caa a22 4500 605472661 CHVBK 20210128100339.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00382-015-2533-1 doi (NATIONALLICENCE)springer-10.1007/s00382-015-2533-1 A correlated shortening of the North and South American monsoon seasons in the past few decades [Elektronische Daten] [Paola Arias, Rong Fu, Carolina Vera, Maisa Rojas] Our observational analysis shows that the wet seasons of the American monsoon systems have shortened since 1978 due to correlated earlier retreats of the North American monsoon (NAM) and late onsets of the southern Amazon wet season, an important part of the South American monsoon (SAM). These changes are related to the combination of the global sea surface temperature (SST) warming mode, the El Niño-Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), the westward shift of the North Atlantic subtropical high (NASH), and the enhancement of Pacific South American and Pacific North American wave train patterns, which induces variations of the regional circulation at interannual and decadal scales. The joint contributions from these forcing factors are associated with a stronger and more equatorward regional Hadley cell, which enhances convergence towards the equator, strengthening and possibly delaying the retreat of the tropical part of the NAM. This in turn accelerates the demise of the northern NAM and delays the reversal of the cross-equatorial flow over South America, reducing moisture transport to the SAM and delaying its onset. In addition, the thermodynamic response to warming appears to cause local drier land conditions over both regions, reinforcing the observed changes in these monsoons. Although previous studies have identified the isolated influence of the regional Hadley cell, ENSO, AMO, global SST warming, and NASH on the NAM, the correlated changes between NAM and SAM through variations of the cross-equatorial flow had not been established before. Springer-Verlag Berlin Heidelberg, 2015 Southern Amazon wet season nationallicence North American monsoon nationallicence South American monsoon nationallicence North Atlantic subtropical high nationallicence Cross-equatorial flow nationallicence Global warming nationallicence Arias Paola Grupo de Ingeniería y Gestión Ambiental (GIGA), Escuela Ambiental, Facultad de Ingeniería, Universidad de Antioquia, Calle 67 # 53-108, Bloque 20, Oficina 441, A. A. 1226, Medellín, Colombia aut Fu Rong Department of Geological Sciences, The University of Texas at Austin, Austin, TX, USA aut Vera Carolina Centro de Investigaciones del Mar y la Atmósfera, CONICET-UBA, DCAO/FCEN, UMI, IFAECI/CNRS, Buenos Aires, Argentina aut Rojas Maisa Departamento de Geofísica, Universidad de Chile, Santiago, Chile aut Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3183-3203 0930-7575 45:11-12<3183 2015 45 382 https://doi.org/10.1007/s00382-015-2533-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-015-2533-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Arias Paola Grupo de Ingeniería y Gestión Ambiental (GIGA), Escuela Ambiental, Facultad de Ingeniería, Universidad de Antioquia, Calle 67 # 53-108, Bloque 20, Oficina 441, A. A. 1226, Medellín, Colombia aut NATIONALLICENCE 700 1- Fu Rong Department of Geological Sciences, The University of Texas at Austin, Austin, TX, USA aut NATIONALLICENCE 700 1- Vera Carolina Centro de Investigaciones del Mar y la Atmósfera, CONICET-UBA, DCAO/FCEN, UMI, IFAECI/CNRS, Buenos Aires, Argentina aut NATIONALLICENCE 700 1- Rojas Maisa Departamento de Geofísica, Universidad de Chile, Santiago, Chile aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3183-3203 0930-7575 45:11-12<3183 2015 45 382