Tropical precipitation anomalies and d-excess evolution during El Niño 2014-16

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• 作者：Ricardo Sá ; nchez-Murillo ; Ana M. Durá ; n-Quesada ; Christian Birkel ; Germain Esquivel-Herná ; ndez and Jan Boll
• 刊名：Hydrological Processes
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：31
• 期：4
• 页码：956-967
• 全文大小：1335K
• ISSN：1099-1085

文摘

The last 2014-16 El Ni&ntilde;o event was among the three strongest episodes on record. El Ni&ntilde;o considerably changes annual and seasonal precipitation across the tropics. Here, we present a unique stable isotope data set of daily precipitation collected in Costa Rica prior to, during, and after El Ni&ntilde;o 2014-16, in combination with Lagrangian moisture source and precipitation anomaly diagnostics. δ²H composition ranged from -129.4 to +18.1 (‰) while δ¹⁸O ranged from -17.3 to +1.0 (‰). No significant difference was observed among δ¹⁸O (P=0.186) and δ²H (P=0.664) mean annual compositions. However, mean annual d-excess showed a significant decreasing trend (from +13.3 to +8.7 ‰) (P<0.001) with values ranging from +26.6 to -13.9 ‰ prior to and during the El Ni&ntilde;o evolution. The latter decrease in d-excess can be partly explained by an enhanced moisture flux convergence across the southeastern Caribbean Sea coupled with moisture transport from northern South America by means of an increased Caribbean Low Level Jet regime. During 2014-15, precipitation deficit across the Pacific domain averaged 46% resulting in a very severe drought; while a 94% precipitation surplus was observed in the Caribbean domain. Understanding these regional moisture transport mechanisms during a strong El Ni&ntilde;o event may contribute to a) better understanding of precipitation anomalies in the tropics and b) re-evaluate past stable isotope interpretations of ENSO events in paleoclimatic archives within the Central America region.