Relations between the oxygen isotope ratios in the Nevado Illimani (Bolivia) snow and ice with the precipitation temporal variability over South America

• Published in: Pesquisas em Geociências
• Main Authors: MAIER, Éder L. B., BARREIRA, Sandra, SIMÕES, Jefferson C.
• Format: Article in Journal/Newspaper
• Language: Portuguese
• Published: Instituto de Geociências /Universidade Federal do Rio Grande do Sul 2016
• Subjects: glaciais tropicais; reconstrução paleoclimática; ACP; tropical glaciers; paleoclimatic reconstruction; PCA; Pacific; ice core; North Atlantic
• Online Access: https://seer.ufrgs.br/index.php/PesquisasemGeociencias/article/view/78197

This article examines the temporal relations between the oxygen stable isotopes ratio (δ18O) in an ice core from the Nevado Illimani, Bolivia (16°37’S, 67°46’W), with precipitation series from South America. We used δ18O data from the upper 50 m of this core and precipitation monthly totals collected at 890 weather stations in South America in the period 1979–2008. Precipitation data were arranged in a grid with ~2° latitude and longitude resolution, for zoning the spatial temporal variability, using the Principal Components Analysis Mode–S. The relation between the δ18O record with drought and rain events above the South America mean values changes seasonally due to spatial migration of transport mechanisms and moisture convergence. The precipitation interannual temporal variability in the equatorial and subtropical regions is the one with the greatest similarity to δ18O variations in the Nevado Illimani. This relationship results from the control of precipitation anomalies in the two regions by the surface temperature of the equatorial Pacific and North Atlantic oceans, at temporal frequencies from 24 to 60 months. The δ18O and precipitation series have temporal cycles of high spectral frequency that vary independently, as those cycles are controlled by local factors. Este artigo examina as relações temporais entre a série de razão de isótopos estáveis de oxigênio (δ18O), obtida de um testemunho de gelo do Nevado Illimani, Bolívia (16°37’S, 67°46’W), com séries da precipitação sobre a América do Sul. Utilizou-se dados de δ18O dos primeiros 50 m desse testemunho e os totais mensais de precipitação coletados em 890 estações meteorológicas sul-americanas no período entre 1979–2008. As amostras da precipitação foram dispostas em uma grade com resolução de ~ 2° de latitude e longitude, para o zoneamento espacial da variabilidade temporal, utilizando-se da Análise das Componentes Principais (ACP) no Modo-S. As relações entre o registro do δ18O com a ocorrência de secas e chuvas acima da média na América do Sul ...