Attribution and projections of temperature extreme trends in South America based on CMIP5 models

Author(s):  
Matilde Rusticucci ◽  
Natalia Zazulie
2020 ◽  
Author(s):  
Rosmeri Porfírio da Rocha ◽  
Michelle Simões Reboita ◽  
Natália Machado Crespo ◽  
Eduardo Marcos de Jesus ◽  
Andressa Andrade Cardoso ◽  
...  

<p>Cyclones developing in eastern coast of South America impact weather and control the climate in most parts of the continent as well as over the South Atlantic Ocean. Current knowledge of these cyclones shows that they can have different thermal and dynamic structures along their lifecycles being classified as tropical, subtropical or extratropical. Cyclones occurring over the sea generate intense near-surface winds with major impacts on human activities and ecosystems. Given this context, we are producing fine resolution (~25 km) dynamic downscaling with RegCM4 to investigate the climatic trends of the different phases of cyclones over the southwest South Atlantic Ocean. Special emphasis will be given on the contribution of subtropical cyclones causing extreme events (rainfall and wind) in eastern Brazil. The simulations cover South America and wider area of South Atlantic Ocean. For evaluation simulation RegCM4 is forced by ERA-Interim reanalysis, while for the projections by CMIP5 models under RCP4.5 and RCP8.5 scenarios. Cyclones are tracked using an algorithm based on cyclonic relative vorticity. In this study we present the climatology of all cyclones provided by the ERA-Interim evaluation simulation in the period 1979-2015. Basically, we discuss the ability of fine resolution simulation in reproducing the main cyclogenetic areas over the continent, seasonality and interannual variability of cyclones. Comparisons with previous simulations allow discussing the impact of fine resolution downscaling on the climatological features of all cyclones and their classification in South America domain.    </p>


2015 ◽  
Vol 131 ◽  
pp. 11-23 ◽  
Author(s):  
Reiner Palomino-Lemus ◽  
Samir Córdoba-Machado ◽  
Sonia Raquel Gámiz-Fortis ◽  
Yolanda Castro-Díez ◽  
María Jesús Esteban-Parra

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Juan P. Sierra ◽  
Paola A. Arias ◽  
Sara C. Vieira

Northern South America is identified as one of the most vulnerable regions to be affected by climate change. Furthermore, recent extreme wet seasons over the region have induced socioeconomic impacts of wide proportions. Hence, the evaluation of rainfall simulations at seasonal and interannual time scales by the CMIP5 models is urgently required. Here, we evaluated the ability of seven CMIP5 models (selected based on literature review) to represent the seasonal mean precipitation and its interannual variability over northern South America. Our results suggest that it is easier for models to reproduce rainfall distribution during boreal summer and fall over both oceans and land. This is probably due to the fact that during these seasons, incoming radiation and ocean-atmosphere feedbacks over Atlantic and Pacific oceans locate the ITCZ on the Northern Hemisphere, as suggested by previous studies. Models exhibit the worse simulations during boreal winter and spring, when these processes have opposite effects locating the ITCZ. Our results suggest that the models with a better representation of the oceanic ITCZ and the local low-level jets over northern South America, such as the Choco low-level jet, are able to realistically simulate the main features of seasonal precipitation pattern over northern South America.


2020 ◽  
Author(s):  
Paul Loikith ◽  
Valerie Thaler ◽  
Luana Albertani Pampuch ◽  
C. Roberto Mechoso ◽  
Armineh Barkhordarian ◽  
...  

<p>A multivariate assessment of climate model projections over South America from the CMIP5 archive is presented. Change in near-surface temperature, precipitation, evapotranspiration, integrated water vapor transport (IVT), sea level pressure, and wind at multiple pressure levels is quantified across the multi-model suite and an assessment of model-to-model agreement on projected change performed. All models project warming by the mid- and late-21<sup>st</sup> century throughout the continent, with the highest magnitude projected over tropical regions. The CMIP5 models are in strong agreement that precipitation will decrease in all seasons over portions of Patagonia, especially along the northern portions of the current-climate mid-latitude storm track. This is consistent with a robustly projected poleward shift of the Pacific extratropical high and mid-latitude storm track indicated by a systematic increase in sea level pressure and decrease in westerly wind over Patagonia. Decreased precipitation for the months of September, October, and November is also projected, with strong model agreement, over portions of northern and northeastern Brazil, coincident with decreases in sea level pressure and increases in evapotranspiration. IVT is broadly projected to decrease over southern South America, coincident with the projected poleward shift of the mid-latitude storm track indicators, with increases projected in the vicinity of the South Atlantic Convergence Zone in austral spring and summer. Further decomposition of the thermodynamic and dynamic components to this change in IVT indicate that the projected decreases in the mid-latitudes are primarily driven by changes in circulation (i.e. dynamic) while the sub-tropical and tropical changes have a predominantly thermodynamic origin. Results provide a comprehensive picture of climate change across South America and highlight where projections should be interpreted with the most confidence.</p>


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