Regional atmospheric dynamics govern interannual and seasonal stable isotope composition in southeastern Brazil

Autor(es)

dos Santos, Vinicius ^[1] ; Gastmans, Didier ^[1] ; Sanchez-Murillo, Ricardo ^[2] ; Gozzo, Luiz Felippe ^[3] ; Batista, Ludmila Vianna ^[1] ; Manzione, Rodrigo Lilla ^[4] ; Martinez, Jorge ^[5]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Ctr Environm Studies, Ave 24A, 1515, BR-13506900 Rio Claro, SP - Brazil

^[2] Univ Nacl, Stable Isotope Res Grp, Heredia - Costa Rica

^[3] Sao Paulo State Univ UNESP, Bauru Meteorol Ctr, Dept Phys, FC Estr Municipal Jose Sandrin S-N, BR-17048699 Bauru, SP - Brazil

^[4] Sao Paulo State Univ UNESP, Fac Sci & Enginery, Tupa, SP - Brazil

^[5] CSIRO Land & Water, POB 2583, Brisbane, Qld 4001 - Australia

• Tipo de documento: Artigo Científico
• Fonte: Journal of Hydrology; v. 579, DEC 2019.
• Citações Web of Science: 1

Resumo

Climatic factors controlling seasonal and interannual changes of stable isotope composition in precipitation remains understudied across the tropics. Daily isotopic measurements of rainfall (2014-2017, Rio Claro, Southeast of Brazil) were used to identify the climatic factors governing the isotopic variability. Overall, precipitation presented large variations, ranging between -18.36 parts per thousand and +4.89 parts per thousand for delta O-18, - 136 parts per thousand to + 43.4 parts per thousand for delta H-2, and -11.8 parts per thousand to +26.6 parts per thousand for d-excess. The Local Meteoric Water Line (delta H-2 = 8.05 +/- 0.1.delta O-18 + 13.08 +/- 0.5) indicated a strong influence of moisture recirculation along the transport of air masses. During the summer (wet season), high moisture content prevailed in the atmosphere. The latter was associated with recycled moisture from Amazonia region due to the influence of the South Atlantic Convergence Zone and Frontal Systems, resulting in depleted precipitation (delta O-18 <= - 6 parts per thousand). During the winter (dry season), the combination of Cold Fronts and minimal moisture transport from the Amazonia region, resulted in more enriched rainfall (delta O-18 a >= -1 parts per thousand). Atmospheric recirculation processes along the moisture pathway were also reflected on the seasonal d-excess variation. The strong correlation of delta O-18 and relative humidity along HYSPLIT trajectories confirmed the influence of regional atmospheric dynamics over isotopic composition of precipitation. Our findings provide new understanding of rainfall generation within the Guarani aquifer recharge area. (AU)

• Processo FAPESP: 15/15749-2 - Aplicação de isótopos estáveis na compreensão de processos no ciclo hidrológico: precipitação e pequenas bacias hidrográficas no estado de São Paulo, BR
• Beneficiário: Didier Gastmans
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 18/06666-4 - Traçadores isotópicos revelando a movimentação da água em bacias hidrográficas do Estado de São Paulo
• Beneficiário: Didier Gastmans
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/18735-5 - Composição isotópica da precipitação e suas relações com a variabilidade climática na porção centro sul do estado de São Paulo (BR)
• Beneficiário: Vinícius dos Santos
• Modalidade de apoio: Bolsas no Brasil - Mestrado