a unified view of the American monsoon system. J. Climate, 19, 49775000, https://doi.org/10.1175/JCLI3896.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, J., and Coauthors, 2009: Impact of deforestation in the Amazon basin on cloud climatology. Proc. Natl. Acad. Sci. USA, 106, 36703674, https://doi.org/10.1073/pnas.0810156106.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Warren, S. G., R. M. Eastman, and C. J. Hahn, 2007: A survey of changes in cloud cover and cloud types over land from surface observations, 1971–96. J. Climate, 20, 717738, https://doi.org/10.1175/JCLI4031.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Werth, D., and R. Avissar, 2002: The local and global effects of Amazon deforestation. J. Geophys. Res., 107, 8087, https://doi.org/10.1029/2001JD000717.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wongchuig-Correa, S., R. C. D. de Paiva, J. C. Espinoza, and W. Collischonn, 2017: Multi-decadal hydrological retrospective: Case study of Amazon floods and droughts. J. Hydrol., 549, 667684, https://doi.org/10.1016/j.jhydrol.2017.04.019.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wright, J. S., R. Fu, J. R. Worden, S. Chakraborty, N. E. Clinton, C. Risi, Y. Sun, and L. Yin, 2017: Rainforest-initiated wet season onset over the southern Amazon. Proc. Natl. Acad. Sci. USA, 114, 84818486, https://doi.org/10.1073/pnas.1621516114.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wu, C.-M., B. Stevens, and A. Arakawa, 2009: What controls the transition from shallow to deep convection? J. Atmos. Sci., 66, 17931806, https://doi.org/10.1175/2008JAS2945.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Xie, P., and P. A. Arkin, 1998: Global monthly precipitation estimates from satellite-observed outgoing longwave radiation. J. Climate, 11, 137164, https://doi.org/10.1175/1520-0442(1998)011<0137:GMPEFS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yin, L., R. Fu, Y. F. Zhang, P. A. Arias, D. N. Fernando, W. Li, K. Fernandes, and A. R. Bowerman, 2014: What controls the interannual variation of the wet season onsets over the Amazon? J. Geophys. Res. Atmos., 119, 23142328, https://doi.org/10.1002/2013JD021349.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yoon, J.-H., and N. Zeng, 2010: An Atlantic influence on Amazon rainfall. Climate Dyn., 34, 249264, https://doi.org/10.1007/s00382-009-0551-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zeng, N., J.-H. Yoon, J. A. Marengo, A. Subramaniam, C. A. Nobre, A. Mariotti, and J. D. Neelin, 2008: Causes and impacts of the 2005 Amazon drought. Environ. Res. Lett., 3, 014002, https://doi.org/10.1088/1748-9326/3/1/014002.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Y., R. Fu, H. Yu, Y. Qian, R. Dickinson, M. A. F. Silva Dias, P. L. da Silva Dias, and K. Fernandes, 2009: Impact of biomass burning aerosol on the monsoon circulation transition over Amazonia. Geophys. Res. Lett., 36, L10814, https://doi.org/10.1029/2009GL037180.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhou, J., and K. M. Lau, 1998: Does a monsoon climate exist over South America? J. Climate, 11, 10201040, https://doi.org/10.1175/1520-0442(1998)011<1020:DAMCEO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhuang, Y., R. Fu, J. A. Marengo, and H. Wang, 2017: Seasonal variation of shallow- to-deep convection transition and its link to the environmental conditions over the central Amazon. J. Geophys. Res., 122, 26492666, https://doi.org/10.1002/2016JD025993.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Reduced Wet-Season Length Detected by Satellite Retrievals of Cloudiness over Brazilian Amazonia: A New Methodology

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  • 1 Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Sao Paulo, and Departamento Multidisciplinar, Escola Paulista de Política, Economia e Negócios, Universidade Federal de São Paulo, Osasco, Brazill
  • | 2 Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Sao Paulo, Brazil
  • | 3 University of California, Santa Barbara, Santa Barbara, California
  • | 4 Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Sao Paulo, Brazil
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Abstract

This study investigates the variability of the seasonal cycle of convection in the Brazilian Amazon basin during the last decades, and examines physical mechanisms that potentially trigger these modifications. A new methodology to evaluate the onset and length of the rainy season using long-term cloud fraction observations from geostationary satellites is proposed and the connection between cloud cycle variability, surface properties, and thermodynamic and dynamic conditions is explored. The results show that cloud cover has significantly decreased over the last decades. The decline in cloudiness is steeper at 1200 UTC (0800 LT), when a trend of up to −6% decade−1 is observed over the central and eastern Amazon. High-cloud-cover reduction is the major contributor to the observed decline in total cloud fraction. Delayed onsets and a reduction of up to 4 days yr−1 in the northern and central Amazon wet-season length are observed. Correlation analyses indicate that the El Niño phenomenon affects the interannual variability of cloudiness in the Amazon, leading to delayed onset and early demise of the rainy season. The tropical South Atlantic, the Pacific warm pool, and the North Atlantic tripole also play a small, but significant, role in the Amazon’s cloudiness variability. The decrease in cloudiness over the Amazon basin reduces the amount of solar radiation reflected back to space while increasing irradiance at the surface. This local warming alters surface heat fluxes and the atmospheric thermodynamic profile, further affecting cloud development. The strong tendencies reported here indicate a significant shift in the Amazonian hydroclimate during the last few decades.

© 2018 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Elisa T. Sena, elisa.sena@unifesp.br

Abstract

This study investigates the variability of the seasonal cycle of convection in the Brazilian Amazon basin during the last decades, and examines physical mechanisms that potentially trigger these modifications. A new methodology to evaluate the onset and length of the rainy season using long-term cloud fraction observations from geostationary satellites is proposed and the connection between cloud cycle variability, surface properties, and thermodynamic and dynamic conditions is explored. The results show that cloud cover has significantly decreased over the last decades. The decline in cloudiness is steeper at 1200 UTC (0800 LT), when a trend of up to −6% decade−1 is observed over the central and eastern Amazon. High-cloud-cover reduction is the major contributor to the observed decline in total cloud fraction. Delayed onsets and a reduction of up to 4 days yr−1 in the northern and central Amazon wet-season length are observed. Correlation analyses indicate that the El Niño phenomenon affects the interannual variability of cloudiness in the Amazon, leading to delayed onset and early demise of the rainy season. The tropical South Atlantic, the Pacific warm pool, and the North Atlantic tripole also play a small, but significant, role in the Amazon’s cloudiness variability. The decrease in cloudiness over the Amazon basin reduces the amount of solar radiation reflected back to space while increasing irradiance at the surface. This local warming alters surface heat fluxes and the atmospheric thermodynamic profile, further affecting cloud development. The strong tendencies reported here indicate a significant shift in the Amazonian hydroclimate during the last few decades.

© 2018 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Elisa T. Sena, elisa.sena@unifesp.br
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