Central Chile and Cuyo bear a severe water crisis caused by one of the longest droughts in the Arid Andes. It is postulated that, as a consequence of Global Warming (GC), an acceleration of the Hadley cell would be generated, which would bring about an increase in the subsidence in the subtropical regions and it could produce pressurization and displacement of the anticyclones by mass gain. The overflow of Cuyuan and central Chile depends on the passage of frontal systems, troughs, segregated lows and the orographic forcing of the mountain range, which are conditioned by the following factors: sea surface temperatures (SST) in the Niño 3+ area 4, the activity of the South Pacific Subtropical Anti-cyclone (ASPSO) and Pacific Decadal Oscillation (PDO), among others. We used the Correlation Analysis, Break Regression and the Reanalysis I of the NCEP / NCAR. It is verified that the drought registered in the Arid Andes could be induced by the GC through the acceleration of the Hadley cell, since the increased subsidence in the ASPSO potentiates it blocking and/or diverting the precipitating mechanisms moving from sub-polar regions to lower latitudes

Cuyo y Chile central soportan una grave crisis hídrica generada por una de las sequías más prolongadas en los Andes Áridos. Se postula que, como consecuencia del Calentamiento Global (CG), se generaría una aceleración de la celda de Hadley, la que repercutiría en un incremento de la subsidencia en las regiones subtropicales que podría producir una presurización y desplazamiento de los anticiclones por ganancia de masa. El derrame de los ríos cuyanos y Chile Central depende del paso de sistemas frontales, vaguadas, bajas segregadas y el forzamiento orográfico de la cordillera, que están condicionados por los siguientes factores: las temperaturas superficiales del mar (SST) en el área Niño 3+4, la actividad del Anticiclón Subtropical del Pacífico Sur (ASPSO) y Oscilación Decadal Pacífica (PDO), entre otros. Se utilizó el Análisis de Correlación, Break Regression y el Reanalysis I del NCEP/NCAR. Se comprueba que la sequía que se registra en los Andes Áridos podría estar inducida por el CG a través de la aceleración de la celda de Hadley, puesto que la subsidencia aumentada en el ASPSO lo potencia bloqueando y/o desviando los mecanismos precipitantes que se desplazan desde regiones sub-polares a latitudes más bajas

The purpose of this paper is to objectively evaluate the possible impact of the activation of the Hadley cell, presumably due to global warming (CG), on the intensity and likely latitudinal displacement of the South Pacific anticyclone. This anticyclone is the main inhibitor of the precipitant mechanisms involved in snowfall in the Arid Andes, which is the main water source of the rivers in Cuyo and Central Chile areas. A Correlation Analysis and Break Regression were used to detect breaks in the slope of the regression line. Likewise, the Reanalysis NCEP / NCAR was implemented for spatial validation. Conclusion: three growth rates were detected in global temperature for April-September period delimiting the following intervals where the progress of the CG was quite uneven: 1909-1944 (weak growth), 1945-1976 (almost stationary), and 1977-2012 (marked acceleration). The influence of the possible activation of the Hadley cell over pressurization subsidence of the anticyclone and the consequent decrease of water resources have been verified in the study area since 1977.

El propósito de este trabajo es evaluar objetivamente el posible impacto de la activación de la celda de Hadley, supuestamente debida al calentamiento global (CG), en la intensidad y probable desplazamiento latitudinal del anticiclón del Pacífico Sur. Este anticiclón es el principal inhibidor de los mecanismos precipitantes que intervienen en la caída de nieve en los Andes Áridos, fuente de agua de los ríos cuyanos y de Chile Central. Se empleó el Análisis de Correlación y el Break Regression para detección de rupturas en la pendiente de la recta de regresión y el Reanalysis del NCEP/NCAR para la validación espacial. Conclusiones: Se detectaron tres ritmos de crecimiento en la temperatura global del periodo abril-septiembre demarcando los intervalos 1909-1944 (crecimiento débil), 1945-1976 (casi estacionaria) y 1977-2012 (fuerte aceleración); en los cuales la marcha del CG tuvo el comportamiento desigual descripto. Desde 1977 se verificó la influencia de la posible activación de la celda de Hadley sobre la presurización por subsidencia del anticiclón y con ello la disminución del recurso hídrico en el área de estudio.

As causas físicas prováveis das secas em seis regiões no sul da América do Sul são analisadas, através de índices da seca climática mensal e em suas associações com dezessete preditores. Esses indices são usados no monitoramento operacional do clima, e descrevem a temperatura atmosférica e a temperatura de superfície do mar (TSM) perto de América do Sul. A atividade do anticiclone subtropical sobre ambas as costas de América do Sul é um dos preditores principais, junto com sua interação com a depressão continental e a SST na costa do Brasil. A previsibilidade mais elevada concentra-se nos meses Novembro-Dezembro-Maio e a mais baixa, em março, junho e agosto. Na escala regional secundária, os principais preditores respondem às anomalias da pressão atmosférica sobre o Oceano Atlântico para Noroeste Argentino (NOA), TSM na costa do Brasil para condições do Nordeste Argentino (NEA), actividade anticiclónica no Pacífico e Atlântico para o Oeste Central (CO), os últimos e sua interação com a depressão continental para o Pampa Húmido (PH), a actividade anticiclónica sobre o Pacífico para o Patagonia (PAT) e a circulação através da Cordilheira para o Chile Central e Comahue (CHI).

From the indices of monthly and annual climatic drought in six regions in southern South America and their associations with seventeen predictors, the probable physical causes of droughts are analyzed. These indices are used in operational climate monitoring and describe the atmospheric temperature and sea surface temperature (SST) near South America. Subtropical anticyclone activity over both coasts of South America is one of the main predictors, together with its interaction with the continental depression and SST at the coast of Brazil. The highest predictability concentrates in November-December-May and the lowest in March, June and August. In the sub regional scale, the main predictors respond to atmospheric pressure anomalies in the Atlantic Ocean for Argentinean Northwest (NOA), SST in the Brazilian coast for Argentinean Northeast (NEA), anticyclonic conditions over the Pacific and Atlantic for the Central West (CO), the latter and their interaction with the continental depression for Humid Pampa (PH), anticyclonic activity over the Pacific for the Patagonia (PAT) and trans cordillera circulation for Central Chile and Comahue (CHI).